Magnifier window that follows mouse - how?

So I have a thought that I want to make a magnifier application. I have seen some of them but they miss one useful feature: I need something that works actually like a hand-held magnifier - moves with the mouse and magnifies the portion of the screen under the mouse cursor.

I have played a bit with BitBlt and DCs and know how to transform bitmaps. The problem is that if app window follows the mouse, it obscures the screen area which I want to magnify and also steels the mouse focus. I need something "transparent". Is there any way I can get DesktopDC for entire desktop except my own application and also pass mouse clicks to windows behind my app (without causing my app to flicker a lot)?

If someone have an idea of a good solution for this, I would be grateful.



  • Just some random tips:

    You could always make your app ignore WM_SETFOCUS and such messages. For the transparent effect, I suppose you could check out AnimateWindow() and toy with the alpha-blend stuff. Otherwise there is likely some property in the VC++ forms for blending if you aren't writing the program entirely in win32 (at least Borland Builder has it, so it wouldn't surprise me if MS has it too).

    To pass clicks to other apps, use the mouse_event() function.
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