Python API reference

Meta

cairocffi.install_as_pycairo()

Install cairocffi so that import cairo imports it.

cairoffi’s API is compatible with pycairo as much as possible.

cairocffi.cairo_version()

Return the cairo version number as a single integer, such as 11208 for 1.12.8. Major, minor and micro versions are “worth” 10000, 100 and 1 respectively.

Can be useful as a guard for method not available in older cairo versions:

if cairo_version() >= 11000:
    surface.set_mime_data('image/jpeg', jpeg_bytes)

cairocffi.cairo_version_string(): Return the cairo version number as a string, such as 1.12.8.

exception cairocffi.CairoError(message, status): Raised when cairo returns an error status.

cairocffi.Error: An alias for CairoError, for compatibility with pycairo.

Surfaces

class cairocffi.Surface(pointer, target_keep_alive=None)

The base class for all surface types.

Should not be instantiated directly, but see CFFI API. An instance may be returned for cairo surface types that are not (yet) defined in cairocffi.

A Surface represents an image, either as the destination of a drawing operation or as source when drawing onto another surface. To draw to a Surface, create a cairo Context with the surface as the target.

There are different sub-classes of Surface for different drawing backends; for example, ImageSurface is a bitmap image in memory.

The initial contents of a surface after creation depend upon the manner of its creation. If cairo creates the surface and backing storage for the user, it will be initially cleared; for example, ImageSurface and create_similar(). Alternatively, if the user passes in a reference to some backing storage and asks cairo to wrap that in a Surface, then the contents are not modified; for example, ImageSurface with a data argument.

copy_page()

Emits the current page for backends that support multiple pages, but doesn’t clear it, so that the contents of the current page will be retained for the next page.

Use show_page() if you want to get an empty page after the emission.

create_for_rectangle(x, y, width, height)

Create a new surface that is a rectangle within this surface. All operations drawn to this surface are then clipped and translated onto the target surface. Nothing drawn via this sub-surface outside of its bounds is drawn onto the target surface, making this a useful method for passing constrained child surfaces to library routines that draw directly onto the parent surface, i.e. with no further backend allocations, double buffering or copies.

Note

As of cairo 1.12, the semantics of subsurfaces have not been finalized yet unless the rectangle is in full device units, is contained within the extents of the target surface, and the target or subsurface’s device transforms are not changed.

Parameters:

x (float) – The x-origin of the sub-surface from the top-left of the target surface (in device-space units)
y (float) – The y-origin of the sub-surface from the top-left of the target surface (in device-space units)
width (float) – Width of the sub-surface (in device-space units)
height (float) – Height of the sub-surface (in device-space units)

Returns:

A new Surface object.

New in cairo 1.10.

create_similar(content, width, height)

Create a new surface that is as compatible as possible for uploading to and the use in conjunction with this surface. For example the new surface will have the same fallback resolution and FontOptions. Generally, the new surface will also use the same backend as other, unless that is not possible for some reason.

Initially the surface contents are all 0 (transparent if contents have transparency, black otherwise.)

Use create_similar_image() if you need an image surface which can be painted quickly to the target surface.

Parameters:

content (str) – the Content string for the new surface.
width (int) – width of the new surface (in device-space units)
height (int) – height of the new surface (in device-space units)

Returns:

A new instance of Surface or one of its subclasses.

create_similar_image(content, width, height)

Create a new image surface that is as compatible as possible for uploading to and the use in conjunction with this surface. However, this surface can still be used like any normal image surface.

Initially the surface contents are all 0 (transparent if contents have transparency, black otherwise.)

Use create_similar() if you don’t need an image surface.

Parameters:

format (str) – the Pixel format string for the new surface
width (int) – width of the new surface, (in device-space units)
height (int) – height of the new surface (in device-space units)

Returns:

A new ImageSurface instance.

finish()

This method finishes the surface and drops all references to external resources. For example, for the Xlib backend it means that cairo will no longer access the drawable, which can be freed. After calling finish() the only valid operations on a surface are getting and setting user data, flushing and finishing it. Further drawing to the surface will not affect the surface but will instead trigger a CairoError with a SURFACE_FINISHED status.

When the surface is garbage-collected, cairo will call finish() if it hasn’t been called already, before freeing the resources associated with the surface.

flush(): Do any pending drawing for the surface and also restore any temporary modifications cairo has made to the surface’s state. This method must be called before switching from drawing on the surface with cairo to drawing on it directly with native APIs. If the surface doesn’t support direct access, then this method does nothing.

get_content(): Returns the Content string of this surface, which indicates whether the surface contains color and/or alpha information.

get_device_offset()

Returns the previous device offset set by set_device_offset().

Returns:: (x_offset, y_offset)

get_device_scale()

Returns the previous device offset set by set_device_scale().

New in cairo 1.14.

New in cairocffi 0.9.

get_fallback_resolution()

Returns the previous fallback resolution set by set_fallback_resolution(), or default fallback resolution if never set.

Returns:: (x_pixels_per_inch, y_pixels_per_inch)

get_font_options()

Retrieves the default font rendering options for the surface.

This allows display surfaces to report the correct subpixel order for rendering on them, print surfaces to disable hinting of metrics and so forth. The result can then be used with ScaledFont.

Returns:: A new FontOptions object.

get_mime_data(mime_type)

Return mime data previously attached to surface using the specified mime type.

Parameters:: mime_type (str) – The MIME type of the image data.
Returns:: A CFFI buffer object, or None if no data has been attached with the given mime type.

New in cairo 1.10.

has_show_text_glyphs(): Returns whether the surface supports sophisticated Context.show_text_glyphs() operations. That is, whether it actually uses the text and cluster data provided to a Context.show_text_glyphs() call.

Note

Even if this method returns False, Context.show_text_glyphs() operation targeted at surface will still succeed. It just will act like a Context.show_glyphs() operation. Users can use this method to avoid computing UTF-8 text and cluster mapping if the target surface does not use it.

mark_dirty(): Tells cairo that drawing has been done to surface using means other than cairo, and that cairo should reread any cached areas. Note that you must call flush() before doing such drawing.

mark_dirty_rectangle(x, y, width, height)

Like mark_dirty(), but drawing has been done only to the specified rectangle, so that cairo can retain cached contents for other parts of the surface.

Any cached clip set on the surface will be reset by this method, to make sure that future cairo calls have the clip set that they expect.

Parameters:

x (float) – X coordinate of dirty rectangle.
y (float) – Y coordinate of dirty rectangle.
width (float) – Width of dirty rectangle.
height (float) – Height of dirty rectangle.

set_device_offset(x_offset, y_offset)

Sets an offset that is added to the device coordinates determined by the CTM when drawing to surface. One use case for this method is when we want to create a Surface that redirects drawing for a portion of an onscreen surface to an offscreen surface in a way that is completely invisible to the user of the cairo API. Setting a transformation via Context.translate() isn’t sufficient to do this, since methods like Context.device_to_user() will expose the hidden offset.

Note that the offset affects drawing to the surface as well as using the surface in a source pattern.

Parameters:

x_offset – The offset in the X direction, in device units
y_offset – The offset in the Y direction, in device units

set_device_scale(x_scale, y_scale)

Sets a scale that is multiplied to the device coordinates determined by the CTM when drawing to surface.

One common use for this is to render to very high resolution display devices at a scale factor, so that code that assumes 1 pixel will be a certain size will still work. Setting a transformation via cairo_translate() isn’t sufficient to do this, since functions like cairo_device_to_user() will expose the hidden scale.

Note that the scale affects drawing to the surface as well as using the surface in a source pattern.

Parameters:

x_scale – the scale in the X direction, in device units.
y_scale – the scale in the Y direction, in device units.

New in cairo 1.14.

New in cairocffi 0.9.

set_fallback_resolution(x_pixels_per_inch, y_pixels_per_inch)

Set the horizontal and vertical resolution for image fallbacks.

When certain operations aren’t supported natively by a backend, cairo will fallback by rendering operations to an image and then overlaying that image onto the output. For backends that are natively vector-oriented, this method can be used to set the resolution used for these image fallbacks, (larger values will result in more detailed images, but also larger file sizes).

Some examples of natively vector-oriented backends are the ps, pdf, and svg backends.

For backends that are natively raster-oriented, image fallbacks are still possible, but they are always performed at the native device resolution. So this method has no effect on those backends.

Note

The fallback resolution only takes effect at the time of completing a page (with show_page() or copy_page()) so there is currently no way to have more than one fallback resolution in effect on a single page.

The default fallback resoultion is 300 pixels per inch in both dimensions.

Parameters:

x_pixels_per_inch (float) – horizontal resolution in pixels per inch
y_pixels_per_inch (float) – vertical resolution in pixels per inch

set_mime_data(mime_type, data)

Attach an image in the format mime_type to this surface.

To remove the data from a surface, call this method with same mime type and None for data.

The attached image (or filename) data can later be used by backends which support it (currently: PDF, PS, SVG and Win32 Printing surfaces) to emit this data instead of making a snapshot of the surface. This approach tends to be faster and requires less memory and disk space.

The recognized MIME types are the following:

"image/png": The Portable Network Graphics image file format (ISO/IEC 15948).
"image/jpeg": The Joint Photographic Experts Group (JPEG) image coding standard (ISO/IEC 10918-1).
"image/jp2": The Joint Photographic Experts Group (JPEG) 2000 image coding standard (ISO/IEC 15444-1).
"text/x-uri": URL for an image file (unofficial MIME type).

See corresponding backend surface docs for details about which MIME types it can handle. Caution: the associated MIME data will be discarded if you draw on the surface afterwards. Use this method with care.

Parameters:

mime_type (str) – The MIME type of the image data.
data (bytes) – The image data to attach to the surface.

New in cairo 1.10.

show_page()

Emits and clears the current page for backends that support multiple pages. Use copy_page() if you don’t want to clear the page.

Context.show_page() is a convenience method for this.

supports_mime_type(mime_type)

Return whether surface supports mime_type.

Parameters:: mime_type (str) – The MIME type of the image data.

New in cairo 1.12.

write_to_png(target=None)

Writes the contents of surface as a PNG image.

Parameters:: target – A filename, a binary mode file object with a write method, or None.
Returns:: If target is None, return the PNG contents as a byte string.

ImageSurface

class cairocffi.ImageSurface(format, width, height, data=None, stride=None)

Creates an image surface of the specified format and dimensions.

If data is not None its initial contents will be used as the initial image contents; you must explicitly clear the buffer, using, for example, Context.rectangle() and Context.fill() if you want it cleared.

Note

Currently only array.array buffers are supported on PyPy.

Otherwise, the surface contents are all initially 0. (Specifically, within each pixel, each color or alpha channel belonging to format will be 0. The contents of bits within a pixel, but not belonging to the given format are undefined).

Parameters:

format (str) – Pixel format string for the surface to create.
width (int) – Width of the surface, in pixels.
height (int) – Height of the surface, in pixels.
data – Buffer supplied in which to write contents, or None to create a new buffer.
stride (int) – The number of bytes between the start of rows in the buffer as allocated. This value should always be computed by format_stride_for_width() before allocating the data buffer. If omitted but data is given, format_stride_for_width() is used.

classmethod create_for_data(data, format, width, height, stride=None): Same as ImageSurface(format, width, height, data, stride). Exists for compatibility with pycairo.

classmethod create_from_png(source)

Decode a PNG file into a new image surface.

Parameters:: source – A filename or a binary mode file object with a read method. If you already have a byte string in memory, use io.BytesIO.
Returns:: A new ImageSurface instance.

static format_stride_for_width(format, width)

This method provides a stride value (byte offset between rows) that will respect all alignment requirements of the accelerated image-rendering code within cairo. Typical usage will be of the form:

from cairocffi import ImageSurface
stride = ImageSurface.format_stride_for_width(format, width)
data = bytearray(stride * height)
surface = ImageSurface(format, width, height, data, stride)

Parameters:

format (str) – A Pixel format string.
width (int) – The desired width of the surface, in pixels.

Returns:

The appropriate stride to use given the desired format and width, or -1 if either the format is invalid or the width too large.

get_data()

Return the buffer pointing to the image’s pixel data, encoded according to the surface’s Pixel format string.

A call to flush() is required before accessing the pixel data to ensure that all pending drawing operations are finished. A call to mark_dirty() is required after the data is modified.

Returns:: A read-write CFFI buffer object.

get_format(): Return the Pixel format string of the surface.

get_height(): Return the width of the surface, in pixels.

get_stride()

Return the stride of the image surface in bytes (or 0 if surface is not an image surface).

The stride is the distance in bytes from the beginning of one row of the image data to the beginning of the next row.

get_width(): Return the width of the surface, in pixels.

