Question

I am making a screen capturing application.

There’s answer on how to capture an active window, but I want to be able to capture a window under mouse even if it’s not active.

Do I understand correctly that I need to find handle of a window under mouse and then call Image.captureWindow(IntPtr handle)?

Answer 1

Use following function to get the cursor position in context of screen

    POINT p;
if (GetCursorPos(&p))
{
    //cursor position now in p.x and p.y
}

Now you will have to use the EnumWindow function to enumerate all top level windows and then for each try this

    if (ScreenToClient(hwnd, &p))
{
    //p.x and p.y are now relative to hwnd's client area
}

when you get both the values positive for a window, thats the window on which your cursor is. Here is an example of how to capture a window from its handle

http://www.codeproject.com/Articles/19192/How-to-capture-a-Window-as-an-Image-and-save-it

Hope this helps you