Functions
cairo_surface_create_similar ()
cairo_surface_t *
cairo_surface_create_similar (cairo_surface_t *other,
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
device scale, 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
cairo_surface_get_type().
Initially the surface contents are all 0 (transparent if contents
have transparency, black otherwise.)
Use cairo_surface_create_similar_image() if you need an image surface
which can be painted quickly to the target surface.
Returns
a pointer to the newly allocated surface. The caller
owns the surface and should call cairo_surface_destroy() 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.
Since: 1.0
cairo_surface_create_similar_image ()
cairo_surface_t *
cairo_surface_create_similar_image (cairo_surface_t *other,
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. Unlike
cairo_surface_create_similar() the new image surface won't inherit
the device scale from other
.
Initially the surface contents are all 0 (transparent if contents
have transparency, black otherwise.)
Use cairo_surface_create_similar() if you don't need an image surface.
Returns
a pointer to the newly allocated image surface. The caller
owns the surface and should call cairo_surface_destroy() 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.
Since: 1.12
cairo_surface_create_for_rectangle ()
cairo_surface_t *
cairo_surface_create_for_rectangle (cairo_surface_t *target,
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.
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.
Returns
a pointer to the newly allocated surface. The caller
owns the surface and should call cairo_surface_destroy() 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.
Since: 1.10
cairo_surface_destroy ()
void
cairo_surface_destroy (cairo_surface_t *surface);
Decreases the reference count on surface
by one. If the result is
zero, then surface
and all associated resources are freed. See
cairo_surface_reference().
Since: 1.0
cairo_surface_status ()
cairo_status_t
cairo_surface_status (cairo_surface_t *surface);
Checks whether an error has previously occurred for this
surface.
Since: 1.0
cairo_surface_finish ()
void
cairo_surface_finish (cairo_surface_t *surface);
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 cairo_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 cairo_surface_destroy() decreases the
reference count to zero, cairo will call cairo_surface_finish() if
it hasn't been called already, before freeing the resources
associated with the surface.
Since: 1.0
cairo_surface_flush ()
void
cairo_surface_flush (cairo_surface_t *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.
Since: 1.0
cairo_surface_get_device ()
cairo_device_t *
cairo_surface_get_device (cairo_surface_t *surface);
This function returns the device for a surface
.
See cairo_device_t.
Returns
The device for surface
or NULL if the surface does
not have an associated device.
Since: 1.10
cairo_surface_get_font_options ()
void
cairo_surface_get_font_options (cairo_surface_t *surface,
cairo_font_options_t *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
cairo_scaled_font_create().
Since: 1.0
cairo_surface_get_content ()
cairo_content_t
cairo_surface_get_content (cairo_surface_t *surface);
This function returns the content type of surface
which indicates
whether the surface contains color and/or alpha information. See
cairo_content_t.
Returns
The content type of surface
.
Since: 1.2
cairo_surface_mark_dirty ()
void
cairo_surface_mark_dirty (cairo_surface_t *surface);
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 cairo_surface_flush() before doing such drawing.
Since: 1.0
cairo_surface_mark_dirty_rectangle ()
void
cairo_surface_mark_dirty_rectangle (cairo_surface_t *surface,
int x,
int y,
int width,
int height);
Like cairo_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.
Since: 1.0
cairo_surface_set_device_offset ()
void
cairo_surface_set_device_offset (cairo_surface_t *surface,
double x_offset,
double 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 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
cairo_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.
Since: 1.0
cairo_surface_set_device_scale ()
void
cairo_surface_set_device_scale (cairo_surface_t *surface,
double x_scale,
double 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.
Since: 1.14
cairo_surface_set_fallback_resolution ()
void
cairo_surface_set_fallback_resolution (cairo_surface_t *surface,
double x_pixels_per_inch,
double 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 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
cairo_surface_get_fallback_resolution ()
void
cairo_surface_get_fallback_resolution (cairo_surface_t *surface,
double *x_pixels_per_inch,
double *y_pixels_per_inch);
This function returns the previous fallback resolution set by
cairo_surface_set_fallback_resolution(), or default fallback
resolution if never set.
Since: 1.8
cairo_surface_get_reference_count ()
unsigned int
cairo_surface_get_reference_count (cairo_surface_t *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.
Since: 1.4
cairo_surface_get_user_data ()
void *
cairo_surface_get_user_data (cairo_surface_t *surface,
const 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.
Returns
the user data previously attached or NULL.
Since: 1.0
cairo_surface_copy_page ()
void
cairo_surface_copy_page (cairo_surface_t *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 cairo_surface_show_page() 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
cairo_surface_show_page ()
void
cairo_surface_show_page (cairo_surface_t *surface);
Emits and clears the current page for backends that support multiple
pages. Use cairo_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 cairo_show_page().
Since: 1.6
cairo_surface_set_mime_data ()
cairo_status_t
cairo_surface_set_mime_data (cairo_surface_t *surface,
const char *mime_type,
const unsigned char *data,
unsigned long length,
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,
CAIRO_MIME_TYPE_UNIQUE_ID, CAIRO_MIME_TYPE_JBIG2,
CAIRO_MIME_TYPE_JBIG2_GLOBAL, CAIRO_MIME_TYPE_JBIG2_GLOBAL_ID,
CAIRO_MIME_TYPE_CCITT_FAX, CAIRO_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.