PDFSurface

class cairocffi.PDFSurface(target, width_in_points, height_in_points)

Creates a PDF surface of the specified size in PostScript points to be written to target.

Note that the size of individual pages of the PDF output can vary. See set_size().

The PDF surface backend recognizes the following MIME types for the data attached to a surface (see set_mime_data()) when it is used as a source pattern for drawing on this surface: image/jpeg and image/jp2. If any of them is specified, the PDF backend emits an image with the content of MIME data (with the /DCTDecode or /JPXDecode filter, respectively) instead of a surface snapshot (with the /FlateDecode filter), which typically produces PDF with a smaller file size.

target can be None to specify no output. This will generate a surface that may be queried and used as a source, without generating a temporary file.

Parameters:

target – A filename, a binary mode file object with a write method, or None.
width_in_points (float) – Width of the surface, in points (1 point == 1/72.0 inch)
height_in_points (float) – Height of the surface, in points (1 point == 1/72.0 inch)

add_outline(parent_id, utf8, link_attribs, flags=None)

Add an item to the document outline hierarchy.

The outline has the utf8 name and links to the location specified by link_attribs. Link attributes have the same keys and values as the Link Tag, excluding the rect attribute. The item will be a child of the item with id parent_id. Use PDF_OUTLINE_ROOT as the parent id of top level items.

Parameters:

parent_id – the id of the parent item or PDF_OUTLINE_ROOT if this is a top level item.
utf8 – the name of the outline.
link_attribs – the link attributes specifying where this outline links to.
flags – outline item flags.

Returns:

the id for the added item.

New in cairo 1.16.

New in cairocffi 0.9.

static get_versions()

Return the list of supported PDF versions. See restrict_to_version().

Returns:: A list of PDF version strings.

New in cairo 1.10.

restrict_to_version(version)

Restricts the generated PDF file to version.

See get_versions() for a list of available version values that can be used here.

This method should only be called before any drawing operations have been performed on the given surface. The simplest way to do this is to call this method immediately after creating the surface.

Parameters:: version – A PDF version string.

New in cairo 1.10.

set_metadata(metadata, utf8)

Sets document metadata.

The PDF_METADATA_CREATE_DATE and PDF_METADATA_MOD_DATE values must be in ISO-8601 format: YYYY-MM-DDThh:mm:ss. An optional timezone of the form “[+/-]hh:mm” or “Z” for UTC time can be appended. All other metadata values can be any UTF-8 string.

Parameters:

metadata – the metadata item to set.
utf8 – metadata value.

New in cairo 1.16.

New in cairocffi 0.9.

set_page_label(utf8)

Set page label for the current page.

Parameters:: utf8 – the page label.

New in cairo 1.16.

New in cairocffi 0.9.

set_size(width_in_points, height_in_points)

Changes the size of a PDF surface for the current (and subsequent) pages.

This method should only be called before any drawing operations have been performed on the current page. The simplest way to do this is to call this method immediately after creating the surface or immediately after completing a page with either show_page() or copy_page().

Parameters:

width_in_points (float) – New width of the page, in points (1 point = 1/72.0 inch)
height_in_points (float) – New height of the page, in points (1 point = 1/72.0 inch)

set_thumbnail_size(width, height)

Set thumbnail image size for the current and all subsequent pages.

Setting a width or height of 0 disables thumbnails for the current and subsequent pages.

Parameters:

width – thumbnail width.
height – thumbnail height.

New in cairo 1.16.

New in cairocffi 0.9.

static version_to_string(version)

Return the string representation of the given PDF version. See get_versions() for a way to get the list of valid version ids.

New in cairo 1.10.

PSSurface

class cairocffi.PSSurface(target, width_in_points, height_in_points)

Creates a PostScript surface of the specified size in PostScript points to be written to target.

Note that the size of individual pages of the PostScript output can vary. See set_size().

target can be None to specify no output. This will generate a surface that may be queried and used as a source, without generating a temporary file.

The PostScript surface backend recognizes the image/jpeg MIME type for the data attached to a surface (see set_mime_data()) when it is used as a source pattern for drawing on this surface. If it is specified, the PostScript backend emits an image with the content of MIME data (with the /DCTDecode filter) instead of a surface snapshot (with the /FlateDecode filter), which typically produces PostScript with a smaller file size.

Parameters:

target – A filename, a binary mode file object with a write method, or None.
width_in_points (float) – Width of the surface, in points (1 point == 1/72.0 inch)
height_in_points (float) – Height of the surface, in points (1 point == 1/72.0 inch)

dsc_begin_page_setup()

Indicate that subsequent calls to dsc_comment() should direct comments to the PageSetup section of the PostScript output.

This method is only needed for the first page of a surface. It must be called after any call to dsc_begin_setup() and before any drawing is performed to the surface.

See dsc_comment() for more details.

dsc_begin_setup()

Indicate that subsequent calls to dsc_comment() should direct comments to the Setup section of the PostScript output.

This method should be called at most once per surface, and must be called before any call to dsc_begin_page_setup() and before any drawing is performed to the surface.

See dsc_comment() for more details.

dsc_comment(comment)

Emit a comment into the PostScript output for the given surface.

The comment is expected to conform to the PostScript Language Document Structuring Conventions (DSC). Please see that manual for details on the available comments and their meanings. In particular, the %%IncludeFeature comment allows a device-independent means of controlling printer device features. So the PostScript Printer Description Files Specification will also be a useful reference.

The comment string must begin with a percent character (%) and the total length of the string (including any initial percent characters) must not exceed 255 bytes. Violating either of these conditions will place surface into an error state. But beyond these two conditions, this method will not enforce conformance of the comment with any particular specification.

The comment string should not have a trailing newline.

The DSC specifies different sections in which particular comments can appear. This method provides for comments to be emitted within three sections: the header, the Setup section, and the PageSetup section. Comments appearing in the first two sections apply to the entire document while comments in the BeginPageSetup section apply only to a single page.

For comments to appear in the header section, this method should be called after the surface is created, but before a call to dsc_begin_setup().

For comments to appear in the Setup section, this method should be called after a call to dsc_begin_setup() but before a call to dsc_begin_page_setup().

For comments to appear in the PageSetup section, this method should be called after a call to dsc_begin_page_setup().

Note that it is only necessary to call dsc_begin_page_setup() for the first page of any surface. After a call to show_page() or copy_page() comments are unambiguously directed to the PageSetup section of the current page. But it doesn’t hurt to call this method at the beginning of every page as that consistency may make the calling code simpler.

As a final note, cairo automatically generates several comments on its own. As such, applications must not manually generate any of the following comments:

Header section: %!PS-Adobe-3.0, %%Creator, %%CreationDate, %%Pages, %%BoundingBox, %%DocumentData, %%LanguageLevel, %%EndComments.

Setup section: %%BeginSetup, %%EndSetup.

PageSetup section: %%BeginPageSetup, %%PageBoundingBox, %%EndPageSetup.

Other sections: %%BeginProlog, %%EndProlog, %%Page, %%Trailer, %%EOF.

get_eps(): Check whether the PostScript surface will output Encapsulated PostScript.

static get_levels()

Return the list of supported PostScript levels. See restrict_to_level().

Returns:: A list of PostScript level strings.

static ps_level_to_string(level): Return the string representation of the given PostScript level. See get_levels() for a way to get the list of valid level ids.

restrict_to_level(level)

Restricts the generated PostScript file to level.

See get_levels() for a list of available level values that can be used here.

This method should only be called before any drawing operations have been performed on the given surface. The simplest way to do this is to call this method immediately after creating the surface.

Parameters:: version – A PostScript level string.

set_eps(eps)

If eps is True, the PostScript surface will output Encapsulated PostScript.

This method should only be called before any drawing operations have been performed on the current page. The simplest way to do this is to call this method immediately after creating the surface. An Encapsulated PostScript file should never contain more than one page.

set_size(width_in_points, height_in_points)

Changes the size of a PostScript surface for the current (and subsequent) pages.

This method should only be called before any drawing operations have been performed on the current page. The simplest way to do this is to call this method immediately after creating the surface or immediately after completing a page with either show_page() or copy_page().

Parameters:

width_in_points (float) – New width of the page, in points (1 point == 1/72.0 inch)
height_in_points (float) – New height of the page, in points (1 point == 1/72.0 inch)

SVGSurface

class cairocffi.SVGSurface(target, width_in_points, height_in_points)

Creates a SVG surface of the specified size in points to be written to target.

target can be None to specify no output. This will generate a surface that may be queried and used as a source, without generating a temporary file.

The SVG surface backend recognizes the following MIME types for the data attached to a surface (see set_mime_data()) when it is used as a source pattern for drawing on this surface: image/png, image/jpeg and text/x-uri. If any of them is specified, the SVG backend emits a href with the content of MIME data instead of a surface snapshot (PNG, Base64-encoded) in the corresponding image tag.

The unofficial MIME type text/x-uri is examined first. If present, the URL is emitted as is: assuring the correctness of URL is left to the client code.

If text/x-uri is not present, but image/jpeg or image/png is specified, the corresponding data is Base64-encoded and emitted.

Parameters:

target – A filename, a binary mode file object with a write method, or None.
width_in_points (float) – Width of the surface, in points (1 point == 1/72.0 inch)
height_in_points (float) – Height of the surface, in points (1 point == 1/72.0 inch)

get_document_unit()

Get the unit of the SVG surface.

If the surface passed as an argument is not a SVG surface, the function sets the error status to STATUS_SURFACE_TYPE_MISMATCH and returns SVG_UNIT_USER.

Returns:: The SVG unit of the SVG surface.

New in cairo 1.16.

New in cairocffi 0.9.

static get_versions()

Return the list of supported SVG versions. See restrict_to_version().

Returns:: A list of SVG version strings.

restrict_to_version(version)

Restricts the generated SVG file to version.

See get_versions() for a list of available version values that can be used here.

This method should only be called before any drawing operations have been performed on the given surface. The simplest way to do this is to call this method immediately after creating the surface.

Parameters:: version – A SVG version string.

set_document_unit(unit)

Use specified unit for width and height of generated SVG file.

See SVG_UNIT_* enumerated values for a list of available unit values that can be used here.

This function can be called at any time before generating the SVG file.

However to minimize the risk of ambiguities it’s recommended to call it before any drawing operations have been performed on the given surface, to make it clearer what the unit used in the drawing operations is.

The simplest way to do this is to call this function immediately after creating the SVG surface.

Note if this function is never called, the default unit for SVG documents generated by cairo will be “pt”. This is for historical reasons.

Parameters:: unit – SVG unit.

New in cairo 1.16.

New in cairocffi 0.9.

static version_to_string(version): Return the string representation of the given SVG version. See get_versions() for a way to get the list of valid version ids.

RecordingSurface

class cairocffi.RecordingSurface(content, extents)

A recording surface is a surface that records all drawing operations at the highest level of the surface backend interface, (that is, the level of paint, mask, stroke, fill, and show_text_glyphs). The recording surface can then be “replayed” against any target surface by using it as a source surface.

If you want to replay a surface so that the results in target will be identical to the results that would have been obtained if the original operations applied to the recording surface had instead been applied to the target surface, you can use code like this:

context = Context(target)
context.set_source_surface(recording_surface, 0, 0)
context.paint()

A recording surface is logically unbounded, i.e. it has no implicit constraint on the size of the drawing surface. However, in practice this is rarely useful as you wish to replay against a particular target surface with known bounds. For this case, it is more efficient to specify the target extents to the recording surface upon creation.

The recording phase of the recording surface is careful to snapshot all necessary objects (paths, patterns, etc.), in order to achieve accurate replay.

Parameters:

content – The Content string of the recording surface
extents – The extents to record as a (x, y, width, height) tuple of floats in device units, or None to record unbounded operations. (x, y) are the coordinates of the top-left corner of the rectangle, (width, height) its dimensions.

New in cairo 1.10

New in cairocffi 0.2

get_extents()

Return the extents of the recording-surface.

Returns:: A (x, y, width, height) tuple of floats, or None if the surface is unbounded.

New in cairo 1.12

ink_extents()

Measures the extents of the operations stored within the recording-surface. This is useful to compute the required size of an image surface (or equivalent) into which to replay the full sequence of drawing operations.

Returns:: A (x, y, width, height) tuple of floats.

Win32PrintingSurface

class cairocffi.Win32PrintingSurface(hdc)

Creates a cairo surface that targets the given DC.

The DC will be queried for its initial clip extents, and this will be used as the size of the cairo surface. The DC should be a printing DC; antialiasing will be ignored, and GDI will be used as much as possible to draw to the surface.

