/// <summary>
/// Capture transparent Screenshot of a Window.
/// </summary>
/// <param name="Window">The <see cref="Window"/> to Capture.</param>
/// <param name="IncludeCursor">Whether to include Mouse Cursor.</param>
public static Bitmap CaptureTransparent(Window Window, bool IncludeCursor = false)
{
if (Window == null)
{
throw new ArgumentNullException(nameof(Window));
}
var backdrop = new Form
{
AllowTransparency = true,
BackColor = Color.White,
FormBorderStyle = FormBorderStyle.None,
ShowInTaskbar = false,
Opacity = 0
};
var r = new RECT();
const int extendedFrameBounds = 0;
if (DwmGetWindowAttribute(Window.Handle, extendedFrameBounds, ref r, Marshal.SizeOf <RECT>()) != 0)
{
// DwmGetWindowAttribute() failed, usually means Aero is disabled so we fall back to GetWindowRect()
User32.GetWindowRect(Window.Handle, out r);
}
var R = r.ToRectangle();
// Add a 100px margin for window shadows. Excess transparency is trimmed out later
R.Inflate(100, 100);
// This check handles if the window is outside of the visible screen
R.Intersect(WindowProvider.DesktopRectangle);
ShowWindow(backdrop.Handle, 4);
SetWindowPos(backdrop.Handle, Window.Handle,
R.Left, R.Top,
R.Width, R.Height,
SetWindowPositionFlags.NoActivate);
backdrop.Opacity = 1;
Application.DoEvents();
// Capture screenshot with white background
using (var whiteShot = Capture(R))
{
backdrop.BackColor = Color.Black;
Application.DoEvents();
// Capture screenshot with black background
using (var blackShot = Capture(R))
{
backdrop.Dispose();
var transparentImage = Extensions.DifferentiateAlpha(whiteShot, blackShot);
if (transparentImage == null)
{
return(null);
}
if (IncludeCursor)
{
using (var g = Graphics.FromImage(transparentImage))
MouseCursor.Draw(g, P => new Point(P.X - R.X, P.Y - R.Y));
}
return(transparentImage.CropEmptyEdges());
}
}
}
