This documentation differs from the official API. Jadeite adds extra features to the API including: variable font sizes, constructions examples, placeholders for classes and methods, and auto-generated “See Also” links. Additionally it is missing some items found in standard Javadoc documentation, including: generics type information, “Deprecated” tags and comments, “See Also” links, along with other minor differences. Please send any questions or feedback to bam@cs.cmu.edu.


java.awt
class Canvas

java.lang.Object extended by java.awt.Component extended by java.awt.Canvas
All Implemented Interfaces:
MenuContainer, ImageObserver, Serializable, Accessible

Most common way to construct:

Canvas canvas = new Canvas();

Based on 7 examples


public class Canvas
extends Component
implements Accessible

A Canvas component represents a blank rectangular area of the screen onto which the application can draw or from which the application can trap input events from the user.

An application must subclass the Canvas class in order to get useful functionality such as creating a custom component. The paint method must be overridden in order to perform custom graphics on the canvas.


Nested Class Summary
protected class

           This class implements accessibility support for the Canvas class.
Nested classes/interfaces inherited from class java.awt.Component
Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy
   
Field Summary
 
Fields inherited from class java.awt.Component
BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT
 
Constructor Summary

          Constructs a new Canvas.

          Constructs a new Canvas given a GraphicsConfiguration object.
 
Method Summary
 void

          Creates the peer of the canvas.
 void
createBufferStrategy(int numBuffers)

          Creates a new strategy for multi-buffering on this component.
 void

          Creates a new strategy for multi-buffering on this component with the required buffer capabilities.
 AccessibleContext

          Gets the AccessibleContext associated with this Canvas.
 BufferStrategy

          Returns the BufferStrategy used by this component.
 void

          Paints this canvas.
 void

          Updates this canvas.
 
Methods inherited from class java.awt.Component
action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, addNotify, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, createVolatileImage, createVolatileImage, deliverEvent, disable, disableEvents, dispatchEvent, doLayout, enable, enable, enableEvents, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, getAccessibleContext, getAlignmentX, getAlignmentY, getBackground, getBaseline, getBaselineResizeBehavior, 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, getMousePosition, 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, isMaximumSizeSet, isMinimumSizeSet, isOpaque, isPreferredSizeSet, isShowing, isValid, isVisible, keyDown, keyUp, layout, list, list, list, list, list, locate, location, lostFocus, minimumSize, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paint, 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, setMaximumSize, setMinimumSize, setName, setPreferredSize, setSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle, update, validate
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Canvas

public Canvas()
Constructs a new Canvas.


Canvas

public Canvas(GraphicsConfiguration config)
Constructs a new Canvas given a GraphicsConfiguration object.

Parameters:
config - a reference to a GraphicsConfiguration object.
Method Detail

addNotify

public void addNotify()
Creates the peer of the canvas. This peer allows you to change the user interface of the canvas without changing its functionality.

Overrides:
addNotify in class Component

createBufferStrategy

public void createBufferStrategy(int numBuffers)
Creates a new strategy for multi-buffering on this component. Multi-buffering is useful for rendering performance. This method attempts to create the best strategy available with the number of buffers supplied. It will always create a BufferStrategy with that number of buffers. A page-flipping strategy is attempted first, then a blitting strategy using accelerated buffers. Finally, an unaccelerated blitting strategy is used.

Each time this method is called, the existing buffer strategy for this component is discarded.

Overrides:
createBufferStrategy in class Component
Parameters:
numBuffers - number of buffers to create, including the front buffer

createBufferStrategy

public void createBufferStrategy(int numBuffers,
                                 BufferCapabilities caps)
                          throws AWTException
Creates a new strategy for multi-buffering on this component with the required buffer capabilities. This is useful, for example, if only accelerated memory or page flipping is desired (as specified by the buffer capabilities).

Each time this method is called, the existing buffer strategy for this component is discarded.

Overrides:
createBufferStrategy in class Component
Parameters:
numBuffers - number of buffers to create
caps - the required capabilities for creating the buffer strategy; cannot be null
Throws:
AWTException - if the capabilities supplied could not be supported or met; this may happen, for example, if there is not enough accelerated memory currently available, or if page flipping is specified but not possible.

getAccessibleContext

public AccessibleContext getAccessibleContext()
Gets the AccessibleContext associated with this Canvas. For canvases, the AccessibleContext takes the form of an AccessibleAWTCanvas. A new AccessibleAWTCanvas instance is created if necessary.

Overrides:
getAccessibleContext in class Component
Returns:
an AccessibleAWTCanvas that serves as the AccessibleContext of this Canvas

getBufferStrategy

public BufferStrategy getBufferStrategy()
Returns the BufferStrategy used by this component. This method will return null if a BufferStrategy has not yet been created or has been disposed.

Overrides:
getBufferStrategy in class Component
Returns:
the buffer strategy used by this component

paint

public void paint(Graphics g)
Paints this canvas.

Most applications that subclass Canvas should override this method in order to perform some useful operation (typically, custom painting of the canvas). The default operation is simply to clear the canvas. Applications that override this method need not call super.paint(g).

Overrides:
paint in class Component
Parameters:
g - the specified Graphics context

update

public void update(Graphics g)
Updates this canvas.

This method is called in response to a call to repaint. The canvas is first cleared by filling it with the background color, and then completely redrawn by calling this canvas's paint method. Note: applications that override this method should either call super.update(g) or incorporate the functionality described above into their own code.

Overrides:
update in class Component
Parameters:
g - the specified Graphics context


This documentation differs from the official API. Jadeite adds extra features to the API including: variable font sizes, constructions examples, placeholders for classes and methods, and auto-generated “See Also” links. Additionally it is missing some items found in standard Javadoc documentation, including: generics type information, “Deprecated” tags and comments, “See Also” links, along with other minor differences. Please send any questions or feedback to bam@cs.cmu.edu.
This page displays the Jadeite version of the documention, which is derived from the offical documentation that contains this copyright notice:
Copyright 2008 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.
The official Sun™ documentation can be found here at http://java.sun.com/javase/6/docs/api/.