The returned surface will be wrapped using the paginated surface to provide correct complex rendering behaviour; cairo_surface_show_page() and associated methods must be used for correct output.

Parameters:: hdc (int) – The DC to create a surface for, as obtained from win32gui.CreateDC. Note: this unsafely inteprets an integer as a pointer. Make sure it actually points to a valid DC!

New in cairocffi 0.6

Context

class cairocffi.Context(target)

A Context contains the current state of the rendering device, including coordinates of yet to be drawn shapes.

Cairo contexts are central to cairo and all drawing with cairo is always done to a Context object.

Parameters:: target – The target Surface object.

Cairo contexts can be used as Python context managers. See save().

append_path(path)

Append path onto the current path. The path may be either the return value from one of copy_path() or copy_path_flat() or it may be constructed manually.

Parameters:: path – An iterable of tuples in the same format as returned by copy_path().

arc(xc, yc, radius, angle1, angle2)

Adds a circular arc of the given radius to the current path. The arc is centered at (xc, yc), begins at angle1 and proceeds in the direction of increasing angles to end at angle2. If angle2 is less than angle1 it will be progressively increased by 2 * pi until it is greater than angle1.

If there is a current point, an initial line segment will be added to the path to connect the current point to the beginning of the arc. If this initial line is undesired, it can be avoided by calling new_sub_path() before calling arc().

Angles are measured in radians. An angle of 0 is in the direction of the positive X axis (in user space). An angle of pi / 2 radians (90 degrees) is in the direction of the positive Y axis (in user space). Angles increase in the direction from the positive X axis toward the positive Y axis. So with the default transformation matrix, angles increase in a clockwise direction.

(To convert from degrees to radians, use degrees * pi / 180.)

This method gives the arc in the direction of increasing angles; see arc_negative() to get the arc in the direction of decreasing angles.

The arc is circular in user space. To achieve an elliptical arc, you can scale the current transformation matrix by different amounts in the X and Y directions. For example, to draw an ellipse in the box given by x, y, width, height:

from math import pi
with context:
    context.translate(x + width / 2., y + height / 2.)
    context.scale(width / 2., height / 2.)
    context.arc(0, 0, 1, 0, 2 * pi)

Parameters:

xc (float) – X position of the center of the arc.
yc (float) – Y position of the center of the arc.
radius (float) – The radius of the arc.
angle1 (float) – The start angle, in radians.
angle2 (float) – The end angle, in radians.

arc_negative(xc, yc, radius, angle1, angle2)

Adds a circular arc of the given radius to the current path. The arc is centered at (xc, yc), begins at angle1 and proceeds in the direction of decreasing angles to end at angle2. If angle2 is greater than angle1 it will be progressively decreased by 2 * pi until it is greater than angle1.

See arc() for more details. This method differs only in the direction of the arc between the two angles.

Parameters:

xc (float) – X position of the center of the arc.
yc (float) – Y position of the center of the arc.
radius (float) – The radius of the arc.
angle1 (float) – The start angle, in radians.
angle2 (float) – The end angle, in radians.

clip()

Establishes a new clip region by intersecting the current clip region with the current path as it would be filled by fill() and according to the current fill rule (see set_fill_rule()).

After clip(), the current path will be cleared from the cairo context.

The current clip region affects all drawing operations by effectively masking out any changes to the surface that are outside the current clip region.

Calling clip() can only make the clip region smaller, never larger. But the current clip is part of the graphics state, so a temporary restriction of the clip region can be achieved by calling clip() within a save() / restore() pair. The only other means of increasing the size of the clip region is reset_clip().

clip_extents()

Computes a bounding box in user coordinates covering the area inside the current clip.

Returns:: A (x1, y1, x2, y2) tuple of floats: the left, top, right and bottom of the resulting extents, respectively.

clip_preserve()

Establishes a new clip region by intersecting the current clip region with the current path as it would be filled by fill() and according to the current fill rule (see set_fill_rule()).

Unlike clip(), clip_preserve() preserves the path within the cairo context.

The current clip region affects all drawing operations by effectively masking out any changes to the surface that are outside the current clip region.

Calling clip_preserve() can only make the clip region smaller, never larger. But the current clip is part of the graphics state, so a temporary restriction of the clip region can be achieved by calling clip_preserve() within a save() / restore() pair. The only other means of increasing the size of the clip region is reset_clip().

close_path()

Adds a line segment to the path from the current point to the beginning of the current sub-path, (the most recent point passed to cairo_move_to()), and closes this sub-path. After this call the current point will be at the joined endpoint of the sub-path.

The behavior of close_path() is distinct from simply calling line_to() with the equivalent coordinate in the case of stroking. When a closed sub-path is stroked, there are no caps on the ends of the sub-path. Instead, there is a line join connecting the final and initial segments of the sub-path.

If there is no current point before the call to close_path(), this method will have no effect.

copy_clip_rectangle_list()

Return the current clip region as a list of rectangles in user coordinates.

Returns:: A list of rectangles, as (x, y, width, height) tuples of floats.
Raises:: CairoError if the clip region cannot be represented as a list of user-space rectangles.

copy_page()

Emits the current page for backends that support multiple pages, but doesn’t clear it, so the contents of the current page will be retained for the next page too. Use show_page() if you want to clear the page.

This is a convenience method that simply calls Surface.copy_page() on the context’s target.

copy_path()

Return a copy of the current path.

Returns:

A list of (path_operation, coordinates) tuples of a Path operation string and a tuple of floats coordinates whose content depends on the operation type:

MOVE_TO: 1 point (x, y)
LINE_TO: 1 point (x, y)
CURVE_TO: 3 points (x1, y1, x2, y2, x3, y3)
CLOSE_PATH 0 points () (empty tuple)

copy_path_flat()

Return a flattened copy of the current path

This method is like copy_path() except that any curves in the path will be approximated with piecewise-linear approximations, (accurate to within the current tolerance value, see set_tolerance()). That is, the result is guaranteed to not have any elements of type CURVE_TO which will instead be replaced by a series of LINE_TO elements.

Returns:: A list of (path_operation, coordinates) tuples. See copy_path() for the data structure.

curve_to(x1, y1, x2, y2, x3, y3)

Adds a cubic Bézier spline to the path from the current point to position (x3, y3) in user-space coordinates, using (x1, y1) and (x2, y2) as the control points. After this call the current point will be (x3, y3).

If there is no current point before the call to curve_to() this method will behave as if preceded by a call to context.move_to(x1, y1).

Parameters:

x1 (float) – The X coordinate of the first control point.
y1 (float) – The Y coordinate of the first control point.
x2 (float) – The X coordinate of the second control point.
y2 (float) – The Y coordinate of the second control point.
x3 (float) – The X coordinate of the end of the curve.
y3 (float) – The Y coordinate of the end of the curve.

device_to_user(x, y)

Transform a coordinate from device space to user space by multiplying the given point by the inverse of the current transformation matrix (CTM).

Parameters:

x (float) – X position.
y (float) – Y position.

Returns:

A (user_x, user_y) tuple of floats.

device_to_user_distance(dx, dy)

Transform a distance vector from device space to user space. This method is similar to Context.device_to_user() except that the translation components of the inverse CTM will be ignored when transforming (dx, dy).

Parameters:

dx – X component of a distance vector.
dy – Y component of a distance vector.

Returns:

A (user_dx, user_dy) tuple of floats.

fill()

A drawing operator that fills the current path according to the current fill rule, (each sub-path is implicitly closed before being filled). After fill(), the current path will be cleared from the cairo context.

See set_fill_rule() and fill_preserve().

fill_extents()

Computes a bounding box in user-space coordinates covering the area that would be affected, (the “inked” area), by a fill() operation given the current path and fill parameters. If the current path is empty, returns an empty rectangle (0, 0, 0, 0). Surface dimensions and clipping are not taken into account.

Contrast with path_extents() which is similar, but returns non-zero extents for some paths with no inked area, (such as a simple line segment).

Note that fill_extents() must necessarily do more work to compute the precise inked areas in light of the fill rule, so path_extents() may be more desirable for sake of performance if the non-inked path extents are desired.

See fill(), set_fill_rule() and fill_preserve().

Returns:: A (x1, y1, x2, y2) tuple of floats: the left, top, right and bottom of the resulting extents, respectively.

fill_preserve()

A drawing operator that fills the current path according to the current fill rule, (each sub-path is implicitly closed before being filled). Unlike fill(), fill_preserve() preserves the path within the cairo context.

See set_fill_rule() and fill().

font_extents()

Return the extents of the currently selected font.

Values are given in the current user-space coordinate system.

Because font metrics are in user-space coordinates, they are mostly, but not entirely, independent of the current transformation matrix. If you call context.scale(2), text will be drawn twice as big, but the reported text extents will not be doubled. They will change slightly due to hinting (so you can’t assume that metrics are independent of the transformation matrix), but otherwise will remain unchanged.

Returns:: A (ascent, descent, height, max_x_advance, max_y_advance) tuple of floats.

ascent: The distance that the font extends above the baseline. Note that this is not always exactly equal to the maximum of the extents of all the glyphs in the font, but rather is picked to express the font designer’s intent as to how the font should align with elements above it.
descent: The distance that the font extends below the baseline. This value is positive for typical fonts that include portions below the baseline. Note that this is not always exactly equal to the maximum of the extents of all the glyphs in the font, but rather is picked to express the font designer’s intent as to how the font should align with elements below it.
height: The recommended vertical distance between baselines when setting consecutive lines of text with the font. This is greater than ascent + descent by a quantity known as the line spacing or external leading. When space is at a premium, most fonts can be set with only a distance of ascent + descent between lines.
max_x_advance: The maximum distance in the X direction that the origin is advanced for any glyph in the font.
max_y_advance: The maximum distance in the Y direction that the origin is advanced for any glyph in the font. This will be zero for normal fonts used for horizontal writing. (The scripts of East Asia are sometimes written vertically.)

get_antialias(): Return the Antialiasing mode string.

get_current_point()

Return the current point of the current path, which is conceptually the final point reached by the path so far.

The current point is returned in the user-space coordinate system. If there is no defined current point or if the context is in an error status, (0, 0) is returned. It is possible to check this in advance with has_current_point().

Most path construction methods alter the current point. See the following for details on how they affect the current point: new_path(), new_sub_path(), append_path(), close_path(), move_to(), line_to(), curve_to(), rel_move_to(), rel_line_to(), rel_curve_to(), arc(), arc_negative(), rectangle(), text_path(), glyph_path().

Some methods use and alter the current point but do not otherwise change current path: show_text(), show_glyphs(), show_text_glyphs().

Some methods unset the current path and as a result, current point: fill(), stroke().

Returns:: A (x, y) tuple of floats, the coordinates of the current point.

get_dash()

Return the current dash pattern.

Returns:: A (dashes, offset) tuple of a list and a float. dashes is a list of floats, empty if no dashing is in effect.

get_dash_count(): Same as len(context.get_dash()[0]).

get_fill_rule(): Return the current Fill rule string.

get_font_face()

Return the current font face.

Parameters:: font_face – A new FontFace object wrapping an existing cairo object.

get_font_matrix()

Copies the current font matrix. See set_font_matrix().

Returns:: A new Matrix.

get_font_options()

Retrieves font rendering options set via set_font_options(). Note that the returned options do not include any options derived from the underlying surface; they are literally the options passed to set_font_options().

Returns:: A new FontOptions object.

get_group_target(): Returns the current destination surface for the context. This is either the original target surface as passed to Context or the target surface for the current group as started by the most recent call to push_group() or push_group_with_content().

get_hairline()

Returns whether or not hairline mode is set, as set by cairo_set_hairline().

Returns:: whether hairline mode is set

New in cairo 1.18.

get_line_cap(): Return the current Line cap style string.

get_line_join(): Return the current Line join style string.

get_line_width(): Return the current line width as a float.

get_matrix(): Return a copy of the current transformation matrix (CTM).

get_miter_limit(): Return the current miter limit as a float.

get_operator(): Return the current Compositiong operator string.

get_scaled_font()

Return the current scaled font.

Returns:: A new ScaledFont object, wrapping an existing cairo object.

get_source()

Return this context’s source.

Returns:: An instance of Pattern or one of its sub-classes, a new Python object referencing the existing cairo pattern.

get_target()

Return this context’s target surface.

Returns:: An instance of Surface or one of its sub-classes, a new Python object referencing the existing cairo surface.

get_tolerance(): Return the current tolerance as a float.

glyph_extents(glyphs)

Returns the extents for a list of glyphs.

