CODEWITHSUNDEEP
c#windowstreeview
Walt W
Walt W

Reputation: 3349

C# System.Windows.Forms.TreeView: Stop auto expand/collapse on double-click (and execute another handler)

Is there a simple way to disable the auto-expand/collapse of a TreeView node when it is double-clicked? I've been unable to find an answer to this question that works without checking in BeforeExpand/BeforeCollapse if the current system time matches that expected for a double-click - overriding OnNodeMouseDoubleClick and/or OnDoubleClick does not seem to suffice.

Or, is checking the system time and seeing if it fits a double-click the only way to do this?

Thanks for your help, -Walt

Upvotes: 5

Views: 10273

Answers (3)

Frank Wolter
Frank Wolter

Reputation: 1

Nevertheless this thread is old... I didn't find an easy solution for this problem, so I investigated on my own. This is the result:

Inherit a specialized Treeview which has the desired behaviour from Treeview. Overriding the MouseDown and checking if it will be a doubleclick. If so, prevent expansion/collapse by setting a flag to supress the action. BeforeExpand/collapse are overridden to cancel the action if the flag is set. You could reset the flag in your BeforeExpand/Collapse-EventHandler if you want to.

  Public Class DblClickTreeview
    Inherits TreeView

    Private _SupressExpColl As Boolean = False
    Private _LastClick As DateTime = Now

    Protected Overrides Sub OnMouseDown(e As MouseEventArgs)
        _SupressExpColl = Now.Subtract(_LastClick).TotalMilliseconds <= SystemInformation.DoubleClickTime
        _LastClick = Now
        MyBase.OnMouseDown(e)
    End Sub

    Protected Overrides Sub OnBeforeCollapse(e As TreeViewCancelEventArgs)
        e.Cancel = _SupressExpColl
        MyBase.OnBeforeCollapse(e)
    End Sub

    Protected Overrides Sub OnBeforeExpand(e As TreeViewCancelEventArgs)
        e.Cancel = _SupressExpColl
        MyBase.OnBeforeExpand(e)
    End Sub
End Class

Upvotes: 0

Qodex
Qodex

Reputation: 329

Haven't had much luck with any of the answers I've found so far, but Walt's answer provided the inspiration for this:

int treeX;   // somewhere in class scope

// Add a MouseMove event handler
private void treeView1_MouseMove(object sender, MouseEventArgs e)
{
    treeX = e.X;
}

// Add a BeforeExpand event handler
private void treeView1_BeforeExpand(object sender, TreeViewCancelEventArgs e)
{
    if (treeX > e.Node.Bounds.Left) e.Cancel = true;
}

Upvotes: 0

Walt W
Walt W

Reputation: 3349

Solved: Actually, the entire solution was at http://www.developersdex.com/gurus/code/831.asp . Apparently OnNodeMouseDoubleClick() is not called in the WM_LBUTTONDBLCLK handler for TreeView at all . . . it's called in the LBUTTONUP handler. So, The following is what's at that site:

    protected override void DefWndProc(ref Message m) {
        if (m.Msg == 515) { /* WM_LBUTTONDBLCLK */
        }
        else
            base.DefWndProc(ref m);
    }

If you want to halt handling to the left of the node, then in OnNodeMouseDoubleClick() do the following:

if (e.X >= e.Node.Bounds.Left) {
    return;
}

Upvotes: 15

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