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The gdk-pixbuf Library | ![]() |
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Image Data in MemoryImage Data in Memory — Creating a pixbuf from image data that is already in memory. |
#include <gdk-pixbuf/gdk-pixbuf.h> GdkPixbuf* gdk_pixbuf_new (GdkColorspace colorspace, gboolean has_alpha, int bits_per_sample, int width, int height); GdkPixbuf* gdk_pixbuf_new_from_data (const guchar *data, GdkColorspace colorspace, gboolean has_alpha, int bits_per_sample, int width, int height, int rowstride, GdkPixbufDestroyNotify destroy_fn, gpointer destroy_fn_data); GdkPixbuf* gdk_pixbuf_new_from_xpm_data (const char **data); GdkPixbuf* gdk_pixbuf_new_from_inline (gint data_length, const guint8 *data, gboolean copy_pixels, GError **error); GdkPixbuf* gdk_pixbuf_new_subpixbuf (GdkPixbuf *src_pixbuf, int src_x, int src_y, int width, int height); GdkPixbuf* gdk_pixbuf_copy (const GdkPixbuf *pixbuf);
The most basic way to create a pixbuf is to wrap an existing pixel
buffer with a GdkPixbuf structure. You can use the
gdk_pixbuf_new_from_data()
function to do this You need to specify
the destroy notification function that will be called when the
data buffer needs to be freed; this will happen when a GdkPixbuf
is finalized by the reference counting functions If you have a
chunk of static data compiled into your application, you can pass
in NULL
as the destroy notification function so that the data
will not be freed.
The gdk_pixbuf_new()
function can be used as a convenience to
create a pixbuf with an empty buffer. This is equivalent to
allocating a data buffer using
and
then wrapping it with malloc()
gdk_pixbuf_new_from_data()
. The gdk_pixbuf_new()
function will compute an optimal rowstride so that rendering can be
performed with an efficient algorithm.
As a special case, you can use the gdk_pixbuf_new_from_xpm_data()
function to create a pixbuf from inline XPM image data.
You can also copy an existing pixbuf with the gdk_pixbuf_copy()
function. This is not the same as just doing a g_object_ref()
on the old pixbuf; the copy function will actually duplicate the
pixel data in memory and create a new GdkPixbuf structure for it.
GdkPixbuf* gdk_pixbuf_new (GdkColorspace colorspace, gboolean has_alpha, int bits_per_sample, int width, int height);
Creates a new GdkPixbuf structure and allocates a buffer for it. The buffer has an optimal rowstride. Note that the buffer is not cleared; you will have to fill it completely yourself.
colorspace : |
Color space for image |
has_alpha : |
Whether the image should have transparency information |
bits_per_sample : |
Number of bits per color sample |
width : |
Width of image in pixels, must be > 0 |
height : |
Height of image in pixels, must be > 0 |
Returns : | A newly-created GdkPixbuf with a reference count of 1, or
NULL if not enough memory could be allocated for the image buffer.
|
GdkPixbuf* gdk_pixbuf_new_from_data (const guchar *data, GdkColorspace colorspace, gboolean has_alpha, int bits_per_sample, int width, int height, int rowstride, GdkPixbufDestroyNotify destroy_fn, gpointer destroy_fn_data);
Creates a new GdkPixbuf out of in-memory image data. Currently only RGB images with 8 bits per sample are supported.
data : |
Image data in 8-bit/sample packed format |
colorspace : |
Colorspace for the image data |
has_alpha : |
Whether the data has an opacity channel |
bits_per_sample : |
Number of bits per sample |
width : |
Width of the image in pixels, must be > 0 |
height : |
Height of the image in pixels, must be > 0 |
rowstride : |
Distance in bytes between row starts |
destroy_fn : |
Function used to free the data when the pixbuf's reference count
drops to zero, or NULL if the data should not be freed
|
destroy_fn_data : |
Closure data to pass to the destroy notification function |
Returns : | A newly-created GdkPixbuf structure with a reference count of 1. |
GdkPixbuf* gdk_pixbuf_new_from_xpm_data (const char **data);
Creates a new pixbuf by parsing XPM data in memory. This data is commonly the result of including an XPM file into a program's C source.
data : |
Pointer to inline XPM data. |
Returns : | A newly-created pixbuf with a reference count of 1. |
GdkPixbuf* gdk_pixbuf_new_from_inline (gint data_length, const guint8 *data, gboolean copy_pixels, GError **error);
Create a GdkPixbuf from a flat representation that is suitable for storing as inline data in a program. This is useful if you want to ship a program with images, but don't want to depend on any external files.
GTK+ ships with a program called gdk-pixbuf-csource
which allows for conversion of GdkPixbufs into such a inline representation.
In almost all cases, you should pass the --raw
flag to
gdk-pixbuf-csource. A sample invocation would be:
gdk-pixbuf-csource --raw --name=myimage_inline myimage.png
For the typical case where the inline pixbuf is read-only static data,
you don't need to copy the pixel data unless you intend to write to
it, so you can pass FALSE
for copy_pixels
. (If you pass
--rle
to gdk-pixbuf-csource, a copy
will be made even if copy_pixels
is FALSE
, so using this option is
generally a bad idea.)
If you create a pixbuf from const inline data compiled into your program, it's probably safe to ignore errors and disable length checks, since things will always succeed:
pixbuf = gdk_pixbuf_new_from_inline (-1, myimage_inline, FALSE, NULL);
For non-const inline data, you could get out of memory. For untrusted inline data located at runtime, you could have corrupt inline data in addition.
data_length : |
Length in bytes of the data argument or -1 to
disable length checks
|
data : |
Byte data containing a serialized GdkPixdata structure |
copy_pixels : |
Whether to copy the pixel data, or use direct pointers
data for the resulting pixbuf
|
error : |
GError return location, may be NULL to ignore errors
|
Returns : | A newly-created GdkPixbuf structure with a reference,
count of 1, or NULL if an error occurred.
|
GdkPixbuf* gdk_pixbuf_new_subpixbuf (GdkPixbuf *src_pixbuf, int src_x, int src_y, int width, int height);
Creates a new pixbuf which represents a sub-region of
src_pixbuf
. The new pixbuf shares its pixels with the
original pixbuf, so writing to one affects both.
The new pixbuf holds a reference to src_pixbuf
, so
src_pixbuf
will not be finalized until the new pixbuf
is finalized.
src_pixbuf : |
a GdkPixbuf |
src_x : |
X coord in src_pixbuf
|
src_y : |
Y coord in src_pixbuf
|
width : |
width of region in src_pixbuf
|
height : |
height of region in src_pixbuf
|
Returns : | a new pixbuf |