Condition in an EventTrigger

Question

Can I check condition inside an event trigger? how can I do something like that using only XAML?

 <EventTrigger RoutedEvent="MouseDown">
    <Trigger Property="IsPressed" Value="true">
       <Setter Property = "Foreground" Value="Green"/>

Answer 1

May help clarify this:

Condition for EventTrigger

Can an Event Trigger only go off when certain properties are met?

Answer 2

Buttons and menu items have an IsPressed property that would work for you but other controls does. It is however easy to add an IsPressed property using some attached behavior. This will let you write XAML like this:

<TextBlock Text="Hello" TriggerTest:IsPressedBehavior.MonitorMouse="true">
    <TextBlock.Style>
        <Style TargetType="{x:Type TextBlock}"> 
            <Setter Property="Foreground" Value="Red" />
            <Style.Triggers> 
                <Trigger Property="TriggerTest:IsPressedBehavior.IsPressed" Value="True"> 
                    <Setter Property="Foreground" Value="Green" /> 
                </Trigger>
            </Style.Triggers> 
        </Style> 
    </TextBlock.Style>
</TextBlock>

Attached behavior class:

using System;
using System.Windows;
using System.Windows.Input;

namespace TriggerTest
{
    public static class IsPressedBehavior
    {
        public static bool GetMonitorMouse(DependencyObject obj)
        {
            return (bool)obj.GetValue(MonitorMouseProperty);
        }

        public static void SetMonitorMouse(DependencyObject obj, bool value)
        {
            obj.SetValue(IsPressedProperty, value);
        }

        public static readonly DependencyProperty MonitorMouseProperty =
            DependencyProperty.RegisterAttached("MonitorMouse",
                                                typeof(bool),
                                                typeof(IsPressedBehavior),
                                                new UIPropertyMetadata(false, OnMonitorMouse));

        public static bool GetIsPressed(DependencyObject obj)
        {
            return (bool)obj.GetValue(IsPressedProperty);
        }

        public static void SetIsPressed(DependencyObject obj, bool value)
        {
            obj.SetValue(IsPressedProperty, value);
        }

        public static readonly DependencyProperty IsPressedProperty =
            DependencyProperty.RegisterAttached("IsPressed",
                                                typeof(bool),
                                                typeof(IsPressedBehavior),
                                                new UIPropertyMetadata(false));

        private static void OnMonitorMouse(DependencyObject depObj, DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
        {
            UIElement uiElement = depObj as UIElement;
            if (uiElement == null)
            {
                return;
            }
            if ((bool)dependencyPropertyChangedEventArgs.NewValue)
            {
                uiElement.MouseDown += OnMouseDown;
                uiElement.MouseUp += OnMouseUp;
                uiElement.MouseLeave += OnMouseLeave;
                uiElement.MouseEnter += OnMouseEnter;
            }
            else
            {
                uiElement.MouseDown -= OnMouseDown;
                uiElement.MouseUp -= OnMouseUp;
                uiElement.MouseLeave -= OnMouseLeave;
                uiElement.MouseEnter -= OnMouseEnter;
            }
        }

        private static void OnMouseDown(object sender, MouseButtonEventArgs e)
        {
            SetIsPressed(sender as DependencyObject, true);
        }

        private static void OnMouseUp(object sender, MouseButtonEventArgs e)
        {
            SetIsPressed(sender as DependencyObject, false);
        }

        private static void OnMouseLeave(object sender, MouseEventArgs e)
        {
            SetIsPressed(sender as DependencyObject, false);
        }

        static void OnMouseEnter(object sender, MouseEventArgs e)
        {
            SetIsPressed(sender as DependencyObject, e.LeftButton == MouseButtonState.Pressed || e.MiddleButton == MouseButtonState.Pressed || e.RightButton == MouseButtonState.Pressed);
        }
    }
}