Functions
cairo_format_stride_for_width ()
int
cairo_format_stride_for_width (cairo_format_t format,
int width);
This function provides a stride value that will respect all
alignment requirements of the accelerated image-rendering code
within cairo. Typical usage will be of the form:
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.
Since: 1.6
cairo_image_surface_create ()
cairo_surface_t *
cairo_image_surface_create (cairo_format_t format,
int width,
int height);
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).
Returns
a pointer to the newly created 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 an error such as out of memory
occurs. You can use cairo_surface_status() to check for this.
Since: 1.0
cairo_image_surface_create_for_data ()
cairo_surface_t *
cairo_image_surface_create_for_data (unsigned char *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 cairo_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.
Returns
a pointer to the newly created 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 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
CAIRO_STATUS_INVALID_STRIDE. You can use
cairo_surface_status() to check for this.
See cairo_surface_set_user_data() for a means of attaching a
destroy-notification fallback to the surface if necessary.
Since: 1.0
cairo_image_surface_get_data ()
unsigned char *
cairo_image_surface_get_data (cairo_surface_t *surface);
Get a pointer to the data of the image surface, for direct
inspection or modification.
A call to cairo_surface_flush() is required before accessing the
pixel data to ensure that all pending drawing operations are
finished. A call to cairo_surface_mark_dirty() is required after
the data is modified.
Returns
a pointer to the image data of this surface or NULL
if surface
is not an image surface, or if cairo_surface_finish()
has been called.
Since: 1.2
cairo_image_surface_get_format ()
cairo_format_t
cairo_image_surface_get_format (cairo_surface_t *surface);
Get the format of the surface.
Returns
the format of the surface
Since: 1.2
cairo_image_surface_get_width ()
int
cairo_image_surface_get_width (cairo_surface_t *surface);
Get the width of the image surface in pixels.
Returns
the width of the surface in pixels.
Since: 1.0
cairo_image_surface_get_height ()
int
cairo_image_surface_get_height (cairo_surface_t *surface);
Get the height of the image surface in pixels.
Returns
the height of the surface in pixels.
Since: 1.0
cairo_image_surface_get_stride ()
int
cairo_image_surface_get_stride (cairo_surface_t *surface);
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.
Since: 1.2
Types and Values
CAIRO_HAS_IMAGE_SURFACE
#define CAIRO_HAS_IMAGE_SURFACE 1
Defined if the image surface backend is available.
The image surface backend is always built in.
This macro was added for completeness in cairo 1.8.
Since: 1.8
enum cairo_format_t
cairo_format_t is used to identify the memory format of
image data.
New entries may be added in future versions.
Since: 1.0