Description If gdk-pixbuf; has been compiled with GModule support, it can be extended by modules which can load (and perhaps also save) new image and animation formats. Each loadable module must export a GdkPixbufModuleFillInfoFunc function named fill_info and a GdkPixbufModuleFillVtableFunc function named fill_vtable. In order to make format-checking work before actually loading the modules (which may require dlopening image libraries), modules export their signatures (and other information) via the fill_info function. An external utility, gdk-pixbuf-query-loaders, uses this to create a text file containing a list of all available loaders and their signatures. This file is then read at runtime by gdk-pixbuf; to obtain the list of available loaders and their signatures. Modules may only implement a subset of the functionality available via GdkPixbufModule. If a particular functionality is not implemented, the fill_vtable function will simply not set the corresponding function pointers of the GdkPixbufModule structure. If a module supports incremental loading (i.e. provides begin_load, stop_load and load_increment), it doesn't have to implement load, since gdk-pixbuf; can supply a generic load implementation wrapping the incremental loading. Installing a module is a two-step process: copy the module file(s) to the loader directory (normally libdir/gtk-2.0/version/loaders, unless overridden by the environment variable GDK_PIXBUF_MODULEDIR) call gdk-pixbuf-query-loaders to update the module file (normally sysconfdir/gtk-2.0/gdk-pixbuf.loaders, unless overridden by the environment variable GDK_PIXBUF_MODULE_FILE) The gdk-pixbuf; interfaces needed for implementing modules are contained in gdk-pixbuf-io.h (and gdk-pixbuf-animation.h if the module supports animations). They are not covered by the same stability guarantees as the regular gdk-pixbuf; API. To underline this fact, they are protected by #ifdef GDK_PIXBUF_ENABLE_BACKEND.