DescriptionViewer Class

Displays a description and tracks error state for an associated control.

Inheritance Hierarchy

System.Object
  System.Windows.DependencyObject
    System.Windows.UIElement
      System.Windows.FrameworkElement
        System.Windows.Controls.Control
          System.Windows.Controls.DescriptionViewer

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

Syntax

'Declaration
<TemplateVisualStateAttribute(Name := "InvalidFocused", GroupName := "ValidationStates")> _
<TemplateVisualStateAttribute(Name := "InvalidUnfocused", GroupName := "ValidationStates")> _
<TemplateVisualStateAttribute(Name := "Disabled", GroupName := "CommonStates")> _
<TemplateVisualStateAttribute(Name := "ValidUnfocused", GroupName := "ValidationStates")> _
<TemplateVisualStateAttribute(Name := "NoDescription", GroupName := "DescriptionStates")> _
<TemplateVisualStateAttribute(Name := "HasDescription", GroupName := "DescriptionStates")> _
<TemplateVisualStateAttribute(Name := "ValidFocused", GroupName := "ValidationStates")> _
<TemplateVisualStateAttribute(Name := "Normal", GroupName := "CommonStates")> _
<StyleTypedPropertyAttribute(Property := "ToolTipStyle", StyleTargetType := GetType(ToolTip))> _
Public Class DescriptionViewer _
    Inherits Control
[TemplateVisualStateAttribute(Name = "InvalidFocused", GroupName = "ValidationStates")]
[TemplateVisualStateAttribute(Name = "InvalidUnfocused", GroupName = "ValidationStates")]
[TemplateVisualStateAttribute(Name = "Disabled", GroupName = "CommonStates")]
[TemplateVisualStateAttribute(Name = "ValidUnfocused", GroupName = "ValidationStates")]
[TemplateVisualStateAttribute(Name = "NoDescription", GroupName = "DescriptionStates")]
[TemplateVisualStateAttribute(Name = "HasDescription", GroupName = "DescriptionStates")]
[TemplateVisualStateAttribute(Name = "ValidFocused", GroupName = "ValidationStates")]
[TemplateVisualStateAttribute(Name = "Normal", GroupName = "CommonStates")]
[StyleTypedPropertyAttribute(Property = "ToolTipStyle", StyleTargetType = typeof(ToolTip))]
public class DescriptionViewer : Control
<sdk:DescriptionViewer .../>

The DescriptionViewer type exposes the following members.

Constructors

  Name Description
Public method DescriptionViewer Initializes a new instance of the DescriptionViewer class.

