Creates an image surface for the provided pixel data. The output buffer must be kept around until the Surface is destroyed or Surface#finish is called on the surface. The initial contents of data 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 that the stride may be larger than width * bytes_per_pixel to provide proper alignment for each pixel and row. This alignment is required to allow high-performance rendering within cairo. The correct way to obtain a legal stride value is to call Format#stride_for_width with the desired format and maximum image width value, and then use the resulting stride value to allocate the data and to create the image surface. See Format#stride_for_width for example code.

###Parameters

• data a pointer to a buffer supplied by the application in which to write contents. This pointer must be suitably aligned for any kind of variable.
• format the format of pixels in the buffer
• width the width of the image to be stored in the buffer
• height the height of the image to be stored in the buffer
• stride 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.

###Returns A pointer to the newly created surface. The caller owns the surface and should call Surface#finalize when done with it.

This function always returns a valid pointer, but it will return a pointer to a "nil" surface in the case of an error such as out of memory or an invalid stride value. In case of invalid stride value the error status of the returned surface will be Status::InvalidStride. You can use Surface#status to check for this.

See Surface#set_user_data for a means of attaching a destroy-notification fallback to the surface if necessary.

Creates an image surface of the specified format and dimensions. Initially the surface contents are set to 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 format of pixels in the surface to create
• width width of the surface, in pixels
• height height of the surface, in pixels

###Returns A pointer to the newly created surface. The caller owns the surface and should call `Surface#finalize when done with it.

This function always returns a valid pointer, but it will return a pointer to a "nil" surface if an error such as out of memory occurs. You can use Surface#status to check for this.

Creates a new image surface from PNG data read incrementally via the read_func function.

###Parameters

• read_func function called to read the data of the file
• closure data to pass to read_func.

###Returns A new Surface initialized with the contents of the PNG file or a "nil" surface if the data read is not a valid PNG image or memory could not be allocated for the operation. A nil surface can be checked for with Surface#status which may return one of the following values:

Status#NoMemory Status#ReadError Status#PngError

Alternatively, you can allow errors to propagate through the drawing operations and check the status on the context upon completion using Context#status.

Creates a recording-surface which can be used to record all drawing operations at the highest level (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 to drawing operations.

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 of the recording surface
• extents the extents to record in pixels, can be nil to record unbounded operations.

###Returns A pointer to the newly created surface. The caller owns the surface and should call Surface#finalize when done with it.

Creates a new image surface and initializes the contents to the given PNG file.

###Parameters

• filename name of PNG file to load. On Windows this filename is encoded in UTF-8.

###Returns A new Surface initialized with the contents of the PNG file, or a "nil" surface if any error occurred. A nil surface can be checked for with Surface#status which may return one of the following values:

Status#NoMemory Status#FileNotFound Status#ReadError Status#PngError

Alternatively, you can allow errors to propagate through the drawing operations and check the status on the context upon completion using Context#status.

This function returns the content type of surface which indicates whether the surface contains color and/or alpha information. See Content.

###Returns The content type of surface.

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 Surface#show_page if you want to get an empty page after the emission.

There is a convenience function for this that takes a Context, namely Context#copy_page.

Create a new surface that is a rectangle within the target 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.

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 the x-origin of the sub-surface from the top-left of the target surface (in device-space units)
• y the y-origin of the sub-surface from the top-left of the target surface (in device-space units)
• width width of the sub-surface (in device-space units)
• height height of the sub-surface (in device-space units)

###Returns A pointer to the newly allocated surface. The caller owns the surface and should call Surface#finalize when done with it.

This function always returns a valid pointer, but it will return a pointer to a "nil" surface if other is already in an error state or any other error occurs.

Create a new surface that is as compatible as possible with an existing surface. For example the new surface will have the same device scale, fallback resolution and font options as self. Generally, the new surface will also use the same backend as self, unless that is not possible for some reason. The type of the returned surface may be examined with Surface#type.

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

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

###Parameters

• content the content for the new surface
• width width of the new surface, (in device-space units)
• height height of the new surface (in device-space units)

###Returns A pointer to the newly allocated surface. The caller owns the surface and should call Surface#finalize when done with it.

This function always returns a valid pointer, but it will return a pointer to a "nil" surface if other is already in an error state or any other error occurs.

Create a new image surface that is as compatible as possible for uploading to and the use in conjunction with an existing surface. However, this surface can still be used like any normal image surface. Unlike Surface#create_similar the new image surface won't inherit the device scale from self.

