WPF - Detect mouse down for a set period of time

Question

what's the best way to detect when a mouse button has been held down on a particular element for a specific period of time?

Answer 1

Thanks for the tip, I've made an attached property to avoid any codebehind:

using System;
using System.Windows;
using System.Windows.Threading;

/// <summary>
/// Represents a particular mouse button being pressed
/// </summary>
public enum MouseButtonType
{
    /// <summary>
    /// Default selection
    /// </summary>
    None,

    /// <summary>
    /// Left mouse button
    /// </summary>
    Left,

    /// <summary>
    /// Right mouse button
    /// </summary>
    Right,

    /// <summary>
    /// Either mouse button
    /// </summary>
    Both
}

/// <summary>
/// Provides functionality for detecting when a mouse button has been held
/// </summary>
public class MouseDownWait
{
    /// <summary>
    /// States which mouse button press should be detected
    /// </summary>
    public static readonly DependencyProperty MouseButtonProperty =
        DependencyProperty.RegisterAttached(
            "MouseButton",
            typeof(MouseButtonType),
            typeof(MouseDownWait),
            new PropertyMetadata(
                (o, e) =>
                    {
                    var ctrl = o as UIElement;
                    if (ctrl != null)
                    {
                        new MouseDownWait(ctrl);
                    }
                }));

    /// <summary>
    /// The time (in milliseconds) to wait before detecting mouse press
    /// </summary>
    public static readonly DependencyProperty TimeProperty = DependencyProperty.RegisterAttached(
        "Time", typeof(int), typeof(MouseDownWait), new FrameworkPropertyMetadata(0, OnTimePropertyChanged));

    /// <summary>
    /// Method to be called when the mouse press is detected
    /// </summary>
    public static readonly DependencyProperty DetectMethodProperty =
        DependencyProperty.RegisterAttached(
            "DetectMethod",
            typeof(string),
            typeof(MouseDownWait));

    /// <summary>
    /// Target object for the method calls (if not the datacontext)
    /// </summary>
    public static readonly DependencyProperty MethodTargetProperty =
        DependencyProperty.RegisterAttached("MethodTarget", typeof(object), typeof(MouseDownWait));      

    /// <summary>
    /// The timer used to detect mouse button holds
    /// </summary>
    private static readonly DispatcherTimer Timer = new DispatcherTimer();

    /// <summary>
    /// The element containing the attached property
    /// </summary>
    private readonly UIElement element;

    /// <summary>
    /// Initializes a new instance of the <see cref="MouseDownWait"/> class.
    /// </summary>
    /// <param name="element">The element.</param>
    public MouseDownWait(UIElement element)
    {
        this.element = element;

        if (this.element == null)
        {
            return;
        }

        this.element.MouseLeftButtonDown += ElementMouseLeftButtonDown;
        this.element.MouseLeftButtonUp += ElementMouseLeftButtonUp;
        this.element.MouseRightButtonDown += ElementMouseRightButtonDown;
        this.element.MouseRightButtonUp += ElementMouseRightButtonUp;
        this.element.MouseDown += ElementMouseDown;
        this.element.MouseUp += ElementMouseUp;

        Timer.Tick += this.TimerTick;
    }

    /// <summary>
    /// Gets the mouse button type
    /// </summary>
    /// <param name="element">The element.</param>
    /// <returns>
    /// The mouse button type
    /// </returns>
    public static MouseButtonType GetMouseButton(UIElement element)
    {
        return (MouseButtonType)element.GetValue(MouseButtonProperty);
    }

    /// <summary>
    /// Sets the mouse button type
    /// </summary>
    /// <param name="element">The element.</param>
    /// <param name="value">The type of mouse button</param>
    public static void SetMouseButton(UIElement element, MouseButtonType value)
    {
        element.SetValue(MouseButtonProperty, value);
    }

    /// <summary>
    /// Gets the time.
    /// </summary>
    /// <param name="element">The element.</param>
    /// <returns>The time in milliseconds</returns>
    public static int GetTime(UIElement element)
    {
        return (int)element.GetValue(TimeProperty);
    }

    /// <summary>
    /// Sets the time.
    /// </summary>
    /// <param name="element">The element.</param>
    /// <param name="value">The value.</param>
    public static void SetTime(UIElement element, int value)
    {
        element.SetValue(TimeProperty, value);
    }

    /// <summary>
    /// Sets the detect method
    /// </summary>
    /// <param name="element">The element.</param>
    /// <param name="value">The value.</param>
    public static void SetDetectMethod(UIElement element, string value)
    {
        element.SetValue(DetectMethodProperty, value);
    }

    /// <summary>
    /// Gets the detect method
    /// </summary>
    /// <param name="element">The element.</param>
    /// <returns>method name</returns>
    public static string GetDetectMethod(UIElement element)
    {
        return (string)element.GetValue(DetectMethodProperty);
    }

    /// <summary>
    /// Gets the method target.
    /// </summary>
    /// <param name="ctrl">The CTRL .</param>
    /// <returns>method target (i.e. viewmodel)</returns>
    public static object GetMethodTarget(UIElement ctrl)
    {
        var result = ctrl.GetValue(MethodTargetProperty);
        if (result == null)
        {
            var fe = ctrl as FrameworkElement;
            if (fe != null)
            {
                result = fe.DataContext;
            }
        }

        return result;
    }

    /// <summary>
    /// Sets the method target.
    /// </summary>
    /// <param name="ctrl">The CTRL .</param>
    /// <param name="value">The value.</param>
    public static void SetMethodTarget(UIElement ctrl, object value)
    {
        ctrl.SetValue(MethodTargetProperty, value);
    }

