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Практическое руководство. Создание отражения

  • Статья

В этой статье показано, как использовать для VisualBrush создания отражения. Так как можно использовать VisualBrush для отображения существующего визуального элемента, это позволяет создавать интересные визуальные эффекты, например отражения и увеличение.

A XAML element with latin text and two circles, whose upside down reflection is displayed below it.

Пример XAML

В следующем примере используется кисть VisualBrush для создания отражения объекта Border, содержащего несколько элементов.

<StackPanel Margin="25" Height="400">

    <!-- The object to reflect. -->
    <Border Name="ReflectedVisual" Width="400">
        <Border.Background>
            <LinearGradientBrush StartPoint="0,0.5" EndPoint="1,0.5">
                <GradientStop Offset="0.0" Color="#CCCCFF" />
                <GradientStop Offset="1.0" Color="White" />
            </LinearGradientBrush>
        </Border.Background>
        <StackPanel Orientation="Horizontal" Margin="10">
            <TextBlock TextWrapping="Wrap" Width="200" Margin="10">
              Lorem ipsum dolor sit amet, consectetuer adipiscing elit.
              Suspendisse vel ante. Donec luctus tortor sit amet est.
              Nullam pulvinar odio et wisi.
              Pellentesque quis magna. Sed pellentesque.
            </TextBlock>
            <StackPanel>
                <Ellipse Margin="10" Height="50" Width="50" Fill="Black" />
                <Ellipse Margin="10" Height="50" Width="50" Fill="Purple" />
            </StackPanel>
        </StackPanel>
    </Border>

    <Rectangle Height="1" Fill="Gray" HorizontalAlignment="Stretch" />

    <!-- The object to contain the reflection.-->
    <Rectangle DataContext="{Binding ElementName=ReflectedVisual}"
               Height="{Binding Path=ActualHeight}" 
               Width="{Binding Path=ActualWidth}">
        <Rectangle.Fill>

            <!-- Creates the reflection. -->
            <VisualBrush Opacity="0.75" Stretch="None"
                         Visual="{Binding}">
                <VisualBrush.RelativeTransform>

                    <!-- Flip the reflection. -->
                    <TransformGroup>
                        <ScaleTransform ScaleX="1" ScaleY="-1" />
                        <TranslateTransform  Y="1" />
                    </TransformGroup>
                </VisualBrush.RelativeTransform>
            </VisualBrush>
        </Rectangle.Fill>

        <Rectangle.OpacityMask>
            <LinearGradientBrush StartPoint="0.5,0" EndPoint="0.5,1">
                <GradientStop Color="#FF000000" Offset="0.0" />
                <GradientStop Color="#33000000" Offset="0.5" />
                <GradientStop Color="#00000000" Offset="0.75" />
            </LinearGradientBrush>
        </Rectangle.OpacityMask>

        <Rectangle.Effect>
            <BlurEffect Radius="1.5" />
        </Rectangle.Effect>

    </Rectangle>
</StackPanel>

Пример на основе кода

В следующем примере используется кисть VisualBrush для создания отражения объекта Border, содержащего несколько элементов. Этот код выполняется в обработчике Window.Loaded событий:

private void Window_Loaded(object sender, RoutedEventArgs e)
{
    var container = new StackPanel();
    container.Height = 400;
    container.Margin = new Thickness(25);

    // Visual Element that will be reflected
    var visualElement = new Border
    {
        Width = 400,
        Background = new LinearGradientBrush(
                                    (Color)ColorConverter.ConvertFromString("#CCCCFF"),
                                    Colors.White,
                                    new Point(0.0, 0.5),
                                    new Point(1.0, 0.5))
    };

    // Stack panel inside parent border
    {
        var visualElementChild1 = new StackPanel
        {
            Orientation = Orientation.Horizontal,
            Margin = new Thickness(10)
        };

        // Stack panel content
        {
            var paragraphContent = new TextBlock
            {
                Text = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit.\nSuspendisse vel ante. Donec luctus tortor sit amet est.\nNullam pulvinar odio et wisi.\nPellentesque quis magna. Sed pellentesque.",
                Width = 200,
                Margin = new Thickness(10),
                TextWrapping = TextWrapping.Wrap
            };

            var ellipsePanel = new StackPanel();
            ellipsePanel.Children.Add(new Ellipse() { Margin = new Thickness(10), Height = 50, Width = 50, Fill = Brushes.Black });
            ellipsePanel.Children.Add(new Ellipse() { Margin = new Thickness(10), Height = 50, Width = 50, Fill = Brushes.Purple });

            // Add to parent
            visualElementChild1.Children.Add(paragraphContent);
            visualElementChild1.Children.Add(ellipsePanel);
        }

        // Add to parent
        visualElement.Child = visualElementChild1;
    }

    // Add visual to reflect to container
    container.Children.Add(visualElement);

    // Line separator
    container.Children.Add(new Rectangle() { Height = 1, Fill = Brushes.Gray, HorizontalAlignment = HorizontalAlignment.Stretch });

