callback with this that will be called whenever the
this framebuffer changes size.
callback can be removed using remove_resize_callback
passing the returned closure pointer.
<note>Since Cogl automatically updates the viewport of an this framebuffer that is resized, a resize callback can also be used to track when the viewport has been changed automatically by Cogl in case your application needs more specialized control over the viewport.</note>
<note>A resize callback will only ever be called while dispatching Cogl events from the system mainloop; so for example during poll_renderer_dispatch. This is so that callbacks shouldn't occur while an application might have arbitrary locks held for example.</note>
A Onscreen framebuffer
A OnscreenResizeCallback to call when the this changes size.
An optional callback to destroy
Private data to be passed to
a OnscreenResizeClosure pointer that can be used to remove the
callback and associated