无法在TRichEdit中加载长RTF文本 [英] Loading long RTF-Text in TRichEdit does not work

问题描述

如果将较长的RTF序列（例如150000个字符）流式传输到 TRichEdit 控件（在XE4中），则该控件不会显示文本，而是显示原始RTF代码：

  {\rtf1\ansi\ansicpg1252\deff0 ... 
  

出什么问题了？

 程序TForm1.Button1Click（Sender：TObject）; 
 var 
 RtfText：字符串; 
流：TStringStream; 
开始
 RtfText：= GenerateRtfText（）; 
 
 Stream：= TStringStream.Create（RtfText）; 
试试
 RichEdit2.PlainText：= False; 
 RichEdit2.Lines.LoadFromStream（Stream）; //< ---错误：RichEdit显示原始RTF代码
 //如果RtfText太长
，如果StartsText（'{\rtf'，RichEdit2.Lines.Text）然后
开始
 ShowMessage（'哦，不，不转换！'）; 
 // WORKAROUND：第二次尝试似乎可行... 
 //Stream.Position：= 0; 
 //RichEdit2.Lines.LoadFromStream(Stream）; 
结尾； 
最后
流。免费； 
结尾； 
结尾； 
  

例如，具有以下RTF生成功能：

 函数TForm1.GenerateRtfText：字符串; 
 var 
 I：整数； 
流：TStringStream; 
 const 
 DOES_WORK_COUNT = 10000; 
 DOES_NOT_WORK_COUNT = 15000; 
 begin 
 //填充
 RichEdit1.Lines.BeginUpdate; 
试试
 //对于I：= 0到DOES_WORK_COUNT做
对于I：= 0到DOES_NOT_WORK_COUNT做
 RichEdit1.Lines.Add（IntToStr（I））; 
最后
 RichEdit1.Lines.EndUpdate; 
结尾； 
 //转换为RTF 
 Stream：= TStringStream.Create; 
试试
 RichEdit1.Lines.SaveToStream（Stream）; 
结果：= Stream.DataString; 
最后
流。免费； 
结尾； 
结尾； 
  

已编辑：即使复制和粘贴也无法正常工作：

这就是我所做的：

• 我复制了RichEdit1的生成内容（第1行） ..15000（具有数字1..15000）到notpad.exe中以删除任何RTF


• 我将记事本的内容复制到RichEdit2中

结果：

• 仅正确显示12773行。最后一行只有 12


• 如果我尝试向TRichEdit中添加其他字符，则什么也没发生


• 如果我删除了10个字符（每个退格键），则以后可以添加正好10个字符...

是否存在隐藏字符

解决方案

丰富的编辑控件具有文本限制。

尝试使用 EM_EXLIMITTEXT 消息，它为用户可以输入或粘贴到丰富编辑中的文本量设置了上限控制。此消息还限制了在流式传输RTF时可以流式传输到丰富编辑控件中的文本量（ PlainText = False ）。但不限制流式传输纯文本时的控制。

例如：

  const 
 RE_MAX_TEXT_SIZE = 256000; 
 
 SendMessage（RichEdit1.Handle，EM_EXLIMITTEXT，0，RE_MAX_TEXT_SIZE）; 
  

或：

  SendMessage（RichEdit1.Handle，EM_EXLIMITTEXT，0，$ 7FFFFFF0）; 
  

获取 TRichEditStrings.LoadFromFile（）： RichEdit.DoSetMaxLength（$ 7FFFFFF0）;
但是， DoSetMaxLength（）是在源中使用不正确，因为应在流加载之前将其称为。此外， TRichEditStrings.LoadFromStream（）完全不使用 DoSetMaxLength（）。雷米在评论中提及了他的答案。

If a long RTF-sequenz (eg 150 000 chars) is streamed into a TRichEdit control (in XE4), the control does not display the text but instead shows the raw RTF code:

{\rtf1\ansi\ansicpg1252\deff0...

What is wrong?

procedure TForm1.Button1Click(Sender: TObject);
var
    RtfText: string;
    Stream: TStringStream;
begin
    RtfText := GenerateRtfText();

    Stream := TStringStream.Create(RtfText);
    try
        RichEdit2.PlainText := False;
        RichEdit2.Lines.LoadFromStream(Stream); //<--- ERROR: RichEdit displays raw RTF-Code
                                                //     if RtfText is too long
        if StartsText('{\rtf', RichEdit2.Lines.Text) then
        begin
            ShowMessage('Oh no, not converted!');
            //WORKAROUND: 2nd try seems to work...
            //Stream.Position := 0;
            //RichEdit2.Lines.LoadFromStream(Stream);
        end;
    finally
        Stream.Free;
    end;
end;

For instance with following RTF generation function:

function TForm1.GenerateRtfText: string;
var
    I: Integer;
    Stream: TStringStream;
const
    DOES_WORK_COUNT = 10000;
    DOES_NOT_WORK_COUNT = 15000;
begin
    //Fill
    RichEdit1.Lines.BeginUpdate;
    try
        //for I := 0 to DOES_WORK_COUNT do
        for I := 0 to DOES_NOT_WORK_COUNT do
          RichEdit1.Lines.Add(IntToStr(I));
    finally
        RichEdit1.Lines.EndUpdate;
    end;
    //Convert to RTF
    Stream := TStringStream.Create;
    try
        RichEdit1.Lines.SaveToStream(Stream);
        Result := Stream.DataString;
    finally
        Stream.Free;
    end;
end;

Edited: Even copy and paste does not work correctly:

This is what I did:

• I copied the generated content of RichEdit1 (lines 1..15000 with numbers 1..15000) into notpad.exe to remove any RTF
• I copied the content of notepad into RichEdit2

Result:

• only 12773 lines are displayed correctly. The last line is only 12
• if I try to add another char into the TRichEdit nothing happens
• if I remove 10 chars (per backspace) I can add exactly 10 chars afterwards...

Is there a hidden character limit for TRichEdit?

解决方案

Rich edit control has a text limit.

Try using EM_EXLIMITTEXT message, which sets an upper limit to the amount of text the user can type or paste into a rich edit control. This message also limit the amount of text that you can stream into a rich edit control when streaming RTF (PlainText = False). but does not limit the control when streaming plain text.

e.g.:

const
  RE_MAX_TEXT_SIZE = 256000;

SendMessage(RichEdit1.Handle, EM_EXLIMITTEXT, 0, RE_MAX_TEXT_SIZE);

or:

SendMessage(RichEdit1.Handle, EM_EXLIMITTEXT, 0, $7FFFFFF0);

for the maximum limit as implemented in TRichEditStrings.LoadFromFile(): RichEdit.DoSetMaxLength($7FFFFFF0); However, DoSetMaxLength() is not correctly used in the sources, as it should be called before the stream is loaded. Also, DoSetMaxLength() is not used at all for TRichEditStrings.LoadFromStream(). Remy mentioned this in the comments of his answers.

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