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>Converting Applications to gdk-pixbuf</TITLE
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TITLE="The gdk-pixbuf Library"
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TITLE="Porting applications from Imlib to gdk-pixbuf"
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TITLE="Differences between Imlib and gdk-pixbuf"
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NAME="AEN3767">Converting Applications to <SPAN
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> This sections describes the actual changes you need to make in
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> program to make it use <SPAN
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NAME="AEN3773">Image loading and creation</H2
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> library can load image files synchronously
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(i.e. with a single function call), create images from RGB
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data in memory, and as a convenience, it can also create
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images from inline XPM data.
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> To load an image file in a single function call, simply use
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>gdk_pixbuf_new_from_file()</TT
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this will make the program block until the whole file has
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been read. This function effectively replaces
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>gdk_imlib_load_image()</TT
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> If you have RGB data in memory, you can use
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>gdk_pixbuf_new_from_data()</TT
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pixbuf out of it; this is a replacement for
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>gdk_imlib_create_image_from_data()</TT
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> does not copy the image data; it is up to you
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to define the ownership policy by providing a destroy
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notification function that will be called when the image
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data needs to be freed. The function you provide can then
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free the data or do something else, as appropriate.
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> As a convenience, you can use the
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>gdk_pixbuf_new_from_xpm_data()</TT
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to create a pixbuf out of inline XPM data that was compiled
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into your C program. This is a replacement for
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>gdk_imlib_create_image_from_xpm_data()</TT
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> After you have created a pixbuf, you can manipulate it in
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any way you please and then finally call
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>gdk_pixbuf_unref()</TT
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with it. This can be thought of as a replacement for
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>gdk_imlib_destroy_image()</TT
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NAME="AEN3790">Rendering Images</H2
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> Applications that use <SPAN
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>gdk_imlib_render()</TT
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> to render the whole
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image data onto a pixmap that <SPAN
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must copy that pixmap's data into the final destination for
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> provides convenience functions to
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render arbitrary rectangular regions of an image onto a
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drawable that your application provides. You can use
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>gdk_pixbuf_render_to_drawable()</TT
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>gdk_pixbuf_render_to_drawable_alpha()</TT
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to do this; having your application provide the destination
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drawable and specify an arbitrary region means your
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application has complete control over the way images are
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> As a convenience, <SPAN
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>gdk_pixbuf_render_pixmap_and_mask()</TT
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function; this will create new pixmap and mask drawables for
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a whole pixbuf and render the image data onto them. Only
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trivially simple applications should find a use for this
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function, since usually you want finer control of how things
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NAME="AEN3803">Scaling Images</H2
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> lets you render scaled image data at the time you
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>gdk_imlib_render()</TT
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unfortunately scales and renders the whole image onto a new
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> provides a number of functions that do scaling
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of arbitrary regions of a source pixbuf onto a destination
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one. These functions can also perform compositing
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operations against the data in the destination pixbuf or
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against a solid color or a colored checkerboard.
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> Very simple applications may find it sufficient to use
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>gdk_pixbuf_scale_simple()</TT
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>gdk_pixbuf_composite_color_simple()</TT
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These functions scale the whole source image at a time and
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create a new pixbuf with the result.
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> More sophisticated applications will need to use
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>gdk_pixbuf_scale()</TT
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>gdk_pixbuf_composite()</TT
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>gdk_pixbuf_composite_color()</TT
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These functions let you scale and composite an arbitrary
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region of the source pixbuf onto a destination pixbuf that
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NAME="AEN3820">Getting Image Data from a Drawable</H2
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> lets you create an image by fetching a drawable's
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contents from the X server and converting those into RGB
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data. This is done with the
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>gdk_imlib_create_image_from_drawable()</TT
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>gdk_pixbuf_get_from_drawable()</TT
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instead. It lets you specify a destination pixbuf instead
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of always creating a new one for you.
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HREF="x3767.html#AEN3810"
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> You can use a colored checkerboard as the background for
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compositing when you want to provide a visual indication
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that the image has partially opaque areas. This is
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normally used in image editing and viewing programs.
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> Compositing against a single solid color is actually a
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special case of a checkerboard; it simply uses checks of
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