/// <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)
/// Note: now that GDI capture is more robust, DWM capture is not that useful anymore.
/// </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 CaptureWindowWithTransparencyDWM(IntPtr handle, Rectangle windowRect, out Bitmap redBGImage, bool captureRedBGImage)
{
Image windowImage = null;
redBGImage = null;
using (Form form = new Form())
{
form.FormBorderStyle = FormBorderStyle.None;
form.ShowInTaskbar = false;
form.BackColor = Color.White;
form.TopMost = true;
form.Bounds = windowRect;
IntPtr thumb;
NativeMethods.DwmRegisterThumbnail(form.Handle, handle, out thumb);
SIZE size;
NativeMethods.DwmQueryThumbnailSourceSize(thumb, out size);
if (size.x <= 0 || size.y <= 0)
{
return(null);
}
form.Location = new Point(windowRect.X, windowRect.Y);
form.Size = new Size(size.x, size.y);
form.Show();
NativeMethods.DWM_THUMBNAIL_PROPERTIES props = new NativeMethods.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.x, size.y);
NativeMethods.DwmUpdateThumbnailProperties(thumb, ref props);
NativeMethods.ActivateWindowRepeat(handle, 250);
Bitmap whiteBGImage = CaptureRectangle(windowRect) as Bitmap;
form.BackColor = Color.Black;
form.Refresh();
NativeMethods.ActivateWindowRepeat(handle, 250);
Bitmap blackBGImage = CaptureRectangle(windowRect) as Bitmap;
if (captureRedBGImage)
{
form.BackColor = Color.Red;
form.Refresh();
NativeMethods.ActivateWindowRepeat(handle, 250);
redBGImage = CaptureRectangle(windowRect) as Bitmap;
}
form.BackColor = Color.White;
form.Refresh();
NativeMethods.ActivateWindowRepeat(handle, 250);
Bitmap whiteBGImage2 = CaptureRectangle(windowRect) as Bitmap;
// Don't do transparency calculation if an animated picture is detected
if (whiteBGImage.AreBitmapsEqual(whiteBGImage2))
{
windowImage = GraphicsMgr.ComputeOriginal(whiteBGImage, blackBGImage);
}
else
{
FileSystem.AppendDebug("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;
}
NativeMethods.DwmUnregisterThumbnail(thumb);
blackBGImage.Dispose();
whiteBGImage.Dispose();
whiteBGImage2.Dispose();
}
return(windowImage);
}
/// <summary>
/// Captures a screenshot of a window using Windows GDI. Captures transparency.
/// </summary>
/// <param name="handle">handle of the window to capture</param>
/// <returns>the captured window image</returns>
private static Image CaptureWindowWithTransparencyGDI(IntPtr handle, Rectangle windowRect)
{
Image windowImage = null;
Bitmap whiteBGImage = null, blackBGImage = null, white2BGImage = null;
try
{
using (new Freeze(handle))
using (Form form = new Form())
{
form.BackColor = Color.White;
form.FormBorderStyle = FormBorderStyle.None;
form.ShowInTaskbar = false;
int offset = Engine.conf.ActiveWindowIncludeShadows && !NativeMethods.IsWindowMaximized(handle) ? 20 : 0;
windowRect = windowRect.AddMargin(offset);
windowRect.Intersect(GraphicsMgr.GetScreenBounds());
NativeMethods.ShowWindow(form.Handle, (int)NativeMethods.WindowShowStyle.ShowNormalNoActivate);
NativeMethods.SetWindowPos(form.Handle, handle, windowRect.X, windowRect.Y, windowRect.Width, windowRect.Height, NativeMethods.SWP_NOACTIVATE);
Application.DoEvents();
whiteBGImage = (Bitmap)CaptureRectangle(NativeMethods.GetDesktopWindow(), windowRect);
form.BackColor = Color.Black;
Application.DoEvents();
blackBGImage = (Bitmap)CaptureRectangle(NativeMethods.GetDesktopWindow(), windowRect);
if (!Engine.conf.ActiveWindowGDIFreezeWindow)
{
form.BackColor = Color.White;
Application.DoEvents();
white2BGImage = (Bitmap)CaptureRectangle(NativeMethods.GetDesktopWindow(), windowRect);
}
}
if (Engine.conf.ActiveWindowGDIFreezeWindow || whiteBGImage.AreBitmapsEqual(white2BGImage))
{
windowImage = GraphicsMgr.ComputeOriginal(whiteBGImage, blackBGImage);
}
else
{
windowImage = (Image)whiteBGImage.Clone();
}
}
finally
{
if (whiteBGImage != null)
{
whiteBGImage.Dispose();
}
if (blackBGImage != null)
{
blackBGImage.Dispose();
}
if (white2BGImage != null)
{
white2BGImage.Dispose();
}
}
if (windowImage != null)
{
Rectangle windowRectCropped = GraphicsMgr.GetCroppedArea((Bitmap)windowImage);
windowImage = GraphicsMgr.CropImage(windowImage, windowRectCropped);
if (Engine.conf.ShowCursor)
{
windowRect.X += windowRectCropped.X;
windowRect.Y += windowRectCropped.Y;
DrawCursor(windowImage, windowRect.Location);
}
if (Engine.conf.ActiveWindowShowCheckers)
{
windowImage = ImageEffects.DrawCheckers(windowImage);
}
}
return(windowImage);
}