在 WPF 控件可见性更改上应用动画 [英] Apply animation on WPF control visibility change

问题描述

我的 xaml 是

   <Grid DockPanel.Dock="Top" >
<DockPanel Background="#bdbec0"  MouseEnter="showTopMenu_MouseEnter" HorizontalAlignment="Stretch" Height="55" >                    
    <Button HorizontalAlignment="Center" VerticalAlignment="Center">Down</Button>
</DockPanel>
<DockPanel Background="#151515" LastChildFill="True" Visibility="Collapsed" Name="TopMenuArea"  Height="55">
 some controls here in a horizontal strip , by default its hidden and when some one click on top button its visible and it wil be hidden when some one click outside this area
</DockPanel>

按钮鼠标悬停的代码是

    private void showTopMenu_MouseEnter(object sender, MouseEventArgs e)
    {          
        TopMenuArea.Visibility = Visibility.Visible;
    }

如何在更改 TopMenuArea 的可见性时应用动画效果?有什么办法可以直接从xaml做吗?

How can i apply a animation effect while changing the visibility of TopMenuArea ? Is any way to do it from xaml directly?

推荐答案

Eventtrigger

<DockPanel Background="#bdbec0"  MouseEnter="showTopMenu_MouseEnter" HorizontalAlignment="Stretch" Height="55" >
    <DockPanel.Triggers>
        <EventTrigger RoutedEvent="DockPanel.MouseEnter">
            <BeginStoryboard>
                <Storyboard>
                    <DoubleAnimation Storyboard.TargetProperty="Opacity" Storyboard.TargetName="TopMenuArea"
                        From="0.0" To="1.0" Duration="0:0:1"></DoubleAnimation>                            
                </Storyboard>
            </BeginStoryboard>
        </EventTrigger>
        <EventTrigger RoutedEvent="DockPanel.MouseLeave">
            <BeginStoryboard>
                <Storyboard>
                    <DoubleAnimation Storyboard.TargetProperty="Opacity" Storyboard.TargetName="TopMenuArea"
                        From="1.0" To="0" Duration="0:0:1"></DoubleAnimation>
                </Storyboard>
            </BeginStoryboard>
        </EventTrigger>
    </DockPanel.Triggers>
    <Button HorizontalAlignment="Center" VerticalAlignment="Center">Down</Button>
</DockPanel>
<DockPanel Background="#151515" LastChildFill="True" Visibility="Collapsed" Opacity="0" Name="TopMenuArea"  Height="55">
</DockPanel>

或者使用淡入淡出的样式(使用鼠标进入/退出事件处理程序，就像你那样)

<Style TargetType="FrameworkElement" x:Key="VisibleAnimation">
  <Setter Property="Visibility" Value="Collapsed"/>
  <Setter Property="Opacity" Value="0"/>
  <Style.Triggers>
    <Trigger Property="Visibility" Value="Visible">
      <Trigger.EnterActions>
        <BeginStoryboard>
          <Storyboard>
            <DoubleAnimation Storyboard.TargetProperty="Opacity"
                             From="0.0" To="1.0" Duration="0:0:0.2"/>
          </Storyboard>
        </BeginStoryboard>
      </Trigger.EnterActions>
    </Trigger>
  </Style.Triggers>
</Style>

<DockPanel Background="#151515" LastChildFill="True" Style="{StaticResource VisibleAnimation}" Name="TopMenuArea"  Height="55">

只需在您的应用资源中定义样式，或者在本地窗口或用户控件中定义样式.您可以为任何控件重复使用动画样式.

Just define the style in your App Resources, or in the local Window or UserControl. You reuse the Animation style for any control.

在您的 Stackpanel 中使用它

use this in your Stackpanel

<StackPanel Background="Red" HorizontalAlignment="Stretch" >
    <StackPanel.Triggers>
        <EventTrigger RoutedEvent="StackPanel.MouseLeftButtonDown" >
            <BeginStoryboard>
                <Storyboard>
                    <DoubleAnimation Storyboard.TargetProperty="Opacity" Storyboard.TargetName="TopMenuArea"
                From="1.0" To="0" Duration="0:0:1"></DoubleAnimation>
                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="TopMenuArea"
                        Storyboard.TargetProperty="Visibility">
                        <DiscreteObjectKeyFrame KeyTime="0:0:2" Value="{x:Static Visibility.Collapsed}"/>
                    </ObjectAnimationUsingKeyFrames>
                </Storyboard>
            </BeginStoryboard>
        </EventTrigger>
    </StackPanel.Triggers>
    <Label HorizontalAlignment="Center">Area outside top panel . Clicking here will hide top panel again</Label>
</StackPanel>

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