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Properties

  Name Description
Public property ActualHeight Gets the rendered height of a FrameworkElement. (Inherited from FrameworkElement.)
Public property ActualWidth Gets the rendered width of a FrameworkElement. (Inherited from FrameworkElement.)
Public property 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.)
Public property Background Gets or sets a brush that provides the background of the control. (Inherited from Control.)
Public property BorderBrush Gets or sets a brush that describes the border background of a control. (Inherited from Control.)
Public property BorderThickness Gets or sets the border thickness of a control. (Inherited from Control.)
Public property CacheMode Gets or sets a value that indicates that rendered content should be cached when possible. (Inherited from UIElement.)
Public property CharacterSpacing Gets or sets the distance between characters of text in the control measured in 1000ths of the font size. (Inherited from Control.)
Public property Clip Gets or sets the Geometry used to define the outline of the contents of a UIElement. (Inherited from UIElement.)
Public property Cursor Gets or sets the cursor image that displays while the mouse pointer is over a FrameworkElement. (Inherited from FrameworkElement.)
Public property DataContext Gets or sets the data context for a FrameworkElement when it participates in data binding. (Inherited from FrameworkElement.)
Protected property DefaultStyleKey Gets or sets the key that references the default style for the control. (Inherited from Control.)
Public property Description Gets or sets the description text displayed by the viewer.
Public property DesiredSize Gets the size that this UIElement computed during the measure pass of the layout process. (Inherited from UIElement.)
Public property Dispatcher Gets the Dispatcher this object is associated with. (Inherited from DependencyObject.)
Public property Effect Gets or sets the pixel shader effect to use for rendering this UIElement. (Inherited from UIElement.)
Public property 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.)
Public property FontFamily Gets or sets the font used to display text in the control. (Inherited from Control.)
Public property FontSize Gets or sets the size of the text in this control. (Inherited from Control.)
Public property FontStretch Gets or sets the degree to which a font is condensed or expanded on the screen. (Inherited from Control.)
Public property FontStyle Gets or sets the style in which the text is rendered. (Inherited from Control.)
Public property FontWeight Gets or sets the thickness of the specified font. (Inherited from Control.)
Public property Foreground Gets or sets a brush that describes the foreground color. (Inherited from Control.)
Public property GlyphTemplate Gets or sets the template that is used to display the description viewer glyph.
Public property Height Gets or sets the suggested height of a FrameworkElement. (Inherited from FrameworkElement.)
Public property 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.)
Public property HorizontalContentAlignment Gets or sets the horizontal alignment of the control's content. (Inherited from Control.)
Public property IsEnabled Gets or sets a value indicating whether the user can interact with the control. (Inherited from Control.)
Protected property IsFocused Gets a value that indicates whether the control that is the Target of the DescriptionViewer has focus.
Public property IsHitTestVisible Gets or sets whether the contained area of this UIElement can return true values for hit testing. (Inherited from UIElement.)
Public property IsTabStop Gets or sets a value that indicates whether a control is included in tab navigation. (Inherited from Control.)
Public property IsValid Gets a value that indicates whether the Target field data is valid.
Public property Language Gets or sets localization/globalization language information that applies to a FrameworkElement. (Inherited from FrameworkElement.)
Public property Margin Gets or sets the outer margin of a FrameworkElement. (Inherited from FrameworkElement.)
Public property MaxHeight Gets or sets the maximum height constraint of a FrameworkElement. (Inherited from FrameworkElement.)
Public property MaxWidth Gets or sets the maximum width constraint of a FrameworkElement. (Inherited from FrameworkElement.)
Public property MinHeight Gets or sets the minimum height constraint of a FrameworkElement. (Inherited from FrameworkElement.)
Public property MinWidth Gets or sets the minimum width constraint of a FrameworkElement. (Inherited from FrameworkElement.)
Public property 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.)
Public property Opacity Gets or sets the degree of the object's opacity. (Inherited from UIElement.)
Public property OpacityMask Gets or sets the brush used to alter the opacity of regions of this object. (Inherited from UIElement.)
Public property Padding Gets or sets the padding inside a control. (Inherited from Control.)
Public property Parent Gets the parent object of this FrameworkElement in the object tree. (Inherited from FrameworkElement.)
Public property Projection Gets or sets the perspective projection (3-D effect) to apply when rendering this UIElement. (Inherited from UIElement.)
Public property PropertyPath Gets or sets the path to the dependency property on the DataContext of the Target control that this DescriptionViewer is associated with.
Public property RenderSize Gets the final render size of a UIElement. (Inherited from UIElement.)
Public property RenderTransform Gets or sets transform information that affects the rendering position of a UIElement. (Inherited from UIElement.)
Public property 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.)
Public property 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.)
Public property Style Gets or sets an instance Style that is applied for this object during rendering. (Inherited from FrameworkElement.)
Public property TabIndex Gets or sets a value that determines the order in which elements receive focus when the user navigates through controls by using the TAB key. (Inherited from Control.)
Public property TabNavigation Gets or sets a value that modifies how tabbing and TabIndex work for this control. (Inherited from Control.)
Public property Tag Gets or sets an arbitrary object value that can be used to store custom information about this object. (Inherited from FrameworkElement.)
Public property Target Gets or sets the control that this DescriptionViewer is associated with.
Public property Template Gets or sets a control template. (Inherited from Control.)
Public property ToolTipStyle Gets or sets the style used to display tooltips.
Public property Triggers Gets the collection of triggers for animations that are defined for a FrameworkElement. (Inherited from FrameworkElement.)
Public property 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.)
Public property 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.)
Public property VerticalContentAlignment Gets or sets the vertical alignment of the control's content. (Inherited from Control.)
Public property 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.)
Public property Width Gets or sets the width of a FrameworkElement. (Inherited from FrameworkElement.)

