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How to: Apply Stretch Properties to the Contents of a Viewbox

This example shows how to change the value of the StretchDirection and Stretch properties of a Viewbox.

The first example uses Extensible Application Markup Language (XAML) to define a Viewbox element. It assigns a MaxWidth and MaxHeight of 400. The example nests an Image element within the Viewbox. Button elements that correspond to the property values for the Stretch and StretchDirection enumerations manipulate the stretching behavior of the nested Image.

<StackPanel Margin="0,0,0,10" HorizontalAlignment="Center" Orientation="Horizontal" DockPanel.Dock="Top">
    <Button Name="btn1" Click="stretchNone">Stretch="None"</Button>
    <Button Name="btn2" Click="stretchFill">Stretch="Fill"</Button>
    <Button Name="btn3" Click="stretchUni">Stretch="Uniform"</Button>
    <Button Name="btn4" Click="stretchUniFill">Stretch="UniformToFill"</Button>
</StackPanel>

<StackPanel Margin="0,0,0,10" HorizontalAlignment="Center" Orientation="Horizontal" DockPanel.Dock="Top">
    <Button Name="btn5" Click="sdUpOnly">StretchDirection="UpOnly"</Button>
    <Button Name="btn6" Click="sdDownOnly">StretchDirection="DownOnly"</Button>
    <Button Name="btn7" Click="sdBoth">StretchDirection="Both"</Button>
 </StackPanel>        

<TextBlock DockPanel.Dock="Top" Name="txt1" />
<TextBlock DockPanel.Dock="Top" Name="txt2" />

<StackPanel HorizontalAlignment="Center" VerticalAlignment="Center">
    <Viewbox MaxWidth="500" MaxHeight="500" Name="vb1">
        <Image Source="tulip_farm.jpg"/>
    </Viewbox>    
</StackPanel>

The following code-behind file handles the Button Click events that the previous XAML example defines.

private void stretchNone(object sender, RoutedEventArgs e)
{
    vb1.Stretch = System.Windows.Media.Stretch.None;
    txt1.Text = "Stretch is now set to None.";
}

private void stretchFill(object sender, RoutedEventArgs e)
{
    vb1.Stretch = System.Windows.Media.Stretch.Fill;
    txt1.Text = "Stretch is now set to Fill.";
}

private void stretchUni(object sender, RoutedEventArgs e)
{
    vb1.Stretch = System.Windows.Media.Stretch.Uniform;
    txt1.Text = "Stretch is now set to Uniform.";
}

private void stretchUniFill(object sender, RoutedEventArgs e)
{
    vb1.Stretch = System.Windows.Media.Stretch.UniformToFill;
    txt1.Text = "Stretch is now set to UniformToFill.";
}

private void sdUpOnly(object sender, RoutedEventArgs e)
{
    vb1.StretchDirection = System.Windows.Controls.StretchDirection.UpOnly;
    txt2.Text = "StretchDirection is now UpOnly.";
}

private void sdDownOnly(object sender, RoutedEventArgs e)
{
    vb1.StretchDirection = System.Windows.Controls.StretchDirection.DownOnly;
    txt2.Text = "StretchDirection is now DownOnly.";
}

private void sdBoth(object sender, RoutedEventArgs e)
{
    vb1.StretchDirection = System.Windows.Controls.StretchDirection.Both;
    txt2.Text = "StretchDirection is now Both.";
}
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