    /// <summary>
    /// Called when the time property changes.
    /// </summary>
    /// <param name="d">The dependency object.</param>
    /// <param name="e">The <see cref="System.Windows.DependencyPropertyChangedEventArgs"/> instance containing the event data.</param>
    private static void OnTimePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        Timer.Interval = TimeSpan.FromMilliseconds((int)e.NewValue);
    }

    /// <summary>
    /// Called when a mouse down is detected
    /// </summary>
    private static void MouseDownDetected()
    {
        Timer.Start();
    }

    /// <summary>
    /// Called when a mouse up is detected
    /// </summary>
    private static void MouseUpDetected()
    {
        Timer.Stop();
    }

    /// <summary>
    /// Checks if the mouse button has been detected.
    /// </summary>
    /// <param name="sender">The sender.</param>
    /// <param name="type">The mouse button type.</param>
    /// <param name="mouseDown">if set to <c>true</c> [mouse down].</param>
    private static void CheckMouseDetected(object sender, MouseButtonType type, bool mouseDown)
    {
        var uiElement = sender as UIElement;

        if (uiElement == null)
        {
            return;
        }

        if (GetMouseButton(uiElement) != type)
        {
            return;
        }

        if (mouseDown)
        {
            MouseDownDetected();
        }
        else
        {
            MouseUpDetected();
        }
    }

    /// <summary>
    /// Called when the mouse down event fires
    /// </summary>
    /// <param name="sender">The sender.</param>
    /// <param name="e">The <see cref="System.Windows.Input.MouseButtonEventArgs"/> instance containing the event data.</param>
    private static void ElementMouseDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
    {
        CheckMouseDetected(sender, MouseButtonType.Both, true);
    }

    /// <summary>
    /// Called when the mouse up event fires
    /// </summary>
    /// <param name="sender">The sender.</param>
    /// <param name="e">The <see cref="System.Windows.Input.MouseButtonEventArgs"/> instance containing the event data.</param>
    private static void ElementMouseUp(object sender, System.Windows.Input.MouseButtonEventArgs e)
    {
        CheckMouseDetected(sender, MouseButtonType.Both, false);
    }

    /// <summary>
    /// Called when the left mouse down event fires
    /// </summary>
    /// <param name="sender">The sender.</param>
    /// <param name="e">The <see cref="System.Windows.Input.MouseButtonEventArgs"/> instance containing the event data.</param>
    private static void ElementMouseLeftButtonDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
    {
        CheckMouseDetected(sender, MouseButtonType.Left, true);
    }

    /// <summary>
    /// Called when the left mouse up event fires
    /// </summary>
    /// <param name="sender">The sender.</param>
    /// <param name="e">The <see cref="System.Windows.Input.MouseButtonEventArgs"/> instance containing the event data.</param>
    private static void ElementMouseLeftButtonUp(object sender, System.Windows.Input.MouseButtonEventArgs e)
    {
        CheckMouseDetected(sender, MouseButtonType.Left, false);
    }

    /// <summary>
    /// Called when the right mouse down event fires
    /// </summary>
    /// <param name="sender">The sender.</param>
    /// <param name="e">The <see cref="System.Windows.Input.MouseButtonEventArgs"/> instance containing the event data.</param>
    private static void ElementMouseRightButtonDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
    {
        CheckMouseDetected(sender, MouseButtonType.Right, true);
    }

    /// <summary>
    /// Called when the right mouse up event fires
    /// </summary>
    /// <param name="sender">The sender.</param>
    /// <param name="e">The <see cref="System.Windows.Input.MouseButtonEventArgs"/> instance containing the event data.</param>
    private static void ElementMouseRightButtonUp(object sender, System.Windows.Input.MouseButtonEventArgs e)
    {
        CheckMouseDetected(sender, MouseButtonType.Right, false);
    }

    /// <summary>
    /// Called on each timer tick
    /// </summary>
    /// <param name="sender">The sender.</param>
    /// <param name="e">The <see cref="System.EventArgs"/> instance containing the event data.</param>
    private void TimerTick(object sender, EventArgs e)
    {
        Timer.Stop();

        var method = GetDetectMethod(this.element);

        if (!string.IsNullOrEmpty(method))
        {
            this.InvokeMethod(method);
        }
    }

    /// <summary>
    /// Invokes the method.
    /// </summary>
    /// <param name="methodName">Name of the method.</param>
    /// <param name="parameters">The parameters.</param>
    private void InvokeMethod(string methodName, params object[] parameters)
    {
        var target = GetMethodTarget(this.element);
        var targetMethod = target.GetType().GetMethod(methodName);
        if (targetMethod == null)
        {
            throw new MissingMethodException(methodName);
        }

        targetMethod.Invoke(target, parameters);
    }
}

Usage:

<Border BorderBrush="Gray" BorderThickness="1" Height="200" Width="200" Background="Transparent" 
        local:MouseDownWait.MouseButton="Both"
        local:MouseDownWait.Time="1000"
        local:MouseDownWait.DetectMethod="MouseDetected">

        <TextBlock x:Name="Title" HorizontalAlignment="Stretch" VerticalAlignment="Center" TextAlignment="Center" FontSize="28"  />

</Border>

This will call a method on your DataContext (ViewModel) when the specified time has ellapsed. You can detect Left, Right, or Both mouse buttons.

Answer 2

You need to add MouseDown and MouseUp handlers to the object. In the MouseDown record DateTime.Now. If in the MouseUp handler:

DateTime.Now.Subtract(clickTime).TotalSeconds > your_seconds_value

then fire a new event MouseClickedForXseconds.

If you don't want to wait for a mouse up event then you need to start a timer on the MouseDown method which fires your MouseClickedForXSeconds event. This timer will be canceled by a mouse up event.