如何动画元素的出现

Question

我对Expression Blend 4有疑问.

我想创建一个简单的组件出现动画,当组件的高度从0变为100%,而它下面的组件向下移动以分配所需的空间.

我的问题是只允许以像素为单位的静态值来创建这种类型的动画.但我不知道我的控制高度(实际上,它是内容和内容长度可能不同的textBox),我无法设置Height最后一个关键帧的值Auto.

我该怎么做才能完成这项任务？

提前致谢.

Answer 1

我想最简单的方法是使用Fluid Layout.

在下面的例子中,我创建了一个TextBlock并将其设置Visibility为Collpased.然后当Show触发视觉状态时,我将其设置Visibility为Visible.通常情况下,您无法设置动画,Visibility但如果您启用了Fluid Layout行为(还记得定义一个TransitionEffect),它会自动为您设置动画.

<UserControl
    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:ei="http://schemas.microsoft.com/expression/2010/interactions" xmlns:ee="http://schemas.microsoft.com/expression/2010/effects" xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity" mc:Ignorable="d"
    x:Class="transformanimation.MainPage"
    Width="640" Height="480">
    <UserControl.Resources>
        <Storyboard x:Name="Storyboard1">
            <DoubleAnimation Duration="0:0:0.7" To="0.2" Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.ScaleX)" Storyboard.TargetName="textBlock" d:IsOptimized="True"/>
            <DoubleAnimation Duration="0:0:0.7" To="0.2" Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.ScaleY)" Storyboard.TargetName="textBlock" d:IsOptimized="True"/>
        </Storyboard>
    </UserControl.Resources>

    <Grid x:Name="LayoutRoot" Background="White">
        <VisualStateManager.VisualStateGroups>
            <VisualStateGroup x:Name="VisualStateGroup" ei:ExtendedVisualStateManager.UseFluidLayout="True">
                <VisualStateGroup.Transitions>
                    <VisualTransition GeneratedDuration="0:0:0.2">
                        <ei:ExtendedVisualStateManager.TransitionEffect>
                            <ee:FadeTransitionEffect/>
                        </ei:ExtendedVisualStateManager.TransitionEffect>
                    </VisualTransition>
                </VisualStateGroup.Transitions>
                <VisualState x:Name="Hide"/>
                <VisualState x:Name="Show">
                    <Storyboard>
                        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="textBlock">
                            <DiscreteObjectKeyFrame KeyTime="0">
                                <DiscreteObjectKeyFrame.Value>
                                    <Visibility>Visible</Visibility>
                                </DiscreteObjectKeyFrame.Value>
                            </DiscreteObjectKeyFrame>
                        </ObjectAnimationUsingKeyFrames>
                    </Storyboard>
                </VisualState>
            </VisualStateGroup>
        </VisualStateManager.VisualStateGroups>
        <VisualStateManager.CustomVisualStateManager>
            <ei:ExtendedVisualStateManager/>
        </VisualStateManager.CustomVisualStateManager>
        <Grid Margin="205,96,275,150">
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto"/>
                <RowDefinition/>
            </Grid.RowDefinitions>
            <TextBlock x:Name="textBlock" TextWrapping="Wrap" Text="TextBlock" FontSize="26.667" RenderTransformOrigin="0.5,0.5" Visibility="Collapsed">
                <TextBlock.RenderTransform>
                    <CompositeTransform/>
                </TextBlock.RenderTransform>
            </TextBlock>
            <Rectangle Fill="#FF767689" Stroke="Black" Grid.Row="1"/>
        </Grid>
        <Button Content="hide" HorizontalAlignment="Left" VerticalAlignment="Top" Width="75" Margin="63,19,0,0">
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="Click">
                    <ei:GoToStateAction StateName="Hide"/>
                </i:EventTrigger>
            </i:Interaction.Triggers>
        </Button>
        <Button Content="show" HorizontalAlignment="Left" VerticalAlignment="Top" Width="75" Margin="183,20,0,0">
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="Click">
                    <ei:GoToStateAction StateName="Show"/>
                </i:EventTrigger>
            </i:Interaction.Triggers>
        </Button>
    </Grid>
</UserControl>

当然,如果你不想使用这个神奇的动画,你可以尝试动画它ScaleY.像这样的东西,

        <DoubleAnimation Duration="0:0:0.2" To="0" Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.ScaleY)" Storyboard.TargetName="textBlock" d:IsOptimized="True"/>

希望这可以帮助!:)