WPF RenderTargetBitmap downscales TextRenderMode to GreyScale

Question

RenderTargetBitmap removes the RichtextBox TextRenderingMode downgrade to GreyScale. Thus, the captured PNG looks of poor quality and does not comply with WPF management.

If I use WINDOWS ALT + PRINT SCREEN, the text will be shot perfectly.

So, how can I make the text control the same as ALT + PRINT SCREEN.

Any advice would be seriously appreciated.

All the best

Answer 1

, , Alt + Print. , , , BitBlt.

( System.Drawing.dll , ):

public static void SaveToBitmapNative(Window window, FrameworkElement element, string fileName)
{
    WindowInteropHelper helper = new WindowInteropHelper(window);

    // detect the window client area position if rendering a child element
    double incX = 0, incY = 0;
    if (window != element)
    {
        System.Drawing.Point pos = new System.Drawing.Point(0, 0);
        ClientToScreen(helper.Handle, ref pos);
        incX = pos.X - (int)window.Left;
        incY = pos.Y - (int)window.Top;
    }

    // transform child position to window coordinates
    GeneralTransform transform = element.TransformToVisual(window);
    Point point = transform.Transform(new Point(0, 0));
    Rect rect = new Rect(point.X + incX, point.Y + incY, element.ActualWidth, element.ActualHeight);

    // render window into bitmap
    using (System.Drawing.Bitmap bitmap = new System.Drawing.Bitmap(
        (int)rect.Width, (int)rect.Height, System.Drawing.Imaging.PixelFormat.Format32bppArgb))
    {
        using (System.Drawing.Graphics memoryGraphics = System.Drawing.Graphics.FromImage(bitmap))
        {
            IntPtr dc = memoryGraphics.GetHdc();
            IntPtr windowDC = GetWindowDC(helper.Handle);

            BitBlt(dc, 0, 0, (int)rect.Width, (int)rect.Height,
                    windowDC, (int)rect.Left, (int)rect.Top, TernaryRasterOperations.SRCCOPY);

            memoryGraphics.ReleaseHdc(dc);
            ReleaseDC(helper.Handle, windowDC);
        }
        // save bitmap to file
        bitmap.Save(fileName);
    }
}

[DllImport("gdi32.dll")]
static extern bool BitBlt(IntPtr hdcDest, int xDest, int yDest, int wDest, int hDest, IntPtr hdcSource, int xSrc, int ySrc, TernaryRasterOperations rop);
[DllImport("user32.dll")]
public static extern IntPtr GetWindowDC(IntPtr ptr);
[DllImport("user32.dll")]
static extern bool ReleaseDC(IntPtr hWnd, IntPtr hDc);
[DllImport("user32.dll")]
static extern bool ClientToScreen(IntPtr hWnd, ref System.Drawing.Point lpPoint);

public enum TernaryRasterOperations : uint
{
    SRCCOPY = 0x00CC0020,
    SRCPAINT = 0x00EE0086,
    SRCAND = 0x008800C6,
    SRCINVERT = 0x00660046,
    SRCERASE = 0x00440328,
    NOTSRCCOPY = 0x00330008,
    NOTSRCERASE = 0x001100A6,
    MERGECOPY = 0x00C000CA,
    MERGEPAINT = 0x00BB0226,
    PATCOPY = 0x00F00021,
    PATPAINT = 0x00FB0A09,
    PATINVERT = 0x005A0049,
    DSTINVERT = 0x00550009,
    BLACKNESS = 0x00000042,
    WHITENESS = 0x00FF0062
}

,

private void saveButton_Click(object sender, RoutedEventArgs e)
{
    // saves the entire window into the bitmap
    SaveToBitmapNative(this, this, "c:\\test0.png");
    // saves a child control (RichTextBox) into the bitmap
    SaveToBitmapNative(this, richTextBox, "c:\\test1.png"); 
}

: , UpdateLayeredWindow.

, ,