Getting an Image of a window

[T i T i]

How can I get an image of a window or an application that I got its handle... I did it by activating this window then capturing the screen and saving this image , but I'm asking about a way to get that image without activating the window .

[Heath Stewart]

You actually don't need to capture the screen to get the window, which would require the window to be active so you see it all. Instead of getting the desktop window (a la GetDesktopWindow or something), get the window handle and basically do the same thing. In C#, you can do this easily by enumerating the processes from Process.GetProcesses, find the right process, and then get the main window handle using Process.MainWindowHandle. This still doesn't change the fact that the window needs to be active (i.e., in the foreground) to get the entire image. Windows (a window manager) draws a 2D surface and nothing more. While a window appears to be "behind" another, it's actually just that the foreground window is being painted in place of the "hidden" regions. In order to accomplish what you want, you'd have to create a virtual frame buffer of sorts in which the window would be paintined in its entirety instead of to the screen buffer, which is all but trivial and would still pose problems (believe me, it's not an easy thing - especially in higher-level languages like C3 and others that target the CLR).

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[Jeremy Kimball]

[sarcasm: on] All but trivial? Eh, just write all the window painting routines in DirectX, then peel the image from the surface backbuffer :) [sarcasm:off] As far as I know, there's no way to "get at" the 2d image of a given window without activating it. Windows doesn't store a background image of each running app, it relies on the paint routines to draw them on the fly. Jeremy Kimball