增加/缩小 WPF 动画

Question

在WPF中，当用户在TextBox中获得焦点时，我希望有一些动画效果，使TextBox变成多行，并使其Width变大（在用户输入时），当失去焦点时，TextBox会恢复到原始大小。大小是未知的。此外，最终，TextBox需要在WPF DataGrid内。我以前从未做过动画，希望得到一些帮助来开始。谢谢。

编辑：我已经成功实现了动画，但宽度值是固定的（使其多行并不起作用，但这并不重要）。所以我的问题现在是，如果原始大小未知，我该如何返回？在Width属性上是否有乘数可以使用？

以下是我目前的代码：

<Window.Resources>
        <Storyboard x:Key="GrowStoryboard">
            <DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Storyboard.TargetName="textBox" Storyboard.TargetProperty="(FrameworkElement.Width)">
                <SplineDoubleKeyFrame KeyTime="00:00:00.4000000" Value="400" KeySpline="0.54,0.27,0.38,0.69"/>
            </DoubleAnimationUsingKeyFrames>
            <Int32Animation Duration="0:0:0.4" From="1" To="3" Storyboard.TargetName="textBox" Storyboard.TargetProperty="(TextBox.MinLines)">
            </Int32Animation>
        </Storyboard>
        <Storyboard x:Key="ShrinkStoryboard">
            <DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Storyboard.TargetName="textBox" Storyboard.TargetProperty="(FrameworkElement.Width)">
                <SplineDoubleKeyFrame KeyTime="00:00:00.4000000" Value="200" KeySpline="0.54,0.27,0.38,0.69"/>
            </DoubleAnimationUsingKeyFrames>
        </Storyboard>
    </Window.Resources>
    <Window.Triggers>
        <EventTrigger RoutedEvent="FocusManager.GotFocus" SourceName="textBox">
            <BeginStoryboard x:Name="GrowStoryboard_BeginStoryboard" Storyboard="{StaticResource GrowStoryboard}"/>
        </EventTrigger>
        <EventTrigger RoutedEvent="FocusManager.LostFocus" SourceName="textBox">
            <BeginStoryboard x:Name="ShrinkStoryboard_BeginStoryboard" Storyboard="{StaticResource ShrinkStoryboard}"/>
        </EventTrigger>
    </Window.Triggers>

    <StackPanel>
        <TextBox x:Name="textBox" Width="200" Height="20" Text="TextBox" />
        <TextBox x:Name="textBox1" Width="200" Height="20" Text="TextBox" />
    </StackPanel>

- joerage

Answer 1

虽然在XAML中没有可以使用的乘法器，但您可以创建一个IValueConverter类来实现此目的。例如：

    class Multiplier : IValueConverter
{
    public object Convert( object value, Type targetType, object parameter, System.Globalization.CultureInfo culture )
    {
        var dblValue = 1.0;
        if (value is double)
            dblValue = (double)value;
        else if ( !(value is string) || !double.TryParse( (string)value, out dblValue ) )
            return null;

        var dblParam = 1.0;
        if (parameter is double)
            dblParam = (double)parameter;
        else if ( !(parameter is string) || !double.TryParse( (string)parameter, out dblParam ) )
            return null;

        return dblValue * dblParam;
    }

    public object ConvertBack( object value, Type targetType, object parameter, System.Globalization.CultureInfo culture )
    {
        throw new NotImplementedException();
    }
}

然后您可以在XAML中使用此方法，使文本框的宽度按比例增长和缩小，如下所示...

        <DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Storyboard.TargetName="textBox" Storyboard.TargetProperty="(FrameworkElement.Width)">
            <SplineDoubleKeyFrame KeyTime="0:0:0.4" Value="{Binding ElementName=textBox, Path=Width, Converter={StaticResource Multiplier}, ConverterParameter=2}" KeySpline="0.54,0.27,0.38,0.69"/>
        </DoubleAnimationUsingKeyFrames>

        <DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Storyboard.TargetName="textBox" Storyboard.TargetProperty="(FrameworkElement.Width)">
            <SplineDoubleKeyFrame KeyTime="0:0:0.4" Value="{Binding ElementName=textBox, Path=Width, Converter={StaticResource Multiplier}, ConverterParameter=0.5}" KeySpline="0.54,0.27,0.38,0.69"/>
        </DoubleAnimationUsingKeyFrames>

- MerickOWA