Deconstructing animations

[Matthias Clasen <maclas gmx de>]

The gdk-pixbuf animation api is nicely abstract and relieves
applications from the need to deal with frames themselves. 

What is not so nice is that this abstract interface is the only one
offered, so that it is not even possible to work on a frame level inside
gtk+/gdk/gdk-pixbuf. 

Examples where one needs to obtain a "collection of frames" view of an
animation are:

- creating an animated cursor 

- saving an animation

- modifying an animation, e.g. reversing it.

Therefore, I'd like to propose that we add a way to construct a
collection of frame from an animation (and probably vice versa).
Possible interface:

 void gdk_pixbuf_animation_get_frames (GdkPixbufAnimation *animation,
                                       GdkPixbufAnimationFrame **frames,
                                       gint                 *n_frames);


The minimal api addition that is necessary to allow reliable
reconstruction of the frames would be a way to find out when an iter
starts to loop:

gint gdk_pixbuf_animation_iter_get_loop (GdkPixbufAnimationIter *iter);

then one could "harvest" the frames by iterating once over the
animation.

Matthias