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Methods

  Name Description
Public method 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.)
Public method ApplyTemplate Loads the relevant control template so that its parts can be referenced. (Inherited from Control.)
Public method 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.)
Protected method 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.)
Public method CaptureMouse Sets mouse capture to a UIElement. (Inherited from UIElement.)
Public method CheckAccess Determines whether the calling thread has access to this object. (Inherited from DependencyObject.)
Public method ClearValue Clears the local value of a dependency property. (Inherited from DependencyObject.)
Public method Equals(Object) Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected method 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.)
Public method FindName Retrieves an object that has the specified identifier name. (Inherited from FrameworkElement.)
Public method Focus Attempts to set the focus on the control. (Inherited from Control.)
Public method 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.)
Public method GetBindingExpression Retrieves the BindingExpression for a dependency property where a binding is established. (Inherited from FrameworkElement.)
Public method GetHashCode Serves as a hash function for a particular type. (Inherited from Object.)
Protected method GetTemplateChild Retrieves the named element in the instantiated ControlTemplate visual tree. (Inherited from Control.)
Public method GetType Gets the Type of the current instance. (Inherited from Object.)
Public method GetValue Returns the current effective value of a dependency property from a DependencyObject. (Inherited from DependencyObject.)
Public method 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.)
Public method InvalidateMeasure Invalidates the measurement state (layout) for a UIElement. (Inherited from UIElement.)
Public method 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.)
Protected method 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.)
Protected method MemberwiseClone Creates a shallow copy of the current Object. (Inherited from Object.)
Public method OnApplyTemplate Builds the visual tree for the DescriptionViewer control when a new template is applied. (Overrides FrameworkElement.OnApplyTemplate().)
Protected method OnCreateAutomationPeer Returns a DescriptionViewerAutomationPeer for use by the Silverlight automation infrastructure. (Overrides UIElement.OnCreateAutomationPeer().)
Protected method OnDragEnter Called before the DragEnter event occurs. (Inherited from Control.)
Protected method OnDragLeave Called before the DragLeave event occurs. (Inherited from Control.)
Protected method OnDragOver Called before the DragOver event occurs. (Inherited from Control.)
Protected method OnDrop Called before the Drop event occurs. (Inherited from Control.)
Protected method OnGotFocus Called before the GotFocus event occurs. (Inherited from Control.)
Protected method OnKeyDown Called before the KeyDown event occurs. (Inherited from Control.)
Protected method OnKeyUp Called before the KeyUp event occurs. (Inherited from Control.)
Protected method OnLostFocus Called before the LostFocus event occurs. (Inherited from Control.)
Protected method OnLostMouseCapture Called before the LostMouseCapture event occurs to provide handling for the event in a derived class without attaching a delegate. (Inherited from Control.)
Protected method OnMouseEnter Called before the MouseEnter event occurs. (Inherited from Control.)
Protected method OnMouseLeave Called before the MouseLeave event occurs. (Inherited from Control.)
Protected method OnMouseLeftButtonDown Called before the MouseLeftButtonDown event occurs. (Inherited from Control.)
Protected method OnMouseLeftButtonUp Called before the MouseLeftButtonUp event occurs. (Inherited from Control.)
Protected method OnMouseMove Called before the MouseMove event occurs. (Inherited from Control.)
Protected method OnMouseRightButtonDown Called before the MouseRightButtonDown event occurs. (Inherited from Control.)
Protected method OnMouseRightButtonUp Called before the MouseRightButtonUp event occurs. (Inherited from Control.)
Protected method OnMouseWheel Called before the MouseWheel event occurs to provide handling for the event in a derived class without attaching a delegate. (Inherited from Control.)
Protected method OnTextInput Called before the TextInput event occurs. (Inherited from Control.)
