This function can be used to set the height of the given view port. You give the view port index (from 0 to 7) and the new height to use.
Argument Description view_port The view port to target (0 - 7) h The new height (in pixels)
if view_get_hport(0) != (display_get_height () /
view_set_hport(0, display_get_height() / 2);
The above code will check the height of the view port and if it is not half of the display height it is set to that value.