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java.awt
Class Canvas  

java.lang.Object
  java.awt.Component
      java.awt.Canvas

All Implemented Interfaces:

javax.accessibility.Accessible, java.awt.image.ImageObserver, MenuContainer, java.io.Serializable

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public class Canvas

extends Component

implements java.io.Serializable, javax.accessibility.Accessible

The Canvas component provides a blank rectangular area, which the client application can use for drawing and for capturing events. By overriding the paint() method, the canvas can be used for anything from simple line drawings to full-scale custom components.

Since:

1.0

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Nested Class Summary
protected  class	Canvas.AccessibleAWTCanvas           This class provides accessibility support for the canvas.
private  class	Canvas.CanvasBltBufferStrategy           A BltBufferStrategy for canvases.
private  class	Canvas.CanvasFlipBufferStrategy           A FlipBufferStrategy for canvases.

 

Nested classes inherited from class java.awt.Component

Component.AccessibleAWTComponent, Component.BltBufferStrategy, Component.FlipBufferStrategy, Component.HeavyweightInLightweightListener

 

Field Summary
(package private)  java.awt.image.BufferStrategy	bufferStrategy           The buffer strategy associated with this canvas.
(package private)  GraphicsConfiguration	graphicsConfiguration           The graphics configuration associated with the canvas.
private static long	serialVersionUID           Compatible with Sun's JDK.

 

Fields inherited from class java.awt.Component

accessibleContext, background, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, changeSupport, componentListener, componentSerializedDataVersion, cursor, dropTarget, enabled, eventMask, focusable, focusListener, focusTraversalKeys, focusTraversalKeysEnabled, font, foreground, graphicsConfig, height, hierarchyBoundsListener, hierarchyListener, ignoreRepaint, inputMethodListener, isFocusTraversableOverridden, isPacked, keyListener, LEFT_ALIGNMENT, locale, minSize, mouseListener, mouseMotionListener, mouseWheelListener, name, nameExplicitlySet, newEventsOnly, orientation, parent, peer, peerFont, popups, prefSize, RIGHT_ALIGNMENT, TOP_ALIGNMENT, treeLock, valid, visible, width, x, y

 

Fields inherited from interface java.awt.image.ImageObserver

ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH

 

Constructor Summary

Canvas()           Initializes a new instance of Canvas.

Canvas(GraphicsConfiguration graphicsConfiguration)           Initializes a new instance of Canvas with the supplied graphics configuration.

 

Method Summary
void	addNotify()           Creates the native peer for this object.
void	createBufferStrategy(int numBuffers)           Creates a buffering strategy that manages how this canvas is repainted.
void	createBufferStrategy(int numBuffers, BufferCapabilities caps)           Creates a buffering strategy that manages how this canvas is repainted.
javax.accessibility.AccessibleContext	getAccessibleContext()           Gets the AccessibleContext associated with this Canvas.
java.awt.image.BufferStrategy	getBufferStrategy()           Returns the buffer strategy used by the canvas.
(package private)  GraphicsConfiguration	getGraphicsConfigurationImpl()           Implementation method that allows classes such as Canvas and Window to override the graphics configuration without violating the published API.
void	paint(Graphics gfx)           Repaints the canvas window.
void	update(Graphics graphics)           Updates the canvas in response to a request to repaint() it.

 

