RichEdit 中的 Unicode RTF 文本

2022-01-12 00:00:00 unicode rtf mfc richedit

我无法让 RichEdit 控件显示 unicode RTF 文本.我的应用程序是 Unicode，所以所有字符串都是 wchar_t 字符串.
如果我将控件创建为RichEdit20A"，我可以使用例如SetWindowText，并以正确的格式显示文本.如果我将控件创建为RichEdit20W"，则使用 SetWindowText 会逐字显示文本，即显示所有 RTF 代码.如果我使用 EM_SETTEXTEX 参数，指定代码页 1200，MSDN 告诉我用于指示 unicode，也会发生同样的情况.
我尝试过使用 StreamIn 函数，但这似乎只有在我以 ASCII 文本进行流式传输时才有效.如果我在widechars中流式传输，那么我会在控件中得到空文本.我使用 SF_RTF|SF_UNICODE 标志，而 MSDN 提示可能不允许这种组合.

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.

那该怎么办?有什么方法可以在不丢失 RTF 解释的情况下将宽字符放入 RichEdit，还是我需要对其进行编码?我曾考虑尝试 UTF-8，或者可能使用 RTF 中的编码工具，但不确定最佳选择是什么.

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.

推荐答案

我最近不得不这样做，并注意到你正在做的同样的观察.

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

看起来，尽管 MSDN 几乎建议，RTF"解析器仅适用于 8 位编码.所以我最终做的是使用 UTF-8，这是一种 8 位编码，但是仍然可以表示全范围的 Unicode 字符.您可以通过 PWSTR 获取 UTF-8noreferrer">WideCharToMultiByte():

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 */ }

一旦你拥有 UTF-8 格式，你就可以这样做:

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);

当然(我最初忽略了这个，但是当我很明确时......):

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

free(Utf8);

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