The extents describe a user-space rectangle that encloses the “inked” portion of the glyphs, (as it would be drawn by show_glyphs()). Additionally, the x_advance and y_advance values indicate the amount by which the current point would be advanced by show_glyphs().

Parameters:: glyphs – A list of glyphs. See show_text_glyphs() for the data structure.
Returns:: A (x_bearing, y_bearing, width, height, x_advance, y_advance) tuple of floats. See text_extents() for details.

glyph_path(glyphs)

Adds closed paths for the glyphs to the current path. The generated path if filled, achieves an effect similar to that of show_glyphs().

Parameters:: glyphs – The glyphs to show. See show_text_glyphs() for the data structure.

has_current_point(): Returns whether a current point is defined on the current path. See get_current_point().

identity_matrix(): Resets the current transformation matrix (CTM) by setting it equal to the identity matrix. That is, the user-space and device-space axes will be aligned and one user-space unit will transform to one device-space unit.

in_clip(x, y)

Tests whether the given point is inside the area that would be visible through the current clip, i.e. the area that would be filled by a paint() operation.

See clip(), and clip_preserve().

Parameters:

x (float) – X coordinate of the point to test
y (float) – Y coordinate of the point to test

Returns:

A boolean.

New in cairo 1.10.

in_fill(x, y)

Tests whether the given point is inside the area that would be affected by a fill() operation given the current path and filling parameters. Surface dimensions and clipping are not taken into account.

See fill(), set_fill_rule() and fill_preserve().

Parameters:

x (float) – X coordinate of the point to test
y (float) – Y coordinate of the point to test

Returns:

A boolean.

in_stroke(x, y)

Tests whether the given point is inside the area that would be affected by a stroke() operation given the current path and stroking parameters. Surface dimensions and clipping are not taken into account.

See stroke(), set_line_width(), set_line_join(), set_line_cap(), set_dash(), and stroke_preserve().

Parameters:

x (float) – X coordinate of the point to test
y (float) – Y coordinate of the point to test

Returns:

A boolean.

line_to(x, y)

Adds a line to the path from the current point to position (x, y) in user-space coordinates. After this call the current point will be (x, y).

If there is no current point before the call to line_to() this method will behave as context.move_to(x, y).

Parameters:

x – X coordinate of the end of the new line.
y – Y coordinate of the end of the new line.

mask(pattern)

A drawing operator that paints the current source using the alpha channel of pattern as a mask. (Opaque areas of pattern are painted with the source, transparent areas are not painted.)

Parameters:: pattern – A Pattern object.

mask_surface(surface, surface_x=0, surface_y=0)

A drawing operator that paints the current source using the alpha channel of surface as a mask. (Opaque areas of surface are painted with the source, transparent areas are not painted.)

Parameters:

pattern – A Surface object.
surface_x (float) – X coordinate at which to place the origin of surface.
surface_y (float) – Y coordinate at which to place the origin of surface.

move_to(x, y)

Begin a new sub-path. After this call the current point will be (x, y).

Parameters:

x – X position of the new point.
y – Y position of the new point.

new_path(): Clears the current path. After this call there will be no path and no current point.

new_sub_path()

Begin a new sub-path. Note that the existing path is not affected. After this call there will be no current point.

In many cases, this call is not needed since new sub-paths are frequently started with move_to().

A call to new_sub_path() is particularly useful when beginning a new sub-path with one of the arc() calls. This makes things easier as it is no longer necessary to manually compute the arc’s initial coordinates for a call to move_to().

paint(): A drawing operator that paints the current source everywhere within the current clip region.

paint_with_alpha(alpha)

A drawing operator that paints the current source everywhere within the current clip region using a mask of constant alpha value alpha. The effect is similar to paint(), but the drawing is faded out using the alpha value.

Parameters:: alpha (float) – Alpha value, between 0 (transparent) and 1 (opaque).

path_extents()

Computes a bounding box in user-space coordinates covering the points on the current path. If the current path is empty, returns an empty rectangle (0, 0, 0, 0). Stroke parameters, fill rule, surface dimensions and clipping are not taken into account.

Contrast with fill_extents() and stroke_extents() which return the extents of only the area that would be “inked” by the corresponding drawing operations.

The result of path_extents() is defined as equivalent to the limit of stroke_extents() with LINE_CAP_ROUND as the line width approaches 0, (but never reaching the empty-rectangle returned by stroke_extents() for a line width of 0).

Specifically, this means that zero-area sub-paths such as move_to(); line_to() segments, (even degenerate cases where the coordinates to both calls are identical), will be considered as contributing to the extents. However, a lone move_to() will not contribute to the results of path_extents().

Returns:: A (x1, y1, x2, y2) tuple of floats: the left, top, right and bottom of the resulting extents, respectively.

pop_group()

Terminates the redirection begun by a call to push_group() or push_group_with_content() and returns a new pattern containing the results of all drawing operations performed to the group.

The pop_group() method calls restore(), (balancing a call to save() by the push_group method), so that any changes to the graphics state will not be visible outside the group.

Returns:: A newly created SurfacePattern containing the results of all drawing operations performed to the group.

pop_group_to_source()

Terminates the redirection begun by a call to push_group() or push_group_with_content() and installs the resulting pattern as the source pattern in the given cairo context.

The behavior of this method is equivalent to:

context.set_source(context.pop_group())

push_group()

Temporarily redirects drawing to an intermediate surface known as a group. The redirection lasts until the group is completed by a call to pop_group() or pop_group_to_source(). These calls provide the result of any drawing to the group as a pattern, (either as an explicit object, or set as the source pattern).

This group functionality can be convenient for performing intermediate compositing. One common use of a group is to render objects as opaque within the group, (so that they occlude each other), and then blend the result with translucence onto the destination.

Groups can be nested arbitrarily deep by making balanced calls to push_group() / pop_group(). Each call pushes / pops the new target group onto / from a stack.

The push_group() method calls save() so that any changes to the graphics state will not be visible outside the group, (the pop_group methods call restore()).

By default the intermediate group will have a content type of COLOR_ALPHA. Other content types can be chosen for the group by using push_group_with_content() instead.

As an example, here is how one might fill and stroke a path with translucence, but without any portion of the fill being visible under the stroke:

context.push_group()
context.set_source(fill_pattern)
context.fill_preserve()
context.set_source(stroke_pattern)
context.stroke()
context.pop_group_to_source()
context.paint_with_alpha(alpha)

push_group_with_content(content)

Temporarily redirects drawing to an intermediate surface known as a group. The redirection lasts until the group is completed by a call to pop_group() or pop_group_to_source(). These calls provide the result of any drawing to the group as a pattern, (either as an explicit object, or set as the source pattern).

The group will have a content type of content. The ability to control this content type is the only distinction between this method and push_group() which you should see for a more detailed description of group rendering.

Parameters:: content – A Content string.

rectangle(x, y, width, height)

Adds a closed sub-path rectangle of the given size to the current path at position (x, y) in user-space coordinates.

This method is logically equivalent to:

context.move_to(x, y)
context.rel_line_to(width, 0)
context.rel_line_to(0, height)
context.rel_line_to(-width, 0)
context.close_path()

Parameters:

x – The X coordinate of the top left corner of the rectangle.
y – The Y coordinate of the top left corner of the rectangle.
width – Width of the rectangle.
height – Height of the rectangle.

rel_curve_to(dx1, dy1, dx2, dy2, dx3, dy3)

Relative-coordinate version of curve_to(). All offsets are relative to the current point. Adds a cubic Bézier spline to the path from the current point to a point offset from the current point by (dx3, dy3), using points offset by (dx1, dy1) and (dx2, dy2) as the control points. After this call the current point will be offset by (dx3, dy3).

Given a current point of (x, y), context.rel_curve_to(dx1, dy1, dx2, dy2, dx3, dy3) is logically equivalent to context.curve_to(x+dx1, y+dy1, x+dx2, y+dy2, x+dx3, y+dy3).

Parameters:

dx1 (float) – The X offset to the first control point.
dy1 (float) – The Y offset to the first control point.
dx2 (float) – The X offset to the second control point.
dy2 (float) – The Y offset to the second control point.
dx3 (float) – The X offset to the end of the curve.
dy3 (float) – The Y offset to the end of the curve.

Raises:

CairoError if there is no current point. Doing so will cause leave the context in an error state.

rel_line_to(dx, dy)

Relative-coordinate version of line_to(). Adds a line to the path from the current point to a point that is offset from the current point by (dx, dy) in user space. After this call the current point will be offset by (dx, dy).

Given a current point of (x, y), context.rel_line_to(dx, dy) is logically equivalent to context.line_to(x + dx, y + dy).

Parameters:

dx – The X offset to the end of the new line.
dy – The Y offset to the end of the new line.

Raises:

CairoError if there is no current point. Doing so will cause leave the context in an error state.

rel_move_to(dx, dy)

Begin a new sub-path. After this call the current point will be offset by (dx, dy).

Given a current point of (x, y), context.rel_move_to(dx, dy) is logically equivalent to context.move_to(x + dx, y + dy).

Parameters:

dx – The X offset.
dy – The Y offset.

Raises:

CairoError if there is no current point. Doing so will cause leave the context in an error state.

reset_clip()

Reset the current clip region to its original, unrestricted state. That is, set the clip region to an infinitely large shape containing the target surface. Equivalently, if infinity is too hard to grasp, one can imagine the clip region being reset to the exact bounds of the target surface.

Note that code meant to be reusable should not call reset_clip() as it will cause results unexpected by higher-level code which calls clip(). Consider using cairo() and restore() around clip() as a more robust means of temporarily restricting the clip region.

restore(): Restores the context to the state saved by a preceding call to save() and removes that state from the stack of saved states.

rotate(radians)

Modifies the current transformation matrix (CTM) by rotating the user-space axes by angle radians. The rotation of the axes takes places after any existing transformation of user space.

Parameters:: radians (float) – Angle of rotation, in radians. The direction of rotation is defined such that positive angles rotate in the direction from the positive X axis toward the positive Y axis. With the default axis orientation of cairo, positive angles rotate in a clockwise direction.

save()

Makes a copy of the current state of this context and saves it on an internal stack of saved states. When restore() is called, the context will be restored to the saved state. Multiple calls to save() and restore() can be nested; each call to restore() restores the state from the matching paired save().

Instead of using save() and restore() directly, it is recommended to use a with statement:

with context:
    do_something(context)

… which is equivalent to:

context.save()
try:
    do_something(context)
finally:
    context.restore()

scale(sx, sy=None)

Modifies the current transformation matrix (CTM) by scaling the X and Y user-space axes by sx and sy respectively. The scaling of the axes takes place after any existing transformation of user space.

If sy is omitted, it is the same as sx so that scaling preserves aspect ratios.

Parameters:

sx (float) – Scale factor in the X direction.
sy (float) – Scale factor in the Y direction.

select_font_face(family='', slant=0, weight=0)

Selects a family and style of font from a simplified description as a family name, slant and weight.

Note

The select_font_face() method is part of what the cairo designers call the “toy” text API. It is convenient for short demos and simple programs, but it is not expected to be adequate for serious text-using applications. See Fonts & text for details.

Cairo provides no operation to list available family names on the system (this is a “toy”, remember), but the standard CSS2 generic family names, ("serif", "sans-serif", "cursive", "fantasy", "monospace"), are likely to work as expected.

If family starts with the string "cairo:", or if no native font backends are compiled in, cairo will use an internal font family. The internal font family recognizes many modifiers in the family string, most notably, it recognizes the string "monospace". That is, the family name "cairo:monospace" will use the monospace version of the internal font family.

If text is drawn without a call to select_font_face(), (nor set_font_face() nor set_scaled_font()), the default family is platform-specific, but is essentially "sans-serif". Default slant is NORMAL, and default weight is NORMAL.

This method is equivalent to a call to ToyFontFace followed by set_font_face().

set_antialias(antialias)

Set the Antialiasing mode of the rasterizer used for drawing shapes. This value is a hint, and a particular backend may or may not support a particular value. At the current time, no backend supports SUBPIXEL when drawing shapes.

Note that this option does not affect text rendering, instead see FontOptions.set_antialias().

Parameters:: antialias – An Antialiasing mode string.

set_dash(dashes, offset=0)

Sets the dash pattern to be used by stroke(). A dash pattern is specified by dashes, a list of positive values. Each value provides the length of alternate “on” and “off” portions of the stroke. offset specifies an offset into the pattern at which the stroke begins.

Each “on” segment will have caps applied as if the segment were a separate sub-path. In particular, it is valid to use an “on” length of 0 with LINE_CAP_ROUND or LINE_CAP_SQUARE in order to distributed dots or squares along a path.

