WPF - 交互

在 WPF 中，交互显示视图如何与该视图中位于的控件交互。最常见的交互类型有两种：

行为
拖放

行为

行为是在 Expression Blend 3 中引入的，它可以将某些功能封装到可重用的组件中。要添加其他行为，您可以将这些组件附加到控件。行为提供了更大的灵活性，可以轻松设计复杂的用户交互。

让我们来看一个简单的示例，其中 ControlStoryBoardAction 行为附加到控件。

创建一个名为 WPFBehavior 的新 WPF 项目。
以下 XAML 代码创建了一个椭圆和两个按钮来控制椭圆的移动。

<Window 
   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" 
   xmlns:local = "clr-namespace:WPFBehaviors" 
   xmlns:i = "http://schemas.microsoft.com/expression/2010/interactivity" 
   xmlns:ei = "http://schemas.microsoft.com/expression/2010/interactions" 
   x:Class = "WPFBehaviors.MainWindow" 
   mc:Ignorable = "d" Title = "MainWindow" Height = "350" Width = "604">
	
   <Window.Resources> 
      <Storyboard x:Key = "Storyboard1" RepeatBehavior = "Forever" AutoReverse = "True"> 
		
         <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty =
            "(UIElement.RenderTransform).(TransformGroup.Children )[3].(TranslateTransform.X)"
            Storyboard.TargetName = "ellipse"> 
            <EasingDoubleKeyFrame KeyTime = "0:0:1" Value = "301.524"/> 
            <EasingDoubleKeyFrame KeyTime = "0:0:2" Value = "2.909"/> 
         </DoubleAnimationUsingKeyFrames>
			
         <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty = 
            "(UIElement.RenderTransform).(TransformGroup.Children )[3].(TranslateTransform.Y)"
            Storyboard.TargetName = "ellipse"> 
            <EasingDoubleKeyFrame KeyTime = "0:0:1" Value = "-0.485"/> 
            <EasingDoubleKeyFrame KeyTime = "0:0:2" Value = "0"/> 
         </DoubleAnimationUsingKeyFrames> 
			
         <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty = "(ContentControl.Content)"
            Storyboard.TargetName = "button"> 
            <DiscreteObjectKeyFrame KeyTime = "0" Value = "Play"/> 
         </ObjectAnimationUsingKeyFrames>
			
         <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty = "(ContentControl.Content)"
            Storyboard.TargetName = "button1"> 
            <DiscreteObjectKeyFrame KeyTime = "0" Value = "Stop"/> 
            <DiscreteObjectKeyFrame KeyTime = "0:0:2" Value = "Stop"/> 
         </ObjectAnimationUsingKeyFrames> 
      </Storyboard> 
   </Window.Resources> 
	
   <Window.Triggers> 
      <EventTrigger RoutedEvent = "FrameworkElement.Loaded"> 
         <BeginStoryboard Storyboard = "{StaticResource Storyboard1}"/> 
      </EventTrigger> 
   </Window.Triggers> 
	
   <Grid> 
      <Ellipse x:Name = "ellipse" Fill = "#FFAAAAC5" HorizontalAlignment = "Left"
         Height = "50.901" Margin = "49.324,70.922,0,0" Stroke = "Black"
         VerticalAlignment = "Top" Width = "73.684" RenderTransformOrigin = "0.5,0.5"> 
         <Ellipse.RenderTransform> 
            <TransformGroup> 
               <ScaleTransform/> 
               <SkewTransform/> 
               <RotateTransform/> 
               <TranslateTransform/> 
            </TransformGroup> 
         </Ellipse.RenderTransform> 
      </Ellipse>
		
      <Button x:Name = "button" Content = "Play" HorizontalAlignment = "Left" Height = "24.238"
         Margin = "63.867,0,0,92.953" VerticalAlignment = "Bottom" Width = "74.654"> 
         <i:Interaction.Triggers> 
            <i:EventTrigger EventName = "Click"> 
               <ei:ControlStoryboardAction Storyboard = "{StaticResource Storyboard1}"/> 
            </i:EventTrigger> 
         </i:Interaction.Triggers> 
      </Button>
		
      <Button x:Name = "button1" Content = "Stop" HorizontalAlignment = "Left" Height = "24.239"
         Margin = "160.82,0,0,93.922" VerticalAlignment = "Bottom" Width = "75.138"> 
         <i:Interaction.Triggers> 
            <i:EventTrigger EventName = "Click"> 
               <ei:ControlStoryboardAction ControlStoryboardOption = "Stop"
                  Storyboard = "{StaticResource Storyboard1}"/> 
            </i:EventTrigger> 
         </i:Interaction.Triggers> 
      </Button> 
		
