如何使多行文本框传递MouseWheel事件，以便容器可滚动

Question

我有一个面板（用户控件），它需要滚动鼠标滚轮。在面板上有许多多行文本框。即使它们没有滚动条，它们在聚焦时捕捉鼠标轮事件。如何将事件传递给父控件，以便面板在选中多行文本框时使用鼠标滚轮进行滚动？

Answer 1

解决方案是使用从TextBox继承并重写WndProc方法的自定义控件。以下溶液从一个答案适应于similar question：

class MouseTransparentTextBox : TextBox 
{ 
    protected override void WndProc(ref Message m) 
    { 
     switch (m.Msg) 
     { 
      case 0x020A: // WM_MOUSEWHEEL 
      case 0x020E: // WM_MOUSEHWHEEL 
       if (this.ScrollBars == ScrollBars.None && this.Parent != null) 
        m.HWnd = this.Parent.Handle; // forward this to your parent 
       base.WndProc(ref m); 
       break; 

      default: 
       base.WndProc(ref m); 
       break; 
     } 
    } 
} 

Answer 2

一个更直接的方法是捕集鼠标滚轮事件。在发射时，向上或向下移动插入符号很容易，然后使用ScrollToCaret（）使htat线可见。

private void ScrollTextBox(object sender, MouseEventArgs e) 
     // Mouse wheel has been turned while text box has focus 
    { 

     // Check scroll amount (+ve is upwards) 
     int deltaWheel = e.Delta; 
     if (deltaWheel != 0) 
     { 
      // Find total number of lines 
      int nLines = edtAddress.Lines.Length; 
      if (nLines > 0) 
      { 
       // Find line containing caret 
       int iLine = edtAddress.GetLineFromCharIndex(edtAddress.SelectionStart); 
       if (iLine >= 0) 
       { 
        // Scroll down 
        if (deltaWheel > 0) 
        { 
         // Move caret to start of previous line 
         if (iLine > 0) 
         { 
          int position = edtAddress.GetFirstCharIndexFromLine(iLine - 1); 
          edtAddress.Select(position, 0); 

         } 
        } 
        else // Scroll up 
        { 
         // Move caret to start of next line 
         if (iLine < (nLines - 1)) 
         { 
          int position = edtAddress.GetFirstCharIndexFromLine(iLine + 1); 
          edtAddress.Select(position, 0); 
         } 
        } 

        // Scroll to new caret position 
        edtAddress.ScrollToCaret(); 
       } 
      }   

     } 

    }