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I'm wondering how to render Screen as a middle level.

that is, I can produce the screen HDC after every repaint of screen, and before the screen is actually display on monitor.

for example, the magnifier utility of Window 7. you can see the content under the magnifier window, how does it made?

Thank you :-)

regards, Xavier Wang.

Xavier Wang
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    Screens don't repaint, windows do. You get the magnifier effect by using a timer and using BitBlt() to make a screenshot. Make it tick at every, say, 50 msec and it looks smooth. – Hans Passant Oct 13 '12 at 15:06
  • but in that way I will capture my window myself. What I want is get content just **under** my window so as other region. EDIT: I have found on WinVista/7, there are a Magnification API to made this, thank you all the same :-) – Xavier Wang Oct 19 '12 at 09:04

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There are three steps

  1. Identify visible windows using EnumWindows
  2. Listen on window creation to update the set of visible windows, Shell Hook
  3. Listen on WM_PAINT messages with a Message Hook, where the Desktop has a dedicated handle
Sam Ginrich
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