algebra

hi marble, would you attach solution that has been you correcting? or you can send to my email. Agecell@gmail.com thanks.

hi all, thanks for replied my problems. actually i have already tried to using CompositingMode.SourceCopy, but the result is not solving my problem. i use layered form to make transparent. because i need to get real time dekstop background, if i use region or copy a screen image to my form its not my purpose. i attach solution for little code to make you understand our problem, this code cut from my project. hopefully people on extremedonettalk.com could give me a solution for my problem. thanks. SampleTransparentdekstop.zip

Hi all, I'm trying to build a simple drawing application which would allow people to drawing on their screen. The application makes use of a maximum form which is transparent, which allows people to optionally annotate items that exist behind the application. For the most part, it seems to work fine. I am able to use DrawLine to draw lines on the form. Now, i want to be able to provide a way to erase random portions of the screen using a eraser. However, I can't seem to figure out the best way to actually do that. Drawing with a transparent Pen doesn't achieve this. Drawing with a pen that has the same color as the TransparencyKey of the form just draws a line with the same color as the TransparencyKey (it doesn't make that line "transparent"). Second problem is we need to make drawing line with a semi-transparent (like a felt-tip marker). But when we set alpha color value to 128, the line is not semi-transparent, but the color that same color as the TransparencyKey show up too. Anyone have any thoughts on this? please help me. thanks