ImageSurface

Image surfaces provide the ability to render to memory buffers either allocated by cairo or by the calling code. The supported image formats are those defined in cairo_format_t.

Constructors

this
this(cairo_surface_t* cairo_surface)

Sets our main struct and passes it to the parent class

Members

Functions

getData
ubyte* getData()

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.markDirty is required after the data is modified. Since 1.2

getFormat
cairo_format_t getFormat()

Get the format of the surface. Since 1.2

getHeight
int getHeight()

Get the height of the image surface in pixels. Since 1.0

getImageSurfaceStruct
cairo_surface_t* getImageSurfaceStruct()

Get the main Gtk struct

getStride
int getStride()

Get the stride of the image surface in bytes Since 1.2

getStruct
void* getStruct()

the main Gtk struct as a void*

getWidth
int getWidth()

Get the width of the image surface in pixels. Since 1.0

writeToPng
cairo_status_t writeToPng(string filename)

Writes the contents of surface to a new file filename as a PNG image. Since 1.0

writeToPngStream
cairo_status_t writeToPngStream(cairo_write_func_t writeFunc, void* closure)

Writes the image surface to the write function. Since 1.0

Static functions

create
ImageSurface create(cairo_format_t format, int width, int height)

Creates an image surface of the specified format and dimensions. Initially the surface contents are all 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). Since 1.0

createForData
ImageSurface createForData(ubyte* data, cairo_format_t format, int width, int height, int stride)

Creates an image surface for the provided pixel data. The output buffer must be kept around until the cairo_surface_t 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, cairo_rectangle() and cairo_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 cairo_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 cairo_format_stride_for_width() for example code. Since 1.0

createFromPng
ImageSurface createFromPng(string filename)

Creates a new image surface and initializes the contents to the given PNG file. Since 1.0

createFromPngStream
ImageSurface createFromPngStream(cairo_read_func_t readFunc, void* closure)

Creates a new image surface from PNG data read incrementally via the read_func function. Since 1.0

formatStrideForWidth
int formatStrideForWidth(cairo_format_t format, int width)

This function provides a stride value that will respect all alignment requirements of the accelerated image-rendering code Since 1.6

Variables

cairo_surface
cairo_surface_t* cairo_surface;

the main Gtk struct

Inherited Members

From Surface

cairo_surface
cairo_surface_t* cairo_surface;

the main Gtk struct

getSurfaceStruct
cairo_surface_t* getSurfaceStruct()

Get the main Gtk struct

getStruct
void* getStruct()

the main Gtk struct as a void*

getMimeData
void getMimeData(string mimeType, out ubyte[] data)

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 NULL. Since 1.10

createSimilar
Surface createSimilar(cairo_content_t content, int width, int height)

Create a new surface that is as compatible as possible with an existing surface. For example the new surface will have the same fallback resolution and font options as other. Generally, the new surface will also use the same backend as other, unless that is not possible for some reason. The type of the returned surface may be examined with Surface.getType. Initially the surface contents are all 0 (transparent if contents have transparency, black otherwise.) Use Surface.createSimilarImage if you need an image surface which can be painted quickly to the target surface. Since 1.0

createSimilarImage
Surface createSimilarImage(cairo_format_t format, int width, int height)

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. Initially the surface contents are all 0 (transparent if contents have transparency, black otherwise.) Use Surface.createSimilar if you don't need an image surface. Since 1.12

createForRectangle
Surface createForRectangle(double x, double y, double width, double height)

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. Note 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. Since 1.10

reference
Surface reference()

Increases the reference count on surface by one. This prevents surface from being destroyed until a matching call to Surface.destroy is made. The number of references to a cairo_surface_t can be get using Surface.getReferenceCount. Since 1.0

destroy
void destroy()

Decreases the reference count on surface by one. If the result is zero, then surface and all associated resources are freed. See Surface.reference. Since 1.0

status
cairo_status_t status()

