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 then accessing the .RTF property) which purge the clipboard (as this will be a bother and confusion for my end users).

The code I have so far returns the string that needs to be inserted into the RTF document to print the image. The inputted image (located at $path) is usually in bmp or jpeg format, but at this stage I am not concerned with how the image is stored within the RTF only that i can get it to work.

public string GetImage(string path, int width, int height)
{
    MemoryStream stream = new MemoryStream();
    string newPath = Path.Combine(Environment.CurrentDirectory, path);
    Image img = Image.FromFile(newPath);
    img.Save(stream, System.Drawing.Imaging.ImageFormat.Png);

    byte [] bytes = stream.ToArray();

    string str = BitConverter.ToString(bytes, 0).Replace("-", string.Empty);
    //string str = System.Text.Encoding.UTF8.GetString(bytes);

    string mpic = @"{\pict\pngblip\picw" + 
        img.Width.ToString() + @"\pich" + img.Height.ToString() +
        @"\picwgoa" + width.ToString() + @"\pichgoa" + height.ToString() + 
        @"\hex " + str + "}";
    return mpic
}

However the problem is that this code does not work because as far as I can tell, the string str does not have the correct string conversion to work within the RTF.

Edit: My problem was missing a space after the \hex in @"\hex " and also not stripping out the "-" characters from the returned value of the BitConverter

user_4675770 · Answer

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;
}

Programmatically adding Images to RTF Document

5 Answers