| Top |  |
 |
 |
 |
Image Data in MemoryImage Data in Memory — Creating a pixbuf from image data that is already in memory. |
Description
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.
Functions
gdk_pixbuf_new ()
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.
Parameters
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.
[nullable]
gdk_pixbuf_new_from_bytes ()
GdkPixbuf * gdk_pixbuf_new_from_bytes (GBytes *data,GdkColorspace colorspace,gboolean has_alpha,int bits_per_sample,int width,int height,int rowstride);
Creates a new GdkPixbuf out of in-memory readonly image data.
Currently only RGB images with 8 bits per sample are supported.
This is the GBytes variant of gdk_pixbuf_new_from_data().
Parameters
data |
Image data in 8-bit/sample packed format inside a GBytes |
|
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 |
Since: 2.32
gdk_pixbuf_new_from_data ()
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.
Since you are providing a pre-allocated pixel buffer, you must also specify a way to free that data. This is done with a function of type GdkPixbufDestroyNotify. When a pixbuf created with is finalized, your destroy notification function will be called, and it is its responsibility to free the pixel array.
See also gdk_pixbuf_new_from_bytes().
Parameters
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 |
|
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 |
[scope async][allow-none] |
destroy_fn_data |
Closure data to pass to the destroy notification function. |
[closure] |
gdk_pixbuf_new_from_xpm_data ()
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.
gdk_pixbuf_new_from_inline ()
GdkPixbuf * gdk_pixbuf_new_from_inline (gint data_length,const guint8 *data,gboolean copy_pixels,GError **error);
gdk_pixbuf_new_from_inline has been deprecated since version 2.32 and should not be used in newly-written code.
Use GResource instead.
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:
1 |
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:
1 |
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.
Parameters
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
|
|
error |
GError return location, may be |
Returns
A newly-created GdkPixbuf structure with a reference,
count of 1, or NULL if an error occurred.
gdk_pixbuf_new_subpixbuf ()
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.
Note that if src_pixbuf
is read-only, this function will force it
to be mutable.
gdk_pixbuf_copy ()
GdkPixbuf *
gdk_pixbuf_copy (const GdkPixbuf *pixbuf);
Creates a new GdkPixbuf with a copy of the information in the specified
pixbuf
. Note that this does not copy the options set on the original GdkPixbuf,
use gdk_pixbuf_copy_options() for this.