current.time would normally come from g, and
must be greater than or equal to the time passed to
gdkPixbufAnimationGetIter, and must increase or remain
unchanged each time gdkPixbufAnimationIterGetPixbuf is
called. That is, you can't go backward in time; animations only
play forward.
As a shortcut, pass NULL for the current time and g
will be invoked on your behalf. So you only need to explicitly pass
current.time if you're doing something odd like playing the animation
at double speed.
If this function returns FALSE, there's no need to update the animation
display, assuming the display had been rendered prior to advancing;
if TRUE, you need to call gdk() and update the
display with the new pixbuf.[logical] TRUE if the image may need updating
[object Object]
internal