const cairo_region_t* region
Renders the scene graph, described by a tree of
to the renderer’s surface, ensuring that the given
region gets redrawn.
If the renderer has no associated surface, this function does nothing.
Renderers must ensure that changes of the contents given by the
node as well as the area given by
region are redrawn. They are however
free to not redraw any pixel outside of
region if they can guarantee that
it didn’t change.
renderer will acquire a reference on the
GskRenderNode tree while
the rendering is in progress.