Note: The length values are in user-space units as evaluated at the time of stroking. This is not necessarily the same as the user space at the time of set_dash().

If dashes is empty dashing is disabled. If it is of length 1 a symmetric pattern is assumed with alternating on and off portions of the size specified by the single value.

Parameters:

dashes – A list of floats specifying alternate lengths of on and off stroke portions.
offset (float) – An offset into the dash pattern at which the stroke should start.

Raises:

CairoError if any value in dashes is negative, or if all values are 0. The context will be put into an error state.

set_fill_rule(fill_rule)

Set the current Fill rule within the cairo context. The fill rule is used to determine which regions are inside or outside a complex (potentially self-intersecting) path. The current fill rule affects both fill() and clip().

The default fill rule is WINDING.

Parameters:: fill_rule – A Fill rule string.

set_font_face(font_face)

Replaces the current font face with font_face.

Parameters:: font_face – A FontFace object, or None to restore the default font.

set_font_matrix(matrix)

Sets the current font matrix to matrix. The font matrix gives a transformation from the design space of the font (in this space, the em-square is 1 unit by 1 unit) to user space. Normally, a simple scale is used (see set_font_size()), but a more complex font matrix can be used to shear the font or stretch it unequally along the two axes

Parameters:: matrix – A Matrix describing a transform to be applied to the current font.

set_font_options(font_options)

Sets a set of custom font rendering options. Rendering options are derived by merging these options with the options derived from underlying surface; if the value in options has a default value (like ANTIALIAS_DEFAULT), then the value from the surface is used.

Parameters:: font_options – A FontOptions object.

set_font_size(size)

Sets the current font matrix to a scale by a factor of size, replacing any font matrix previously set with set_font_size() or set_font_matrix(). This results in a font size of size user space units. (More precisely, this matrix will result in the font’s em-square being a size by size square in user space.)

If text is drawn without a call to set_font_size(), (nor set_font_matrix() nor set_scaled_font()), the default font size is 10.0.

Parameters:: size (float) – The new font size, in user space units

set_hairline(enabled)

Sets lines within the cairo context to be hairlines.

Hairlines are logically zero-width lines that are drawn at the thinnest renderable width possible in the current context.

Parameters:: enabled (bool) – whether or not to set hairline mode

New in cairo 1.18.

set_line_cap(line_cap)

Set the current Line cap style within the cairo context. As with the other stroke parameters, the current line cap style is examined by stroke() and stroke_extents(), but does not have any effect during path construction.

The default line cap is BUTT.

Parameters:: line_cap – A Line cap style string.

set_line_join(line_join)

Set the current Line join style within the cairo context. As with the other stroke parameters, the current line cap style is examined by stroke() and stroke_extents(), but does not have any effect during path construction.

The default line cap is MITER.

Parameters:: line_join – A Line join style string.

set_line_width(width)

Sets the current line width within the cairo context. The line width value specifies the diameter of a pen that is circular in user space, (though device-space pen may be an ellipse in general due to scaling / shear / rotation of the CTM).

Note

When the description above refers to user space and CTM it refers to the user space and CTM in effect at the time of the stroking operation, not the user space and CTM in effect at the time of the call to set_line_width(). The simplest usage makes both of these spaces identical. That is, if there is no change to the CTM between a call to set_line_width() and the stroking operation, then one can just pass user-space values to set_line_width() and ignore this note.

As with the other stroke parameters, the current line cap style is examined by stroke() and stroke_extents(), but does not have any effect during path construction.

The default line width value is 2.0.

Parameters:: width (float) – The new line width.

set_matrix(matrix)

Modifies the current transformation matrix (CTM) by setting it equal to matrix.

Parameters:: matrix – A transformation Matrix from user space to device space.

set_miter_limit(limit)

Sets the current miter limit within the cairo context.

If the current line join style is set to MITER (see set_line_join()), the miter limit is used to determine whether the lines should be joined with a bevel instead of a miter. Cairo divides the length of the miter by the line width. If the result is greater than the miter limit, the style is converted to a bevel.

As with the other stroke parameters, the current line cap style is examined by stroke() and stroke_extents(), but does not have any effect during path construction.

The default miter limit value is 10.0, which will convert joins with interior angles less than 11 degrees to bevels instead of miters. For reference, a miter limit of 2.0 makes the miter cutoff at 60 degrees, and a miter limit of 1.414 makes the cutoff at 90 degrees.

A miter limit for a desired angle can be computed as: miter_limit = 1. / sin(angle / 2.)

Parameters:: limit (float) – The miter limit to set.

set_operator(operator)

Set the current Compositiong operator to be used for all drawing operations.

The default operator is OVER.

Parameters:: operator – A Compositiong operator string.

set_scaled_font(scaled_font)

Replaces the current font face, font matrix, and font options with those of scaled_font. Except for some translation, the current CTM of the context should be the same as that of the scaled_font, which can be accessed using ScaledFont.get_ctm().

Parameters:: scaled_font – A ScaledFont object.

set_source(source)

Sets the source pattern within this context to source. This pattern will then be used for any subsequent drawing operation until a new source pattern is set.

Note

The pattern’s transformation matrix will be locked to the user space in effect at the time of set_source(). This means that further modifications of the current transformation matrix will not affect the source pattern. See Pattern.set_matrix().

The default source pattern is opaque black, (that is, it is equivalent to context.set_source_rgba(0, 0, 0)).

Parameters:: source – A Pattern to be used as the source for subsequent drawing operations.

set_source_rgb(red, green, blue): Same as set_source_rgba() with alpha always 1. Exists for compatibility with pycairo.

set_source_rgba(red, green, blue, alpha=1)

Sets the source pattern within this context to a solid color. This color will then be used for any subsequent drawing operation until a new source pattern is set.

The color and alpha components are floating point numbers in the range 0 to 1. If the values passed in are outside that range, they will be clamped.

The default source pattern is opaque black, (that is, it is equivalent to context.set_source_rgba(0, 0, 0)).

Parameters:

red (float) – Red component of the color.
green (float) – Green component of the color.
blue (float) – Blue component of the color.
alpha (float) – Alpha component of the color. 1 (the default) is opaque, 0 fully transparent.

set_source_surface(surface, x=0, y=0)

This is a convenience method for creating a pattern from surface and setting it as the source in this context with set_source().

The x and y parameters give the user-space coordinate at which the surface origin should appear. (The surface origin is its upper-left corner before any transformation has been applied.) The x and y parameters are negated and then set as translation values in the pattern matrix.

Other than the initial translation pattern matrix, as described above, all other pattern attributes, (such as its extend mode), are set to the default values as in SurfacePattern. The resulting pattern can be queried with get_source() so that these attributes can be modified if desired, (eg. to create a repeating pattern with Pattern.set_extend()).

Parameters:

surface – A Surface to be used to set the source pattern.
x (float) – User-space X coordinate for surface origin.
y (float) – User-space Y coordinate for surface origin.

set_tolerance(tolerance)

Sets the tolerance used when converting paths into trapezoids. Curved segments of the path will be subdivided until the maximum deviation between the original path and the polygonal approximation is less than tolerance. The default value is 0.1. A larger value will give better performance, a smaller value, better appearance. (Reducing the value from the default value of 0.1 is unlikely to improve appearance significantly.) The accuracy of paths within Cairo is limited by the precision of its internal arithmetic, and the prescribed tolerance is restricted to the smallest representable internal value.

Parameters:: tolerance (float) – The tolerance, in device units (typically pixels)

show_glyphs(glyphs)

A drawing operator that generates the shape from a list of glyphs, rendered according to the current font face, font size (font matrix), and font options.

Parameters:: glyphs – The glyphs to show. See show_text_glyphs() for the data structure.

show_page()

Emits and clears the current page for backends that support multiple pages. Use copy_page() if you don’t want to clear the page.

This is a convenience method that simply calls Surface.show_page() on the context’s target.

show_text(text)

A drawing operator that generates the shape from a string text, rendered according to the current font face, font size (font matrix), and font options.

This method first computes a set of glyphs for the string of text. The first glyph is placed so that its origin is at the current point. The origin of each subsequent glyph is offset from that of the previous glyph by the advance values of the previous glyph.

After this call the current point is moved to the origin of where the next glyph would be placed in this same progression. That is, the current point will be at the origin of the final glyph offset by its advance values. This allows for easy display of a single logical string with multiple calls to show_text().

Parameters:: text – The text to show, as an Unicode or UTF-8 string.

Note

This method is part of what the cairo designers call the “toy” text API. It is convenient for short demos and simple programs, but it is not expected to be adequate for serious text-using applications. See Fonts & text for details and show_glyphs() for the “real” text display API in cairo.

show_text_glyphs(text, glyphs, clusters, cluster_flags=0)

This operation has rendering effects similar to show_glyphs() but, if the target surface supports it (see Surface.has_show_text_glyphs()), uses the provided text and cluster mapping to embed the text for the glyphs shown in the output. If the target does not support the extended attributes, this method acts like the basic show_glyphs() as if it had been passed glyphs.

The mapping between text and glyphs is provided by an list of clusters. Each cluster covers a number of UTF-8 text bytes and glyphs, and neighboring clusters cover neighboring areas of text and glyphs. The clusters should collectively cover text and glyphs in entirety.

Parameters:

text – The text to show, as an Unicode or UTF-8 string. Because of how cluster work, using UTF-8 bytes might be more convenient.
glyphs – A list of glyphs. Each glyph is a (glyph_id, x, y) tuple. glyph_id is an opaque integer. Its exact interpretation depends on the font technology being used. x and y are the float offsets in the X and Y direction between the origin used for drawing or measuring the string and the origin of this glyph. Note that the offsets are not cumulative. When drawing or measuring text, each glyph is individually positioned with respect to the overall origin.
clusters – A list of clusters. A text cluster is a minimal mapping of some glyphs corresponding to some UTF-8 text, represented as a (num_bytes, num_glyphs) tuple of integers, the number of UTF-8 bytes and glyphs covered by the cluster. For a cluster to be valid, both num_bytes and num_glyphs should be non-negative, and at least one should be non-zero. Note that clusters with zero glyphs are not as well supported as normal clusters. For example, PDF rendering applications typically ignore those clusters when PDF text is being selected.
cluster_flags (int) – Flags (as a bit field) for the cluster mapping. The first cluster always covers bytes from the beginning of text. If cluster_flags does not have the TEXT_CLUSTER_FLAG_BACKWARD flag set, the first cluster also covers the beginning of glyphs, otherwise it covers the end of the glyphs list and following clusters move backward.

stroke()

A drawing operator that strokes the current path according to the current line width, line join, line cap, and dash settings. After stroke(), the current path will be cleared from the cairo context. See set_line_width(), set_line_join(), set_line_cap(), set_dash(), and stroke_preserve().

Note: Degenerate segments and sub-paths are treated specially and provide a useful result. These can result in two different situations:

Zero-length “on” segments set in set_dash(). If the cap style is ROUND or SQUARE then these segments will be drawn as circular dots or squares respectively. In the case of SQUARE, the orientation of the squares is determined by the direction of the underlying path.
A sub-path created by move_to() followed by either a close_path() or one or more calls to line_to() to the same coordinate as the move_to(). If the cap style is ROUND then these sub-paths will be drawn as circular dots. Note that in the case of SQUARE a degenerate sub-path will not be drawn at all, (since the correct orientation is indeterminate).

In no case will a cap style of BUTT cause anything to be drawn in the case of either degenerate segments or sub-paths.

stroke_extents()

Computes a bounding box in user-space coordinates covering the area that would be affected, (the “inked” area), by a stroke() operation given the current path and stroke parameters. If the current path is empty, returns an empty rectangle (0, 0, 0, 0). Surface dimensions and clipping are not taken into account.

Note that if the line width is set to exactly zero, then stroke_extents() will return an empty rectangle. Contrast with path_extents() which can be used to compute the non-empty bounds as the line width approaches zero.

Note that stroke_extents() must necessarily do more work to compute the precise inked areas in light of the stroke parameters, so path_extents() may be more desirable for sake of performance if the non-inked path extents are desired.

See stroke(), set_line_width(), set_line_join(), set_line_cap(), set_dash(), and stroke_preserve().

Returns:: A (x1, y1, x2, y2) tuple of floats: the left, top, right and bottom of the resulting extents, respectively.

stroke_preserve(): A drawing operator that strokes the current path according to the current line width, line join, line cap, and dash settings. Unlike stroke(), stroke_preserve() preserves the path within the cairo context. See set_line_width(), set_line_join(), set_line_cap(), set_dash(), and stroke().

tag_begin(tag_name, attributes=None)

Marks the beginning of the tag_name structure.

