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Canvas class

Defines an area within which you can explicitly position child objects, using coordinates that are relative to the Canvas area.

Inheritance

Object
DependencyObject
UIElement
FrameworkElement
Panel
Canvas

Syntax

C++


public class Canvas : Panel

XAML Object Element Usage


<Canvas ...>
  oneOrMoreUIElements
</Canvas>
-or-
<Canvas .../>

XAML Values

oneOrMoreUIElements: One or more object elements that derive from the UIElement class. Object elements defined here become members of the Children collection.

Attributes

MarshalingBehaviorAttribute(Agile)
StaticAttribute(Windows.UI.Xaml.Controls.ICanvasStatics, NTDDI_WIN8)
ThreadingAttribute(Both)
VersionAttribute(NTDDI_WIN8)
WebHostHiddenAttribute()

Members

The Canvas class has these types of members:

Constructors
Events
Methods
Attached Properties
Properties

Constructors

The Canvas class has these constructors.

Constructor	Description
Canvas	Initializes a new instance of the Canvas class.

Events

The Canvas class has these events.

Event	Description
DoubleTapped	Occurs when an otherwise unhandled DoubleTap interaction occurs over the hit test area of this element. (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)
Holding	Occurs when an otherwise unhandled Hold interaction occurs over the hit test area of this element. (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 visual tree changes. (Inherited from FrameworkElement)
Loaded	Occurs when a FrameworkElement has been constructed and added to the object tree, and is ready for interaction. (Inherited from FrameworkElement)
LostFocus	Occurs when a UIElement loses focus. (Inherited from UIElement)
ManipulationCompleted	Occurs when a manipulation on the UIElement is complete. (Inherited from UIElement)
ManipulationDelta	Occurs when the input device changes position during a manipulation. (Inherited from UIElement)
ManipulationInertiaStarting	Occurs when the input device loses contact with the UIElement object during a manipulation and inertia begins. (Inherited from UIElement)
ManipulationStarted	Occurs when an input device begins a manipulation on the UIElement. (Inherited from UIElement)
ManipulationStarting	Occurs when the manipulation processor is first created. (Inherited from UIElement)
PointerCanceled	Occurs when a pointer that made contact abnormally loses contact. (Inherited from UIElement)
PointerCaptureLost	Occurs when pointer capture previously held by this element moves to another element or elsewhere. (Inherited from UIElement)
PointerEntered	Occurs when a pointer enters the hit test area of this element. (Inherited from UIElement)
PointerExited	Occurs when a pointer leaves the hit test area of this element. (Inherited from UIElement)
PointerMoved	Occurs when a pointer moves while the pointer remains within the hit test area of this element. (Inherited from UIElement)
PointerPressed	Occurs when the pointer device initiates a Press action within this element. (Inherited from UIElement)
PointerReleased	Occurs when the pointer device that previously initiated a Press action is released, while within this element. (Inherited from UIElement)
PointerWheelChanged	Occurs when the delta value of a pointer wheel changes. (Inherited from UIElement)
RightTapped	Occurs when a right-tap input stimulus happens while the pointer is over the element. (Inherited from UIElement)
SizeChanged	Occurs when either the ActualHeight or the ActualWidth property changes value on a FrameworkElement. (Inherited from FrameworkElement)
Tapped	Occurs when an otherwise unhandled Tap interaction occurs over the hit test area of this element. (Inherited from UIElement)
Unloaded	Occurs when this object is no longer connected to the main object tree. (Inherited from FrameworkElement)

Methods

The Canvas class has these methods. It also inherits methods from the Object class.

Method	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 even if the event is handled elsewhere. (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 layout. Classes can override this method to define their own Arrange pass behavior. (Inherited from FrameworkElement)
CapturePointer	Sets pointer capture to a UIElement. Once captured, only the element that has capture will fire pointer-related events. (Inherited from UIElement)
ClearValue	Clears the local value of a dependency property. (Inherited from DependencyObject)
FindName	Retrieves an object that has the specified identifier name. (Inherited from FrameworkElement)
FindSubElementsForTouchTargeting	Enables a UIElement subclass to expose child elements that assist with resolving touch targeting. (Inherited from UIElement)
GetAnimationBaseValue	Returns any base value established for a dependency property, which would apply in cases where an animation is not active. (Inherited from DependencyObject)
GetLeft	Gets the value of the Canvas.Left XAML attached property for the target element.
GetTop	Gets the value of the Canvas.Top XAML attached property for the target element.
GetValue	Returns the current effective value of a dependency property from a DependencyObject. (Inherited from DependencyObject)
GetZIndex	Gets the value of the Canvas.ZIndex XAML attached property for the target element.
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 the layout cycle. Classes can override this method to define their own Measure pass behavior. (Inherited from FrameworkElement)
OnApplyTemplate	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 your app. Override this method to influence the default post-template logic of a class. (Inherited from FrameworkElement)
OnCreateAutomationPeer	When implemented in a derived class, returns class-specific AutomationPeer implementations for the Microsoft UI Automation infrastructure. (Inherited from UIElement)
OnDisconnectVisualChildren	Override this method to implement how layout and logic should behave when items are removed from a class-specific content or children property. (Inherited from UIElement)
ReadLocalValue	Returns the local value of a dependency property, if a local value is set. (Inherited from DependencyObject)
ReleasePointerCapture	Releases pointer captures for capture of one specific pointer by this UIElement. (Inherited from UIElement)
ReleasePointerCaptures	Releases all pointer captures held by this element. (Inherited from UIElement)
RemoveHandler	Removes the specified routed event handler from this UIElement. Typically the handler in question was added by AddHandler. (Inherited from UIElement)
SetBinding	Attaches a binding to a FrameworkElement, using the provided binding object. (Inherited from FrameworkElement)
SetLeft	Sets the value of the Canvas.Left XAML attached property for a target element.
SetTop	Sets the value of the Canvas.Top XAML attached property for a target element.
SetValue	Sets the local value of a dependency property on a DependencyObject. (Inherited from DependencyObject)
SetZIndex	Sets the value of the Canvas.ZIndex XAML attached property for a target element.
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)

