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Java(TM) 2 Platform, Standard Edition, v1.2.2 API Specification: Class Canvas - JDK 5 Documentation v1.2.2, Java 2 SDK 英文文档

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java.awt
Class Canvas

java.lang.Object
  |
  +--java.awt.Component
        |
        +--java.awt.Canvas

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public class Canvas

extends Component

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

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Fields inherited from class java.awt.Component

BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT

 

Constructor Summary

Canvas()           Constructs a new Canvas.

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

 

Method Summary
void	addNotify()           Creates the peer of the canvas.
void	paint(Graphics g)           This method is called to repaint this canvas.

 

Methods inherited from class java.awt.Component

action, add, addComponentListener, addFocusListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addPropertyChangeListener, addPropertyChangeListener, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, deliverEvent, disable, disableEvents, dispatchEvent, doLayout, enable, enable, enableEvents, enableInputMethods, firePropertyChange, getAlignmentX, getAlignmentY, getBackground, getBounds, getBounds, getColorModel, getComponentAt, getComponentAt, getComponentOrientation, getCursor, getDropTarget, getFont, getFontMetrics, getForeground, getGraphics, getHeight, getInputContext, getInputMethodRequests, getLocale, getLocation, getLocation, getLocationOnScreen, getMaximumSize, getMinimumSize, getName, getParent, getPeer, getPreferredSize, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, invalidate, isDisplayable, isDoubleBuffered, isEnabled, isFocusTraversable, 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, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, remove, removeComponentListener, removeFocusListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeNotify, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, reshape, resize, resize, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFont, setForeground, setLocale, setLocation, setLocation, setName, setSize, setSize, setVisible, show, show, size, toString, transferFocus, update, validate

 

Methods inherited from class java.lang.Object

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

 

Constructor Detail

Canvas

public Canvas()

Constructs a new Canvas.

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Canvas

public Canvas(GraphicsConfiguration config)

Constructs a new Canvas given a GraphicsConfiguration object.

Parameters:

config - a reference to a GraphicsConfiguration object.

See Also:

GraphicsConfiguration

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

See Also:

Toolkit.createCanvas(java.awt.Canvas), Component.getToolkit()

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paint

public void paint(Graphics g)

This method is called to repaint this canvas. Most applications that subclass Canvas should override this method in order to perform some useful operation.

The paint method provided by Canvas redraws this canvas's rectangle in the background color.

The graphics context's origin (0, 0) is the top-left corner of this canvas. Its clipping region is the area of the context.

Overrides:

paint in class Component

Parameters:

g - the graphics context.

See Also:

Graphics

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