troubleshooting Question

paint in GDI to contrast background?

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riceman0 asked on
.NET ProgrammingC#Visual Basic.NET
4 Comments1 Solution524 ViewsLast Modified:

Hello, if (using GDI) I need to annotate an arbitrary bitmap, I don't know what color is behind what I'm drawing.  It would be convenient if there was a brush or color that would automatically contrast the pixels behind it.  I remember this from way back in the day, BASICA had a XOR brush which would basically invert what was behind it.  Is it possible there is something BASICA could do that .NET can't?

Anyway is there any simple/fast technique in GDI to accomplish an automatic contrast (or distinction) with the background?  Obviously I could test the background, do some averaging, and choose a contrasting color but that's time consuming and exactly what im trying to avoid.
Also, alpha doesn't really work very well for this.

Any thoughts are appreciated, thanks.
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