Unicode RTF text in RichEdit

问题

I'm having trouble getting a RichEdit control to display unicode RTF text. My application is Unicode, so all strings are wchar_t strings.
If I create the control as "RichEdit20A" I can use e.g. SetWindowText, and the text is displayed with the proper formatting. If I create the control as "RichEdit20W" then using SetWindowText shows the text verbatim, i.e. all the RTF code is displayed. The same happens if I use the EM_SETTEXTEX parameter, specifying codepage 1200 which MSDN tells me is used to indicate unicode.
I've tried using the StreamIn function, but this only seems to work if I stream in ASCII text. If I stream in widechars then I get empty text in the control. I use the SF_RTF|SF_UNICODE flags, and MSDN hints that this combination may not be allowed.

So what to do? Is there any way to get widechars into a RichEdit without losing RTF interpretation, or do I need to encode it? I've thought about trying UTF-8, or perhaps use the encoding facilities in RTF, but am unsure what the best choice is.

回答1:

I had to do this recently, and noticed the same sorts of observations you're making.

It seems that, despite what MSDN almost suggests, the "RTF" parser will only work with 8-bit encodings. So what I ended up doing was using UTF-8, which is an 8 bit encoding but still can represent the full range of Unicode characters. You can get UTF-8 from a PWSTR via WideCharToMultiByte():

PWSTR WideString = /* Some string... */;
DWORD WideLength = wcslen(WideString) + 1;
PSTR Utf8;
DWORD Length;
INT ReturnedLength;

// A utf8 representation shouldn't be longer than 4 times the size
// of the utf16 one.
Length = WideLength * 4;
Utf8 = malloc(Length);
if (!Utf8) { /* TODO: handle failure */ }

ReturnedLength = WideCharToMultiByte(CP_UTF8,
                                     0,
                                     WideString,
                                     WideLength-1,
                                     Utf8,
                                     Length-1,
                                     NULL,
                                     NULL);
if (ReturnedLength)
{
   // Need to zero terminate...
   Utf8[ReturnedLength] = 0;
}
else { /* TODO: handle failure */ }

Once you have it in UTF-8, you can do:

SETTEXTEX TextInfo = {0};

TextInfo.flags = ST_SELECTION;
TextInfo.codepage = CP_UTF8;

SendMessage(hRichText, EM_SETTEXTEX, (WPARAM)&TextInfo, (LPARAM)Utf8);

And of course (I left this out originally, but while I'm being explicit...):

free(Utf8);

回答2:

RTF is ASCII, any charactor out of ASCII would be encoded using escape sequence. RTF 1.9.1 specification (March 2008)

回答3:

Take a look at \uN literal in rtf specification so you have to convert your wide string to string of unicode characters like \u902?\u300?\u888? http://www.biblioscape.com/rtf15_spec.htm#Heading9 The numbers in this case represent the characters decimal code and the question mark is the character which will replace the unicode char in case if RichEdit does not support unicode (RichEdit v1.0).

For example for unicode string L"TIME" the rtf data will be "\u84?\u73?\u77?\u69?"

来源：https://stackoverflow.com/questions/1782409/unicode-rtf-text-in-richedit

标签

unicode

mfc

rtf

richedit