This command creates a viewport
which leads to canvas.
The viewport is drawn on the
screen at co-ordinates x1,y1 to x2,y2.
A viewport is an area of the
screen which can be 'seen through' to the canvas below it. All
sprites, buttons and backgrounds that are in the canvas are copied
to the screen inside the viewport.
Every time Draw
Frame is called then the viewport is updated just like the
rest of the screen.
Note: Once a viewport has been drawn to the screen
the contents of that area of canvas 0 are overwritten with the
contents of the viewport.
The canvas underneath the viewport
can be larger than the display area. In this case, only a certain
area of the canvas is drawn to the screen. This can be used to
produce scrolling effects (see Set
Viewport Offset).
A viewport can be removed from
the display with the function Close
Viewport.