Artikel
11/18/2011

Viewbox Class

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Defines a content decorator that can stretch and scale a single child to fill the available space.

Inheritance Hierarchy

System.Object
  System.Windows.DependencyObject
    System.Windows.UIElement
      System.Windows.FrameworkElement
        System.Windows.Controls.Viewbox

Namespace: System.Windows.Controls
Assembly: System.Windows (in System.Windows.dll)

Syntax

'Declaration
<ContentPropertyAttribute("Child", True)> _
Public NotInheritable Class Viewbox _
    Inherits FrameworkElement

[ContentPropertyAttribute("Child", true)]
public sealed class Viewbox : FrameworkElement

<ViewBox .../>
-or-
<ViewBox ...>
  child
</ViewBox>

XAML Values

child
A single object element of a type that derives from UIElement, which is contained by this Viewbox. See Child.

The Viewbox type exposes the following members.

Constructors

	Name	Description
	Viewbox	Initializes a new instance of the Viewbox class.

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Properties

	Name	Description
	ActualHeight	Gets the rendered height of a FrameworkElement. (Inherited from FrameworkElement.)
	ActualWidth	Gets the rendered width of a FrameworkElement. (Inherited from FrameworkElement.)
	AllowDrop	Gets or sets a value that determines whether this UIElement can be a drop target for purposes of Silverlight drag-and-drop operations. (Inherited from UIElement.)
	CacheMode	Gets or sets a value that indicates that rendered content should be cached when possible. (Inherited from UIElement.)
	Child	Gets or sets the single child element of a Viewbox element.
	Clip	Gets or sets the Geometry used to define the outline of the contents of a UIElement. (Inherited from UIElement.)
	Cursor	Gets or sets the cursor image that displays while the mouse pointer is over a FrameworkElement. (Inherited from FrameworkElement.)
	DataContext	Gets or sets the data context for a FrameworkElement when it participates in data binding. (Inherited from FrameworkElement.)
	DesiredSize	Gets the size that this UIElement computed during the measure pass of the layout process. (Inherited from UIElement.)
	Dispatcher	Gets the Dispatcher this object is associated with. (Inherited from DependencyObject.)
	Effect	Gets or sets the pixel shader effect to use for rendering this UIElement. (Inherited from UIElement.)
	FlowDirection	Gets or sets the direction that text and other user interface elements flow within any parent element that controls their layout. (Inherited from FrameworkElement.)
	Height	Gets or sets the suggested height of a FrameworkElement. (Inherited from FrameworkElement.)
	HorizontalAlignment	Gets or sets the horizontal alignment characteristics that are applied to a FrameworkElement when it is composed in a layout parent, such as a panel or items control. (Inherited from FrameworkElement.)
	IsHitTestVisible	Gets or sets whether the contained area of this UIElement can return true values for hit testing. (Inherited from UIElement.)
	Language	Gets or sets localization/globalization language information that applies to a FrameworkElement. (Inherited from FrameworkElement.)
	Margin	Gets or sets the outer margin of a FrameworkElement. (Inherited from FrameworkElement.)
	MaxHeight	Gets or sets the maximum height constraint of a FrameworkElement. (Inherited from FrameworkElement.)
	MaxWidth	Gets or sets the maximum width constraint of a FrameworkElement. (Inherited from FrameworkElement.)
	MinHeight	Gets or sets the minimum height constraint of a FrameworkElement. (Inherited from FrameworkElement.)
	MinWidth	Gets or sets the minimum width constraint of a FrameworkElement. (Inherited from FrameworkElement.)
	Name	Gets or sets the identifying name of the object. When a XAML processor creates the object tree from XAML markup, run-time code can refer to the XAML-declared object by this name. (Inherited from FrameworkElement.)
	Opacity	Gets or sets the degree of the object's opacity. (Inherited from UIElement.)
	OpacityMask	Gets or sets the brush used to alter the opacity of regions of this object. (Inherited from UIElement.)
	Parent	Gets the parent object of this FrameworkElement in the object tree. (Inherited from FrameworkElement.)
	Projection	Gets or sets the perspective projection (3-D effect) to apply when rendering this UIElement. (Inherited from UIElement.)
	RenderSize	Gets the final render size of a UIElement. (Inherited from UIElement.)
	RenderTransform	Gets or sets transform information that affects the rendering position of a UIElement. (Inherited from UIElement.)
	RenderTransformOrigin	Gets or sets the origin point of any possible render transform declared by RenderTransform, relative to the bounds of the UIElement. (Inherited from UIElement.)
	Resources	Gets the locally defined resource dictionary. In XAML, you can establish resource items as child object elements of a frameworkElement.Resources property element, through XAML implicit collection syntax. (Inherited from FrameworkElement.)
	Stretch	Gets or sets the Stretch mode, which determines how content fits into the available space.
	StretchDirection	Gets or sets the StretchDirection, which determines how scaling is applied to the contents of a Viewbox.
	Style	Gets or sets an instance Style that is applied for this object during rendering. (Inherited from FrameworkElement.)
	Tag	Gets or sets an arbitrary object value that can be used to store custom information about this object. (Inherited from FrameworkElement.)
	Triggers	Gets the collection of triggers for animations that are defined for a FrameworkElement. (Inherited from FrameworkElement.)
	UseLayoutRounding	Gets or sets a value that determines whether rendering for the object and its visual subtree should use rounding behavior that aligns rendering to whole pixels. (Inherited from UIElement.)
	VerticalAlignment	Gets or sets the vertical alignment characteristics that are applied to a FrameworkElement when it is composed in a parent object such as a panel or items control. (Inherited from FrameworkElement.)
	Visibility	Gets or sets the visibility of a UIElement. A UIElement that is not visible does not render and does not communicate its desired size to layout. (Inherited from UIElement.)
	Width	Gets or sets the width of a FrameworkElement. (Inherited from FrameworkElement.)

