Canvas class

Applies to Windows and Windows Phone

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


Public Class Canvas
    Inherits Panel


<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

[MarshalingBehavior(Agile)]
[Threading(Both)]
[Version(0x06020000)]
[WebHostHidden()]

Members

The Canvas class has these types of members:

Constructors

The Canvas class has these constructors.

ConstructorDescription
Canvas Initializes a new instance of the Canvas class.

 

Events

The Canvas class has these events.

EventDescription
DataContextChanged Occurs when the value of the FrameworkElement.DataContext property changes. (Inherited from FrameworkElement)
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, due to layout-relevant properties changing value or some other action that refreshes the layout. (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.

MethodDescription
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)
CancelDirectManipulations Cancels ongoing direct manipulation processing (system-defined panning/zooming) on any ScrollViewer parent that contains the current UIElement. (Inherited from UIElement)
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)
GetBindingExpression Returns the BindingExpression that represents the binding on the specified property. (Inherited from FrameworkElement)
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.
GoToElementStateCore When implemented in a derived class, enables per-state construction of a visual tree for a control template in code, rather than by loading XAML for all states at control startup. (Inherited from FrameworkElement)
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 typeDescription

Canvas.Left

Read/writeGets or sets the distance between the left side of an object and the left side of its parent Canvas.

Canvas.Top

Read/writeGets or sets the distance between the top of an element and the top of its parent Canvas.

Canvas.ZIndex

Read/writeGets 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.

PropertyAccess typeDescription

ActualHeight

Read-onlyGets the rendered height of a FrameworkElement. (Inherited from FrameworkElement)

ActualWidth

Read-onlyGets the rendered width of a FrameworkElement. (Inherited from FrameworkElement)

AllowDrop

Read/writeGets 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/writeGets or sets a Brush that fills the panel content area. (Inherited from Panel)

BaseUri

Read-onlyGets 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/writeGets or sets a value that indicates that rendered content should be cached as a composited bitmap when possible. (Inherited from UIElement)

Children

Read-onlyGets the collection of child elements of the panel. (Inherited from Panel)

ChildrenTransitions

Read/writeGets or sets the collection of Transition style elements that apply to child content of a Panel subclass. (Inherited from Panel)

Clip

Read/writeGets or sets the RectangleGeometry used to define the outline of the contents of a UIElement. (Inherited from UIElement)

CompositeMode

Read/writeGets or sets a property that declares alternate composition and blending modes for the element in its parent layout and window. This is relevant for elements that are involved in a mixed XAML / Microsoft DirectX UI. (Inherited from UIElement)

DataContext

Read/writeGets or sets the data context for a FrameworkElement when it participates in data binding. (Inherited from FrameworkElement)

DesiredSize

Read-onlyGets the size that this UIElement computed during the measure pass of the layout process. (Inherited from UIElement)

Dispatcher

Read-onlyGets the CoreDispatcher that this object is associated with. The CoreDispatcher represents a facility that can access the DependencyObject on the UI thread even if the code is initiated by a non-UI thread. (Inherited from DependencyObject)

FlowDirection

Read/writeGets 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/writeGets or sets the suggested height of a FrameworkElement. (Inherited from FrameworkElement)

HorizontalAlignment

Read/writeGets 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/writeGets or sets a value that determines whether the DoubleTapped event can originate from that element. (Inherited from UIElement)

IsHitTestVisible

Read/writeGets or sets whether the contained area of this UIElement can return true values for hit testing. (Inherited from UIElement)

IsHoldingEnabled

Read/writeGets or sets a value that determines whether the Holding event can originate from that element. (Inherited from UIElement)

IsItemsHost

Read-onlyGets a value that indicates whether this Panel is a container for UI items that are generated by an ItemsControl. (Inherited from Panel)

IsRightTapEnabled

Read/writeGets or sets a value that determines whether the RightTapped event can originate from that element. (Inherited from UIElement)

IsTapEnabled

Read/writeGets or sets a value that determines whether the Tapped event can originate from that element. (Inherited from UIElement)

Language

Read/writeGets 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-onlyIdentifies the Canvas.Left XAML attached property.

ManipulationMode

Read/writeGets or sets the ManipulationModes value used for UIElement behavior and interaction with gestures. Setting this value enables handling the manipulation events from this element in app code. (Inherited from UIElement)

Margin

Read/writeGets or sets the outer margin of a FrameworkElement. (Inherited from FrameworkElement)

MaxHeight

Read/writeGets or sets the maximum height constraint of a FrameworkElement. (Inherited from FrameworkElement)

MaxWidth

Read/writeGets or sets the maximum width constraint of a FrameworkElement. (Inherited from FrameworkElement)

MinHeight

Read/writeGets or sets the minimum height constraint of a FrameworkElement. (Inherited from FrameworkElement)

MinWidth

Read/writeGets or sets the minimum width constraint of a FrameworkElement. (Inherited from FrameworkElement)

Name

Read/writeGets 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/writeGets or sets the degree of the object's opacity. (Inherited from UIElement)

Parent

Read-onlyGets the parent object of this FrameworkElement in the object tree. (Inherited from FrameworkElement)

PointerCaptures

Read-onlyGets the set of all captured pointers, represented as Pointer values. (Inherited from UIElement)

Projection

Read/writeGets or sets the perspective projection (3-D effect) to apply when rendering this element. (Inherited from UIElement)

RenderSize

Read-onlyGets the final render size of a UIElement. (Inherited from UIElement)

RenderTransform

Read/writeGets or sets transform information that affects the rendering position of a UIElement. (Inherited from UIElement)

RenderTransformOrigin

Read/writeGets or sets the origin point of any possible render transform declared by RenderTransform, relative to the bounds of the UIElement. (Inherited from UIElement)

RequestedTheme

Read/writeGets or sets the UI theme that is used by the UIElement (and its child elements) for resource determination. The UI theme you specify with RequestedTheme can override the app-level RequestedTheme. (Inherited from FrameworkElement)

Resources

Read/writeGets 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/writeGets or sets an instance Style that is applied for this object during layout and rendering. (Inherited from FrameworkElement)

Tag

Read/writeGets or sets an arbitrary object value that can be used to store custom information about this object. (Inherited from FrameworkElement)

TopProperty

Read-onlyIdentifies the Canvas.Top XAML attached property.

Transitions

Read/writeGets or sets the collection of Transition style elements that apply to a UIElement. (Inherited from UIElement)

Triggers

Read-onlyGets the collection of triggers for animations that are defined for a FrameworkElement. Not commonly used. (Inherited from FrameworkElement)

UseLayoutRounding

Read/writeGets 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/writeGets 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/writeGets 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/writeGets or sets the width of a FrameworkElement. (Inherited from FrameworkElement)

ZIndexProperty

Read-onlyIdentifies the Canvas.ZIndex XAML attached property.

 

Remarks

Canvas is a layout panel that supports absolute positioning of child elements relative to the top left corner of the canvas.

Canvas layout panel

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 a container element that adapts to different orientations and screen settings, such as Grid or StackPanel, 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:

  • The Visibility property is set to Collapsed.
  • The Opacity property of the Canvas is 0.

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

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.


<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]

Minimum supported phone

Windows Phone 8.1 [Windows Runtime apps only]

Namespace

Windows.UI.Xaml.Controls
Windows::UI::Xaml::Controls [C++]

Metadata

Windows.winmd

See also

Panel
Quickstart: Defining layouts
Quickstart: Adding layout controls
Alignment, margin, and padding for UI element layout
Attached properties overview
Related controls
Grid
StackPanel
VariableSizedWrapGrid
Controls list
Controls by function

 

 

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