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To scroll an area of the current drawing surface.




This routine allows you to scroll an area the drawing surface. The direction of scrolling is set by the two variables DX and DY. They represent the displacement the image will be copied to. For DX, values less than 0 will move the image left and values greater than 0 will move the image right by the relevant number of pixels. For DY, values less than 0 will move the image up and values greater then 0 will move the image down by the relevant number of pixels.

The LEFT, TOP, RIGHT, BOTTOM arguments define the area to be moved. This can be the whole surface or a sub region within the whole.

SWITCH can either be set to 0 or 1. If it is set to 1 then the area that becomes invalid is set to the COLOUR specified by the final argument (using the current colour mode). If it is 0 then the invalid region is left unchanged. You should note that this is a copy routine not a move and the region of the screen that is not copied will not be automatically modified.

See also




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