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Methods

	Name	Description
	AddHandler	Adds a routed event handler for a specified routed event, adding the handler to the handler collection on the current element. Specify handledEventsToo as true to have the provided handler be invoked for routed event that had already been marked as handled by another element along the event route. (Inherited from UIElement.)
	Arrange	Positions child objects and determines a size for a UIElement. Parent objects that implement custom layout for their child elements should call this method from their layout override implementations to form a recursive layout update. (Inherited from UIElement.)
	ArrangeOverride	Provides the behavior for the Arrange pass of Silverlight layout. Classes can override this method to define their own Arrange pass behavior. (Inherited from FrameworkElement.)
	CaptureMouse	Sets mouse capture to a UIElement. (Inherited from UIElement.)
	CheckAccess	Determines whether the calling thread has access to this object. (Inherited from DependencyObject.)
	ClearValue	Clears the local value of a dependency property. (Inherited from DependencyObject.)
	Equals(Object)	Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
	FindName	Retrieves an object that has the specified identifier name. (Inherited from FrameworkElement.)
	GetAnimationBaseValue	Returns any base value established for a Silverlight dependency property, which would apply in cases where an animation is not active. (Inherited from DependencyObject.)
	GetBindingExpression	Retrieves the BindingExpression for a dependency property where a binding is established. (Inherited from FrameworkElement.)
	GetHashCode	Serves as a hash function for a particular type. (Inherited from Object.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	GetValue	Returns the current effective value of a dependency property from a DependencyObject. (Inherited from DependencyObject.)
	InvalidateArrange	Invalidates the arrange state (layout) for a UIElement. After the invalidation, the UIElement will have its layout updated, which will occur asynchronously. (Inherited from UIElement.)
	InvalidateMeasure	Invalidates the measurement state (layout) for a UIElement. (Inherited from UIElement.)
	Measure	Updates the DesiredSize of a UIElement. Typically, objects that implement custom layout for their layout children call this method from their own MeasureOverride implementations to form a recursive layout update. (Inherited from UIElement.)
	MeasureOverride	Provides the behavior for the Measure pass of Silverlight layout. Classes can override this method to define their own Measure pass behavior. (Inherited from FrameworkElement.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	OnApplyTemplate	When overridden in a derived class, is invoked whenever application code or internal processes (such as a rebuilding layout pass) call ApplyTemplate. In simplest terms, this means the method is called just before a UI element displays in an application. For more information, see Remarks. (Inherited from FrameworkElement.)
	OnCreateAutomationPeer	When implemented in a derived class, returns class-specific AutomationPeer implementations for the Silverlight automation infrastructure. (Inherited from UIElement.)
	ReadLocalValue	Returns the local value of a dependency property, if a local value is set. (Inherited from DependencyObject.)
	ReleaseMouseCapture	Removes mouse capture from a UIElement. After this call, typically no object holds mouse capture. (Inherited from UIElement.)
	RemoveHandler	Removes the specified routed event handler from this UIElement. (Inherited from UIElement.)
	SetBinding	Attaches a binding to a FrameworkElement, using the provided binding object, and returns a BindingExpressionBase for possible later use. (Inherited from FrameworkElement.)
	SetValue	Sets the local value of a dependency property on a DependencyObject. (Inherited from DependencyObject.)
	ToString	Returns a string that represents the current object. (Inherited from Object.)
	TransformToVisual	Returns a transform object that can be used to transform coordinates from the UIElement to the specified object. (Inherited from UIElement.)
	UpdateLayout	Ensures that all positions of child objects of a UIElement are properly updated for layout. (Inherited from UIElement.)