Call tag_end() with the same tag_name to mark the end of the structure.

The attributes string is of the form “key1=value2 key2=value2 …”. Values may be boolean (true/false or 1/0), integer, float, string, or an array.

String values are enclosed in single quotes (‘). Single quotes and backslashes inside the string should be escaped with a backslash.

Boolean values may be set to true by only specifying the key. eg the attribute string “key” is the equivalent to “key=true”.

Arrays are enclosed in ‘[]’. eg “rect=[1.2 4.3 2.0 3.0]”.

If no attributes are required, attributes can be omitted, an empty string or None.

See cairo’s Tags and Links Description for the list of tags and attributes.

Invalid nesting of tags or invalid attributes will cause the context to shutdown with a status of CAIRO_STATUS_TAG_ERROR.

See tag_end().

Parameters:

tag_name – tag name
attributes – tag attributes

New in cairo 1.16.

New in cairocffi 0.9.

tag_end(tag_name)

Marks the end of the tag_name structure.

Invalid nesting of tags will cause @cr to shutdown with a status of CAIRO_STATUS_TAG_ERROR.

See tag_begin().

Parameters:: tag_name – tag name

New in cairo 1.16.

New in cairocffi 0.9.

text_extents(text)

Returns the extents for a string of text.

The extents describe a user-space rectangle that encloses the “inked” portion of the text, (as it would be drawn by show_text()). Additionally, the x_advance and y_advance values indicate the amount by which the current point would be advanced by show_text().

Note that whitespace characters do not directly contribute to the size of the rectangle (width and height). They do contribute indirectly by changing the position of non-whitespace characters. In particular, trailing whitespace characters are likely to not affect the size of the rectangle, though they will affect the x_advance and y_advance values.

Because text extents are in user-space coordinates, they are mostly, but not entirely, independent of the current transformation matrix. If you call context.scale(2), text will be drawn twice as big, but the reported text extents will not be doubled. They will change slightly due to hinting (so you can’t assume that metrics are independent of the transformation matrix), but otherwise will remain unchanged.

Parameters:: text – The text to measure, as an Unicode or UTF-8 string.
Returns:: A (x_bearing, y_bearing, width, height, x_advance, y_advance) tuple of floats.

x_bearing: The horizontal distance from the origin to the leftmost part of the glyphs as drawn. Positive if the glyphs lie entirely to the right of the origin.
y_bearing: The vertical distance from the origin to the topmost part of the glyphs as drawn. Positive only if the glyphs lie completely below the origin; will usually be negative.
width: Width of the glyphs as drawn.
height: Height of the glyphs as drawn.
x_advance: Distance to advance in the X direction after drawing these glyphs.
y_advance: Distance to advance in the Y direction after drawing these glyphs. Will typically be zero except for vertical text layout as found in East-Asian languages.

text_path(text)

Adds closed paths for text to the current path. The generated path if filled, achieves an effect similar to that of show_text().

Text conversion and positioning is done similar to show_text().

Like show_text(), after this call the current point is moved to the origin of where the next glyph would be placed in this same progression. That is, the current point will be at the origin of the final glyph offset by its advance values. This allows for chaining multiple calls to to text_path() without having to set current point in between.

Parameters:: text – The text to show, as an Unicode or UTF-8 string.

Note

The text_path() method is part of what the cairo designers call the “toy” text API. It is convenient for short demos and simple programs, but it is not expected to be adequate for serious text-using applications. See Fonts & text for details, and glyph_path() for the “real” text path API in cairo.

transform(matrix)

Modifies the current transformation matrix (CTM) by applying matrix as an additional transformation. The new transformation of user space takes place after any existing transformation.

Parameters:: matrix – A transformation Matrix to be applied to the user-space axes.

translate(tx, ty)

Modifies the current transformation matrix (CTM) by translating the user-space origin by (tx, ty). This offset is interpreted as a user-space coordinate according to the CTM in place before the new call to translate(). In other words, the translation of the user-space origin takes place after any existing transformation.

Parameters:

tx (float) – Amount to translate in the X direction
ty (float) – Amount to translate in the Y direction

user_to_device(x, y)

Transform a coordinate from user space to device space by multiplying the given point by the current transformation matrix (CTM).

Parameters:

x (float) – X position.
y (float) – Y position.

Returns:

A (device_x, device_y) tuple of floats.

user_to_device_distance(dx, dy)

Transform a distance vector from user space to device space. This method is similar to Context.user_to_device() except that the translation components of the CTM will be ignored when transforming (dx, dy).

Parameters:

dx – X component of a distance vector.
dy – Y component of a distance vector.

Returns:

A (device_dx, device_dy) tuple of floats.

Matrix

class cairocffi.Matrix(xx=1, yx=0, xy=0, yy=1, x0=0, y0=0)

A 2D transformation matrix.

Matrices are used throughout cairo to convert between different coordinate spaces. A Matrix holds an affine transformation, such as a scale, rotation, shear, or a combination of these. The transformation of a point (x,y) is given by:

x_new = xx * x + xy * y + x0
y_new = yx * x + yy * y + y0

The current transformation matrix of a Context, represented as a Matrix, defines the transformation from user-space coordinates to device-space coordinates. See Context.get_matrix() and Context.set_matrix().

The default values produce an identity matrix.

Matrices can be compared with m1 == m2 and m2 != m2 as well as multiplied with m3 = m1 * m2.

as_tuple()

Return all of the matrix’s components.

Returns:: A (xx, yx, xy, yy, x0, y0) tuple of floats.

copy(): Return a new copy of this matrix.

classmethod init_rotate(radians)

Return a new Matrix for a transformation that rotates by radians.

Parameters:: radians (float) – Angle of rotation, in radians. The direction of rotation is defined such that positive angles rotate in the direction from the positive X axis toward the positive Y axis. With the default axis orientation of cairo, positive angles rotate in a clockwise direction.

invert()

Changes matrix to be the inverse of its original value. Not all transformation matrices have inverses; if the matrix collapses points together (it is degenerate), then it has no inverse and this function will fail.

Note

This changes the matrix in-place.

Raises:: CairoError on degenerate matrices.

inverted()

Return the inverse of this matrix. See invert().

Raises:: CairoError on degenerate matrices.
Returns:: A new Matrix object.

multiply(other): Multiply with another matrix and return the result as a new Matrix object. Same as self * other.

rotate(radians)

Applies a rotation by radians to the transformation in this matrix.

The effect of the new transformation is to first rotate the coordinates by radians, then apply the original transformation to the coordinates.

Note

This changes the matrix in-place.

Parameters:: radians (float) – Angle of rotation, in radians. The direction of rotation is defined such that positive angles rotate in the direction from the positive X axis toward the positive Y axis. With the default axis orientation of cairo, positive angles rotate in a clockwise direction.

scale(sx, sy=None)

Applies scaling by sx, sy to the transformation in this matrix.

The effect of the new transformation is to first scale the coordinates by sx and sy, then apply the original transformation to the coordinates.

If sy is omitted, it is the same as sx so that scaling preserves aspect ratios.

Note

This changes the matrix in-place.

Parameters:

sx (float) – Scale factor in the X direction.
sy (float) – Scale factor in the Y direction.

transform_distance(dx, dy)

Transforms the distance vector (dx, dy) by this matrix. This is similar to transform_point() except that the translation components of the transformation are ignored. The calculation of the returned vector is as follows:

dx2 = dx1 * xx + dy1 * xy
dy2 = dx1 * yx + dy1 * yy

Affine transformations are position invariant, so the same vector always transforms to the same vector. If (x1, y1) transforms to (x2, y2) then (x1 + dx1, y1 + dy1) will transform to (x1 + dx2, y1 + dy2) for all values of x1 and x2.

Parameters:

dx (float) – X component of a distance vector.
dy (float) – Y component of a distance vector.

Returns:

A (new_dx, new_dy) tuple of floats.

transform_point(x, y)

Transforms the point (x, y) by this matrix.

Parameters:

x (float) – X position.
y (float) – Y position.

Returns:

A (new_x, new_y) tuple of floats.

translate(tx, ty)

Applies a translation by tx, ty to the transformation in this matrix.

The effect of the new transformation is to first translate the coordinates by tx and ty, then apply the original transformation to the coordinates.

Note

This changes the matrix in-place.

Parameters:

tx (float) – Amount to translate in the X direction.
ty (float) – Amount to translate in the Y direction.

property x0: Read-write attribute access to a single float component.

property xx: Read-write attribute access to a single float component.

property xy: Read-write attribute access to a single float component.

property y0: Read-write attribute access to a single float component.

property yx: Read-write attribute access to a single float component.

property yy: Read-write attribute access to a single float component.

Patterns

class cairocffi.Pattern

The base class for all pattern types.

Should not be instantiated directly, but see CFFI API. An instance may be returned for cairo pattern types that are not (yet) defined in cairocffi.

A Pattern represents a source when drawing onto a surface. There are different sub-classes of Pattern, for different types of sources; for example, SolidPattern is a pattern for a solid color.

Other than instantiating the various Pattern sub-classes, some of the pattern types can be implicitly created using various Context; for example Context.set_source_rgb().

get_extend()

Gets the current extend mode for this pattern.

Returns:: A Pattern extend string.

get_filter(): Return the current filter string for this pattern. See Pixel filter for details on each filter.

get_matrix()

Copies the pattern’s transformation matrix.

Retuns:: A new Matrix object.

set_extend(extend)

Sets the mode to be used for drawing outside the area of this pattern. See Pattern extend for details on the semantics of each extend strategy.

The default extend mode is NONE for SurfacePattern and PAD for Gradient patterns.

set_filter(filter)

Sets the filter to be used for resizing when using this pattern. See Pixel filter for details on each filter.

Note that you might want to control filtering even when you do not have an explicit Pattern, (for example when using Context.set_source_surface()). In these cases, it is convenient to use Context.get_source() to get access to the pattern that cairo creates implicitly.

For example:

context.get_source().set_filter(cairocffi.FILTER_NEAREST)

set_matrix(matrix)

Sets the pattern’s transformation matrix to matrix. This matrix is a transformation from user space to pattern space.

When a pattern is first created it always has the identity matrix for its transformation matrix, which means that pattern space is initially identical to user space.

Important: Please note that the direction of this transformation matrix is from user space to pattern space. This means that if you imagine the flow from a pattern to user space (and on to device space), then coordinates in that flow will be transformed by the inverse of the pattern matrix.

For example, if you want to make a pattern appear twice as large as it does by default the correct code to use is:

pattern.set_matrix(Matrix(xx=0.5, yy=0.5))

Meanwhile, using values of 2 rather than 0.5 in the code above would cause the pattern to appear at half of its default size.

Also, please note the discussion of the user-space locking semantics of Context.set_source().

Parameters:: matrix – A Matrix to be copied into the pattern.

SolidPattern

class cairocffi.SolidPattern(red, green, blue, alpha=1)

Creates a new pattern corresponding to a solid color. The color and alpha components are in the range 0 to 1. If the values passed in are outside that range, they will be clamped.

Parameters:

red (float) – Red component of the color.
green (float) – Green component of the color.
blue (float) – Blue component of the color.
alpha (float) – Alpha component of the color. 1 (the default) is opaque, 0 fully transparent.

get_rgba()

Returns the solid pattern’s color.

Returns:: a (red, green, blue, alpha) tuple of floats.

SurfacePattern

class cairocffi.SurfacePattern(surface)

Create a new pattern for the given surface.

Parameters:: surface – A Surface object.

get_surface()

Return this SurfacePattern’s surface.

Returns:: An instance of Surface or one of its sub-classes, a new Python object referencing the existing cairo surface.

Gradient

class cairocffi.Gradient

The common parent of LinearGradient and RadialGradient. Should not be instantiated directly.

add_color_stop_rgb(offset, red, green, blue): Same as add_color_stop_rgba() with alpha=1. Kept for compatibility with pycairo.

add_color_stop_rgba(offset, red, green, blue, alpha=1)

Adds a translucent color stop to a gradient pattern.

The offset specifies the location along the gradient’s control vector. For example, a linear gradient’s control vector is from (x0,y0) to (x1,y1) while a radial gradient’s control vector is from any point on the start circle to the corresponding point on the end circle.

If two (or more) stops are specified with identical offset values, they will be sorted according to the order in which the stops are added (stops added earlier before stops added later). This can be useful for reliably making sharp color transitions instead of the typical blend.

The color components and offset are in the range 0 to 1. If the values passed in are outside that range, they will be clamped.

Parameters:

offset (float) – Location along the gradient’s control vector
red (float) – Red component of the color.
green (float) – Green component of the color.
blue (float) – Blue component of the color.
alpha (float) – Alpha component of the color. 1 (the default) is opaque, 0 fully transparent.

get_color_stops()

Return this gradient’s color stops so far.

