WPF StackPanel with Click AND DoubleClick

Question

Hi!

I need to be able to handle the double click and single click event on the WPF StackPanel. But there is no such thing as the StackPanel's DoubleClick Event. I want to do 2 different operations in these 2 EventHandlers.

Any idea how to do that?

Thank you

Answer 1

The best way is to right your own mouse button handler with a timeout - if the event is fired again within the timeout period, then fire your doubleclick message, otherwise call the single click handler. Here's some sample code (Edit: originally found here):

/// <summary>
/// For double clicks
/// </summary>
public class MouseClickManager {
    private event MouseButtonEventHandler _click;
    private event MouseButtonEventHandler _doubleClick;

    public event MouseButtonEventHandler Click {
        add { _click += value; }
        remove { _click -= value; }
    }

    public event MouseButtonEventHandler DoubleClick {
        add { _doubleClick += value; }
        remove { _doubleClick -= value; }
    }

    /// <summary>
    /// Gets or sets a value indicating whether this <see cref="MouseClickManager"/> is clicked.
    /// </summary>
    /// <value><c>true</c> if clicked; otherwise, <c>false</c>.</value>
    private bool Clicked { get; set; }

    /// <summary>
    /// Gets or sets the timeout.
    /// </summary>
    /// <value>The timeout.</value>
    public int DoubleClickTimeout { get; set; }

    /// <summary>
    /// Initializes a new instance of the <see cref="MouseClickManager"/> class.
    /// </summary>
    /// <param name="control">The control.</param>
    public MouseClickManager(int doubleClickTimeout) {
        this.Clicked = false;
        this.DoubleClickTimeout = doubleClickTimeout;
    }

    /// <summary>
    /// Handles the click.
    /// </summary>
    /// <param name="sender">The sender.</param>
    /// <param name="e">The <see cref="System.Windows.Input.MouseButtonEventArgs"/> instance containing the event data.</param>
    public void HandleClick(object sender, MouseButtonEventArgs e) {
        lock (this) {
            if (this.Clicked) {
                this.Clicked = false;
                OnDoubleClick(sender, e);
            }
            else {
                this.Clicked = true;
                ParameterizedThreadStart threadStart = new ParameterizedThreadStart(ResetThread);
                Thread thread = new Thread(threadStart);
                thread.Start(e);
            }
        }
    }

    /// <summary>
    /// Resets the thread.
    /// </summary>
    /// <param name="state">The state.</param>
    private void ResetThread(object state) {
        Thread.Sleep(this.DoubleClickTimeout);

        lock (this) {
            if (this.Clicked) {
                this.Clicked = false;
                OnClick(this, (MouseButtonEventArgs)state);
            }
        }
    }

    /// <summary>
    /// Called when [click].
    /// </summary>
    /// <param name="sender">The sender.</param>
    /// <param name="e">The <see cref="System.Windows.Input.MouseButtonEventArgs"/> instance containing the event data.</param>
    private void OnClick(object sender, MouseButtonEventArgs e) {
        if (_click != null) {
            if (sender is Control) {
                (sender as Control).Dispatcher.BeginInvoke(_click, sender, e);
            }
        }
    }

    /// <summary>
    /// Called when [double click].
    /// </summary>
    /// <param name="sender">The sender.</param>
    /// <param name="e">The <see cref="System.Windows.Input.MouseButtonEventArgs"/> instance containing the event data.</param>
    private void OnDoubleClick(object sender, MouseButtonEventArgs e) {
        if (_doubleClick != null) {
            _doubleClick(sender, e);
        }
    }
}

Then, in the control you want to receive the events:

MouseClickManager fMouseManager = new MouseClickManager(200);
fMouseManager.Click += new MouseButtonEventHandler(YourControl_Click); 
fMouseManager.DoubleClick += new MouseButtonEventHandler(YourControl_DoubleClick);

Answer 2

 <StackPanel MouseDown="StackPanel_MouseDown">
   <!--stackpanel content-->
    <TextBlock>Hello</TextBlock>
</StackPanel>

Then in the event handler:

 private void StackPanel_MouseDown(object sender, MouseButtonEventArgs e)
    {
        if (e.ClickCount >= 2)
        { 
            string hello; //only hit here on double click  
        }
    }

Should work. Note that single clicking in the StackPanel would hit the event (but fail the if check)

Answer 3

Another option is to add a MouseBinding to the InputBindings on the StackElement and then add a CommandBinding that gets activated by MouseBinding. On the whole this is a better practice than event based mechanisms because it avoids the memory leak issues caused by strong references. It also provides for separation of command logic from the representation.

That being said, its not as straight forward and attaching to the event makes for a great shortcut.

And it goes without saying, make your stackpanel background at least transparent or it won't be caught by the mouse click hit test when you click on the "background". Null backgrounds are skipped over by hit detection.