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Events

	Name	Description
	BindingValidationError	Occurs when a data validation error is reported by a binding source. (Inherited from FrameworkElement.)
	DataContextChanged	Occurs when the data context for this element changes. (Inherited from FrameworkElement.)
	DoubleTap	Occurs when a DoubleTap gesture is committed while over this UIElement. (Inherited from UIElement.)
	DragEnter	Occurs when the input system reports an underlying drag event with this element as the target. (Inherited from UIElement.)
	DragLeave	Occurs when the input system reports an underlying drag event with this element as the origin. (Inherited from UIElement.)
	DragOver	Occurs when the input system reports an underlying drag event with this element as the potential drop target. (Inherited from UIElement.)
	Drop	Occurs when the input system reports an underlying drop event with this element as the drop target. (Inherited from UIElement.)
	GotFocus	Occurs when a UIElement receives focus. (Inherited from UIElement.)
	Hold	Occurs when a Hold gesture is committed while over this UIElement. (Inherited from UIElement.)
	KeyDown	Occurs when a keyboard key is pressed while the UIElement has focus. (Inherited from UIElement.)
	KeyUp	Occurs when a keyboard key is released while the UIElement has focus. (Inherited from UIElement.)
	LayoutUpdated	Occurs when the layout of the Silverlight visual tree changes. (Inherited from FrameworkElement.)
	Loaded	Occurs when a FrameworkElement has been constructed and added to the object tree. (Inherited from FrameworkElement.)
	LostFocus	Occurs when a UIElement loses focus. (Inherited from UIElement.)
	LostMouseCapture	Occurs when the UIElement loses mouse capture. (Inherited from UIElement.)
	ManipulationCompleted	Occurs when a manipulation and inertia on the UIElement is complete. (Inherited from UIElement.)
	ManipulationDelta	Occurs when the input device changes position during a manipulation. (Inherited from UIElement.)
	ManipulationStarted	Occurs when an input device begins a manipulation on the UIElement. (Inherited from UIElement.)
	MediaCommand	Occurs when a button is pressed on a remote control. (Inherited from UIElement.)
	MouseEnter	Occurs when the mouse (or a stylus) enters the bounding area of a UIElement. (Inherited from UIElement.)
	MouseLeave	Occurs when the mouse (or the stylus) leaves the bounding area of a UIElement. (Inherited from UIElement.)
	MouseLeftButtonDown	Occurs when the left mouse button is pressed (or when the tip of the stylus touches the tablet) while the mouse pointer is over a UIElement. (Inherited from UIElement.)
	MouseLeftButtonUp	Occurs when the left mouse button is released (or the tip of the stylus is removed from the tablet) while the mouse (or the stylus) is over a UIElement (or while a UIElement holds mouse capture). (Inherited from UIElement.)
	MouseMove	Occurs when the coordinate position of the mouse (or stylus) changes while over a UIElement (or while a UIElement holds mouse capture). (Inherited from UIElement.)
	MouseRightButtonDown	Occurs when the right mouse button is pressed while the mouse pointer is over a UIElement. (Inherited from UIElement.)
	MouseRightButtonUp	Occurs when the right mouse button is released while the mouse pointer is over a UIElement. However, this event will only be raised if a caller marks the preceding MouseRightButtonDown event as handled; see Remarks. (Inherited from UIElement.)
	MouseWheel	Occurs when the user rotates the mouse wheel while the mouse pointer is over a UIElement, or the UIElement has focus. (Inherited from UIElement.)
	SizeChanged	Occurs when either the ActualHeight or the ActualWidth properties change value on a FrameworkElement. (Inherited from FrameworkElement.)
	Tap	Occurs when a Tap gesture is committed while over this UIElement. (Inherited from UIElement.)
	TextInput	Occurs when a UI element gets text in a device-independent manner. (Inherited from UIElement.)
	TextInputStart	Occurs when a UI element initially gets text in a device-independent manner. (Inherited from UIElement.)
	TextInputUpdate	Occurs when text continues to be composed via an input method editor (IME). (Inherited from UIElement.)
	Unloaded	Occurs when this object is no longer connected to the main object tree. (Inherited from FrameworkElement.)

