public static extern int DwmUpdateThumbnailProperties(IntPtr hThumb, ref DWM_THUMBNAIL_PROPERTIES props);
public static extern int DwmUpdateThumbnailProperties(IntPtr hThumb, ref DWM_THUMBNAIL_PROPERTIES props);
/// <summary>
/// Make a full-size thumbnail of the captured window on a new topmost form, and capture
/// this new form with a black and then white background. Then compute the transparency by
/// difference between the black and white versions.
/// This method has these advantages:
/// - the full form is captured even if it is obscured on the Windows desktop
/// - there is no problem with unpredictable Z-order anymore (the background and
/// the window to capture are drawn on the same window)
/// </summary>
/// <param name="handle">handle of the window to capture</param>
/// <param name="windowRect">the bounds of the window</param>
/// <param name="redBGImage">the window captured with a red background</param>
/// <param name="captureRedBGImage">whether to do the capture of the window with a red background</param>
/// <returns>the captured window image</returns>
private static Image CaptureWindowWithDWM(IntPtr handle, Rectangle windowRect, out Bitmap redBGImage, Color backColor)
{
Image windowImage = null;
redBGImage = null;
if (backColor != Color.White)
{
backColor = Color.FromArgb(255, backColor.R, backColor.G, backColor.B);
}
using (Form form = new Form())
{
form.StartPosition = FormStartPosition.Manual;
form.FormBorderStyle = FormBorderStyle.None;
form.ShowInTaskbar = false;
form.BackColor = backColor;
form.TopMost = true;
form.Bounds = CaptureHelpers.GetWindowRectangle(handle, false);
IntPtr thumb;
NativeMethods.DwmRegisterThumbnail(form.Handle, handle, out thumb);
SIZE size;
NativeMethods.DwmQueryThumbnailSourceSize(thumb, out size);
#if DEBUG
DebugHelper.WriteLine("Rectangle Size: " + windowRect.ToString());
DebugHelper.WriteLine("Window Size: " + size.ToString());
#endif
if (size.Width <= 0 || size.Height <= 0)
{
return null;
}
DWM_THUMBNAIL_PROPERTIES props = new DWM_THUMBNAIL_PROPERTIES();
props.dwFlags = NativeMethods.DWM_TNP_VISIBLE | NativeMethods.DWM_TNP_RECTDESTINATION | NativeMethods.DWM_TNP_OPACITY;
props.fVisible = true;
props.opacity = (byte)255;
props.rcDestination = new RECT(0, 0, size.Width, size.Height);
NativeMethods.DwmUpdateThumbnailProperties(thumb, ref props);
form.Show();
System.Threading.Thread.Sleep(250);
if (form.BackColor != Color.White)
{
// no need for transparency; user has requested custom background color
NativeMethods.ActivateWindowRepeat(form.Handle, 250);
windowImage = Screenshot.CaptureRectangleNative(windowRect) as Bitmap;
}
else if (form.BackColor == Color.White)
{
// transparent capture
NativeMethods.ActivateWindowRepeat(handle, 250);
Bitmap whiteBGImage = Screenshot.CaptureRectangleNative(windowRect) as Bitmap;
form.BackColor = Color.Black;
form.Refresh();
NativeMethods.ActivateWindowRepeat(handle, 250);
Bitmap blackBGImage = Screenshot.CaptureRectangleNative(windowRect) as Bitmap;
// Capture rounded corners with except for Windows 8
if (ZAppHelper.IsWindows8())
{
form.BackColor = Color.Red;
form.Refresh();
NativeMethods.ActivateWindowRepeat(handle, 250);
redBGImage = Screenshot.CaptureRectangleNative(windowRect) as Bitmap;
}
form.BackColor = Color.White;
form.Refresh();
NativeMethods.ActivateWindowRepeat(handle, 250);
Bitmap whiteBGImage2 = Screenshot.CaptureRectangleNative(windowRect) as Bitmap;
// Don't do transparency calculation if an animated picture is detected
if (whiteBGImage.AreBitmapsEqual(whiteBGImage2))
{
windowImage = HelpersLib.GraphicsHelper.Core.ComputeOriginal(whiteBGImage, blackBGImage);
}
else
{
DebugHelper.WriteLine("Detected animated image => cannot compute transparency");
form.Close();
Application.DoEvents();
Image result = new Bitmap(whiteBGImage.Width, whiteBGImage.Height, PixelFormat.Format32bppArgb);
using (Graphics g = Graphics.FromImage(result))
{
// Redraw the image on a black background to avoid transparent pixels artifacts
g.Clear(Color.Black);
g.DrawImage(whiteBGImage, 0, 0);
}
windowImage = result;
}
blackBGImage.Dispose();
whiteBGImage.Dispose();
whiteBGImage2.Dispose();
}
NativeMethods.DwmUnregisterThumbnail(thumb);
}
return windowImage;
}
