WPF自定义行为Behavior，实现双击控件复制文本

WPF引用xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"后可以设置很多自定义的行为：

           <i:Interaction.Triggers>
                <i:EventTrigger EventName="ValueChanged">
                    <i:InvokeCommandAction Command="{Binding ValueChangedCommand}" />
                </i:EventTrigger>
            </i:Interaction.Triggers>

<UserControl.Resources>
        <ControlTemplate x:Key="trackThumb" TargetType="{x:Type Slider}">
            <Border Background="{TemplateBinding Background}"
                    BorderBrush="{TemplateBinding BorderBrush}"
                    BorderThickness="{TemplateBinding BorderThickness}">
                <Grid>
                    <Track x:Name="PART_Track">
                        <Track.Thumb>
                            <Thumb Width="10">
                                <i:Interaction.Triggers>
                                    <i:EventTrigger EventName="DragCompleted">
                                        <i:InvokeCommandAction Command="{Binding ValueChangedCommand}" />
                                    </i:EventTrigger>
                                </i:Interaction.Triggers>
                            </Thumb>
                        </Track.Thumb>
                    </Track>
                </Grid>
            </Border>
        </ControlTemplate>
    </UserControl.Resources>

当时当我们有一些自定义的需求时，需要自定义行为，例如给每个控件添加一个双击复制文本的行为。

1. 定义行为

public class MouseDoubleClickCopyTextBehavior : Behavior<FrameworkElement>
    {
        /// <summary>
        /// 需要复制的内容
        /// </summary>
        public string CopyText
        {
            get { return (string)GetValue(CopyTextProperty); }
            set { SetValue(CopyTextProperty, value); }
        }

        public static readonly DependencyProperty CopyTextProperty = DependencyProperty.Register("CopyText", typeof(string), typeof(MouseDoubleClickCopyTextBehavior), new PropertyMetadata(null));

        protected override void OnAttached()
        {
            base.OnAttached();
            AssociatedObject.PreviewMouseLeftButtonDown += AssociatedObject_PreviewMouseLeftButtonDown;
        }

        protected override void OnDetaching()
        {
            base.OnDetaching();
            AssociatedObject.PreviewMouseLeftButtonDown -= AssociatedObject_PreviewMouseLeftButtonDown;
        }

        void AssociatedObject_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
        {
            if (e.ClickCount >= )
                Clipboard.SetDataObject(CopyText);
        }

2. 控件绑定行为

<Style TargetType="Label" BasedOn="{StaticResource {x:Type Label}}">
                <Setter Property="VerticalAlignment" Value="Center" />
                <Setter Property="Template">
                    <Setter.Value>
                        <ControlTemplate TargetType="Label">
                            <Border>
                                <ContentPresenter Name="ContentPresenter"
                                                 HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
                                                  VerticalAlignment="{TemplateBinding VerticalContentAlignment}"
                                                  RecognizesAccessKey="True" >
                                    <!-- 绑定自定义行为 -->
                                    <i:Interaction.Behaviors>
                                         <hei:MouseDoubleClickCopyTextBehavior CopyText="{Binding ElementName=ContentPresenter,Path=Content}"/>
                                    </i:Interaction.Behaviors>
                                </ContentPresenter>
                            </Border>
                            <ControlTemplate.Triggers>
                                <Trigger Property="IsEnabled"
                                         Value="false">
                                    <Setter Property="Foreground"><Setter.Value>
                                            <SolidColorBrush Color="{DynamicResource DisabledForegroundColor}" />
                                        </Setter.Value>
                                    </Setter>
                                </Trigger>
                            </ControlTemplate.Triggers>
                        </ControlTemplate></Setter.Value>
                </Setter>
            </Style>