WPF — it's gotta be easier than I'm making it

问题

I'm having the darndest time figuring this out: say I've got two Button and three TextBlocks. I want either button to trigger a simple Storyboard on ALL TextBlocks. Currently I'm trying to define a generic Textblock style that contains the Storyboard, and then the trigger comes from any Button click. This is the closest I've come but the app crashes on startup...what am I don't wrong here:

<Window.Resources>

<Style TargetType="TextBlock" >
    <Setter Property="Foreground" Value="Blue" />
    <Style.Resources>
        <Storyboard x:Key="TextBlockOpacity" Storyboard.TargetProperty="Opacity">
            <DoubleAnimation From="0" To="1" />
        </Storyboard>
    </Style.Resources>      
</Style>

<Window.Triggers>
    <EventTrigger RoutedEvent="ButtonBase.Click" SourceName="button">
        <BeginStoryboard Storyboard="{StaticResource TextBlockOpacity}"/>
    </EventTrigger>
</Window.Triggers>


<Grid x:Name="LayoutRoot">
    <Button x:Name="button" HorizontalAlignment="Left" Margin="51,54,0,0" VerticalAlignment="Top" Width="96" Height="45" Content="Button"/>

    <TextBlock x:Name="textBlock1" Margin="228,54,172,0" VerticalAlignment="Top" Height="45" FontSize="26.667" Text="TextBlock" TextWrapping="Wrap" />
    <TextBlock x:Name="textBlock2" Margin="228,103,172,0" VerticalAlignment="Top" Height="45" FontSize="26.667" Text="Hello" TextWrapping="Wrap"/>
</Grid>

回答1:

Based on kek444's Xaml-only solution, I present a slightly improved version that doesn't rely on the DataContext of the button and can have multiple triggers.

<Window
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    x:Class="WpfApplication1.MainWindow"
    x:Name="Window"
    Title="MainWindow"
    Width="640" Height="480">
    <Window.Resources>
        <UIElement x:Key="OpacityCounter" Opacity="0"/>
        <Style TargetType="TextBlock">
            <Setter Property="Opacity" Value="{Binding Source={StaticResource OpacityCounter}, Path=Opacity}" />
        </Style>
        <Storyboard x:Key="OnClick1">
            <DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Storyboard.Target="{StaticResource OpacityCounter}" Storyboard.TargetProperty="(UIElement.Opacity)">
                <SplineDoubleKeyFrame KeyTime="00:00:00" Value="0"/>
                <SplineDoubleKeyFrame KeyTime="00:00:00.5000000" Value="1"/>
            </DoubleAnimationUsingKeyFrames>
        </Storyboard>
    </Window.Resources>
    <Window.Triggers>
        <EventTrigger RoutedEvent="ButtonBase.Click" SourceName="button1">
            <BeginStoryboard Storyboard="{StaticResource OnClick1}"/>
        </EventTrigger>
        <EventTrigger RoutedEvent="ButtonBase.Click" SourceName="button2">
            <BeginStoryboard Storyboard="{StaticResource OnClick1}"/>
        </EventTrigger>
    </Window.Triggers>

    <Grid x:Name="LayoutRoot">
        <StackPanel>
            <StackPanel Orientation="Horizontal">
                <Button x:Name="button1" Width="131" Height="37" Content="Button 1" Margin="0,0,0,22"/>
                <Button x:Name="button2" Width="131" Height="37" Content="Button 2" Margin="0,0,0,22"/>
            </StackPanel>
            <TextBlock x:Name="textBlock" Height="27" Text="TextBlock 1" TextWrapping="Wrap" />
            <TextBlock x:Name="textBlock1" Height="27" Text="TextBlock 2" TextWrapping="Wrap" />
            <TextBlock x:Name="textBlock2" Height="27" Text="TextBlock 3" TextWrapping="Wrap" />
            <TextBlock x:Name="textBlock3" Height="27" Text="TextBlock 4" TextWrapping="Wrap" />
        </StackPanel>
    </Grid>
</Window>

