Get an iterator for displaying an animation.
The iterator provides the frames that should be displayed at a given time.
start_time would normally come from TimeVal, and marks
the beginning of animation playback. After creating an iterator, you should immediately display the pixbuf returned by
get_pixbuf. Then, you should install a timeout
g_timeout_add) or by some other mechanism ensure that you'll update the image after
get_delay_time milliseconds. Each time the
image is updated, you should reinstall the timeout with the new, possibly-changed delay time.
As a shortcut, if
start_time is `NULL`, the result of
TimeVal will be used automatically.
If you're using PixbufLoader, in addition to updating the image after the delay time, you should also update it whenever you receive the area_updated signal and on_currently_loading_frame returns `TRUE`. In this case, the frame currently being fed into the loader has received new data, so needs to be refreshed. The delay time for a frame may also be modified after an area_updated signal, for example if the delay time for a frame is encoded in the data after the frame itself. So your timeout should be reinstalled after any area_updated signal.
A delay time of -1 is possible, indicating "infinite".
time when the animation starts playing
an iterator to move over the animation