    // Reflection
    Rectangle reflection = new Rectangle();

    reflection.DataContext = visualElement;
    reflection.SetBinding(Rectangle.WidthProperty, "ActualWidth");
    reflection.SetBinding(Rectangle.HeightProperty, "ActualHeight");

    // Create the reflection effect
    var transform = new TransformGroup();
    transform.Children.Add(new ScaleTransform(1, -1));
    transform.Children.Add(new TranslateTransform(0, 1));

    var reflectedBrush = new VisualBrush();
    reflectedBrush.RelativeTransform = transform;
    reflectedBrush.Opacity = 0.75;
    reflectedBrush.Stretch = Stretch.None;
    reflectedBrush.Visual = visualElement;

    // Add the reflection effect
    reflection.Fill = reflectedBrush;

    reflection.OpacityMask = new LinearGradientBrush(
                                new GradientStopCollection(new[]
                                    {
                                        new GradientStop((Color)ColorConverter.ConvertFromString("#FF000000"), 0.0),
                                        new GradientStop((Color)ColorConverter.ConvertFromString("#33000000"), 0.5),
                                        new GradientStop((Color)ColorConverter.ConvertFromString("#00000000"), 0.75)
                                    }),
                                new Point(0.5, 0),
                                new Point(0.5, 1));

    reflection.Effect = new BlurEffect() { Radius = 1.5 };

    // Add the reflection to the container
    container.Children.Add(reflection);

    // Set the container as the content of this window
    Content = container;
}

Private Sub Window_Loaded(sender As Object, e As RoutedEventArgs)
    Dim container As New StackPanel With {.Height = 400, .Margin = New Thickness(25)}

    ' Visual Element that will be reflected
    Dim visualElement As New Border With {
        .Width = 400,
        .Background = New LinearGradientBrush(
                                        ColorConverter.ConvertFromString("#CCCCFF"),
                                        Colors.White,
                                        New Point(0.0, 0.5),
                                        New Point(1.0, 0.5))
    }

    ' Stack panel inside parent border
    Dim visualElementChild1 As New StackPanel With {
        .Orientation = Orientation.Horizontal,
        .Margin = New Thickness(10)
    }

    ' Stack panel content
    Dim paragraphContent As New TextBlock With {
        .Text = $"Lorem ipsum dolor sit amet, consectetuer adipiscing elit.{vbNewLine}Suspendisse vel ante. Donec luctus tortor sit amet est.{vbNewLine}Nullam pulvinar odio et wisi.{vbNewLine}Pellentesque quis magna. Sed pellentesque.",
        .Width = 200,
        .Margin = New Thickness(10),
        .TextWrapping = TextWrapping.Wrap
    }

    Dim ellipsePanel = New StackPanel
    ellipsePanel.Children.Add(New Ellipse() With {.Margin = New Thickness(10), .Height = 50, .Width = 50, .Fill = Brushes.Black})
    ellipsePanel.Children.Add(New Ellipse() With {.Margin = New Thickness(10), .Height = 50, .Width = 50, .Fill = Brushes.Purple})

    ' Add stack panel content
    visualElementChild1.Children.Add(paragraphContent)
    visualElementChild1.Children.Add(ellipsePanel)

    ' Add stack panel to border
    visualElement.Child = visualElementChild1

    ' Add visual to reflect to container
    container.Children.Add(visualElement)

    ' Line separator
    container.Children.Add(New Rectangle() With {.Height = 1, .Fill = Brushes.Gray, .HorizontalAlignment = HorizontalAlignment.Stretch})

    ' Reflection
    Dim reflection As New Rectangle

    reflection.DataContext = visualElement
    reflection.SetBinding(Rectangle.WidthProperty, "ActualWidth")
    reflection.SetBinding(Rectangle.HeightProperty, "ActualHeight")

    ' Create the reflection effect
    Dim Transform = New TransformGroup
    Transform.Children.Add(New ScaleTransform(1, -1))
    Transform.Children.Add(New TranslateTransform(0, 1))

    Dim reflectedBrush As New VisualBrush With {
        .RelativeTransform = Transform,
        .Opacity = 0.75,
        .Stretch = Stretch.None,
        .Visual = visualElement
    }

    ' Add the reflection effect
    reflection.Fill = reflectedBrush

    reflection.OpacityMask = New LinearGradientBrush(
                                    New GradientStopCollection(
                                        {
                                            New GradientStop(ColorConverter.ConvertFromString("#FF000000"), 0.0),
                                            New GradientStop(ColorConverter.ConvertFromString("#33000000"), 0.5),
                                            New GradientStop(ColorConverter.ConvertFromString("#00000000"), 0.75)
                                        }),
                                    New Point(0.5, 0),
                                    New Point(0.5, 1))

    reflection.Effect = New BlurEffect() With {.Radius = 1.5}

    ' Add the reflection to the container
    container.Children.Add(reflection)

    ' Set the container as the content of this window
    Content = container
End Sub

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