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

Spent a day or so googling answers for this. Pieced together tidbits from all over stackoverflow and other sources. Feed this an image, it'll return the string you need to add to your richtextbox.rtf extension. The image width changes and needs to be calculated, the formula is given.

    // RTF Image Format
    // {\pict\wmetafile8\picw[A]\pich[B]\picwgoal[C]\pichgoal[D]
    //  
    // A    = (Image Width in Pixels / Graphics.DpiX) * 2540 
    //  
    // B    = (Image Height in Pixels / Graphics.DpiX) * 2540 
    //  
    // C    = (Image Width in Pixels / Graphics.DpiX) * 1440 
    //  
    // D    = (Image Height in Pixels / Graphics.DpiX) * 1440 

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

    const int MM_ISOTROPIC = 7;
    const int MM_ANISOTROPIC = 8;

    [DllImport("gdiplus.dll")]
    private static extern uint GdipEmfToWmfBits(IntPtr _hEmf, uint _bufferSize,
        byte[] _buffer, int _mappingMode, EmfToWmfBitsFlags _flags);
    [DllImport("gdi32.dll")]
    private static extern IntPtr SetMetaFileBitsEx(uint _bufferSize,
        byte[] _buffer);
    [DllImport("gdi32.dll")]
    private static extern IntPtr CopyMetaFile(IntPtr hWmf,
        string filename);
    [DllImport("gdi32.dll")]
    private static extern bool DeleteMetaFile(IntPtr hWmf);
    [DllImport("gdi32.dll")]
    private static extern bool DeleteEnhMetaFile(IntPtr hEmf);

        public static string GetEmbedImageString(Bitmap image)
        {
                Metafile metafile = null;
                float dpiX; float dpiY;

                using (Graphics g = Graphics.FromImage (image)) 
                {
                    IntPtr hDC = g.GetHdc ();
                    metafile = new Metafile (hDC, EmfType.EmfOnly);
                    g.ReleaseHdc (hDC);
                }

                using (Graphics g = Graphics.FromImage (metafile)) 
                {
                    g.DrawImage (image, 0, 0);
            dpiX = g.DpiX;
            dpiY = g.DpiY;
                }

                IntPtr _hEmf = metafile.GetHenhmetafile ();
                uint _bufferSize = GdipEmfToWmfBits (_hEmf, 0, null, MM_ANISOTROPIC,
                EmfToWmfBitsFlags.EmfToWmfBitsFlagsDefault);
                byte[] _buffer = new byte[_bufferSize];
                GdipEmfToWmfBits (_hEmf, _bufferSize, _buffer, MM_ANISOTROPIC,
                                            EmfToWmfBitsFlags.EmfToWmfBitsFlagsDefault);
                IntPtr hmf = SetMetaFileBitsEx (_bufferSize, _buffer);
                string tempfile = Path.GetTempFileName ();
                CopyMetaFile (hmf, tempfile);
                DeleteMetaFile (hmf);
                DeleteEnhMetaFile (_hEmf);

                var stream = new MemoryStream ();
                byte[] data = File.ReadAllBytes (tempfile);
                //File.Delete (tempfile);
                int count = data.Length;
                stream.Write (data, 0, count);

                string proto = @"{\rtf1{\pict\wmetafile8\picw" + (int)( ( (float)image.Width / dpiX ) * 2540 )
                                  + @"\pich" + (int)( ( (float)image.Height / dpiY ) * 2540 )
                                  + @"\picwgoal" + (int)( ( (float)image.Width / dpiX ) * 1440 )
                                  + @"\pichgoal" + (int)( ( (float)image.Height / dpiY ) * 1440 )
                                  + " " 
                      + BitConverter.ToString(stream.ToArray()).Replace("-", "")
                                  + "}}";                   
                return proto;
        }