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Fields

	Name	Description
	StretchDirectionProperty	Identifies the StretchDirection dependency property.
	StretchProperty	Identifies the Stretch dependency property.

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Remarks

A Viewbox control takes one child element and stretches it or scales it to fit the size of the Viewbox. You can control the stretch or scale levels by using the Stretch, StretchDirection, HorizontalAlignment, and VerticalAlignment properties.

You typically use a Viewbox for 2D graphic images. You typically do not use a Viewbox for ordinary controls.

Viewbox is a sealed class.

Content Model: The content property of a Viewbox is Child. A Viewbox can have only one Child. If you add an additional Child, an ArgumentException will be thrown at run time.

Examples

The following example shows what happens when you change the StretchDirection and Stretch properties of a Viewbox. The example includes three Viewbox controls that have different sizes. The same image is displayed in the Viewbox controls so that you can compare the differences. You can manipulate the stretching and scaling of the image by clicking the buttons that correspond to the values for the Stretch and StretchDirection enumerations.

<Grid Height="600" Width="600">
    <Grid.ColumnDefinitions>
        <ColumnDefinition />
        <ColumnDefinition />
    </Grid.ColumnDefinitions>

    <Grid.RowDefinitions>
        <RowDefinition Height="Auto" />
        <RowDefinition Height="auto" />
        <RowDefinition />
    </Grid.RowDefinitions>

    <StackPanel Grid.Row="0" Grid.Column="0" Margin="5,5,5,5" Orientation="Vertical">
        <TextBlock Text="Stretch" FontWeight="Bold" FontSize="12" />
        <Button Name="btn1" Click="stretchNone" Content="None" />
        <Button Name="btn2" Click="stretchFill" Content="Fill" />
        <Button Name="btn3" Click="stretchUni" Content="Uniform" />
        <Button Name="btn4" Click="stretchUniFill" Content="UniformToFill" />
    </StackPanel>

    <StackPanel Grid.Row="0" Grid.Column="1" Margin="5,5,5,5" Orientation="Vertical">
        <TextBlock Text="StretchDirection" FontWeight="Bold" FontSize="12" />
        <Button Name="btn5" Click="sdUpOnly" Content="UpOnly" />
        <Button Name="btn6" Click="sdDownOnly" Content="DownOnly" />
        <Button Name="btn7" Click="sdBoth" Content="Both" />
    </StackPanel>

    <StackPanel Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="2" Margin="5,5,5,5" Orientation="Vertical">
        <TextBlock Name="txt1" FontSize="12" FontWeight="Bold" />
        <TextBlock Name="txt2" FontSize="12" FontWeight="Bold" />
    </StackPanel>   

    <StackPanel Grid.Row="2" Grid.Column="0" Grid.ColumnSpan="2" Margin="5,5,5,5" Orientation="Horizontal">
        <Viewbox MaxWidth="100" MaxHeight="100" Name="vb1">
            <Image Source="flower.jpg"/>
        </controls:Viewbox>
        <controls:Viewbox MaxWidth="200" MaxHeight="200" Name="vb2">
            <Image Source="flower.jpg"/>
        </Viewbox>

        <Viewbox MaxWidth="300" MaxHeight="300" Name="vb3">
            <Image Source="flower.jpg"/>
        </Viewbox>
    </StackPanel>

</Grid>

The following shows the code for the button click handlers.

