在WPF中动画化RadialGradientBrush的麻烦 [英] Trouble animating RadialGradientBrush in WPF

问题描述

我正在尝试为 RadialGradientBrush 在我的应用程序。我得到了超级有用的例外：

I'm trying to animate a RadialGradientBrush in my application. I get the super helpful exception:

附加信息：'System.Windows.Style'值不能分配给属性'Style' System.Windows.Controls.Border'。 '[Unknown]'属性不指向路径'（0）。（1）。[0]。（2）'中的DependencyObject。标记文件'Eng.Modules.Core; component / system / grid / systemgridview.xaml'中的对象'System.Windows.Style'的错误行252位置51。

我知道我的 DoubleAnimation 的 Storyboard.TargetProperty 中的间接资源定位或部分路径限定是错误的， code>属性。任何想法？

I know it's something wrong with the indirect property targeting or partial path qualification in my DoubleAnimation's Storyboard.TargetProperty attribute. Any ideas?

<Border>
  <Border.Resources>
    <RadialGradientBrush x:Key="SomeBrush">
      <RadialGradientBrush.GradientStops>
        <GradientStop Color="White" Offset="0" />
        <GradientStop Color="Gold" Offset="1" />
      </RadialGradientBrush.GradientStops>
    </RadialGradientBrush>
  </Border.Resources>
  <Border.Style>
    <Style TargetType="{x:Type Border}">
      <Style.Triggers>
        <DataTrigger Binding="{Binding Path=IsEnabled, RelativeSource={RelativeSource Self}}" Value="True">
          <Setter Property="Background" Value="{StaticResource SomeBrush}" />
          <DataTrigger.EnterActions>
            <BeginStoryboard x:Name="SomeStoryBoard">
              <Storyboard>
                <!-- RIGHT HERE -->
                <DoubleAnimation
                  Storyboard.TargetProperty="(Border.Background).(GradientBrush.GradientStops)[0].(GradientStop.Offset)"
                  From="0" To="1" Duration="0:0:1"
                  RepeatBehavior="Forever"
                  AutoReverse="True" />
              </Storyboard>
            </BeginStoryboard>
          </DataTrigger.EnterActions>
          <DataTrigger.ExitActions>
            <RemoveStoryboard BeginStoryboardName="SomeStoryBoard" />
          </DataTrigger.ExitActions>
        </DataTrigger>
      </Style.Triggers>
    </Style>
  </Border.Style>
</Border>

推荐答案

第一个问题是您正在设置背景您的 DataTrigger 中的渐变刷。因为这将在以后被应用，动画将无法找到画笔（因此没有找到依赖属性的隐含错误）。所以我做的第一件事是将边框的背景设置为手动刷新，而不是触发器。

The first problem is that you are setting the background to a gradient brush in your DataTrigger. Because this gets applied later, the animation won't be able to find the brush (hence the cryptic error about not finding a dependency property). So the first thing I did was set the border's background to the brush manually, rather than in the trigger.

第二个问题是如何设置目标属性。您不需要使用括号语法，它的工作原理如下： Background.GradientStops [0] .Offset 。

The second problem was how you were setting up the target property. You don't need to use the parenthesis syntax- it works just fine as follows: Background.GradientStops[0].Offset.

随着这些变化，边框动画完美;这是最后的标记：

With these changes the border animates perfectly; here is the final mark-up:

<Border>
    <Border.Background>
        <RadialGradientBrush>
            <RadialGradientBrush.GradientStops>
                <GradientStop Color="White" Offset="0" />
                <GradientStop Color="Gold" Offset="1" />
            </RadialGradientBrush.GradientStops>
        </RadialGradientBrush>
    </Border.Background>
    <Border.Style>
        <Style TargetType="{x:Type Border}">
            <Style.Triggers>
                <DataTrigger Binding="{Binding Path=IsEnabled, RelativeSource={RelativeSource Self}}" Value="True">
                    <DataTrigger.EnterActions>
                        <BeginStoryboard x:Name="SomeStoryBoard">
                            <Storyboard>
                                <!-- RIGHT HERE -->
                                <DoubleAnimation 
                                      Storyboard.TargetProperty="Background.GradientStops[0].Offset"
                                      From="0" To="1" Duration="0:0:1"
                                      RepeatBehavior="Forever"
                                      AutoReverse="True" />
                            </Storyboard>
                        </BeginStoryboard>
                    </DataTrigger.EnterActions>
                    <DataTrigger.ExitActions>
                        <RemoveStoryboard BeginStoryboardName="SomeStoryBoard" />
                    </DataTrigger.ExitActions>
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </Border.Style>
</Border>

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