如何将文本追加到RichTextBox中不滚动，失去选择？ [英] How to append text to RichTextBox without scrolling and losing selection?

问题描述

我需要将文本追加到RichTextBox中，并且需要执行它，而不进行文本框滚动或失去当前的文本选择，这可能吗？

I need to append text to RichTextBox, and need to perform it without making text box scroll or lose current text selection, is it possible?

推荐答案

在的WinForms RichTextBox的是相当闪烁高兴，当你玩的文字，选择文本的方法。

The RichTextBox in WinForms is quite flicker happy when you play around with the text and select-text methods.

我有一个标准的替代关掉绘画，并与下面的code滚动：

I have a standard replacement to turn off the painting and scrolling with the following code:

class RichTextBoxEx: RichTextBox
{
  [DllImport("user32.dll")]
  static extern IntPtr SendMessage(IntPtr hWnd, Int32 wMsg, Int32 wParam, ref Point lParam);

  [DllImport("user32.dll")]
  static extern IntPtr SendMessage(IntPtr hWnd, Int32 wMsg, Int32 wParam, IntPtr lParam);

  const int WM_USER = 0x400;
  const int WM_SETREDRAW = 0x000B;
  const int EM_GETEVENTMASK = WM_USER + 59;
  const int EM_SETEVENTMASK = WM_USER + 69;
  const int EM_GETSCROLLPOS = WM_USER + 221;
  const int EM_SETSCROLLPOS = WM_USER + 222;

  Point _ScrollPoint;
  bool _Painting = true;
  IntPtr _EventMask;
  int _SuspendIndex = 0;
  int _SuspendLength = 0;

  public void SuspendPainting()
  {
    if (_Painting)
    {
      _SuspendIndex = this.SelectionStart;
      _SuspendLength = this.SelectionLength;
      SendMessage(this.Handle, EM_GETSCROLLPOS, 0, ref _ScrollPoint);
      SendMessage(this.Handle, WM_SETREDRAW, 0, IntPtr.Zero);
      _EventMask = SendMessage(this.Handle, EM_GETEVENTMASK, 0, IntPtr.Zero);
      _Painting = false;
    }
  }

  public void ResumePainting()
  {
    if (!_Painting)
    {
      this.Select(_SuspendIndex, _SuspendLength);
      SendMessage(this.Handle, EM_SETSCROLLPOS, 0, ref _ScrollPoint);
      SendMessage(this.Handle, EM_SETEVENTMASK, 0, _EventMask);
      SendMessage(this.Handle, WM_SETREDRAW, 1, IntPtr.Zero);
      _Painting = true;
      this.Invalidate();
    }
  }
}

，然后从我的形式，我可以高兴地具有无闪烁的RichTextBox控件：

and then from my form, I can happily have a flicker-free richtextbox control:

richTextBoxEx1.SuspendPainting();
richTextBoxEx1.AppendText("Hey!");
richTextBoxEx1.ResumePainting();

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