Synchronize Scroll Position of two RichTextBoxes?

.net, c#, richtextbox, scroll, winforms

Solution

I did this for a small project a while ago, and here's the simplist solution I found.

Create a new control by subclassing RichTextBox:

   public class SynchronizedScrollRichTextBox : System.Windows.Forms.RichTextBox
    {
        public event vScrollEventHandler vScroll;
        public delegate void vScrollEventHandler(System.Windows.Forms.Message message);

        public const int WM_VSCROLL = 0x115;

        protected override void WndProc(ref System.Windows.Forms.Message msg) {
            if (msg.Msg == WM_VSCROLL) {
                if (vScroll != null) {
                    vScroll(msg);
                }
            }
            base.WndProc(ref msg);
        }

        public void PubWndProc(ref System.Windows.Forms.Message msg) {
            base.WndProc(ref msg);
        }
    }

Add the new control to your form and for each control explicitly notify the other instances of the control that its vScroll position has changed. Somthing like this:

private void scrollSyncTxtBox1_vScroll(Message msg) {
    msg.HWnd = scrollSyncTxtBox2.Handle;
    scrollSyncTxtBox2.PubWndProc(ref msg);
}

I think this code has problems if all the 'linked' controls don't have the same number of displayable lines.

Problem

In my application's form, I have two `RichTextBox` objects. They will both always have the same number of lines of text. I would like to "synchronize" the vertical scrolling between these two, so that when the user changes the vertical scroll position on one, the other scrolls the same amount. How might I go about doing this?

Original source

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