To use a ListBox as a trigger mechanism (provided you have a ListBox named "listbox1" someplace, add the following to Window.Triggers:

<EventTrigger RoutedEvent="Selector.SelectionChanged" SourceName="listbox1">
    <BeginStoryboard Storyboard="{StaticResource OnClick1}"/>
</EventTrigger>

or to trigger off a specific ListBoxItem, you'll need (where item1 is a named ListBoxItem):

<EventTrigger RoutedEvent="ListBoxItem.Selected" SourceName="item1">
    <BeginStoryboard Storyboard="{StaticResource OnClick1}"/>
</EventTrigger>

回答2:

If you "dedicate" the button to changing the opacity, you could harness its DataContext and animate it. Then simply bind your elements' Opacity to the DataContext:

(I've also refactored your xaml a bit)

<Window x:Class="SomeNamespace.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:System="clr-namespace:System;assembly=mscorlib"
    Title="Window1" Height="300" Width="300">
    <Window.Resources>        
        <Storyboard x:Key="TextBlockOpacity" Storyboard.TargetName="button1" Storyboard.TargetProperty="DataContext" >
            <DoubleAnimation From="0.1" To="1"/>
        </Storyboard>        
        <Style TargetType="TextBlock" >
            <Setter Property="Foreground" Value="Blue" />
            <Setter Property="Background" Value="LightGray" />
            <Setter Property="FontSize" Value="26.667" />
            <Setter Property="TextWrapping" Value="Wrap" />
            <Setter Property="Height" Value="45" />            
            <Setter Property="Opacity" Value="{Binding ElementName=button1, Path=DataContext}"/>
        </Style>
    </Window.Resources>

    <Window.Triggers>
        <EventTrigger RoutedEvent="ButtonBase.Click">
            <BeginStoryboard Storyboard="{StaticResource TextBlockOpacity}" >
            </BeginStoryboard>
        </EventTrigger>

        <EventTrigger RoutedEvent="ListBox.SelectionChanged">
            <BeginStoryboard Storyboard="{StaticResource TextBlockOpacity}" >
            </BeginStoryboard>
        </EventTrigger>
    </Window.Triggers>

    <Grid x:Name="LayoutRoot">
        <Button x:Name="button1" HorizontalAlignment="Left" Margin="51,54,0,0" VerticalAlignment="Top" Width="96" Height="45" Content="Button">
            <Button.DataContext>
                <System:Double>0</System:Double>
            </Button.DataContext>
        </Button>

        <Button x:Name="button2" HorizontalAlignment="Right" Margin="0,54,29,0" VerticalAlignment="Top" Width="96" Height="45" Content="Button"/>

        <ListBox x:Name="listBox1" Height="50" VerticalAlignment="Top">
            <ListBox.Items>
                <System:String>Text1</System:String>
                <System:String>Text2</System:String>
            </ListBox.Items>
        </ListBox>

        <TextBlock x:Name="textBlock1" Margin="51,114,61,0" Text="TextBlock" Height="45" VerticalAlignment="Top" Width="166" />
        <TextBlock x:Name="textBlock2" Margin="51,0,74,42" Text="Hello" Height="45" Width="153" VerticalAlignment="Bottom" />
    </Grid>
</Window>

Also note one thing - this is the approach to use if you want to minimize your code, and make it all happen in xaml. Your approach would anmate the Opacity of the whole Window. That's why in the code above, TextBlocks bind to the button's DataContext, which is itself animated.

It is of course doable without binding to a common value (the DataContext), but then you need to repeat X animations (because you need to set X TargetNames). This approach above is more easily extendable and maintainable.

EDIT

Added another Button and a ListBox for variety :)

回答3:

In your sample, you are defining the Storyboard inside a Style as a Resource, but then you are trying to access it as a Window resource. Try moving the Storyboard declaration to Window.Resources, then reference the Storyboard in the Style.

I don't know right off if it will do what you want, but I would start there.

来源：https://stackoverflow.com/questions/1238515/wpf-its-gotta-be-easier-than-im-making-it