Protected method OnTextInputStart Called before the TextInputStart event occurs. (Inherited from Control.)
Protected method OnTextInputUpdate Called before the TextInputUpdate event occurs. (Inherited from Control.)
Public method ReadLocalValue Returns the local value of a dependency property, if a local value is set. (Inherited from DependencyObject.)
Public method Refresh Reloads the metadata from the Target element.
Public method ReleaseMouseCapture Removes mouse capture from a UIElement. After this call, typically no object holds mouse capture. (Inherited from UIElement.)
Public method RemoveHandler Removes the specified routed event handler from this UIElement. (Inherited from UIElement.)
Public method SetBinding Attaches a binding to a FrameworkElement, using the provided binding object, and returns a BindingExpressionBase for possible later use. (Inherited from FrameworkElement.)
Public method SetValue Sets the local value of a dependency property on a DependencyObject. (Inherited from DependencyObject.)
Public method ToString Returns a string that represents the current object. (Inherited from Object.)
Public method TransformToVisual Returns a transform object that can be used to transform coordinates from the UIElement to the specified object. (Inherited from UIElement.)
Public method 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
Public event BindingValidationError Occurs when a data validation error is reported by a binding source. (Inherited from FrameworkElement.)
Public event DataContextChanged Occurs when the data context for this element changes. (Inherited from FrameworkElement.)
Public event DragEnter Occurs when the input system reports an underlying drag event with this element as the target. (Inherited from UIElement.)
Public event DragLeave Occurs when the input system reports an underlying drag event with this element as the origin. (Inherited from UIElement.)
Public event DragOver Occurs when the input system reports an underlying drag event with this element as the potential drop target. (Inherited from UIElement.)
Public event Drop Occurs when the input system reports an underlying drop event with this element as the drop target. (Inherited from UIElement.)
Public event GotFocus Occurs when a UIElement receives focus. (Inherited from UIElement.)
Public event IsEnabledChanged Occurs when the IsEnabled property changes. (Inherited from Control.)
Public event KeyDown Occurs when a keyboard key is pressed while the UIElement has focus. (Inherited from UIElement.)
Public event KeyUp Occurs when a keyboard key is released while the UIElement has focus. (Inherited from UIElement.)
Public event LayoutUpdated Occurs when the layout of the Silverlight visual tree changes. (Inherited from FrameworkElement.)
Public event Loaded Occurs when a FrameworkElement has been constructed and added to the object tree. (Inherited from FrameworkElement.)
Public event LostFocus Occurs when a UIElement loses focus. (Inherited from UIElement.)
Public event LostMouseCapture Occurs when the UIElement loses mouse capture. (Inherited from UIElement.)
Public event MediaCommand Occurs when a button is pressed on a remote control. (Inherited from UIElement.)
Public event MouseEnter Occurs when the mouse (or a stylus) enters the bounding area of a UIElement. (Inherited from UIElement.)
Public event MouseLeave Occurs when the mouse (or the stylus) leaves the bounding area of a UIElement. (Inherited from UIElement.)
Public event 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.)
Public event 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.)
Public event 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.)
Public event MouseRightButtonDown Occurs when the right mouse button is pressed while the mouse pointer is over a UIElement. (Inherited from UIElement.)
Public event 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.)
Public event 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.)
Public event SizeChanged Occurs when either the ActualHeight or the ActualWidth properties change value on a FrameworkElement. (Inherited from FrameworkElement.)
Public event TextInput Occurs when a UI element gets text in a device-independent manner. (Inherited from UIElement.)
Public event TextInputStart Occurs when a UI element initially gets text in a device-independent manner. (Inherited from UIElement.)
Public event TextInputUpdate Occurs when text continues to be composed via an input method editor (IME). (Inherited from UIElement.)
Public event Unloaded Occurs when this object is no longer connected to the main object tree. (Inherited from FrameworkElement.)

