Compartilhar via

How to: Create a Custom Double-Click Event 

  • Artigo

The .NET Compact Framework does not support the Windows Forms DoubleClick event for a button. But you can create a control that derives from the Button class to implement the event.

To create a custom double-click event

  1. Create a class that derives from the System.Windows.Forms.Button class.

  2. Declare a DoubleClick event.

  3. Override the OnClick method with code to raise the DoubleClick event if button clicks occur within a specified time.

Example

This example creates a DoubleClickButton custom control and implements it on a form.

using System;
using System.Windows.Forms;
using System.Drawing;

namespace ButtonDClick
{
    public class Form1 : System.Windows.Forms.Form
    {
        // Track the number of 
        // double-clicks with the count variable.
        int count = 0;

        public Form1()
        {
            InitializeComponent();
            
            // Display OK button for closing.
            this.MinimizeBox = false;

            // Create an instance of the DoubleClickButton class.
            DoubleClickButton dClickB = new DoubleClickButton();
            
            dClickB.Bounds = new Rectangle(10,10,200,30);
            dClickB.Text = "Double-click me!";
            Controls.Add(dClickB);

            // Add the DClick event hander to the DoubleClick event.
            dClickB.DoubleClick += new EventHandler(DClick);
        }

        protected override void Dispose( bool disposing )
        {
            base.Dispose( disposing );
        }

        private void InitializeComponent()
        {
            this.Text = "Form1";
        }

        private void DClick(object o, EventArgs e)
        {
            // Display the number of double-clicks.
            MessageBox.Show("Double-click count = " + ++count);
        }

        static void Main() 
        {
            Application.Run(new Form1());
        }

        // Derive a button with extended funtionality
        // from the Button class.
        public class DoubleClickButton : System.Windows.Forms.Button 
        { 
            // Note that the DoubleClickTime property gets 
            // the maximum number of milliseconds allowed between 
            // mouse clicks for a double-click to be valid.
            int previousClick = SystemInformation.DoubleClickTime;

            public new event EventHandler DoubleClick;

            protected override void OnClick(EventArgs e)
            {
                int now = System.Environment.TickCount;

                // A double-click is detected if the the time elapsed
                // since the last click is within DoubleClickTime.
                if ( now - previousClick <= SystemInformation.DoubleClickTime)
                {
                    // Raise the DoubleClick event.
                    if (DoubleClick != null)
                        DoubleClick(this,EventArgs.Empty);
                }

                // Set previousClick to now so that 
                // subsequent double-clicks can be detected.
                previousClick = now;

                // Allow the base class to raise the regular Click event.
                base.OnClick(e);
            }

            // Event handling code for the DoubleClick event.
            protected new virtual void OnDoubleClick(EventArgs e)
            {
                if (this.DoubleClick != null)
                    this.DoubleClick(this, e);
            }
        }
    }
}

Compiling the Code

This example requires references to the following namespaces:

See Also

Concepts

Custom Control Development