WPF中的不规则PNG按钮的单击事件

Question

我需要WPF中不规则形状的按钮。我这样做使用XAML：

<Button Name="toggleButton" Click="toggleButton_Click" Canvas.Left="177" Canvas.Top="0"> 
    <Button.Template> 
    <ControlTemplate> 
     <Image Source="ball.png" /> 
    </ControlTemplate> 
    </Button.Template> 
</Button> 

我的ball.png图像是一个带有透明区域的球的PNG图像。该按钮可以正确显示，但即​​使在图像的透明部分出现咔嗒声，Click事件处理程序也会执行。

有没有什么办法用透明的PNG创建不规则的按钮？

感谢，米哈尔

Answer 1

您可以创建一个继承自Image的类并覆盖HitTestCore，以便它不响应对图像透明部分的命中测试，然后在模板中使用该类而不是普通图像。

下面是一个示例，虽然检查透明像素的代码不是很健壮，因为它对图像源和像素格式作了一些假设。如果你已经有代码检查透明像素，那么你应该插入它。

public class TransparentImage 
    : Image 
{ 
    protected override HitTestResult HitTestCore(
     PointHitTestParameters hitTestParameters) 
    { 
     // Get value of current pixel 
     var source = (BitmapSource)Source; 
     var x = (int)(hitTestParameters.HitPoint.X/
      ActualWidth * source.PixelWidth); 
     var y = (int)(hitTestParameters.HitPoint.Y/
      ActualHeight * source.PixelHeight); 
     var pixels = new byte[4]; 
     source.CopyPixels(new Int32Rect(x, y, 1, 1), pixels, 4, 0); 
     // Check alpha channel 
     if (pixels[3] < 10) 
     { 
      return new PointHitTestResult(this, hitTestParameters.HitPoint); 
     } 
     else 
     { 
      return null; 
     } 
    } 

    protected override GeometryHitTestResult HitTestCore(
     GeometryHitTestParameters hitTestParameters) 
    { 
     // Do something similar here, possibly checking every pixel within 
     // the hitTestParameters.HitGeometry.Bounds rectangle 
     return base.HitTestCore(hitTestParameters); 
    } 
} 

Answer 2

米哈尔， 我不会创建一个真正的 “按钮”。只需进行混合，将图像作为图像刷入矩形，右键单击使其成为按钮。如果您使用Blend 4，这将在Visual状态管理器中生成适当的状态。您可以将鼠标放在上面，按下等等，看起来像一个按钮。即使是禁用状态。

下面是一个例子：

<Window.Resources> 
     <Style x:Key="CrazyButtonStyle" TargetType="{x:Type Button}"> 
      <Setter Property="Template"> 
       <Setter.Value> 
        <ControlTemplate TargetType="{x:Type Button}"> 
         <Grid> 
          <VisualStateManager.VisualStateGroups> 
           <VisualStateGroup x:Name="CommonStates"> 
            <VisualState x:Name="Normal"> 
             <Storyboard> 
              <ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[1].(GradientStop.Color)" Storyboard.TargetName="path"> 
               <EasingColorKeyFrame KeyTime="0" Value="#FFBEBEBE"/> 
              </ColorAnimationUsingKeyFrames> 
              <ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[0].(GradientStop.Color)" Storyboard.TargetName="path"> 
               <EasingColorKeyFrame KeyTime="0" Value="#FF919191"/> 
              </ColorAnimationUsingKeyFrames> 
             </Storyboard> 
            </VisualState> 
            <VisualState x:Name="MouseOver"> 
             <Storyboard> 
              <ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[0].(GradientStop.Color)" Storyboard.TargetName="path"> 
               <EasingColorKeyFrame KeyTime="0" Value="#FF782B2B"/> 
              </ColorAnimationUsingKeyFrames> 
             </Storyboard> 
            </VisualState> 
            <VisualState x:Name="Pressed"> 
             <Storyboard> 
              <ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[0].(GradientStop.Color)" Storyboard.TargetName="path"> 
               <EasingColorKeyFrame KeyTime="0" Value="#FF1D0C0C"/> 
              </ColorAnimationUsingKeyFrames> 
             </Storyboard> 
            </VisualState> 
            <VisualState x:Name="Disabled"> 
             <Storyboard> 
              <ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[0].(GradientStop.Color)" Storyboard.TargetName="path"> 
               <EasingColorKeyFrame KeyTime="0" Value="#FF720505"/> 
              </ColorAnimationUsingKeyFrames> 
              <ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Shape.Fill).(GradientBrush.GradientStops)[1].(GradientStop.Color)" Storyboard.TargetName="path"> 
               <EasingColorKeyFrame KeyTime="0" Value="#FF6E0000"/> 
              </ColorAnimationUsingKeyFrames> 
             </Storyboard> 
            </VisualState> 
           </VisualStateGroup> 
          </VisualStateManager.VisualStateGroups> 
          <Path x:Name="path" Data="M95.5,33.499981 C71.500031,31.499967 76.5,68.5 76.5,68.5 L112.5,75.500276 107.5,92.500393 144.5,105.50048 152.5,79.500301 132.5,63.50019 154.5,54.500128 173.5,68.500225 168.5,87.500356 172.5,97.500425 185.5,96.500418 197.12084,75.753906 200.12084,44.753692 176.5,34.49999 143.5,32.499975 142.5,13.499841 130.5,28.499946 137.5,41.500036 135.5,51.500106 117.5,52.500113 99.5,54.500126 116.5,39.500022 z" Stretch="Fill" Stroke="{x:Null}"> 
           <Path.Fill> 
            <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0"> 
             <GradientStop Color="Black" Offset="0"/> 
             <GradientStop Color="White" Offset="1"/> 
            </LinearGradientBrush> 
           </Path.Fill> 
          </Path> 
          <ContentPresenter HorizontalAlignment="Right" RecognizesAccessKey="True" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalAlignment="Top" Margin="0,24.52,18.715,0"/> 
         </Grid> 
         <ControlTemplate.Triggers> 
          <Trigger Property="IsFocused" Value="True"/> 
          <Trigger Property="IsDefaulted" Value="True"/> 
          <Trigger Property="IsMouseOver" Value="True"/> 
          <Trigger Property="IsPressed" Value="True"/> 
          <Trigger Property="IsEnabled" Value="False"/> 
         </ControlTemplate.Triggers> 
        </ControlTemplate> 
       </Setter.Value> 
      </Setter> 
     </Style> 
    </Window.Resources> 

现在使用按钮如下：

<Button Content="This is my crazy button" Style="{DynamicResource CrazyButtonStyle}"/> 

我这是不是使用透明PNG的按钮，但它会是一个更好的选择，如果知道你有能力将png转换为xaml。