Attached Properties

The Canvas class has these attached properties.

	Access type	Description
Canvas.Left	Read/write	Gets or sets the distance between the left side of an object and the left side of its parent Canvas.
Canvas.Top	Read/write	Gets or sets the distance between the top of an element and the top of its parent Canvas.
Canvas.ZIndex	Read/write	Gets or sets the Z-order of an element when that element is presented in its parent Canvas layout container.

Properties

The Canvas class has these properties.

Property	Access type	Description
ActualHeight	Read-only	Gets the rendered height of a FrameworkElement. (Inherited from FrameworkElement)
ActualWidth	Read-only	Gets the rendered width of a FrameworkElement. (Inherited from FrameworkElement)
AllowDrop	Read/write	Gets or sets a value that determines whether this UIElement can be a drop target for purposes of drag-and-drop operations. (Inherited from UIElement)
Background	Read/write	Gets or sets a Brush that is used to fill the panel. (Inherited from Panel)
BaseUri	Read-only	Gets a Uniform Resource Identifier (URI) that represents the base Uniform Resource Identifier (URI) for an XAML-constructed object at XAML load time. This property is useful for Uniform Resource Identifier (URI) resolution at run time. (Inherited from FrameworkElement)
CacheMode	Read/write	Gets or sets a value that indicates that rendered content should be cached as a composited bitmap when possible. (Inherited from UIElement)
Children	Read-only	Gets the collection of child elements of the panel. (Inherited from Panel)
ChildrenTransitions	Read/write	Gets or sets the collection of Transition style elements that apply to child content of a Panel subclass. (Inherited from Panel)
Clip	Read/write	Gets or sets the RectangleGeometry used to define the outline of the contents of a UIElement. (Inherited from UIElement)
DataContext	Read/write	Gets or sets the data context for a FrameworkElement when it participates in data binding. (Inherited from FrameworkElement)
DesiredSize	Read-only	Gets the size that this UIElement computed during the measure pass of the layout process. (Inherited from UIElement)
Dispatcher	Read-only	Gets the CoreDispatcher that this object is associated with. (Inherited from DependencyObject)
FlowDirection	Read/write	Gets or sets the direction in which text and other UI elements flow within any parent element that controls their layout. This property can be set to either LeftToRight or RightToLeft. Setting FlowDirection to RightToLeft on any element sets the alignment to the right, the reading order to right-to-left and the layout of the control to flow from right to left. (Inherited from FrameworkElement)
Height	Read/write	Gets or sets the suggested height of a FrameworkElement. (Inherited from FrameworkElement)
HorizontalAlignment	Read/write	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)
IsDoubleTapEnabled	Read/write	Gets or sets a value that determines whether the DoubleTapped event can originate from that element. (Inherited from UIElement)
IsHitTestVisible	Read/write	Gets or sets whether the contained area of this UIElement can return true values for hit testing. (Inherited from UIElement)
IsHoldingEnabled	Read/write	Gets or sets a value that determines whether the Holding event can originate from that element. (Inherited from UIElement)
IsItemsHost	Read-only	Gets a value that indicates whether this Panel is a container for UI items that are generated by an ItemsControl. (Inherited from Panel)
IsRightTapEnabled	Read/write	Gets or sets a value that determines whether the RightTapped event can originate from that element. (Inherited from UIElement)
IsTapEnabled	Read/write	Gets or sets a value that determines whether the Tapped event can originate from that element. (Inherited from UIElement)
Language	Read/write	Gets or sets localization/globalization language information that applies to a FrameworkElement, and also to all child elements of the current FrameworkElement in the object representation and in UI. (Inherited from FrameworkElement)
LeftProperty	Read-only	Identifies the Canvas.Left XAML attached property.
ManipulationMode	Read/write	Gets or sets the ManipulationModes value used for UIElement behavior and interaction with gestures. (Inherited from UIElement)
Margin	Read/write	Gets or sets the outer margin of a FrameworkElement. (Inherited from FrameworkElement)
MaxHeight	Read/write	Gets or sets the maximum height constraint of a FrameworkElement. (Inherited from FrameworkElement)
MaxWidth	Read/write	Gets or sets the maximum width constraint of a FrameworkElement. (Inherited from FrameworkElement)
MinHeight	Read/write	Gets or sets the minimum height constraint of a FrameworkElement. (Inherited from FrameworkElement)
MinWidth	Read/write	Gets or sets the minimum width constraint of a FrameworkElement. (Inherited from FrameworkElement)
Name	Read/write	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	Read/write	Gets or sets the degree of the object's opacity. (Inherited from UIElement)
Parent	Read-only	Gets the parent object of this FrameworkElement in the object tree. (Inherited from FrameworkElement)
PointerCaptures	Read-only	Gets the set of all captured pointers, represented as Pointer values. (Inherited from UIElement)
Projection	Read/write	Gets or sets the perspective projection (3-D effect) to apply when rendering this element. (Inherited from UIElement)
RenderSize	Read-only	Gets the final render size of a UIElement. (Inherited from UIElement)
RenderTransform	Read/write	Gets or sets transform information that affects the rendering position of a UIElement. (Inherited from UIElement)
RenderTransformOrigin	Read/write	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	Read/write	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)
Style	Read/write	Gets or sets an instance Style that is applied for this object during layout and rendering. (Inherited from FrameworkElement)
Tag	Read/write	Gets or sets an arbitrary object value that can be used to store custom information about this object. (Inherited from FrameworkElement)
TopProperty	Read-only	Identifies the Canvas.Top XAML attached property.
Transitions	Read/write	Gets or sets the collection of Transition style elements that apply to a UIElement. (Inherited from UIElement)
Triggers	Read-only	Gets the collection of triggers for animations that are defined for a FrameworkElement. Not commonly used. (Inherited from FrameworkElement)
UseLayoutRounding	Read/write	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	Read/write	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	Read/write	Gets or sets the visibility of a UIElement. A UIElement that is not visible is not rendered and does not communicate its desired size to layout. (Inherited from UIElement)
Width	Read/write	Gets or sets the width of a FrameworkElement. (Inherited from FrameworkElement)
ZIndexProperty	Read-only	Identifies the Canvas.ZIndex XAML attached property.