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Fields

  Name Description
Public fieldStatic member DescriptionProperty Identifies the Description dependency property.
Public fieldStatic member GlyphTemplateProperty Identifies the GlyphTemplate dependency property.
Public fieldStatic member IsFocusedProperty Identifies the IsFocused dependency property.
Public fieldStatic member IsValidProperty Identifies the IsValid dependency property.
Public fieldStatic member PropertyPathProperty Identifies the PropertyPath dependency property.
Public fieldStatic member TargetProperty Identifies the Target dependency property.
Public fieldStatic member ToolTipStyleProperty Identifies the ToolTipStyle dependency property.

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Remarks

A DescriptionViewer control displays an information glyph and shows a text description in a tooltip when the mouse pointer is over the glyph. It also tracks validation error states so that you can implement a custom error display. It can be used to display a description by itself or be associated with another control.

The following illustration shows a Label, a DatePicker, and an associated DescriptionViewer with its tooltip shown.

DescriptionViewer Control

Description Viewer control

To associate a DescriptionViewer with another control, you set the Target property of the DescriptionViewer. The Target is a reference to a UIElement. You can set the Target in code or through an ElementName binding in XAML.

When the Target property is set, a DescriptionViewer inspects each DependencyProperty on the Target control for a Binding. For each Binding that is found, it inspects the Source of the Binding for metadata. The metadata can be used to set the Description text and to specify validation rules. If the Target control has more than one Binding, you can specify the one to retrieve metadata from by setting the PropertyPath property.

You use the Description property to set the text of a DescriptionViewer. If the property associated with the DescriptionViewer has a DisplayAttribute and the DisplayAttribute.Description property is not nulla null reference (Nothing in Visual Basic) or an empty string, the DescriptionViewer.Description will be set to the value of the DisplayAttribute.Description property. For more information, see Using Data Annotations to Customize Data Classes.

By default, the DescriptionViewer control does not display validation errors. However, it does provide the IsValid property for tracking validation states. You can implement the validation states in the control template to display a custom user interface for validation errors. When the Target property is set, a DescriptionViewer responds to the BindingValidationError event for the Target control. It changes to its Invalid visual state when an error occurs, and to its Valid visual state when the error is resolved. In order to receive error notifications, you must set the ValidatesOnExceptions and NotifyOnValidationError properties on the Target controls Binding to true.

NoteNote:

The DescriptionViewer control is available as part of the libraries in the Silverlight Software Development Kit (SDK). For more information, see the Silverlight Tools.

Customizing the DescriptionViewer Control

To apply the same property settings to multiple DescriptionViewer controls, use the Style property. To change the visual structure and visual behavior of a DescriptionViewer, copy and modify its default style and template. For more information, see Control Customization.

Dependency properties for this control might be set by the default style of the control. If a dependency property for a DescriptionViewer is set by its default style, the property might change from its default value when the DescriptionViewer appears in the application. For more information, see Dependency Property Value Precedence. You can get the default style and template for DescriptionViewer from DescriptionViewer Styles and Templates.

NoteNote:

Setting a visual property will only have an effect if that property is both present in DescriptionViewer control's default template and is set by using a TemplateBinding. You can find a list of visual properties in the "Changing the Visual Structure of a Control" section of Customizing the Appearance of an Existing Control by Using a ControlTemplate.

Examples

The following example demonstrates two DescriptionViewer controls on a form. The first DescriptionViewer is used unbound to describe a DatePicker control. The second DescriptionViewer is bound to a TextBox named tbIdNumber, which is bound to the IdNumber property of a Customer object. This example is part of a larger example available in the ValidationSummary class overview.

Run this sample

<!-- Unbound Date of Birth field -->
<sdk:Label Content="Date of Birth" IsRequired="True" Margin="5" />
<StackPanel Orientation="Horizontal" Grid.Column="1">
    <sdk:DatePicker Height="23" />
    <sdk:DescriptionViewer Description="Please enter your date of birth."/>
</StackPanel>

<!-- ID Number field -->
<sdk:Label Grid.Row="1" Margin="5" 
                 Target="{Binding ElementName=tbIdNumber}" />
<StackPanel Orientation="Horizontal" Grid.Column="1" Grid.Row="1">
    <TextBox x:Name="tbIdNumber" Height="23" Width="100"
             Text="{Binding IdNumber, Mode=TwoWay, 
                    ValidatesOnExceptions=true, NotifyOnValidationError=true}" />
    <sdk:DescriptionViewer Target="{Binding ElementName=tbIdNumber}"/>
</StackPanel>

Version Information

Silverlight

Supported in: 5, 4, 3

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.