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Synchronizing Multiline Textbox Positions in C#

由 此生再无相见时 提交于 2019-12-05 06:00:35
Jay Riggs

I subclassed a RichTextBox and listened for the WM_VSCROLL message to do what you're trying to do. Perhaps you can do that instead of using a TextBox.

RESPONSE TO YOUR EDIT:

Note: I'm assuming you made a minor error in the copy and paste in your Application form and that textBoxSyncBusTraffic == textBoxSync1

The problem is in your declaration of your control's VerticalScroll event, in this line:

this.textBoxSyncBusTraffic.VerticalScroll += new System.EventHandler(this.textBoxSyncBusTraffic_VerticalScroll);
  1. Your custom controls need to subscribe to your controls' TextBoxSynchronizedScroll.vScrollEventHandler events (not to System.EventHandler).
  2. The method referenced in your event handler doesn't exist (at least not in the code you posted).

So change this:

this.textBoxSyncBusTraffic.VerticalScroll += new System.EventHandler(this.textBoxSyncBusTraffic_VerticalScroll);

To this:

this.textBoxSync1.VerticalScroll += new TextBoxSynchronizedScroll.vScrollEventHandler(textBoxSync1_VerticalScroll);

This uses the correct event handler and references the method you need and already have.

Also, make sure that the declaration for textBoxSync2's VerticalScroll event looks like this:

this.textBoxSync2.VerticalScroll += new TextBoxSynchronizedScroll.vScrollEventHandler(textBoxSync2_VerticalScroll);

Incidentally, there are a couple techniques you can use to make it easier to declare events:

The first is to use the form designer. If you open the Events window in the Properties window of an instance of your extended control in the forms designer, you'll see an event called VerticalScroll. Double click this item to have Visual Studio declare the event and create a method to call when the event fires.

There's also a shortcut you can use when you set up your event in code. You'll find that after you type the following code:

youtextBoxSync1.VerticalScroll +=

You'll be prompted to press Tab to finish the declaration. If you do this Visual Studio will create a method with the correct signature.

Based of the existing code I came up with the following. Seems to work for me.

class TextBoxSynchronizedScroll : TextBox
{
    public const int WM_VSCROLL = 0x115;

    List<TextBoxSynchronizedScroll> peers = new List<TextBoxSynchronizedScroll>();

    public void AddPeer(TextBoxSynchronizedScroll peer)
    {
        this.peers.Add(peer);
    }

    private void DirectWndProc(ref Message m)
    {
        base.WndProc(ref m);
    }

    protected override void WndProc(ref Message m)
    {
        if (m.Msg == WM_VSCROLL)
        {
            foreach (var peer in this.peers)
            {
                var peerMessage = Message.Create(peer.Handle, m.Msg, m.WParam, m.LParam);
                peer.DirectWndProc(ref peerMessage);
            }
        }

        base.WndProc(ref m);
    }
}

http://gist.github.com/593809

标签
c#
synchronization
scroll
textbox
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