'Setting the Stretch property to None
Private Sub stretchNone(ByVal sender As Object, ByVal e As RoutedEventArgs)
    vb1.Stretch = Stretch.None
    vb2.Stretch = Stretch.None
    vb3.Stretch = Stretch.None
    txt1.Text = "Stretch is now set to None."
End Sub

'Setting the Stretch property to Fill
Private Sub stretchFill(ByVal sender As Object, ByVal e As RoutedEventArgs)
    vb1.Stretch = Stretch.Fill
    vb2.Stretch = Stretch.Fill
    vb3.Stretch = Stretch.Fill
    txt1.Text = "Stretch is now set to Fill."
End Sub

'Setting the Stretch property to Uniform
Private Sub stretchUni(ByVal sender As Object, ByVal e As RoutedEventArgs)
    vb1.Stretch = Stretch.Uniform
    vb2.Stretch = Stretch.Uniform
    vb3.Stretch = Stretch.Uniform
    txt1.Text = "Stretch is now set to Uniform."
End Sub

'Setting the Stretch property to UniformToFill
Private Sub stretchUniFill(ByVal sender As Object, ByVal e As RoutedEventArgs)
    vb1.Stretch = Stretch.UniformToFill
    vb2.Stretch = Stretch.UniformToFill
    vb3.Stretch = Stretch.UniformToFill
    txt1.Text = "Stretch is now set to UniformToFill."
End Sub

'Setting the StretchDirection property to UpOnly
Private Sub sdUpOnly(ByVal sender As Object, ByVal e As RoutedEventArgs)
    vb1.StretchDirection = StretchDirection.UpOnly
    vb2.StretchDirection = StretchDirection.UpOnly
    vb3.StretchDirection = StretchDirection.UpOnly
    txt2.Text = "StretchDirection is now UpOnly."
End Sub

'Setting the StretchDirection property to DownOnly
Private Sub sdDownOnly(ByVal sender As Object, ByVal e As RoutedEventArgs)
    vb1.StretchDirection = StretchDirection.DownOnly
    vb2.StretchDirection = StretchDirection.DownOnly
    vb3.StretchDirection = StretchDirection.DownOnly
    txt2.Text = "StretchDirection is now DownOnly."
End Sub

'Setting the StretchDirection property to Both
Private Sub sdBoth(ByVal sender As Object, ByVal e As RoutedEventArgs)
    vb1.StretchDirection = StretchDirection.Both
    vb2.StretchDirection = StretchDirection.Both
    vb3.StretchDirection = StretchDirection.Both
    txt2.Text = "StretchDirection is now Both."
End Sub

//Setting the Stretch property to None
private void stretchNone(object sender, RoutedEventArgs e)
{
    vb1.Stretch = Stretch.None;
    vb2.Stretch = Stretch.None;
    vb3.Stretch = Stretch.None;
    txt1.Text = "Stretch is now set to None.";
}

//Setting the Stretch property to Fill
private void stretchFill(object sender, RoutedEventArgs e)
{
    vb1.Stretch = Stretch.Fill;
    vb2.Stretch = Stretch.Fill;
    vb3.Stretch = Stretch.Fill;
    txt1.Text = "Stretch is now set to Fill.";
}

//Setting the Stretch property to Uniform
private void stretchUni(object sender, RoutedEventArgs e)
{
    vb1.Stretch = Stretch.Uniform;
    vb2.Stretch = Stretch.Uniform;
    vb3.Stretch = Stretch.Uniform;
    txt1.Text = "Stretch is now set to Uniform.";
}

//Setting the Stretch property to UniformToFill
private void stretchUniFill(object sender, RoutedEventArgs e)
{
    vb1.Stretch = Stretch.UniformToFill;
    vb2.Stretch = Stretch.UniformToFill;
    vb3.Stretch = Stretch.UniformToFill;
    txt1.Text = "Stretch is now set to UniformToFill.";
}

//Setting the StretchDirection property to UpOnly
private void sdUpOnly(object sender, RoutedEventArgs e)
{
    vb1.StretchDirection = StretchDirection.UpOnly;
    vb2.StretchDirection = StretchDirection.UpOnly;
    vb3.StretchDirection = StretchDirection.UpOnly;
    txt2.Text = "StretchDirection is now UpOnly.";
}

//Setting the StretchDirection property to DownOnly
private void sdDownOnly(object sender, RoutedEventArgs e)
{
    vb1.StretchDirection = StretchDirection.DownOnly;
    vb2.StretchDirection = StretchDirection.DownOnly;
    vb3.StretchDirection = StretchDirection.DownOnly;
    txt2.Text = "StretchDirection is now DownOnly.";
}

//Setting the StretchDirection property to Both
private void sdBoth(object sender, RoutedEventArgs e)
{
    vb1.StretchDirection = StretchDirection.Both;
    vb2.StretchDirection = StretchDirection.Both;
    vb3.StretchDirection = StretchDirection.Both;
    txt2.Text = "StretchDirection is now Both.";
}

Version Information

Silverlight

Supported in: 5, 4

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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