Drawing surfaces

ClearWin+ includes a library of drawing routines for drawing lines and text, for filling areas, for copying from one place to another, etc.. These drawing routines are applied to the current drawing surface. This surface could be one of a number of rectangular areas of the screen generated by %gr, it could be one of a number of printer bitmaps (created for example by OPEN_PRINTER@) or it might be an internal bitmap created by CREATE_GRAPHICS_REGION@ (that is, a bitmap that is created for copying to another drawing surface). SELECT_GRAPHICS_OBJECT@ is used to switch from one drawing surface to another.



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