You can use this function to update the size of the view camera within the room. You give the unique camera ID value (as returned by the different camera_create functions) and then give the width and height (in pixels) to set the camera to.
camera_set_view_size(camera_id, width, height)
|camera_id||The unique camera ID value returned when you created the camera.|
|width||The width of the camera view in pixels|
|height||The height of the camera view in pixels|
camera_set_view_size(view_camera, view_wport, view_hport);
The above code will set the view camera size for the camera assigned to view port.