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

Use Surface#create_similar if you don't need an image surface.

###Parameters

• format the format for the new surface
• width width of the new surface, (in pixels)
• height height of the new surface (in pixels)

###Returns A pointer to the newly allocated image surface. The caller owns the surface and should call Surface#finalizte when done with it.

This function always returns a valid pointer, but it will return a pointer to a "nil" surface if other is already in an error state or any other error occurs.

Get a pointer to the data of the image surface, for direct inspection or modification.

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

###Returns A pointer to the image data of this surface or nil if surface is not an image surface, or if Surface#finish has been called.

This function returns the device for a surface. See Device.

###Returns The device for surface or Nil if the surface does not have an associated device.

This function returns the previous device offset set by Surface#device_offset=.

###Returns A Point contains x and y offset in device units

Sets an offset that is added to the device coordinates determined by the CTM when drawing to surface. One use case for this function 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 functions 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

• offset.x the offset in the X direction, in device units
• offset.y the offset in the Y direction, in device units

This function returns the previous device offset set by Surface#device_scale=.

###Returns A Point contains x and y scale in device units

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 Context#translateisn't sufficient to do this, since functions likeContext#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

• scale.x a scale factor in the X direction
• scale.y a scale factor in the Y direction

Get the extents of the recording-surface.

###Returns

• extents the Rectangle to be assigned the extents
• bounded true if the surface is bounded, of recording type, and not in an error state, otherwise false

This function returns the previous fallback resolution set by Surface#fallback_resolution=, or default fallback resolution if never set.

###Returns A Point contains x for horizontal and y for vertical 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 function 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 function has no effect on those backends.

NOTE The fallback resolution only takes effect at the time of completing a page (with Context#show_page or Context#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

• res.x horizontal setting for pixels per inch
• res.y vertical setting for pixels per inch

Decreases the reference count on surface by one. If the result is zero, then surface and all associated resources are freed. See Surface#reference.

This function 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 Surface#finish the only valid operations on a surface are getting and setting user, referencing and destroying, and flushing and finishing it. Further drawing to the surface will not affect the surface but will instead trigger a Status::SurfaceFinished error.

When the last call to Surface#finalize decreases the reference count to zero, cairo will call Surface#finish if it hasn't been called already, before freeing the resources associated with the surface.

Do any pending drawing for the surface and also restore any temporary modifications cairo has made to the surface's state. This function must be called before switching from drawing on the surface with cairo to drawing on it directly with native APIs, or accessing its memory outside of Cairo. If the surface doesn't support direct access, then this function does nothing.

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#initialize.

###Returns A FontOptions object into which to store the retrieved options. All existing values are overwritten.

Get the format of the surface.

###Returns The format of the surface.

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

NOTE Even if this function returns false, a 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 function to avoid computing UTF-8 text and cluster mapping if the target surface does not use it.

###Returns true if surface supports Context#show_text_glyphs, false otherwise.

Get the height of the image surface in pixels.

###Returns The height of the surface in pixels.

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 Rectangle of ink bounding-box.

Returns an image surface that is the most efficient mechanism for modifying the backing store of the target surface. The region retrieved may be limited to the extents or nil for the whole surface

NOTE , the use of the original surface as a target or source whilst it is mapped is undefined. The result of mapping the surface multiple times is undefined. Calling Surface#finalize or Surface#finish on the resulting image surface results in undefined behavior. Changing the device transform of the image surface or of surface before the image surface is unmapped results in undefined behavior.

###Parameters

• extents limit the extraction to an rectangular region

###Returns A pointer to the newly allocated image surface. The caller must use Surface#unmap_image to destroy this image surface.

This function always returns a valid pointer, but it will return a pointer to a "nil" surface if other is already in an error state or any other error occurs. If the returned pointer does not have an error status, it is guaranteed to be an image surface whose format is not Format::Invalid.

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 Surface#flush before doing such drawing.

Like Surface#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 function, to make sure that future cairo calls have the clip set that they expect.

###Parameters

• x X coordinate of dirty rectangle
• y Y coordinate of dirty rectangle
• width width of dirty rectangle
• height height of dirty rectangle

Return mime data previously attached to surface using the specified mime type. If no data has been attached with the given mime type, data is set empty.

###Parameters

• mime_type the mime type of the image data

###Returns The image data to attached to the surface.

Increases the reference count on surface by one. This prevents surface from being destroyed until a matching call to Surface#finalize is made.

