pixmap.return
and mask.return arguments, respectively, and renders a pixbuf and its
corresponding thresholded 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 gdkDrawPixbuf and gdkPixbufRenderThresholdAlpha.gdkPixbufRenderPixmapAndMask(object, alpha.threshold = 127)objectalpha.thresholdpixmap.returnNULL if the pixmap is not needed.mask.returnNULL if the mask is not needed.gdkRgbGetColormap. You normally will want to instead use
the actual colormap for a widget, and use
gdkPixbufRenderPixmapAndMaskForColormap.
If the pixbuf does not have an alpha channel, then *mask.return will be set
to NULL.