gdk_pixbuf_xlib_render_threshold_alpha ()

void        gdk_pixbuf_xlib_render_threshold_alpha
                                            (GdkPixbuf *pixbuf,
                                             Pixmap bitmap,
                                             int src_x,
                                             int src_y,
                                             int dest_x,
                                             int dest_y,
                                             int width,
                                             int height,
                                             int alpha_threshold);

Takes the opacity values in a rectangular portion of a pixbuf and thresholds them to produce a bi-level alpha mask that can be used as a clipping mask for a drawable.

gdk_pixbuf_xlib_render_to_drawable ()

void        gdk_pixbuf_xlib_render_to_drawable
                                            (GdkPixbuf *pixbuf,
                                             Drawable drawable,
                                             GC gc,
                                             int src_x,
                                             int src_y,
                                             int dest_x,
                                             int dest_y,
                                             int width,
                                             int height,
                                             XlibRgbDither dither,
                                             int x_dither,
                                             int y_dither);

Renders a rectangular portion of a pixbuf to a drawable while using the specified GC. This is done using XlibRGB, so the specified drawable must have the XlibRGB visual and colormap. Note that this function will ignore the opacity information for images with an alpha channel; the GC must already have the clipping mask set if you want transparent regions to show through.

For an explanation of dither offsets, see the XlibRGB documentation. In brief, the dither offset is important when re-rendering partial regions of an image to a rendered version of the full image, or for when the offsets to a base position change, as in scrolling. The dither matrix has to be shifted for consistent visual results. If you do not have any of these cases, the dither offsets can be both zero.

gdk_pixbuf_xlib_render_to_drawable_alpha ()

void        gdk_pixbuf_xlib_render_to_drawable_alpha
                                            (GdkPixbuf *pixbuf,
                                             Drawable drawable,
                                             int src_x,
                                             int src_y,
                                             int dest_x,
                                             int dest_y,
                                             int width,
                                             int height,
                                             GdkPixbufAlphaMode alpha_mode,
                                             int alpha_threshold,
                                             XlibRgbDither dither,
                                             int x_dither,
                                             int y_dither);

Renders a rectangular portion of a pixbuf to a drawable. This is done using XlibRGB, so the specified drawable must have the XlibRGB visual and colormap.

When used with GDK_PIXBUF_ALPHA_BILEVEL, this function has to create a bitmap out of the thresholded alpha channel of the image and, it has to set this bitmap as the clipping mask for the GC used for drawing. This can be a significant performance penalty depending on the size and the complexity of the alpha channel of the image. If performance is crucial, consider handling the alpha channel yourself (possibly by caching it in your application) and using gdk_pixbuf_xlib_render_to_drawable() or GdkRGB directly instead.

gdk_pixbuf_xlib_render_pixmap_and_mask ()

void        gdk_pixbuf_xlib_render_pixmap_and_mask
                                            (GdkPixbuf *pixbuf,
                                             Pixmap *pixmap_return,
                                             Pixmap *mask_return,
                                             int alpha_threshold);

Creates a pixmap and a mask bitmap which are returned in the pixmap_return and mask_return arguments, respectively, and renders a pixbuf and its corresponding tresholded alpha mask to them. This is merely a convenience function; applications that need to render pixbufs with dither offsets or to given drawables should use gdk_pixbuf_xlib_render_to_drawable_alpha() or gdk_pixbuf_xlib_render_to_drawable(), and gdk_pixbuf_xlib_render_threshold_alpha().

If the pixbuf does not have an alpha channel, then *mask_return will be set to None.