Remarks

A Canvas is one of the Panel elements that enable layout. Canvas uses absolute positioning as its layout technique for its contained child elements. Each child element is rendered within the Canvas area. You control the positioning of elements inside the Canvas by specifying x and y coordinates. These coordinates are in pixels. The x and y coordinates are often specified by using the Canvas.Left and Canvas.Top attached properties. Canvas.Left specifies the object's distance from the left side of the containing Canvas (the x-coordinate), and Canvas.Top specifies the object's distance from the top of the containing Canvas (the y-coordinate).

Caution Because absolute positioning does not take into account the size of the app window, scaling, or other user-selected sizing, using an adaptive layout from Grid or StackPanel as a container is often a better choice than using Canvas. For more information, see Quickstart: Defining layouts.

You can nest Canvas objects. When you nest objects, the coordinates used by each object are relative to its immediate containing Canvas.

Each child object of a Canvas must be a UIElement. In XAML, you declare child objects as content of a Canvas object element. In code, you can manipulate the collection of Canvas child objects by getting the collection that is accessed by the Children property.

In many cases, a Canvas is used solely as a container for other objects and does not have any visible properties. A Canvas and its children (if any) are not visible if any of these conditions are true:

Its Height or Width property are set as 0.
The Visibility property is set to Collapsed.

The children of a Canvas (if any) are still visible even if the Canvas has any of these conditions:

The Background property of the Canvas is null.
The Opacity property of the Canvas is 0.

A Canvas with no children and with a default Height and Width of Auto doesn't have dimensions. This is also the case if the Canvas has children but all the children have Visibility of Collapsed, or zero Height or Width.

Canvas XAML attached properties

Canvas is the host service class for several XAML attached properties. The purpose of these attached properties is to enable child elements in layout to report how they should be positioned in a Canvas parent.

These XAML attached properties are supported by Canvas:

In order to support XAML processor access to the attached properties, and also to expose equivalent get and set operations to code, each XAML attached property has a pair of Get and Set accessor methods. For example, the GetLeft and SetLeft methods support and provide the equivalent code-only support for Canvas.Left. Alternatively, you can use the dependency property system to get or set the value of the attached property. Call GetValue or SetValue, passing the arguments of the dependency property identifier to set, and a reference to the target object on which to get or set the value.

Examples

This example shows how to position a rectangle 30 pixels from the left and 30 pixels from the top of a Canvas.

XAML


<Canvas Width="640" Height="480" >
    <Rectangle Canvas.Left="30" Canvas.Top="30" 
       Fill="Red" Width="200" Height="200" />
</Canvas>

Requirements

Minimum supported client	Windows 8 [Windows Store apps only]
Minimum supported server	Windows Server 2012 [Windows Store apps only]
Namespace	Windows.UI.Xaml.Controls Windows::UI::Xaml::Controls [C++]
Metadata	Windows.winmd