|The gdk-pixbuf Library|
Image Data in Memory
Image 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 malloc() and then wrapping it with 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.|
|height :||Height of image in pixels.|
|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.|
|height :||Height of the image in pixels.|
|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|
|<< File saving||Inline data >>|