c# - 基于网格可见性的 WPF 动画

Question

我有一个开始折叠的网格。当用户单击按钮时，后面的代码将可见性设置为可见。然后按钮 XAML 触发器使网格在 3 秒内从 0 增长到 1925。

我试图弄清楚如何在 XAML 中对触发器进行编程以查找网格的可见性。然后根据其状态使动画增长或收缩。因此，基于下面的代码，如果触发器确定可见性可见，我想让网格从 1925 变为 0，如果单击按钮时网格显示折叠，则为 0 到 1925。想要远离知道 UI 中发生了什么的代码。这就是为什么稍后我会将网格可见性绑定(bind)到一个属性。

XAML 的主要组件

    <Grid Name="gridDisplay" Background="AliceBlue" Visibility="Collapsed">

    </Grid>



    <Button 
        Style="{StaticResource {x:Static ToolBar.ButtonStyleKey}}"
        Width="32" Height="32" FontSize="16" VerticalAlignment="Center" HorizontalAlignment="Right" Background="White" Click="Button_Click">
        &gt;

        <Button.Triggers>
            <EventTrigger RoutedEvent="Button.Click">
                <BeginStoryboard>
                    <Storyboard>
                        <DoubleAnimation 
                            Storyboard.TargetName="gridDisplay"
                            Storyboard.TargetProperty="Width"
                            From="0" To="1925" Duration="0:0:3" />
                    </Storyboard>
                </BeginStoryboard>
            </EventTrigger>
        </Button.Triggers>
    </Button>

按钮事件

        //TODO: Bind grid to visibility property
        if (gridDisplay.Visibility == System.Windows.Visibility.Collapsed)
        {
            gridDisplay.Visibility = System.Windows.Visibility.Visible;
            (sender as Button).Content = "<";
        }
        else
        {
            gridDisplay.Visibility = System.Windows.Visibility.Collapsed;
            (sender as Button).Content = ">";
        }

Answer 1

您可以制作这样的动画，而不是使用触发器。

xaml:

  <Window.Resources>
        <Storyboard x:Key="open">
            <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(FrameworkElement.Width)" Storyboard.TargetName="gridDisplay">
                <EasingDoubleKeyFrame KeyTime="0" Value="0"/>
                <EasingDoubleKeyFrame KeyTime="0:0:0.6" Value="900"/>
            </DoubleAnimationUsingKeyFrames>
            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="gridDisplay">
                <DiscreteObjectKeyFrame KeyTime="0" Value="{x:Static Visibility.Visible}"/>
            </ObjectAnimationUsingKeyFrames>
        </Storyboard>
        <Storyboard x:Key="close">
            <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(FrameworkElement.Width)" Storyboard.TargetName="gridDisplay">
                <EasingDoubleKeyFrame KeyTime="0" Value="900"/>
                <EasingDoubleKeyFrame KeyTime="0:0:0.6" Value="0"/>
            </DoubleAnimationUsingKeyFrames>
            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="gridDisplay">
                <DiscreteObjectKeyFrame KeyTime="0:0:0.6" Value="{x:Static Visibility.Collapsed}"/>
            </ObjectAnimationUsingKeyFrames>
        </Storyboard>
    </Window.Resources>

按钮事件:

//TODO: Bind grid to visibility property
            if (gridDisplay.Visibility == System.Windows.Visibility.Collapsed)
            {
                var storyboard = this.Resources["open"] as Storyboard;
                storyboard.Begin();
                (sender as Button).Content = "<";
            }
            else
            {
                var storyboard = this.Resources["close"] as Storyboard;
                storyboard.Begin();
                (sender as Button).Content = ">";
            }

希望对您有所帮助。如果你想拥有一个可见的属性，你可以拥有这个:

private bool _visibleProp;
public bool VisibleProp{get{return _visibleProp;} 
    set{_visibleProp = value; 
        if(value){var storyboard = this.Resources["open"] as Storyboard;
                storyboard.Begin(); }
        else{var storyboard = this.Resources["close"] as Storyboard;
                storyboard.Begin();}
          }}