Use Surface#reference_count to get the number of references to a Surface.

###Returns The referenced Surface.

Returns the current reference count of surface.

###Returns The current reference count of surface. If the object is a nil object, 0 will be returned.

Sets an offset that is added to the device coordinates determined by the CTM when drawing to surface. One use case for this function 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 functions 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

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 Context#translate isn't sufficient to do this, since functions like Context#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 a scale factor in the X direction
• y_scale a scale factor in the Y direction

Attach an image in the format mime_type to surface. To remove the data from a surface, call this function with same mime type and empty 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: LibCairo::MIME_TYPE_JPEG, LibCaito::MIME_TYPE_PNG, LibCairo::MIME_TYPE_JP2, LibCairo::MIME_TYPE_URI, LibCairo::MIME_TYPE_UNIQUE_ID, LibCairo::MIME_TYPE_JBIG2, LibCairo::MIME_TYPE_JBIG2_GLOBAL, LibCairo::MIME_TYPE_JBIG2_GLOBAL_ID, LibCairo::MIME_TYPE_CCITT_FAX, LibCairo::MIME_TYPE_CCITT_FAX_PARAMS.

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 function with care.

Even if a backend supports a MIME type, that does not mean cairo will always be able to use the attached MIME data. For example, if the backend does not natively support the compositing operation used to apply the MIME data to the backend. In that case, the MIME data will be ignored. Therefore, to apply an image in all cases, it is best to create an image surface which contains the decoded image data and then attach the MIME data to that. This ensures the image will always be used while still allowing the MIME data to be used whenever possible.

###Parameters

• mime_type the MIME type of the image data
• data the image data to attach to the surface
• destroy a LibCairo::DestroyFuncT which will be called when the surface is destroyed or when new image data is attached using the same mime type.
• closure the data to be passed to the destroy notifier

###Returns Status::Success or Status::NoMemory if a slot could not be allocated for the user data.

Attach user data to surface. To remove user data from a surface, call this function with the key that was used to set it and Nil for data .

###Parameters

• key the address of a UserDataKey to attach the user data to
• user_data the user data to attach to the surface
• destroy a LibCairo::DestroyFuncT which will be called when the surface is destroyed or when new user data is attached using the same key.

###Returns Status#Success or Status::NoMemory if a slot could not be allocated for the user data.

Checks whether an error has previously occurred for this surface.

###Returns Status::Success, Status::NullPointer, Status::NoMemory, Status::ReadError, Status::InvalidContent, Status::InvalidFormat, or Status::InvalidVisual.

Get the stride of the image surface in bytes.

###Returns 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.

Return whether surface supports mime_type.

###Parameters

• mime_type the mime type

###Returns true if surface supports mime_type, false otherwise.

Emits and clears the current page for backends that support multiple pages. Use Surface#copy_page if you don't want to clear the page.

There is a convenience function for this that takes a cairo_t, namely Context#show_page.

This function returns the type of the backend used to create a surface. See SurfaceType for available types.

###Returns The type of surface.

Unmaps the image surface as returned from Surface#map_to_image.

The content of the image will be uploaded to the target surface. Afterwards, the image is destroyed.

Using an image surface which wasn't returned by Surface#map_to_image results in undefined behavior.

###Parameters

• image the currently mapped image

Return user data previously attached to surface using the specified key. If no user data has been attached with the given key this function returns Nil.

###Parameters

• key the address of the UserDataKey the user data was attached to

###Returns The user data previously attached or Nil.

Get the width of the image surface in pixels.

###Returns The width of the surface in pixels.

Writes the contents of surface to a new file filename as a PNG image.

###Parameters

• surface a Surface with pixel contents
• filename the name of a file to write to; on Windows this filename is encoded in UTF-8.

###Returns Status#success if the PNG file was written successfully. Otherwise, Status#NoMemory if memory could not be allocated for the operation or Status#SurfaceTypeMismatch if the surface does not have pixel contents, or Status#WriteError if an I/O error occurs while attempting to write the file, or Status#PngError if libpng returned an error.

Writes the image surface to the write function.

###Parameters

• surface a Surface with pixel contents
• write_func a Cairo::C::LibCairo::WriteFuncT
• closure closure data for the write function

###Returns Status#Success if the PNG file was written successfully. Otherwise, Status#NoMemory is returned if memory could not be allocated for the operation, Status#SurfaceTypeMismatch if the surface does not have pixel contents, or Status#PngError if libpng returned an error.