Checks whether an error has previously occurred for this surface. Since 1.0

finish
void finish()

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 CAIRO_STATUS_SURFACE_FINISHED error. When the last call to Surface.destroy 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. Since 1.0

flush
void flush()

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. If the surface doesn't support direct access, then this function does nothing. Since 1.0

getDevice
Device getDevice()

This function returns the device for a surface. See cairo_device_t. Since 1.10

getFontOptions
void getFontOptions(FontOption 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.create. Since 1.0

getContent
cairo_content_t getContent()

This function returns the content type of surface which indicates whether the surface contains color and/or alpha information. See cairo_content_t. Since 1.2

markDirty
void markDirty()

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. Since 1.0

markDirtyRectangle
void markDirtyRectangle(int x, int y, int width, int height)

Like Surface.markDirty, 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. Since 1.0

setDeviceOffset
void setDeviceOffset(double xOffset, double yOffset)

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 cairo_surface_t 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 cairo_translate() isn't sufficient to do this, since functions like Device.toUser will expose the hidden offset. Note that the offset affects drawing to the surface as well as using the surface in a source pattern. Since 1.0

getDeviceOffset
void getDeviceOffset(out double xOffset, out double yOffset)

This function returns the previous device offset set by Surface.setDeviceOffset. Since 1.2

setFallbackResolution
void setFallbackResolution(double xPixelsPerInch, double yPixelsPerInch)

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 cairo_show_page() or cairo_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. Since 1.2

getFallbackResolution
void getFallbackResolution(out double xPixelsPerInch, out double yPixelsPerInch)

This function returns the previous fallback resolution set by Surface.setFallbackResolution, or default fallback resolution if never set. Since 1.8

getType
cairo_surface_type_t getType()

This function returns the type of the backend used to create a surface. See cairo_surface_type_t for available types. Since 1.2

getReferenceCount
uint getReferenceCount()

Returns the current reference count of surface. Since 1.4

setUserData
cairo_status_t setUserData(cairo_user_data_key_t* key, void* userData, cairo_destroy_func_t destroy)

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 NULL for data. Since 1.0

getUserData
void* getUserData(cairo_user_data_key_t* key)

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 NULL. Since 1.0

copyPage
void copyPage()

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.showPage if you want to get an empty page after the emission. There is a convenience function for this that takes a cairo_t, namely cairo_copy_page(). Since 1.6

showPage
void showPage()

Emits and clears the current page for backends that support multiple pages. Use Surface.copyPage if you don't want to clear the page. There is a convenience function for this that takes a cairo_t, namely cairo_show_page(). Since 1.6

hasShowTextGlyphs
cairo_bool_t hasShowTextGlyphs()

Returns whether the surface supports sophisticated cairo_show_text_glyphs() operations. That is, whether it actually uses the provided text and cluster data to a cairo_show_text_glyphs() call. Note: Even if this function returns FALSE, a cairo_show_text_glyphs() operation targeted at surface will still succeed. It just will act like a cairo_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. Since 1.8

setMimeData
cairo_status_t setMimeData(string mimeType, ubyte[] data, cairo_destroy_func_t destroy, void* closure)

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 NULL 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: CAIRO_MIME_TYPE_JPEG, CAIRO_MIME_TYPE_PNG, CAIRO_MIME_TYPE_JP2, CAIRO_MIME_TYPE_URI. 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. Since 1.10

supportsMimeType
cairo_bool_t supportsMimeType(string mimeType)

Return whether surface supports mime_type. Since 1.12

mapToImage
Surface mapToImage(ref cairo_rectangle_int_t extents)

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 NULL 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.destroy or Surface.finish on the resulting image surface results in undefined behavior. Since 1.12

unmapImage
void unmapImage(Surface image)

Unmaps the image surface as returned from cairo_surface_map_to_image|cairo_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.mapToImage results in undefined behavior. Since 1.12