[英]InvalidOperationException when trying to animate background color of a styled button in WPF
I'm trying to programmatically trigger a color animation on a button, but getting a System.InvalidOperationException
when I do. 我正在尝试以编程方式触发按钮上的彩色动画,但是当我这样做时却遇到了
System.InvalidOperationException
。 It seems it can't resolve the TargetProperty
because I've styled the button using a template/content presenter. 似乎无法解析
TargetProperty
因为我已经使用模板/内容演示者设置了按钮的样式。
The reason I style <Button>
this way is to force the style to be consistent (and avoid the default blue hover effect). 我使用
<Button>
样式的原因是强制样式保持一致(并避免使用默认的蓝色悬停效果)。 I also have a DataTrigger that animates the background color of this button whenever it's shown (ie made Visible). 我也有一个DataTrigger,可以在显示该按钮时将其背景颜色设置为动画(即使其可见)。 Here's the full
<Style>
definition: 这是完整的
<Style>
定义:
<Style x:Key="PopUnder" TargetType="Button">
<Setter Property="Foreground" Value="Black" />
<Setter Property="FontSize" Value="34" />
<Setter Property="FontWeight" Value="SemiBold" />
<Setter Property="OverridesDefaultStyle" Value="True" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="Button">
<Border Name="Border" Background="White" BorderBrush="Red" BorderThickness="0,1,0,1">
<TextBlock TextWrapping="Wrap" TextAlignment="Center" VerticalAlignment="Center" LineStackingStrategy="BlockLineHeight" LineHeight="40" Text="{TemplateBinding Content}" />
</Border>
<ControlTemplate.Triggers>
<DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=Visibility}" Value="Visible">
<DataTrigger.EnterActions>
<BeginStoryboard>
<Storyboard>
<ColorAnimationUsingKeyFrames Storyboard.TargetName="Border" Storyboard.TargetProperty="(Background).(SolidColorBrush.Color)" RepeatBehavior="Forever">
<LinearColorKeyFrame Value="White" KeyTime="0:0:0" />
<LinearColorKeyFrame Value="LightCoral" KeyTime="0:0:1" />
<LinearColorKeyFrame Value="White" KeyTime="0:0:2" />
</ColorAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</DataTrigger.EnterActions>
</DataTrigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
But I also want to be able to trigger a different animation on this same button, from code. 但我也希望能够通过代码在同一按钮上触发不同的动画。 So I have a separate
<Storyboard>
defined elsewhere (outside the Style definition), which I trigger using TryFindResource()
... Begin()
. 因此,我在其他地方(在样式定义之外)定义了一个单独的
<Storyboard>
,我可以使用TryFindResource()
... Begin()
触发该TryFindResource()
。 However, because the button is using a Template, I'm having trouble getting the Background color property to properly resolve in my XAML (below). 但是,由于该按钮使用的是模板,因此我无法在我的XAML中正确获取Background color属性(如下所示)。
<Storyboard x:Key="StatusGood" Completed="AnimationStatusGood_Completed">
<ColorAnimationUsingKeyFrames Storyboard.TargetName="PopUnderMessage" Storyboard.TargetProperty="(Border).(Background).(SolidColorBrush.Color)">
<LinearColorKeyFrame Value="LightGreen" KeyTime="0:0:0" />
<LinearColorKeyFrame Value="White" KeyTime="0:0:1" />
</ColorAnimationUsingKeyFrames>
</Storyboard>
I've tried a couple of different values for the Storyboard.TargetProperty
attribute here: 我在这里为
Storyboard.TargetProperty
属性尝试了几个不同的值:
But all of them yield different variations on the same exception. 但是它们都在相同的异常上产生不同的变化。 I confess I'm kind of throwing darts on a board blindly as my knowledge of XAML templates and property paths is lacking.
我承认由于缺乏对XAML模板和属性路径的了解,我有点盲目地将飞镖扔在板上。 How can I get this to work?
我该如何工作?
Try this, omitting Storyboard.TargetName
entirely, and omitting Border
from Storyboard.TargetProperty
: 尝试执行此操作,完全省略
Storyboard.TargetName
,并从Storyboard.TargetProperty
省略Border
:
<Storyboard x:Key="StatusGood" Completed="AnimationStatusGood_Completed">
<ColorAnimationUsingKeyFrames
Storyboard.TargetProperty="(Background).(SolidColorBrush.Color)">
<LinearColorKeyFrame Value="LightGreen" KeyTime="0:0:0" />
<LinearColorKeyFrame Value="White" KeyTime="0:0:1" />
</ColorAnimationUsingKeyFrames>
</Storyboard>
Give the styled button a name: 为样式按钮命名:
<Button
x:Name="button"
Content="Hello, world!"
Style="{StaticResource PopUnder}" Click="ButtonBase_OnClick" />
To activate the storyboard: 要激活情节提要:
private void ButtonBase_OnClick(object sender, RoutedEventArgs e)
{
Storyboard storyboard = (Storyboard)this.TryFindResource("StatusGood");
Border border = FindVisualChild<Border>(button, "Border");
storyboard.Begin(border);
}
For reference, the FindVisualChild
helper function: 作为参考,
FindVisualChild
帮助函数:
private static T FindVisualChild<T>(
DependencyObject parent,
string name = null)
where T : DependencyObject
{
if (parent != null)
{
int childrenCount = VisualTreeHelper.GetChildrenCount(parent);
for (int i = 0; i < childrenCount; i++)
{
DependencyObject child = VisualTreeHelper.GetChild(parent, i);
T candidate = child as T;
if (candidate != null)
{
if (name == null)
{
return candidate;
}
FrameworkElement element = candidate as FrameworkElement;
if (name == element?.Name)
{
return candidate;
}
}
T childOfChild = FindVisualChild<T>(child, name);
if (childOfChild != null)
{
return childOfChild;
}
}
}
return default(T);
}
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