   </Grid> 
</Window>

编译并执行上述代码后，将生成以下包含一个椭圆和两个按钮的窗口。

按下播放按钮时，它将从左向右开始移动，然后返回其原始位置。停止按钮将停止椭圆的移动。

拖放

用户界面上的拖放功能可以显著提高应用程序的效率和生产力。很少有应用程序使用拖放功能，因为人们认为它很难实现。在某种程度上，处理拖放功能确实很难，但在 WPF 中，您可以很容易地处理它。

让我们来看一个简单的例子来了解它是如何工作的。我们将创建一个应用程序，您可以在其中将颜色从一个矩形拖放到另一个矩形。

创建一个名为 WPFDragAndDrop 的新 WPF 项目。
将五个矩形拖到设计窗口，并设置如下 XAML 文件所示的属性。

<Window x:Class = "WPFDragAndDrop.MainWindow" 
   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" 
   xmlns:local = "clr-namespace:WPFDragAndDrop" 
   mc:Ignorable = "d" Title = "MainWindow" Height = "402.551" Width = "604"> 
	
   <Grid> 
      <Rectangle Name = "Target" Fill = "AliceBlue" HorizontalAlignment = "Left"  
         Height = "345" Margin = "10,10,0,0" Stroke = "Black"  
         VerticalAlignment = "Top" Width = "387" AllowDrop = "True" Drop = "Target_Drop"/> 
			
      <Rectangle Fill = "Beige" HorizontalAlignment = "Left" Height = "65"  
         Margin = "402,10,0,0" Stroke = "Black" VerticalAlignment = "Top"  
         Width = "184" MouseLeftButtonDown = "Rect_MLButtonDown"/> 
			
      <Rectangle Fill = "LightBlue" HorizontalAlignment = "Left" Height = "65"  
         Margin = "402,80,0,0" Stroke = "Black" VerticalAlignment = "Top"  
         Width = "184" MouseLeftButtonDown = "Rect_MLButtonDown"/> 
			
      <Rectangle Fill = "LightCoral" HorizontalAlignment = "Left" Height = "65"  
         Margin = "402,150,0,0" Stroke = "Black" VerticalAlignment = "Top"  
         Width = "184" MouseLeftButtonDown = "Rect_MLButtonDown"/> 
			
      <Rectangle Fill = "LightGray" HorizontalAlignment = "Left" Height = "65"  
         Margin = "402,220,0,0" Stroke = "Black" VerticalAlignment = "Top"  
         Width = "184" MouseLeftButtonDown = "Rect_MLButtonDown"/> 
			
      <Rectangle Fill = "OliveDrab" HorizontalAlignment = "Left" Height = "65"  
         Margin = "402,290,0,-7" Stroke = "Black" VerticalAlignment = "Top"  
         Width = "184" MouseLeftButtonDown = "Rect_MLButtonDown"/>  
   </Grid> 
	
</Window>

第一个矩形是目标矩形，因此用户可以将颜色从另一个矩形拖放到目标矩形。
以下是 C# 中拖放的事件实现。

using System.Windows; 
using System.Windows.Input; 
using System.Windows.Media; 
using System.Windows.Shapes; 
 
namespace WPFDragAndDrop { 
   /// <summary> 
      /// Interaction logic for MainWindow.xaml 
   /// </summary> 
	
   public partial class MainWindow : Window { 
	
      public MainWindow() { 
         InitializeComponent(); 
      }  
		
      private void Rect_MLButtonDown(object sender, MouseButtonEventArgs e) { 
         Rectangle rc = sender as Rectangle; 
         DataObject data = new DataObject(rc.Fill); 
         DragDrop.DoDragDrop(rc, data,DragDropEffects.Move); 
      }  
		
      private void Target_Drop(object sender, DragEventArgs e) { 
         SolidColorBrush scb = (SolidColorBrush)e.Data.GetData(typeof(SolidColorBrush)); 
         Target.Fill = scb; 
      } 
   } 
}

运行应用程序后，将生成以下窗口。

如果将颜色从右侧的矩形拖动并将其放在左侧的大矩形上，您将立即看到其效果。

让我们拖动右侧的第 4 个。

您可以看到目标矩形的颜色已更改。我们建议您执行上述代码并试验其功能。

打印页面