XOR mode for drawing lines

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From: Dr. Norbert R. Nowaczyk (nowa@gfz-potsdam.de)
Date: Thu 05 Apr 2001 - 16:19:52 IST


Dear Ladies and Gentlemen,

I have started to port C graphics programs from MSDOS using Borland Turbo C
to Linux using SVGAlib. As far as I recognized (as a beginner), there is no
way to create a feature like a vertical/horizontal line cursor similar to
the one on an oscilloscope. With Turbo C I used the 'setwritemode' function
which specifies whether a pixel or a line is plotted with COPY_PUT or XOR
operation. When using XOR, one draws a line that would disappear when
drawing it again. By this way I could emulate a cursor that was moved by
the arrow keys in order to scan a measured curve which is displayed on the
screen and so on... 
Is there any (hidden) possiblity in SVGAlib that I can use to do the same
under Linux and SVGAlib? It should be, because there is a mouse cursor that
obviously does similar things..

best regards, Norbert Nowaczyk



----------

Dr. Norbert R. Nowaczyk
GeoForschungsZentrum Potsdam
Laboratory for Paleo- and Rock Magnetism
Telegrafenberg Haus C
D-14473 Potsdam
Germany

Tel.: +49 331 288 1369 (Office)
                  1362 (Lab)
                  1302 (Fax)
e-mail: nowa@gfz-potsdam.de

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