Returns:: A list of (offset, red, green, blue, alpha) tuples of floats.

LinearGradient

class cairocffi.LinearGradient(x0, y0, x1, y1)

Create a new linear gradient along the line defined by (x0, y0) and (x1, y1). Before using the gradient pattern, a number of color stops should be defined using add_color_stop_rgba().

Note: The coordinates here are in pattern space. For a new pattern, pattern space is identical to user space, but the relationship between the spaces can be changed with set_matrix().

Parameters:

x0 (float) – X coordinate of the start point.
y0 (float) – Y coordinate of the start point.
x1 (float) – X coordinate of the end point.
y1 (float) – Y coordinate of the end point.

get_linear_points()

Return this linear gradient’s endpoints.

Returns:: A (x0, y0, x1, y1) tuple of floats.

RadialGradient

class cairocffi.RadialGradient(cx0, cy0, radius0, cx1, cy1, radius1)

Creates a new radial gradient pattern between the two circles defined by (cx0, cy0, radius0) and (cx1, cy1, radius1). Before using the gradient pattern, a number of color stops should be defined using add_color_stop_rgba().

Note: The coordinates here are in pattern space. For a new pattern, pattern space is identical to user space, but the relationship between the spaces can be changed with set_matrix().

Parameters:

cx0 (float) – X coordinate of the start circle.
cy0 (float) – Y coordinate of the start circle.
radius0 (float) – Radius of the start circle.
cx1 (float) – X coordinate of the end circle.
cy1 (float) – Y coordinate of the end circle.
radius1 (float) – Y coordinate of the end circle.

get_radial_circles()

Return this radial gradient’s endpoint circles, each specified as a center coordinate and a radius.

Returns:: A (cx0, cy0, radius0, cx1, cy1, radius1) tuple of floats.

Fonts & text

A font is (in simple terms) a collection of shapes used to draw text. A glyph is one of these shapes. There can be multiple glyphs for the same character (alternates to be used in different contexts, for example), or a glyph can be a ligature of multiple characters. Converting text to positioned glyphs is shaping.

Cairo itself provides a “toy” text API that only does simple shaping: no ligature or kerning; one glyph per character, positioned by moving the cursor by the X and Y advance of each glyph.

It is expected that most applications will need to use Pango or a similar library in conjunction with cairo for more comprehensive font handling and text layout.

Font faces

Note

At the moment cairocffi only supports cairo’s “toy” font selection API. FontFace objects of other types could be obtained eg. from Context.get_font_face(), but they can not be instantiated directly.

class cairocffi.FontFace

The base class for all font face types.

Should not be instantiated directly, but see CFFI API. An instance may be returned for cairo font face types that are not (yet) defined in cairocffi.

ToyFontFace

class cairocffi.ToyFontFace(family='', slant=0, weight=0)

Creates a font face from a triplet of family, slant, and weight. These font faces are used in implementation of cairo’s “toy” font API.

If family is the zero-length string "", the platform-specific default family is assumed. The default family then can be queried using get_family().

The Context.select_font_face() method uses this to create font faces. See that method for limitations and other details of toy font faces.

Parameters:

family – a font family name, as an Unicode or UTF-8 string.
slant – The Font slant string for the font face.
weight – The Font weight string for the font face.

get_family(): Return this font face’s family name.

get_slant(): Return this font face’s Font slant string.

get_weight(): Return this font face’s Font weight string.

ScaledFont

class cairocffi.ScaledFont(font_face, font_matrix=None, ctm=None, options=None)

Creates a ScaledFont object from a font face and matrices that describe the size of the font and the environment in which it will be used.

Parameters:

font_face – A FontFace object.
font_matrix (Matrix) – Font space to user space transformation matrix for the font. In the simplest case of a N point font, this matrix is just a scale by N, but it can also be used to shear the font or stretch it unequally along the two axes. If omitted, a scale by 10 matrix is assumed (ie. a 10 point font size). See Context.set_font_matrix.
ctm (Matrix) – User to device transformation matrix with which the font will be used. If omitted, an identity matrix is assumed.
options – The FontOptions object to use when getting metrics for the font and rendering with it. If omitted, the default options are assumed.

extents()

Return the scaled font’s extents. See Context.font_extents().

Returns:: A (ascent, descent, height, max_x_advance, max_y_advance) tuple of floats.

get_ctm()

Copies the scaled font’s font current transform matrix.

Note that the translation offsets (x0, y0) of the CTM are ignored by ScaledFont. So, the matrix this method returns always has 0 as x0 and y0.

Returns:: A new Matrix object.

get_font_face()

Return the font face that this scaled font uses.

Returns:: A new instance of FontFace (or one of its sub-classes). Might wrap be the same font face passed to ScaledFont, but this does not hold true for all possible cases.

get_font_matrix()

Copies the scaled font’s font matrix.

Returns:: A new Matrix object.

get_font_options()

Copies the scaled font’s options.

Returns:: A new FontOptions object.

get_scale_matrix()

Copies the scaled font’s scaled matrix.

The scale matrix is product of the font matrix and the ctm associated with the scaled font, and hence is the matrix mapping from font space to device space.

Returns:: A new Matrix object.

glyph_extents(glyphs)

Returns the extents for a list of glyphs.

The extents describe a user-space rectangle that encloses the “inked” portion of the glyphs, (as it would be drawn by Context.show_glyphs()). Additionally, the x_advance and y_advance values indicate the amount by which the current point would be advanced by Context.show_glyphs().

Parameters:: glyphs – A list of glyphs, as returned by text_to_glyphs(). Each glyph is a (glyph_id, x, y) tuple of an integer and two floats.
Returns:: A (x_bearing, y_bearing, width, height, x_advance, y_advance) tuple of floats. See Context.text_extents() for details.

text_extents(text)

Returns the extents for a string of text.

The extents describe a user-space rectangle that encloses the “inked” portion of the text, (as it would be drawn by Context.show_text()). Additionally, the x_advance and y_advance values indicate the amount by which the current point would be advanced by Context.show_text().

Parameters:: text – The text to measure, as an Unicode or UTF-8 string.
Returns:: A (x_bearing, y_bearing, width, height, x_advance, y_advance) tuple of floats. See Context.text_extents() for details.

text_to_glyphs(x, y, text, with_clusters)

Converts a string of text to a list of glyphs, optionally with cluster mapping, that can be used to render later using this scaled font.

The output values can be readily passed to Context.show_text_glyphs(), Context.show_glyphs() or related methods, assuming that the exact same ScaledFont is used for the operation.

Parameters:

x (float) – X position to place first glyph.
y (float) – Y position to place first glyph.
text – The text to convert, as an Unicode or UTF-8 string.
with_clusters (bool) – Whether to compute the cluster mapping.

Returns:

A (glyphs, clusters, clusters_flags) tuple if with_clusters is true, otherwise just glyphs. See Context.show_text_glyphs() for the data structure.

Note

This method is part of what the cairo designers call the “toy” text API. It is convenient for short demos and simple programs, but it is not expected to be adequate for serious text-using applications. See Fonts & text for details and Context.show_glyphs() for the “real” text display API in cairo.

FontOptions

class cairocffi.FontOptions(**values)

An opaque object holding all options that are used when rendering fonts.

Individual features of a FontOptions can be set or accessed using method named set_FEATURE_NAME and get_FEATURE_NAME, like set_antialias() and get_antialias().

New features may be added to FontOptions in the future. For this reason, ==, copy(), merge(), and hash() should be used to check for equality copy,, merge, or compute a hash value of FontOptions objects.

Parameters:

values –

Call the corresponding set_FEATURE_NAME methods after creating a new FontOptions:

options = FontOptions()
options.set_antialias(cairocffi.ANTIALIAS_BEST)
assert FontOptions(antialias=cairocffi.ANTIALIAS_BEST) == options

copy(): Return a new FontOptions with the same values.

equal(other): Return self==value.

get_antialias(): Return the Antialiasing mode string for the font options object.

get_hint_metrics(): Return the Metrics hinting mode string for the font options object.

get_hint_style(): Return the Hint style string for the font options object.

get_subpixel_order(): Return the Subpixel order string for the font options object.

get_variations()

Gets the OpenType font variations for the font options object.

See set_variations() for details about the string format.

Returns:: the font variations for the font options object. The returned string belongs to the options and must not be modified. It is valid until either the font options object is destroyed or the font variations in this object is modified with set_variations().

New in cairo 1.16.

New in cairocffi 0.9.

hash(): Return hash(self).

merge(other): Merges non-default options from other, replacing existing values. This operation can be thought of as somewhat similar to compositing other onto options with the operation of OVER.

set_antialias(antialias): Changes the Antialiasing mode for the font options object. This specifies the type of antialiasing to do when rendering text.

set_hint_metrics(hint_metrics): Changes the Metrics hinting mode for the font options object. This controls whether metrics are quantized to integer values in device units.

set_hint_style(hint_style): Changes the Hint style for the font options object. This controls whether to fit font outlines to the pixel grid, and if so, whether to optimize for fidelity or contrast.

set_subpixel_order(subpixel_order): Changes the Subpixel order for the font options object. The subpixel order specifies the order of color elements within each pixel on the display device when rendering with an antialiasing mode of SUBPIXEL.

set_variations(variations)

Sets the OpenType font variations for the font options object.

Font variations are specified as a string with a format that is similar to the CSS font-variation-settings. The string contains a comma-separated list of axis assignments, which each assignment consists of a 4-character axis name and a value, separated by whitespace and optional equals sign.

Parameters:: variations – the new font variations, or None.

New in cairo 1.16.

New in cairocffi 0.9.

Enumerated values

Some parameters or return values in the cairo API only have a fixed, finite set of valid values. These are represented as enumerated types in C, and as integers in CFFI. Users are encouraged to use the constants defined here in the cairocffi module rather than literal integers. For example:

surface = cairocffi.ImageSurface(cairocffi.FORMAT_ARGB32, 300, 400)

Content

Used to describe the content that a Surface will contain, whether color information, alpha information (translucence vs. opacity), or both.

cairocffi.CONTENT_COLOR: The surface will hold color content only.

cairocffi.CONTENT_ALPHA: The surface will hold alpha content only.

cairocffi.CONTENT_COLOR_ALPHA: The surface will hold color and alpha content.

Pixel format

Used to identify the memory format of image data.

cairocffi.FORMAT_ARGB32: Each pixel is a 32-bit quantity, with alpha in the upper 8 bits, then red, then green, then blue. The 32-bit quantities are stored native-endian. Pre-multiplied alpha is used. (That is, 50% transparent red is 0x80800000, not 0x80ff0000.)

cairocffi.FORMAT_RGB24: Each pixel is a 32-bit quantity, with the upper 8 bits unused. Red, Green, and Blue are stored in the remaining 24 bits in that order.

cairocffi.FORMAT_A8: Each pixel is a 8-bit quantity holding an alpha value.

cairocffi.FORMAT_A1: Each pixel is a 1-bit quantity holding an alpha value. Pixels are packed together into 32-bit quantities. The ordering of the bits matches the endianess of the platform. On a big-endian machine, the first pixel is in the uppermost bit, on a little-endian machine the first pixel is in the least-significant bit.

cairocffi.FORMAT_RGB16_565: Each pixel is a 16-bit quantity with red in the upper 5 bits, then green in the middle 6 bits, and blue in the lower 5 bits.

cairocffi.FORMAT_RGB30: Like FORMAT_RGB24, but with the upper 2 bits unused and 10 bits per components.

Compositiong operator

Used to set the compositing operator for all cairo drawing operations.

The default operator is OPERATOR_OVER.

The operators marked as unbounded modify their destination even outside of the mask layer (that is, their effect is not bound by the mask layer). However, their effect can still be limited by way of clipping.

