Insert an image into RTF document in C#

问题:

I am creating a RichTextBox subclass that can insert images easily. I referred to this question to start, but I can't get the generated RTF string to work. When I try to set the SelectedRtf of the RTB, it errors out with "File format is not valid." Here is my code:

internal void InsertImage(Image img)
{
    string str = @"{\pict\pngblip\picw24\pich24 " + imageToHex(img) + "}";

    this.SelectedRtf = str;    // This line throws the exception
}

private string imageToHex(Image img)
{
    MemoryStream ms = new MemoryStream();
    img.Save(ms, ImageFormat.Png);

    byte[] bytes = ms.ToArray();

    string hex = BitConverter.ToString(bytes);
    return hex.Replace("-", "");
}

I've seen working examples of what I'm trying to do, but using wmetafiles, but I would prefer not to use that method. Any ideas?

Thanks,
Jared

回答1:

I gave up trying to insert the RTF manually, and decided to use the clipboard approach. The only detriment I could find from this type of solution was that it wiped out the clipboard contents. I simply saved them before I paste the image, then set it back like so:

internal void InsertImage(Image img)
{
    IDataObject obj = Clipboard.GetDataObject();
    Clipboard.Clear();

    Clipboard.SetImage(img);
    this.Paste();

    Clipboard.Clear();
    Clipboard.SetDataObject(obj);
}

Works beautifully.

回答2:

RichTextBox doesn't support PNG, it supports WMF - but this isn't variant in C#. Also the RichTextBox supports images in BMP format - this is good idea for C#, because the Bitmap is standard .Net class.

回答3:

Perhaps this is a naive approach, but I just used WordPad to insert a PNG into an RTF document. Below is the first chunk:

{\rtf1\ansi\ansicpg1252\deff0\deflang1033{\fonttbl{\f0\fnil\fcharset0 Calibri;}}
{\*\generator Msftedit 5.41.21.2510;}\viewkind4\uc1\pard\sa200\sl276\slmult1\lang9\f0\fs22 testing\par
\par
\pard\sa200\sl240\slmult1{\pict\wmetafile8\picw27940\pich16378\picwgoal8640\pichgoal5070 
0100090000035af60e00000031f60e0000000400000003010800050000000b0200000000050000
000c026b022004030000001e000400000007010400040000000701040031f60e00410b2000cc00
6b022004000000006b0220040000000028000000200400006b020000010018000000000020ec1d
0000000000000000000000000000000000ffffffffffffffffffffffffffffffffffffffffffff
ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
fffffffffffffffffffffffffffffffffff

As you can see, even with the PNG file format, the image header starts with \pict\wmetafile8. Try changing your header to that format and see if it works.