Methods inherited from class java.awt.Component

action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, createVolatileImage, createVolatileImage, deliverEvent, disable, disableEvents, dispatchEvent, dispatchEventImpl, doLayout, enable, enable, enableEvents, enableInputMethods, eventTypeEnabled, findNextFocusComponent, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, generateName, getAlignmentX, getAlignmentY, getBackground, getBounds, getBounds, getColorModel, getComponentAt, getComponentAt, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeys, getFocusTraversalKeysEnabled, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getListeners, getLocale, getLocation, getLocation, getLocationOnScreen, getMaximumSize, getMinimumSize, getMouseListeners, getMouseMotionListeners, getMouseWheelListeners, getName, getParent, getPeer, getPreferredSize, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, invalidate, isBackgroundSet, isCursorSet, isDisplayable, isDoubleBuffered, isEnabled, isFocusable, isFocusCycleRoot, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, isOpaque, isShowing, isValid, isVisible, keyDown, keyUp, layout, list, list, list, list, list, locate, location, lostFocus, minimumSize, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paintAll, paramString, postEvent, preferredSize, prepareImage, prepareImage, print, printAll, processComponentEvent, processEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removeNotify, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, reshape, resize, resize, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeys, setFocusTraversalKeysEnabled, setFont, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setName, setPeer, setSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle, translateEvent, validate

 

Methods inherited from class java.lang.Object

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

 

Field Detail

serialVersionUID

private static final long serialVersionUID

Compatible with Sun's JDK.

See Also:

Constant Field Values

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graphicsConfiguration

transient GraphicsConfiguration graphicsConfiguration

The graphics configuration associated with the canvas.

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bufferStrategy

transient java.awt.image.BufferStrategy bufferStrategy

The buffer strategy associated with this canvas.

Constructor Detail

Canvas

public Canvas()

Initializes a new instance of Canvas.

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Canvas

public Canvas(GraphicsConfiguration graphicsConfiguration)

Initializes a new instance of Canvas with the supplied graphics configuration.

Method Detail

getGraphicsConfigurationImpl

GraphicsConfiguration getGraphicsConfigurationImpl()

Description copied from class: Component

Implementation method that allows classes such as Canvas and Window to override the graphics configuration without violating the published API.

Overrides:

getGraphicsConfigurationImpl in class Component

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addNotify

public void addNotify()

Creates the native peer for this object.

Overrides:

addNotify in class Component

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paint

public void paint(Graphics gfx)

Repaints the canvas window. This method should be overridden by a subclass to do something useful, as this method simply paints the window with the background color.

Overrides:

paint in class Component

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getAccessibleContext

public javax.accessibility.AccessibleContext getAccessibleContext()

Gets the AccessibleContext associated with this Canvas. The context is created, if necessary.

Specified by:

getAccessibleContext in interface javax.accessibility.Accessible

Overrides:

getAccessibleContext in class Component

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createBufferStrategy

public void createBufferStrategy(int numBuffers)

Creates a buffering strategy that manages how this canvas is repainted. This method attempts to create the optimum strategy based on the desired number of buffers. Hardware or software acceleration may be used. createBufferStrategy attempts different levels of optimization, but guarantees that some strategy with the requested number of buffers will be created even if it is not optimal. First it attempts to create a page flipping strategy, then an accelerated blitting strategy, then an unaccelerated blitting strategy. Calling this method causes any existing buffer strategy to be destroyed.

Since:

1.4

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createBufferStrategy

public void createBufferStrategy(int numBuffers,
                                 BufferCapabilities caps)
                          throws AWTException

Creates a buffering strategy that manages how this canvas is repainted. This method attempts to create a strategy based on the specified capabilities and throws an exception if the requested strategy is not supported. Calling this method causes any existing buffer strategy to be destroyed.

Since:

1.4

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getBufferStrategy

public java.awt.image.BufferStrategy getBufferStrategy()

Returns the buffer strategy used by the canvas.

Since:

1.4

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update

public void update(Graphics graphics)

Updates the canvas in response to a request to repaint() it. The canvas is cleared with the current background colour, before paint() is called to add the new contents. Subclasses which override this method should either call this method via super.update(graphics) or re-implement this behaviour, so as to ensure that the canvas is clear before painting takes place.

Overrides:

update in class Component

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Overview  Package   Class  Use  Deprecated  Index
Home >> All >> java >> [ awt overview ]	PREV CLASS  NEXT CLASS
SUMMARY:  JAVADOC |  SOURCE |  DOWNLOAD | NESTED | FIELD | CONSTR | METHOD	DETAIL: FIELD | CONSTR | METHOD

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