Programmatically adding Images to RTF Document

Question

I am trying to add a image to a RTF document which I am creating. I would prefer to not use \'copy/paste\' methods (that involve pasting the image within a RichTextBox and t

Answer 1

I merged answers from RRUZ and JiffyWhip and cleaned up the code.

Now you can insert an image as PNG or as WMF.

I also replaced transparency with white color, because WMF doesn't support opacity.

private static string GetWidthAndHeight(Image image, float dpiX, float dpiY)
{
    float width = (float)image.Width / dpiX;
    float height = (float)image.Height / dpiY;

    int picw = (int)(width * 2540);
    int pich = (int)(height * 2540);

    int picwgoal = (int)(width * 1440);
    int pichgoal = (int)(height * 1440);

    return "\\picw" + picw + "\\pich" + pich + "\\picwgoal" + picwgoal + "\\pichgoal" + pichgoal;
}

public static string InsertPngImage(Image image)
{
    byte[] buffer;

    using (var stream = new MemoryStream())
    {
        image.Save(stream, ImageFormat.Png);
        buffer = stream.ToArray();
    }

    string hex = BitConverter.ToString(buffer, 0).Replace("-", string.Empty);

    string widthAndHeight = GetWidthAndHeight(image, image.HorizontalResolution, image.VerticalResolution);

    return "{\\pict\\pngblip" + widthAndHeight + " " + hex + "}";
}

[Flags]
enum EmfToWmfBitsFlags
{
    EmfToWmfBitsFlagsDefault = 0x00000000,
    EmfToWmfBitsFlagsEmbedEmf = 0x00000001,
    EmfToWmfBitsFlagsIncludePlaceable = 0x00000002,
    EmfToWmfBitsFlagsNoXORClip = 0x00000004
}

private static int MM_ANISOTROPIC = 8;

[DllImportAttribute("gdiplus.dll")]
private static extern uint GdipEmfToWmfBits(IntPtr hEmf, uint bufferSize, byte[] buffer, int mappingMode, EmfToWmfBitsFlags flags);

public static string InsertWmfImage(Image image)
{
    image = ReplaceTransparency(image, Color.White);

    Metafile metaFile;
    float dpiX;
    float dpiY;

    using (Graphics graphics = Graphics.FromImage(image))
    {
        IntPtr hdc = graphics.GetHdc();
        metaFile = new Metafile(hdc, EmfType.EmfOnly);
        graphics.ReleaseHdc(hdc);
    }

    using (Graphics graphics = Graphics.FromImage(metaFile))
    {
        graphics.DrawImage(image, 0, 0, image.Width, image.Height);
        dpiX = graphics.DpiX;
        dpiY = graphics.DpiY;
    }

    IntPtr hEmf = metaFile.GetHenhmetafile();

    uint bufferSize = GdipEmfToWmfBits(hEmf, 0, null, MM_ANISOTROPIC, EmfToWmfBitsFlags.EmfToWmfBitsFlagsDefault);

    byte[] buffer = new byte[bufferSize];

    uint convertedSize = GdipEmfToWmfBits(hEmf, bufferSize, buffer, MM_ANISOTROPIC, EmfToWmfBitsFlags.EmfToWmfBitsFlagsDefault);

    string hex = BitConverter.ToString(buffer, 0).Replace("-", string.Empty);

    string widthAndHeight = GetWidthAndHeight(image, dpiX, dpiY);

    return "{\\pict\\wmetafile8" + widthAndHeight + " " + hex + "}";
}

private static Image ReplaceTransparency(Image image, Color background)
{
    Bitmap bitmap = new Bitmap(image.Width, image.Height, PixelFormat.Format24bppRgb);

    using (Graphics graphics = Graphics.FromImage(bitmap))
    {
        graphics.Clear(background);
        graphics.CompositingMode = CompositingMode.SourceOver;
        graphics.DrawImage(image, 0, 0, image.Width, image.Height);
    }

    return bitmap;
}