在c＃中的WPF不透明动画？

Question

我有一个设置为隐藏可见性的矩形，当文本框被聚焦时，该矩形的可见性是可见的。这很好但是我想要一个不透明的动画..我怎么能做到这一点在c＃

这是我的代码;

<Grid> 

    <Rectangle Height="650" Width="625" x:Name="Rectangle" Fill="#293241" Opacity="0.8" Visibility="Hidden" Panel.ZIndex="1" ></Rectangle> 

    <StackPanel Margin="0,51,0,-51"> 
     <TextBox x:Name="text" GotKeyboardFocus="text_GotKeyboardFocus" Margin="158,0,169,0" Height="24" Text="Select Your Time..." /> 

     <Popup x:Name="popup" AllowsTransparency="True" Width="430" Height="400" Placement="Center" > 
      <Grid> 
       <StackPanel Width="430" Height="400" Orientation="Horizontal" Margin="0,-118,0,118"> 
        <TextBox x:Name="text2" Background="#f4f4f4" Margin="10" GotKeyboardFocus="text_GotKeyboardFocus2" Cursor="Arrow" Height="64" Width="64" Text="1 second" /> 
        <TextBox x:Name="text3" Background="#f4f4f4" Margin="10" GotKeyboardFocus="text_GotKeyboardFocus2" Cursor="Arrow" Height="64" Width="64" Text="2 seconds" /> 
        <TextBox x:Name="text4" Background="#f4f4f4" Margin="10" GotKeyboardFocus="text_GotKeyboardFocus2" Cursor="Arrow" Height="64" Width="64" Text="5 seconds" /> 
        <TextBox x:Name="text5" Background="#f4f4f4" Margin="10" GotKeyboardFocus="text_GotKeyboardFocus2" Cursor="Arrow" Height="64" Width="64" Text="10 seconds" /> 
        <TextBox x:Name="text6" Background="#f4f4f4" Margin="10" GotKeyboardFocus="text_GotKeyboardFocus2" Cursor="Arrow" Height="64" Width="64" Text="20 seconds" /> 
       </StackPanel> 
       <StackPanel Width="430" Height="400" Orientation="Horizontal" Margin="0,-38,0,38"> 
        <TextBox x:Name="text7" Background="#f4f4f4" Margin="10" GotKeyboardFocus="text_GotKeyboardFocus2" Cursor="Arrow" Height="64" Width="64" Text="30 seconds" /> 
        <TextBox x:Name="text8" Background="#f4f4f4" Margin="10" GotKeyboardFocus="text_GotKeyboardFocus2" Cursor="Arrow" Height="64" Width="64" Text="1 minute" /> 
        <TextBox x:Name="text9" Background="#f4f4f4" Margin="10" GotKeyboardFocus="text_GotKeyboardFocus2" Cursor="Arrow" Height="64" Width="64" Text="5 minutes" /> 
        <TextBox x:Name="text10" Background="#f4f4f4" Margin="10" GotKeyboardFocus="text_GotKeyboardFocus2" Cursor="Arrow" Height="64" Width="64" Text="10 minutes" /> 
        <TextBox x:Name="text11" Background="#f4f4f4" Margin="10" GotKeyboardFocus="text_GotKeyboardFocus2" Cursor="Arrow" Height="64" Width="64" Text="Forever" /> 
       </StackPanel> 
      </Grid> 
     </Popup> 

    </StackPanel> 


</Grid> 

private void text_GotKeyboardFocus(object sender, KeyboardFocusChangedEventArgs e) 
    { 
     popup.IsOpen = true; 
     Rectangle.Visibility = Visibility.Visible; 
    } 

    private void text_GotKeyboardFocus2(object sender, RoutedEventArgs e) 
    { 
     popup.IsOpen = false; 
     text.Text = (sender as TextBox).Text; 
     Rectangle.Visibility = Visibility.Hidden; 
    } 

Answer 1

这应该工作：

private void text_GotKeyboardFocus(object sender, KeyboardFocusChangedEventArgs e) 
{ 
    popup.IsOpen = true; 
    Rectangle.BeginAnimation(UIElement.OpacityProperty, 
     new DoubleAnimation(1d, TimeSpan.FromSeconds(0.5))); 
} 

private void text_GotKeyboardFocus2(object sender, RoutedEventArgs e) 
{ 
    popup.IsOpen = false; 
    text.Text = (sender as TextBox).Text; 
    Rectangle.BeginAnimation(UIElement.OpacityProperty, 
     new DoubleAnimation(0d, TimeSpan.FromSeconds(0.5))); 
}