问题描述:

I have a button that should cause fade-in animation on some other controls(Studio, Animation, Record...) which are located in ANOTHER xaml:

<Button x:Name ="MainButton" Grid.Row="87" Grid.Column="150" Grid.ColumnSpan="2" Grid.RowSpan="2" Command="{Binding AutoClickFadeinButtonCommand}">

<Button.Triggers>

<EventTrigger RoutedEvent="PreviewMouseDown">

<BeginStoryboard>

<Storyboard>

<DoubleAnimation Storyboard.TargetName="Studio" Storyboard.TargetProperty="Opacity" From="0" To="1" Duration="0:0:2"/>

<DoubleAnimation Storyboard.TargetName="Animation" Storyboard.TargetProperty="Opacity" From="0" To="0.3" Duration="0:0:2"/>

<DoubleAnimation Storyboard.TargetName="Record" Storyboard.TargetProperty="Opacity" From="0" To="0.3" Duration="0:0:2"/>

<DoubleAnimation Storyboard.TargetName="Info" Storyboard.TargetProperty="Opacity" From="0" To="1" Duration="0:0:2"/>

<DoubleAnimation Storyboard.TargetName="info_content" Storyboard.TargetProperty="Opacity" From="0" To="1" Duration="0:0:2"/>

</Storyboard>

</BeginStoryboard>

</EventTrigger>

</Button.Triggers>

</Button>

How to reference these controls in my current xaml? Just to mention that I use mvvm, and I would like not to reference button control inside ViewModel class.

网友答案:

Create an event inside your ViewModel and attach an event trigger to your XAML (e.g. ControlStoryboardAction) that starts the animation as soon as the event has been triggered.

Edit:

You could put something like that inside your VM:

public event EventHandler AnimationCalled;

protected virtual void OnAnimationCalled()
{
    AnimationCalled?.Invoke(this, EventArgs.Empty);
}

As soon as anything will call OnAnimationCalled (any method that is triggered by your button or a command) the event will be raised.

You can subscribe to this event inside XAML by using a trigger (the SourceObject has to be the VM containing your event) in combination with the ControlStoryboardAction:

<i:Interaction.Triggers>
    <i:EventTrigger SourceObject="{Binding Mode=OneWay}" EventName="AnimationCalled">
        <ei:ControlStoryboardAction Storyboard="{StaticResource Storyboard1}"/>
    </i:EventTrigger>
</i:Interaction.Triggers>

Edit 2: Complete Example The MainViewModel:

using System;
namespace StoryboardTriggerExample
{
    public class MainViewModel
    {

        //Only needed to have a target for our CallMethodAction
        //In real world it´d be easier to make the call to OnAnimationCalled(); via command
        public void CallAnimation()
        {
            OnAnimationCalled();
        }

        public event EventHandler AnimationCalled;

        protected virtual void OnAnimationCalled()
        {
            AnimationCalled?.Invoke(this, EventArgs.Empty);
        }
    }
}

An UserControl that will contain our Storyboard:

<UserControl
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         xmlns:local="clr-namespace:StoryboardTriggerExample"
         xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity" xmlns:ei="http://schemas.microsoft.com/expression/2010/interactions" x:Class="StoryboardTriggerExample.UserControlContainingStoryboard"
         mc:Ignorable="d" 
         d:DesignHeight="300" d:DesignWidth="300">
<UserControl.Resources>
    <Storyboard x:Key="Storyboard1">
        <ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Shape.Fill).(SolidColorBrush.Color)" Storyboard.TargetName="rectangle">
            <EasingColorKeyFrame KeyTime="0:0:1" Value="#FF101085"/>
        </ColorAnimationUsingKeyFrames>
        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(FrameworkElement.Height)" Storyboard.TargetName="rectangle">
            <EasingDoubleKeyFrame KeyTime="0:0:1" Value="30"/>
        </DoubleAnimationUsingKeyFrames>
        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(FrameworkElement.Width)" Storyboard.TargetName="rectangle">
            <EasingDoubleKeyFrame KeyTime="0:0:1" Value="30"/>
        </DoubleAnimationUsingKeyFrames>
        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(FrameworkElement.Width)" Storyboard.TargetName="rectangle1">
            <EasingDoubleKeyFrame KeyTime="0:0:1" Value="100"/>
        </DoubleAnimationUsingKeyFrames>
        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(FrameworkElement.Height)" Storyboard.TargetName="rectangle1">
            <EasingDoubleKeyFrame KeyTime="0:0:1" Value="100"/>
        </DoubleAnimationUsingKeyFrames>
        <ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Shape.Fill).(SolidColorBrush.Color)" Storyboard.TargetName="rectangle1">
            <EasingColorKeyFrame KeyTime="0:0:1" Value="#FF6BFF63"/>
        </ColorAnimationUsingKeyFrames>
    </Storyboard>
</UserControl.Resources>
<StackPanel>
    <i:Interaction.Triggers>
        <i:EventTrigger EventName="AnimationCalled" SourceObject="{Binding Mode=OneWay}">
            <ei:ControlStoryboardAction Storyboard="{StaticResource Storyboard1}"/>
        </i:EventTrigger>
    </i:Interaction.Triggers>
    <Rectangle x:Name="rectangle1" Fill="#FFF4F4F5" Height="30" Stroke="Black" Width="30" HorizontalAlignment="Left" d:LayoutOverrides="LeftPosition, RightPosition, TopPosition, BottomPosition"/>
    <Rectangle x:Name="rectangle" Fill="#FFF4F4F5" Height="100" Stroke="Black" Width="100" HorizontalAlignment="Left" VerticalAlignment="Top"/>

</StackPanel>

And our MainWindow:

<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:StoryboardTriggerExample"
    xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity" xmlns:ei="http://schemas.microsoft.com/expression/2010/interactions" x:Class="StoryboardTriggerExample.MainWindow"
    mc:Ignorable="d"
    Title="MainWindow" Height="350" Width="525">
<Window.DataContext>
    <local:MainViewModel/>
</Window.DataContext>
<StackPanel>
    <Button x:Name="button" Content="Button">
        <i:Interaction.Triggers>
            <i:EventTrigger EventName="Click">
                <ei:CallMethodAction TargetObject="{Binding Mode=OneWay}" MethodName="CallAnimation"/>
            </i:EventTrigger>
        </i:Interaction.Triggers>
    </Button>
    <local:UserControlContainingStoryboard/>
</StackPanel>

Should look like this:

Should move animated via storyboard to this, by clicking the button:

You can download the solution on GitHub

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