If you want to copy a rect FROM the backbuffer TO the backbuffer, in OpenGL at least you can use glCopyPixels()
You could also use glCopyTexSubImage2D() to copy into a texture then draw the texture.
Otherwise in non-OpenGL specific, use GrabPixmap, then create a second pixmap the size you want, then use Pixmap.paste, then DrawPixmap.
You could also use glCopyTexSubImage2D() to copy into a texture then draw the texture.
Otherwise in non-OpenGL specific, use GrabPixmap, then create a second pixmap the size you want, then use Pixmap.paste, then DrawPixmap.