jaysun@omni.eng.clemson.edu (Jay) (05/09/89)
I have already posted this to comp.graphics but have got no answers so please help me out. I am interested in an easy way to clear a canvas without having to write my own repaint proc. I have tried changing CANVAS_AUTO_CLEAR to TRUE but this does not SEEM to work. The manual says "... if the attribute CANVAS_AUTO_CLEAR is TRUE, the canvas package will clear the repaint area before calling your repaint procedure". Does this mean I have to have my own repaint proc for this to occur????? Any help on this will be much appriciated as I am a relative newcomer to sunview prog. Jay Williamson Engineering Computer Operations jaysun@eng.clemson.edu Clemson University Jay Williamson <jaysun@eng.clemson.edu>
ellery@trantor.harris-atd.com (Ellery Chan) (05/12/89)
The easiest way that I know to clear a canvas is: pw_writebackground (canvas_pixwin(canvas), 0, 0, width, height, PIX_SRC); or, for color canvases: pw_writebackground (canvas_pixwin(canvas), 0, 0, width, height, PIX_SRC | PIX_COLOR(bg_color)); You only need to supply your own repaint procedure if you want to refresh the display manually when previously covered parts of your canvas become exposed. If CANVAS_RETAINED is set to TRUE, the canvas is repainted automatically from a backing pixrect kept in memory. I hope this helps. Ellery Chan | ARPA : ellery@trantor.harris-atd.com Harris Corp., MS 3A-1912 | USENET: ...!uunet!x102a!trantor!ellery PO Box 37, Melbourne, FL 32902 | AT&T : (407) 729-3364