| JavaTM 2 Platform Std. Ed. v1.6.0
java.awt
Class Canvas
java.lang.Object
 java.awt.Component
java.awt.Canvas
- All Implemented Interfaces:
- ImageObserver, MenuContainer, Serializable, Accessible
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.
- Since:
- JDK1.0
- See Also:
- Serialized Form
| 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, doLayout, enable, enable, enableEvents, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, 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, 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, validate |
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.- See Also:
GraphicsConfiguration
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
- See Also:
Toolkit.createCanvas(java.awt.Canvas),
Component.getToolkit()
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- See Also:
update(Graphics),
Component.paint(Graphics)
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- See Also:
paint(Graphics),
Component.update(Graphics)
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.
- Parameters:
numBuffers - number of buffers to create, including the front buffer
- Throws:
IllegalArgumentException - if numBuffers is less than 1.
IllegalStateException - if the component is not displayable- Since:
- 1.4
- See Also:
Component.isDisplayable(),
getBufferStrategy()
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.
- Parameters:
numBuffers - number of buffers to createcaps - 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.
IllegalArgumentException - if numBuffers is less than 1, or if
caps is null- Since:
- 1.4
- See Also:
getBufferStrategy()
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.
- Returns:
- the buffer strategy used by this component
- Since:
- 1.4
- See Also:
createBufferStrategy(int)
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.
- Specified by:
getAccessibleContext in interface Accessible- Overrides:
getAccessibleContext in class Component
- Returns:
- an AccessibleAWTCanvas that serves as the
AccessibleContext of this Canvas
- Since:
- 1.3
Copyright 2003 Sun Microsystems, Inc. All rights reserved
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