How can I sync the scrolling of two multiline textboxes?

by

Yes, you’ll have to create a custom text box so you can detect it scrolling. The trick is to pass the scroll message to the other text box so it will scroll in sync. This really only works well when that other text box is about the same size and has the same number of lines.

Add a new class to your project and paste the code shown below. Compile. Drop two of the new controls from the top of the toolbox onto your form. Set the Buddy property to the other control on both. Run, type some text in both of them and watch them scroll in sync as you drag the scrollbar.

using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;

class SyncTextBox : TextBox {
    public SyncTextBox() {
        this.Multiline = true;
        this.ScrollBars = ScrollBars.Vertical;
    }
    public Control Buddy { get; set; }

    private static bool scrolling;   // In case buddy tries to scroll us
    protected override void WndProc(ref Message m) {
        base.WndProc(ref m);
        // Trap WM_VSCROLL message and pass to buddy
        if (m.Msg == 0x115 && !scrolling && Buddy != null && Buddy.IsHandleCreated) {
            scrolling = true;
            SendMessage(Buddy.Handle, m.Msg, m.WParam, m.LParam);
            scrolling = false;
        }
    }
    [DllImport("user32.dll", CharSet = CharSet.Auto)]
    private static extern IntPtr SendMessage(IntPtr hWnd, int msg, IntPtr wp, IntPtr lp);
}

More Related Contents:

  1. How do I automatically scroll to the bottom of a multiline text box?
  2. TextBox not containing "\r\n" strings
  3. how to write every element of an array in a line of a textbox C# [closed]
  4. read text file chunks by chunks by scrollbar [closed]
  5. How do I make a textbox that only accepts numbers?
  6. Redirect console output to textbox in separate program
  7. Loop through Textboxes
  8. How to remove the focus from a TextBox in WinForms?
  9. How to update textbox in form1 from form2?
  10. Trying to use the C# SpellCheck class
  11. Transparency for windows forms textbox
  12. How to set Z-order of a Control using WinForms
  13. The maximum number of characters a TextBox can display
  14. How to clear the text of all textBoxes in the form?
  15. Change border color in TextBox C#
  16. how to disable copy, Paste and delete features on a textbox using C#
  17. A textbox/richtextbox that has syntax highlighting? [C#] [closed]
  18. Change the borderColor of the TextBox
  19. How can I dynamically change auto complete entries in a C# combobox or textbox?
  20. How to Programmatically Scroll a Panel
  21. How to add a line to a multiline TextBox?
  22. Synchronize Scroll Position of two RichTextBoxes?
  23. How can I get scrollbars on Picturebox
  24. Add vertical scroll bar to panel
  25. Chart Auto Scroll (Oscilloscope Effect)
  26. Only allow specific characters in textbox
  27. Override Paste Into TextBox
  28. Winforms Double Buffering
  29. How to get control under mouse cursor? [duplicate]
  30. How to set a text box for inputing password in winforms?

Leave a Comment