Package com.google.gwt.canvas.client

Class Canvas

java.lang.Object

com.google.gwt.user.client.ui.UIObject

com.google.gwt.user.client.ui.Widget

com.google.gwt.user.client.ui.FocusWidget

com.google.gwt.canvas.client.Canvas

All Implemented Interfaces:

HasAllDragAndDropHandlers, HasAllFocusHandlers, HasAllGestureHandlers, HasAllKeyHandlers, HasAllMouseHandlers, HasAllTouchHandlers, HasBlurHandlers, HasClickHandlers, HasDoubleClickHandlers, HasDragEndHandlers, HasDragEnterHandlers, HasDragHandlers, HasDragLeaveHandlers, HasDragOverHandlers, HasDragStartHandlers, HasDropHandlers, HasFocusHandlers, HasGestureChangeHandlers, HasGestureEndHandlers, HasGestureStartHandlers, HasKeyDownHandlers, HasKeyPressHandlers, HasKeyUpHandlers, HasMouseDownHandlers, HasMouseMoveHandlers, HasMouseOutHandlers, HasMouseOverHandlers, HasMouseUpHandlers, HasMouseWheelHandlers, HasTouchCancelHandlers, HasTouchEndHandlers, HasTouchMoveHandlers, HasTouchStartHandlers, HasAttachHandlers, HasHandlers, EventListener, Focusable, HasEnabled, HasFocus, HasVisibility, IsWidget, SourcesClickEvents, SourcesFocusEvents, SourcesKeyboardEvents, SourcesMouseEvents

public class Canvas
extends FocusWidget

A widget representing a <canvas> element. This widget may not be supported on all browsers.

Nested Class Summary

Nested classes/interfaces inherited from class com.google.gwt.user.client.ui.UIObject

UIObject.DebugIdImpl, UIObject.DebugIdImplEnabled

Field Summary

Fields inherited from class com.google.gwt.user.client.ui.UIObject

DEBUG_ID_PREFIX

Method Summary

Modifier and Type	Method	Description
static Canvas	createIfSupported()	Return a new Canvas if supported, and null otherwise.
CanvasElement	getCanvasElement()	Returns the attached Canvas Element.
Context	getContext(String contextId)	Gets the rendering context that may be used to draw on this canvas.
Context2d	getContext2d()	Returns a 2D rendering context.
int	getCoordinateSpaceHeight()	Gets the height of the internal canvas coordinate space.
int	getCoordinateSpaceWidth()	Gets the width of the internal canvas coordinate space.
static boolean	isSupported()	Runtime check for whether the canvas element is supported in this browser.
void	setCoordinateSpaceHeight(int height)	Sets the height of the internal canvas coordinate space.
void	setCoordinateSpaceWidth(int width)	Sets the width of the internal canvas coordinate space.
String	toDataUrl()	Returns a data URL for the current content of the canvas element.
String	toDataUrl(String type)	Returns a data URL for the current content of the canvas element, with a specified type.
static Canvas	wrap(CanvasElement element)	Wrap an existing canvas element.

Methods inherited from class com.google.gwt.user.client.ui.FocusWidget

addBlurHandler, addClickHandler, addClickListener, addDoubleClickHandler, addDragEndHandler, addDragEnterHandler, addDragHandler, addDragLeaveHandler, addDragOverHandler, addDragStartHandler, addDropHandler, addFocusHandler, addFocusListener, addGestureChangeHandler, addGestureEndHandler, addGestureStartHandler, addKeyboardListener, addKeyDownHandler, addKeyPressHandler, addKeyUpHandler, addMouseDownHandler, addMouseListener, addMouseMoveHandler, addMouseOutHandler, addMouseOverHandler, addMouseUpHandler, addMouseWheelHandler, addMouseWheelListener, addTouchCancelHandler, addTouchEndHandler, addTouchMoveHandler, addTouchStartHandler, getFocusImpl, getTabIndex, isEnabled, onAttach, removeClickListener, removeFocusListener, removeKeyboardListener, removeMouseListener, removeMouseWheelListener, setAccessKey, setEnabled, setFocus, setTabIndex

