public static Bitmap MakeSnapshot(IntPtr AppWndHandle, bool IsClientWnd)
{
if (AppWndHandle == IntPtr.Zero || !User32.IsWindow(AppWndHandle) ||
!User32.IsWindowVisible(AppWndHandle))
{
return(null);
}
if (User32.IsIconic(AppWndHandle))
{
User32.ShowWindow(AppWndHandle, WindowShowStyle.Restore);//show it
}
if (!User32.SetForegroundWindow(AppWndHandle))
{
return(null); //can't bring it to front
}
System.Threading.Thread.Sleep(1000); //give it some time to redraw
RECT appRect;
bool res = IsClientWnd ? User32.GetClientRect(AppWndHandle, out appRect) : User32.GetWindowRect(AppWndHandle, out appRect);
if (!res || appRect.Height == 0 || appRect.Width == 0)
{
return(null);//some hidden window
}
// calculate the app rectangle
if (IsClientWnd)
{
Point lt = new Point(appRect.Left, appRect.Top);
Point rb = new Point(appRect.Right, appRect.Bottom);
User32.ClientToScreen(AppWndHandle, ref lt);
User32.ClientToScreen(AppWndHandle, ref rb);
appRect.Left = lt.X;
appRect.Top = lt.Y;
appRect.Right = rb.X;
appRect.Bottom = rb.Y;
}
//Intersect with the Desktop rectangle and get what's visible
IntPtr DesktopHandle = User32.GetDesktopWindow();
RECT desktopRect;
User32.GetWindowRect(DesktopHandle, out desktopRect);
RECT visibleRect;
if (!User32.IntersectRect
(out visibleRect, ref desktopRect, ref appRect))
{
visibleRect = appRect;
}
if (User32.IsRectEmpty(ref visibleRect))
{
return(null);
}
int Width = visibleRect.Width;
int Height = visibleRect.Height;
IntPtr hdcTo = IntPtr.Zero;
IntPtr hdcFrom = IntPtr.Zero;
IntPtr hBitmap = IntPtr.Zero;
try
{
Bitmap clsRet = null;
// get device context of the window...
hdcFrom = IsClientWnd ? User32.GetDC(AppWndHandle) :
User32.GetWindowDC(AppWndHandle);
// create dc that we can draw to...
hdcTo = GDI32.CreateCompatibleDC(hdcFrom);
hBitmap = GDI32.CreateCompatibleBitmap(hdcFrom, Width, Height);
// validate
if (hBitmap != IntPtr.Zero)
{
// adjust and copy
int x = appRect.Left < 0 ? -appRect.Left : 0;
int y = appRect.Top < 0 ? -appRect.Top : 0;
IntPtr hLocalBitmap = GDI32.SelectObject(hdcTo, hBitmap);
GDI32.BitBlt(hdcTo, 0, 0, Width, Height,
hdcFrom, x, y, GDI32.SRCCOPY);
GDI32.SelectObject(hdcTo, hLocalBitmap);
// create bitmap for window image...
clsRet = System.Drawing.Image.FromHbitmap(hBitmap);
}
return(clsRet);
}
finally
{
// release the unmanaged resources
if (hdcFrom != IntPtr.Zero)
{
User32.ReleaseDC(AppWndHandle, hdcFrom);
}
if (hdcTo != IntPtr.Zero)
{
GDI32.DeleteDC(hdcTo);
}
if (hBitmap != IntPtr.Zero)
{
GDI32.DeleteObject(hBitmap);
}
}
}