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Image Data in MemoryImage Data in Memory — Creating a pixbuf from image data that is already in memory. |
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.
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. |
[array] |
colorspace |
Colorspace for the image data |
|
has_alpha |
Whether the data has an opacity channel |
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bits_per_sample |
Number of bits per sample |
|
width |
Width of the image in pixels, must be > 0 |
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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 |
[scope async][allow-none] |
destroy_fn_data |
Closure data to pass to the destroy notification function. |
[closure] |
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.
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.
gdk-pixbuf 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 option to
gdk-pixbuf-csource. A sample invocation would be:
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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:
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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 |
Byte data containing a serialized GdkPixdata structure. |
[array length=data_length] |
copy_pixels |
Whether to copy the pixel data, or use direct pointers
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error |
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.