objectdraw
Interface DrawingCanvas

All Superinterfaces:

java.awt.event.ComponentListener, java.util.EventListener, java.awt.image.ImageObserver

All Known Implementing Classes:

AWTDrawingCanvas, AWTFrameCanvas, FrameCanvas, JDrawingCanvas

public interface DrawingCanvas

extends java.awt.image.ImageObserver, java.awt.event.ComponentListener

The DrawingCanvas interface describes the methods that are available on a drawing canvas.

Version:

1.1.2 released July 2006

Field Summary

Fields inherited from interface java.awt.image.ImageObserver

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

Method Summary

void	addComponentListener(java.awt.event.ComponentListener l) Requests that the specified ComponentListener be notified when the DrawingCanvas is hidden, shown, resized or moved.
void	addKeyListener(java.awt.event.KeyListener l) Requests that the specified KeyListener be notified when keystokes occur.
void	addMouseListener(java.awt.event.MouseListener l) Requests that the specified MouseListener be notified when the mouse is clicked, pressed, or released.
void	addMouseMotionListener(java.awt.event.MouseMotionListener l) Requests that the specified MouseMotionListener be notified when the mouse is moved or dragged in the DrawingCanvas.
void	clear() Removes all objects from the DrawingCanvas.
java.awt.Image	createImage(int width, int height) Creates an off-screen drawable image to be used for double buffering.
void	disableAutoRepaint() Requests that the DrawingCanvas not be automatically repainted after every change.
void	enableAutoRepaint() Requests that the DrawingCanvas to be automatically repainted after every change without specifically calling repaint().
objectdraw.CanvasManager	getCanvasContent() Retrieves the CanvasManager that keeps track of all of the Drawable objects currently associated with this DrawingCanvas.
DrawableIterator	getDrawableIterator() Creates and returns an iterator of all the objects on the DrawingCanvas
java.awt.Graphics	getGraphics() Get a Graphic object associated with this DrawingCanvas.
int	getHeight() Determine the current height of a DrawingCanvas.
java.awt.Dimension	getSize() Determine the current size of a DrawingCanvas.
int	getWidth() Determine the current width of a DrawingCanvas.
boolean	prepareImage(java.awt.Image im, java.awt.image.ImageObserver observer) Prepares an image for rendering on the DrawingCanvas.
void	repaint() Requests that the contents of the canvas be redrawn.
void	requestFocus() Requests that this Component get the input focus, and that this Component's top-level ancestor become the focused Window.
boolean	requestFocusInWindow() Requests that this Component get the input focus.

Methods inherited from interface java.awt.image.ImageObserver

imageUpdate

Methods inherited from interface java.awt.event.ComponentListener

componentHidden, componentMoved, componentResized, componentShown

Method Detail

getCanvasContent

public objectdraw.CanvasManager getCanvasContent()

Retrieves the CanvasManager that keeps track of all of the Drawable objects currently associated with this DrawingCanvas.

Returns:

the DrawingCanvas' manager

clear

public void clear()

Removes all objects from the DrawingCanvas.

repaint

public void repaint()

Requests that the contents of the canvas be redrawn. It is not necessary to invoke this method unless disableAutoRepaint() has been invoked. In its default state, a DrawingCanvas redraws the display automatically after any change occurs.

enableAutoRepaint

public void enableAutoRepaint()

Requests that the DrawingCanvas to be automatically repainted after every change without specifically calling repaint(). This is the default setting.

disableAutoRepaint

public void disableAutoRepaint()

Requests that the DrawingCanvas not be automatically repainted after every change. When this mode is enabled, an explicit call to repaint() must be made in order to see changes made to the objects displayed on the DrawingCanvas. By default, auto-repaint is enabled in a newly constructed DrawingCanvas.

getGraphics

public java.awt.Graphics getGraphics()

Get a Graphic object associated with this DrawingCanvas.

Returns:

a Graphics object representing the graphics currently on the DrawingCanvas.

prepareImage

public boolean prepareImage(java.awt.Image im,
                            java.awt.image.ImageObserver observer)

Prepares an image for rendering on the DrawingCanvas. The image data is downloaded asynchronously in another thread and the appropriate screen representation of the image is generated.

Parameters:

im - the Image to be prepared

observer - the ImageObserver to be notified when Image is ready

Returns:

true if the image has already been fully prepared; false otherwise

getSize

public java.awt.Dimension getSize()

Determine the current size of a DrawingCanvas.

Returns:

a Dimension referring to the size of the DrawingCanvas.

getWidth

public int getWidth()

Determine the current width of a DrawingCanvas.

Returns:

an int referring to the width of the Drawingcanvas.

getHeight

public int getHeight()

Determine the current height of a DrawingCanvas.

Returns:

an int referring to the height of the Drawingcanvas.

createImage

public java.awt.Image createImage(int width,
                                  int height)

Creates an off-screen drawable image to be used for double buffering.

Parameters:

width - - the specified width

height - - the specified height

Returns:

an off-screen drawable image, which can be used for double buffering. The return value may be null if the component is not displayable. This will always happen if GraphicsEnvironment.isHeadless() returns true.

addMouseListener

public void addMouseListener(java.awt.event.MouseListener l)

Requests that the specified MouseListener be notified when the mouse is clicked, pressed, or released.

Parameters:

l - the listener object to be notified

addMouseMotionListener

public void addMouseMotionListener(java.awt.event.MouseMotionListener l)

Requests that the specified MouseMotionListener be notified when the mouse is moved or dragged in the DrawingCanvas.

Parameters:

l - the listener object to be notified

addComponentListener

public void addComponentListener(java.awt.event.ComponentListener l)

Requests that the specified ComponentListener be notified when the DrawingCanvas is hidden, shown, resized or moved.

Parameters:

l - the listener object to be notified

addKeyListener

public void addKeyListener(java.awt.event.KeyListener l)

Requests that the specified KeyListener be notified when keystokes occur.

Parameters:

l - the listener object to be notified

requestFocusInWindow

public boolean requestFocusInWindow()

Requests that this Component get the input focus.

Returns:

whether canvas is likely to gain focus

requestFocus

public void requestFocus()

Requests that this Component get the input focus, and that this Component's top-level ancestor become the focused Window.

getDrawableIterator

public DrawableIterator getDrawableIterator()

Creates and returns an iterator of all the objects on the DrawingCanvas

Returns:

an iterator of all of the CanvasManager's objects