Methods inherited from class com.google.gwt.user.client.ui.Widget

addAttachHandler, addBitlessDomHandler, addDomHandler, addHandler, asWidget, asWidgetOrNull, createHandlerManager, delegateEvent, doAttachChildren, doDetachChildren, fireEvent, getHandlerCount, getLayoutData, getParent, isAttached, isOrWasAttached, onBrowserEvent, onDetach, onLoad, onUnload, removeFromParent, setLayoutData, sinkEvents, unsinkEvents

Methods inherited from class com.google.gwt.user.client.ui.UIObject

addStyleDependentName, addStyleName, ensureDebugId, ensureDebugId, ensureDebugId, getAbsoluteLeft, getAbsoluteTop, getElement, getOffsetHeight, getOffsetWidth, getStyleElement, getStyleName, getStyleName, getStylePrimaryName, getStylePrimaryName, getTitle, isVisible, isVisible, onEnsureDebugId, removeStyleDependentName, removeStyleName, resolvePotentialElement, setElement, setElement, setHeight, setPixelSize, setSize, setStyleDependentName, setStyleName, setStyleName, setStyleName, setStyleName, setStylePrimaryName, setStylePrimaryName, setTitle, setVisible, setVisible, setWidth, sinkBitlessEvent, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface com.google.gwt.event.shared.HasHandlers

fireEvent

Method Details

createIfSupported

public static Canvas createIfSupported()

Return a new Canvas if supported, and null otherwise.

Returns:

a new Canvas if supported, and null otherwise

wrap

public static Canvas wrap(CanvasElement element)

Wrap an existing canvas element. The element must already be attached to the document. If the element is removed from the document, you must call RootPanel.detachNow(Widget). Note: This method can return null if there is no support for canvas by the current browser.

Parameters:

element - the element to wrap

Returns:

the Canvas widget or null if canvas is not supported by the current browser.

isSupported

public static boolean isSupported()

Runtime check for whether the canvas element is supported in this browser.

Returns:

whether the canvas element is supported

getCanvasElement

public CanvasElement getCanvasElement()

Returns the attached Canvas Element.

Returns:

the Canvas Element

getContext

public Context getContext(String contextId)

Gets the rendering context that may be used to draw on this canvas.

Parameters:

contextId - the context id as a String

Returns:

the canvas rendering context

getContext2d

public Context2d getContext2d()

Returns a 2D rendering context. This is a convenience method, see getContext(String).

Returns:

a 2D canvas rendering context

getCoordinateSpaceHeight

public int getCoordinateSpaceHeight()

Gets the height of the internal canvas coordinate space.

Returns:

the height, in pixels

See Also:

• setCoordinateSpaceHeight(int)

getCoordinateSpaceWidth

public int getCoordinateSpaceWidth()

Gets the width of the internal canvas coordinate space.

Returns:

the width, in pixels

See Also:

• setCoordinateSpaceWidth(int)

setCoordinateSpaceHeight

public void setCoordinateSpaceHeight(int height)

Sets the height of the internal canvas coordinate space.

Parameters:

height - the height, in pixels

See Also:

• getCoordinateSpaceHeight()

setCoordinateSpaceWidth

public void setCoordinateSpaceWidth(int width)

Sets the width of the internal canvas coordinate space.

Parameters:

width - the width, in pixels

See Also:

• getCoordinateSpaceWidth()

toDataUrl

public String toDataUrl()

Returns a data URL for the current content of the canvas element.

Returns:

a data URL for the current content of this element.

toDataUrl

public String toDataUrl(String type)

Returns a data URL for the current content of the canvas element, with a specified type.

Parameters:

type - the type of the data url, e.g., image/jpeg or image/png.

Returns:

a data URL for the current content of this element with the specified type.