/// <summary>
/// Returns the window from the given point (Except hidden / disabled windows).
/// </summary>
/// <param name="point">The point (x, y)</param>
/// <returns>The handle to the window beneath the point</returns>
public static IntPtr LowestLevelWindowFromPoint(WinApi.POINT point)
{
var hWnd = WinApi.WindowFromPoint(point);
//WinApi.ScreenToClient(hWnd, ref cursorPosition);
var child = WinApi.ChildWindowFromPoint(hWnd, point);
// Is there any child window?
if (child != IntPtr.Zero)
{
hWnd = child;
}
// No more child windows? Just return the current window handle
if ((WinApi.GetWindowLong(hWnd, (WinConstants.GWL_STYLE))
& WinConstants.WS_POPUP) != 0)
{
return(hWnd);
}
hWnd = GetChildMost(point, hWnd);
return(hWnd);
}
/// <summary>
/// Return the window handle to the "lowest" child window of a given window handle.
/// This is necessary, for example, for group boxes or something.
/// WindowFromPoint will just return a handle to the group box,
/// instead of returning the handle to one of its child windows (a text box or something).
/// </summary>
/// <param name="point">The point (x, y)</param>
/// <param name="hWnd">The window handle (top window)</param>
/// <returns>The handle to the child window</returns>
private static IntPtr GetChildMost(WinApi.POINT point, IntPtr hWnd)
{
// Max size of a window
var dwWndArea = WinConstants.MAXDWORD;
// size of the parent window
var hWndParent = WinApi.GetParent(hWnd);
// first child window handle
var hWndChild = WinApi.GetWindow(hWndParent, WinConstants.GW_CHILD);
// Iterate child windows
while (hWndChild != IntPtr.Zero)
{
// ignore hidden windows
if (WinApi.IsWindowVisible(hWndChild))
{
// window beneath the point
WinApi.RECT rect;
WinApi.GetWindowRect(hWndChild, out rect);
// Is the given point within the rectangle of the current child window?
if (WinApi.PtInRect(ref rect, point))
{
// find smallest
var dwChildArea = (uint)(rect.Width * rect.Height);
// Is the current child window size smaller than the one of the last child window?
if (dwChildArea < dwWndArea)
{
dwWndArea = dwChildArea;
hWnd = hWndChild;
}
}
}
// retrieving next child window handle
hWndChild = WinApi.GetWindow(hWndChild, WinConstants.GW_HWNDNEXT);
}
return(hWnd);
}
