[lazarus] Triangle Gradients and Alpha Blending

Andrew Johnson aj_genius at hotmail.com
Tue Sep 10 17:09:43 EDT 2002

Okay, I was working on Loading Bitmap Color Tables, and was getting nowhere 
fast, so I decided to take a break. After little while I, for the fun of it, 
decided to try and implement GradientRect from the WinAPI. I got the basic 
framework in place real easy,  added Horizontal and Vertical Rectangle 
support, added some sanity checks, and a few other minor details. 
Everythings works great with Rectangles, but I cannot figure out how to do a 
three way/vertice, aka triangle Gradient. I am completely in the dark on 
such a beast.. So does anybody out there on the mailinglist know how such a 
thing is accomplished? Or how I can add Transparency/Alpha Blending support? 
I know, it a pointess routine.. but I figure if I'm going to try and 
implement as much of the WIN32 GDI as possible I might as well add as full a 
support as I can for this routine too. If not I am not going to spend much 
more time on it, but I figure, we can at least add a Gradient background too 
any installers made with the LCL ;-)


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