Double-click isn't as popular a mouse action as it once was. For many, especially the elderly, clicking twice in the same spot without moving the mouse in between, is actually quite challenging. Nevertheless, double-click (and even triple click in some specialized programs in 3d and music) is a necessary capability.

Please note that this article and the attached sample code was written using the Silverlight 5 Beta, available at MIX11 in April 2011, and updated for the Silverlight 5 RC.

Silverlight 5 has introduced the concept of a click count. Rather than create dedicated double, triple, or septuple click events, you can simply count the number of clicks using the ClickCount property of the MouseButtonEventArgs class. This works for both the left and right mouse buttons.

Implementing this yourself is non-trivial, as you have to take into account some fairly fiddly timings, ensuring that two consecutive single clicks aren't taken as a double-click unless the second click happens within a specific time period after the previous click. I'm happy to let the platform do that work for me.

Project Setup

I created a simple Silverlight web project. In the MainPage.xaml, I added a single red rectangle and wired up an event handler for MouseLeftButtonDown.

<UserControl x:Class="MouseClickCountDemo.MainPage"

             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"

             mc:Ignorable="d"

             d:DesignHeight="300"

             d:DesignWidth="400">



    <Grid x:Name="LayoutRoot" Background="White">

        <Rectangle x:Name="ClickMe"

                   Width="80"

                   Height="80"

                   MouseLeftButtonDown="ClickMe_MouseLeftButtonDown"

                   Fill="Red" />

    </Grid>

</UserControl>

The only code-behind is simply an event handler that helps us count the clicks.

Implementing Double Click

Inside the ClickMe_MouseLeftButtonDown event, I added some debug code to write the number of clicks to the output window, and display a "Double Click" message if there are two clicks in a row.

private void ClickMe_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)

{

    System.Diagnostics.Debug.WriteLine("Click Count: " + e.ClickCount);



    if (e.ClickCount == 2)

        System.Diagnostics.Debug.WriteLine("Double Click");



}

That's all there is to it. I've been able to generate click counts up into the hundreds before my finger started to protest. There is no artificial limit on the number of clicks you can respond to. Try clicking slowly and clicking quickly to get a feel for how it responds.

Source code for the Silverlight 5 Beta version of this application may be downloaded via the link below.

A video version of this tutorial will be on Silverlight.net shortly.