To keep things simple, the operator descriptions here document the behavior for when both source and destination are either fully transparent or fully opaque. The actual implementation works for translucent layers too. For a more detailed explanation of the effects of each operator, including the mathematical definitions, see http://cairographics.org/operators/.

cairocffi.OPERATOR_CLEAR: Clear destination layer. (bounded)

cairocffi.OPERATOR_SOURCE: Replace destination layer. (bounded)

cairocffi.OPERATOR_OVER: Draw source layer on top of destination layer. (bounded)

cairocffi.OPERATOR_IN: Draw source where there was destination content. (unbounded)

cairocffi.OPERATOR_OUT: Draw source where there was no destination content. (unbounded)

cairocffi.OPERATOR_ATOP: Draw source on top of destination content and only there.

cairocffi.OPERATOR_DEST: Ignore the source.

cairocffi.OPERATOR_DEST_OVER: Draw destination on top of source.

cairocffi.OPERATOR_DEST_IN: Leave destination only where there was source content. (unbounded)

cairocffi.OPERATOR_DEST_OUT: Leave destination only where there was no source content.

cairocffi.OPERATOR_DEST_ATOP: Leave destination on top of source content and only there. (unbounded)

cairocffi.OPERATOR_XOR: Source and destination are shown where there is only one of them.

cairocffi.OPERATOR_ADD: Source and destination layers are accumulated.

cairocffi.OPERATOR_SATURATE: Like OPERATOR_OVER, but assuming source and destination are disjoint geometries.

cairocffi.OPERATOR_MULTIPLY: Source and destination layers are multiplied. This causes the result to be at least as dark as the darker inputs. (Since 1.10)

cairocffi.OPERATOR_SCREEN: Source and destination are complemented and multiplied. This causes the result to be at least as light as the lighter inputs. (Since cairo 1.10)

cairocffi.OPERATOR_OVERLAY: Multiplies or screens, depending on the lightness of the destination color. (Since cairo 1.10)

cairocffi.OPERATOR_DARKEN: Replaces the destination with the source if it is darker, otherwise keeps the source. (Since cairo 1.10)

cairocffi.OPERATOR_LIGHTEN: Replaces the destination with the source if it is lighter, otherwise keeps the source. (Since cairo 1.10)

cairocffi.OPERATOR_COLOR_DODGE: Brightens the destination color to reflect the source color. (Since cairo 1.10)

cairocffi.OPERATOR_COLOR_BURN: Darkens the destination color to reflect the source color. (Since cairo 1.10)

cairocffi.OPERATOR_HARD_LIGHT: Multiplies or screens, dependent on source color. (Since cairo 1.10)

cairocffi.OPERATOR_SOFT_LIGHT: Darkens or lightens, dependent on source color. (Since cairo 1.10)

cairocffi.OPERATOR_DIFFERENCE: Takes the difference of the source and destination color. (Since cairo 1.10)

cairocffi.OPERATOR_EXCLUSION: Produces an effect similar to difference, but with lower contrast. (Since cairo 1.10)

cairocffi.OPERATOR_HSL_HUE: Creates a color with the hue of the source and the saturation and luminosity of the target. (Since cairo 1.10)

cairocffi.OPERATOR_HSL_SATURATION: Creates a color with the saturation of the source and the hue and luminosity of the target. Painting with this mode onto a gray area produces no change. (Since cairo 1.10)

cairocffi.OPERATOR_HSL_COLOR: Creates a color with the hue and saturation of the source and the luminosity of the target. This preserves the gray levels of the target and is useful for coloring monochrome images or tinting color images. (Since cairo 1.10)

cairocffi.OPERATOR_HSL_LUMINOSITY: Creates a color with the luminosity of the source and the hue and saturation of the target. This produces an inverse effect to OPERATOR_HSL_COLOR. (Since cairo 1.10)

Antialiasing mode

Specifies the type of antialiasing to do when rendering text or shapes.

cairocffi.ANTIALIAS_DEFAULT: Use the default antialiasing for the subsystem and target device.

cairocffi.ANTIALIAS_NONE: Use a bilevel alpha mask.

cairocffi.ANTIALIAS_GRAY: Perform single-color antialiasing.

cairocffi.ANTIALIAS_SUBPIXEL: Perform antialiasing by taking advantage of the order of subpixel elements on devices such as LCD panels.

As it is not necessarily clear from the above what advantages a particular antialias method provides, since cairo 1.12, there is also a set of hints:

cairocffi.ANTIALIAS_FAST: Allow the backend to degrade raster quality for speed.

cairocffi.ANTIALIAS_GOOD: A balance between speed and quality.

cairocffi.ANTIALIAS_BEST: A high-fidelity, but potentially slow, raster mode.

These make no guarantee on how the backend will perform its rasterisation (if it even rasterises!), nor that they have any differing effect other than to enable some form of antialiasing. In the case of glyph rendering, ANTIALIAS_FAST and ANTIALIAS_GOOD will be mapped to ANTIALIAS_GRAY, with ANTIALIAS_BEST being equivalent to ANTIALIAS_SUBPIXEL.

The interpretation of ANTIALIAS_DEFAULT is left entirely up to the backend, typically this will be similar to ANTIALIAS_GOOD.

Fill rule

Used to select how paths are filled. For both fill rules, whether or not a point is included in the fill is determined by taking a ray from that point to infinity and looking at intersections with the path. The ray can be in any direction, as long as it doesn’t pass through the end point of a segment or have a tricky intersection such as intersecting tangent to the path. (Note that filling is not actually implemented in this way. This is just a description of the rule that is applied.)

The default fill rule is FILL_RULE_WINDING.

New entries may be added in future versions.

cairocffi.FILL_RULE_WINDING: If the path crosses the ray fromleft-to-right, counts +1. If the path crosses the rayfrom right to left, counts -1. (Left and right are determined from the perspective of looking along the ray from the starting point.) If the total count is non-zero, the point will be filled.

cairocffi.FILL_RULE_EVEN_ODD: Counts the total number of intersections, without regard to the orientation of the contour. If the total number of intersections is odd, the point will be filled.

Line cap style

Specifies how to render the endpoints of the path when stroking.

The default line cap style is LINE_CAP_BUTT.

cairocffi.LINE_CAP_BUTT: Start (stop) the line exactly at the start (end) point.

cairocffi.LINE_CAP_ROUND: Use a round ending, the center of the circle is the end point.

cairocffi.LINE_CAP_SQUARE: Use squared ending, the center of the square is the end point.

Line join style

Specifies how to render the junction of two lines when stroking.

The default line join style is LINE_JOIN_MITER.

cairocffi.LINE_JOIN_MITER: Use a sharp (angled) corner, see Context.set_miter_limit().

cairocffi.LINE_JOIN_ROUND: Use a rounded join, the center of the circle is the joint point.

cairocffi.LINE_JOIN_BEVEL: Use a cut-off join, the join is cut off at half the line width from the joint point.

Font slant

Specifies variants of a font face based on their slant.

cairocffi.FONT_SLANT_NORMAL: Upright font style.

cairocffi.FONT_SLANT_ITALIC: Italic font style.

cairocffi.FONT_SLANT_OBLIQUE: Oblique font style.

Font weight

Specifies variants of a font face based on their weight.

cairocffi.FONT_WEIGHT_NORMAL: Normal font weight.

cairocffi.FONT_WEIGHT_BOLD: Bold font weight.

Subpixel order

The subpixel order specifies the order of color elements within each pixel on the display device when rendering with an antialiasing mode of ANTIALIAS_SUBPIXEL.

cairocffi.SUBPIXEL_ORDER_DEFAULT: Use the default subpixel order for for the target device.

cairocffi.SUBPIXEL_ORDER_RGB: Subpixel elements are arranged horizontally with red at the left.

cairocffi.SUBPIXEL_ORDER_BGR: Subpixel elements are arranged horizontally with blue at the left.

cairocffi.SUBPIXEL_ORDER_VRGB: Subpixel elements are arranged vertically with red at the top.

cairocffi.SUBPIXEL_ORDER_VBGR: Subpixel elements are arranged vertically with blue at the top.

Hint style

Specifies the type of hinting to do on font outlines. Hinting is the process of fitting outlines to the pixel grid in order to improve the appearance of the result. Since hinting outlines involves distorting them, it also reduces the faithfulness to the original outline shapes. Not all of the outline hinting styles are supported by all font backends.

New entries may be added in future versions.

cairocffi.HINT_STYLE_DEFAULT: Use the default hint style for font backend and target device.

cairocffi.HINT_STYLE_NONE: Do not hint outlines.

cairocffi.HINT_STYLE_SLIGHT: Hint outlines slightly to improve contrast while retaining good fidelity to the original shapes.

cairocffi.HINT_STYLE_MEDIUM: Hint outlines with medium strength giving a compromise between fidelity to the original shapes and contrast.

cairocffi.HINT_STYLE_FULL: Hint outlines to maximize contrast.

Metrics hinting mode

Specifies whether to hint font metrics; hinting font metrics means quantizing them so that they are integer values in device space. Doing this improves the consistency of letter and line spacing, however it also means that text will be laid out differently at different zoom factors.

cairocffi.HINT_METRICS_DEFAULT: Hint metrics in the default manner for the font backend and target device.

cairocffi.HINT_METRICS_OFF: Do not hint font metrics.

cairocffi.HINT_METRICS_ON: Hint font metrics.

Path operation

Used to describe the type of one portion of a path when represented as a list. See Context.copy_path() for details.

cairocffi.PATH_MOVE_TO

cairocffi.PATH_LINE_TO

cairocffi.PATH_CURVE_TO

cairocffi.PATH_CLOSE_PATH

Pattern extend

Used to describe how pattern color/alpha will be determined for areas “outside” the pattern’s natural area, (for example, outside the surface bounds or outside the gradient geometry).

Mesh patterns are not affected by the extend mode.

The default extend mode is EXTEND_NONE for SurfacePattern and EXTEND_PAD for Gradient patterns.

New entries may be added in future versions.

cairocffi.EXTEND_NONE: Pixels outside of the source pattern are fully transparent.

cairocffi.EXTEND_REPEAT: The pattern is tiled by repeating.

cairocffi.EXTEND_REFLECT: The pattern is tiled by reflecting at the edges.

cairocffi.EXTEND_PAD: Pixels outside of the pattern copy the closest pixel from the source.

Pixel filter

Used to indicate what filtering should be applied when reading pixel values from patterns. See Pattern.set_filter() for indicating the desired filter to be used with a particular pattern.

cairocffi.FILTER_FAST: A high-performance filter, with quality similar to FILTER_NEAREST.

cairocffi.FILTER_GOOD: A reasonable-performance filter, with quality similar to FILTER_BILINEAR.

cairocffi.FILTER_BEST: The highest-quality available, performance may not be suitable for interactive use.

cairocffi.FILTER_NEAREST: Nearest-neighbor filtering.

cairocffi.FILTER_BILINEAR: Linear interpolation in two dimensions.

cairocffi.FILTER_GAUSSIAN: This filter value is currently unimplemented, and should not be used in current code.

PDF version

Used to describe the version number of the PDF specification that a generated PDF file will conform to.

cairocffi.PDF_VERSION_1_4: The version 1.4 of the PDF specification.

cairocffi.PDF_VERSION_1_5: The version 1.5 of the PDF specification.

PDF outline

Used to specify the attributes of an outline item. These flags may be bitwise-or’d to produce any combination of flags.

New in cairo 1.16.

New in cairocffi 0.9.

cairocffi.PDF_OUTLINE_FLAG_OPEN: The outline item defaults to open in the PDF viewer.

cairocffi.PDF_OUTLINE_FLAG_BOLD: The outline item is displayed by the viewer in bold text.

cairocffi.PDF_OUTLINE_FLAG_ITALIC: The outline item is displayed by the viewer in italic text.

There’s also a constant used to specify the root level for outlines.

cairocffi.PDF_OUTLINE_ROOT: Root level for outlines.

PDF metadata

Used to specify the metadata to set.

New in cairo 1.16.

New in cairocffi 0.9.

cairocffi.PDF_METADATA_TITLE: The document title.

cairocffi.PDF_METADATA_AUTHOR: The document author.

cairocffi.PDF_METADATA_SUBJECT: The document subject.

cairocffi.PDF_METADATA_KEYWORDS: The document keywords.

cairocffi.PDF_METADATA_CREATOR: The document creator.

cairocffi.PDF_METADATA_CREATE_DATE: The document creation date.

cairocffi.PDF_METADATA_MOD_DATE: The document modification date.

PostScript level

Used to describe the language level of the PostScript Language Reference that a generated PostScript file will conform to.

cairocffi.PS_LEVEL_2: The language level 2 of the PostScript specification.

cairocffi.PS_LEVEL_3: The language level 3 of the PostScript specification.

SVG version

Used to describe the version number of the SVG specification that a generated SVG file will conform to.

cairocffi.SVG_VERSION_1_1: The version 1.1 of the SVG specification.

cairocffi.SVG_VERSION_1_2: The version 1.2 of the SVG specification.

SVG unit

Used to describe the units valid for coordinates and lengths in the SVG specification.

Cluster flags

Specifies properties of a text cluster mapping. Flags are integer values representing a bit field.

cairocffi.TEXT_CLUSTER_FLAG_BACKWARD = 0x00000001: The clusters in the cluster array map to glyphs in the glyph array from end to start. (Since 1.8)