Since: 1.10
cairo_surface_get_mime_data ()
void
cairo_surface_get_mime_data (cairo_surface_t *surface,
const char *mime_type,
const unsigned char **data,
unsigned long *length);
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
cairo_surface_supports_mime_type ()
cairo_bool_t
cairo_surface_supports_mime_type (cairo_surface_t *surface,
const char *mime_type);
Return whether surface
supports mime_type
.
Returns
TRUE if surface
supports
mime_type
, FALSE otherwise
Since: 1.12
cairo_surface_map_to_image ()
cairo_surface_t *
cairo_surface_map_to_image (cairo_surface_t *surface,
const 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 cairo_surface_destroy() or
cairo_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.
Returns
a pointer to the newly allocated image surface. The caller
must use cairo_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 CAIRO_FORMAT_INVALID.
Since: 1.12
Types and Values
CAIRO_HAS_MIME_SURFACE
#define CAIRO_HAS_MIME_SURFACE 1
CAIRO_MIME_TYPE_CCITT_FAX
#define CAIRO_MIME_TYPE_CCITT_FAX "image/g3fax"
Group 3 or Group 4 CCITT facsimile encoding (International
Telecommunication Union, Recommendations T.4 and T.6.)
Since: 1.16
CAIRO_MIME_TYPE_CCITT_FAX_PARAMS
#define CAIRO_MIME_TYPE_CCITT_FAX_PARAMS "application/x-cairo.ccitt.params"
Decode parameters for Group 3 or Group 4 CCITT facsimile encoding.
See CCITT Fax Images.
Since: 1.16
CAIRO_MIME_TYPE_EPS_PARAMS
#define CAIRO_MIME_TYPE_EPS_PARAMS "application/x-cairo.eps.params"
Embedding parameters Encapsulated PostScript data.
See Embedding EPS files.
Since: 1.16
CAIRO_MIME_TYPE_JBIG2
#define CAIRO_MIME_TYPE_JBIG2 "application/x-cairo.jbig2"
Joint Bi-level Image Experts Group image coding standard (ISO/IEC 11544).
Since: 1.14
CAIRO_MIME_TYPE_JBIG2_GLOBAL
#define CAIRO_MIME_TYPE_JBIG2_GLOBAL "application/x-cairo.jbig2-global"
Joint Bi-level Image Experts Group image coding standard (ISO/IEC 11544) global segment.
Since: 1.14
CAIRO_MIME_TYPE_JBIG2_GLOBAL_ID
#define CAIRO_MIME_TYPE_JBIG2_GLOBAL_ID "application/x-cairo.jbig2-global-id"
An unique identifier shared by a JBIG2 global segment and all JBIG2 images
that depend on the global segment.
Since: 1.14
CAIRO_MIME_TYPE_JP2
#define CAIRO_MIME_TYPE_JP2 "image/jp2"
The Joint Photographic Experts Group (JPEG) 2000 image coding standard (ISO/IEC 15444-1).
Since: 1.10
CAIRO_MIME_TYPE_JPEG
#define CAIRO_MIME_TYPE_JPEG "image/jpeg"
The Joint Photographic Experts Group (JPEG) image coding standard (ISO/IEC 10918-1).
Since: 1.10
CAIRO_MIME_TYPE_PNG
#define CAIRO_MIME_TYPE_PNG "image/png"
The Portable Network Graphics image file format (ISO/IEC 15948).
Since: 1.10
CAIRO_MIME_TYPE_URI
#define CAIRO_MIME_TYPE_URI "text/x-uri"
URI for an image file (unofficial MIME type).
Since: 1.10
CAIRO_MIME_TYPE_UNIQUE_ID
#define CAIRO_MIME_TYPE_UNIQUE_ID "application/x-cairo.uuid"
Unique identifier for a surface (cairo specific MIME type). All surfaces with
the same unique identifier will only be embedded once.
Since: 1.12
enum cairo_content_t
cairo_content_t is used to describe the content that a surface will
contain, whether color information, alpha information (translucence
vs. opacity), or both.
Note: The large values here are designed to keep cairo_content_t
values distinct from cairo_format_t values so that the
implementation can detect the error if users confuse the two types.
Since: 1.0
enum cairo_surface_type_t
cairo_surface_type_t is used to describe the type of a given
surface. The surface types are also known as "backends" or "surface
backends" within cairo.
The type of a surface is determined by the function used to create
it, which will generally be of the form
cairo_type_surface_create(),
(though see cairo_surface_create_similar() as well).
The surface type can be queried with cairo_surface_get_type()
The various cairo_surface_t functions can be used with surfaces of
any type, but some backends also provide type-specific functions
that must only be called with a surface of the appropriate
type. These functions have names that begin with
cairo_type_surface such as cairo_image_surface_get_width().
The behavior of calling a type-specific function with a surface of
the wrong type is undefined.
New entries may be added in future versions.
Since: 1.2