Canvas

Class Canvas

java.lang.Object
  java.awt.Component
      java.awt.Container
          java.awt.Panel
              Canvas

All Implemented Interfaces:: javax.accessibility.Accessible, java.awt.image.ImageObserver, java.awt.MenuContainer, java.io.Serializable

public class Canvas
extends java.awt.Panel

The Canvas is the environment that the Turtles live in. It provides the view on the Turtle world. It also keeps a list of all living turtles, so that it can draw them all in the view and tell a turtle if it is alive. The Canvas has a scale factor that determines how much its view of the Turtle world is zoomed in or out. It may also choose to work with a Stepper to regulate how fast the turtles move. There is only ever one Canvas in existence. It can be retrieved with Canvas.getCanvas().

Version:: 6/2/05
Author:: Russell Zahniser
See Also:: Serialized Form

Nested Class Summary

Nested classes inherited from class java.awt.Panel

java.awt.Panel.AccessibleAWTPanel

Nested classes inherited from class java.awt.Container

java.awt.Container.AccessibleAWTContainer

Nested classes inherited from class java.awt.Component

java.awt.Component.AccessibleAWTComponent, java.awt.Component.BltBufferStrategy, java.awt.Component.FlipBufferStrategy

Field Summary

Fields inherited from class java.awt.Container

Fields inherited from class java.awt.Component

BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT

Fields inherited from interface java.awt.image.ImageObserver

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

Method Summary
`void`	`addTurtle(Turtle turtle)` Add a turtle to the master list of turtles, so that it will be drawn and will be considered alive.
`void`	`clear()` Remove all turtles.
`void`	`didStep()` A Turtle should call this whenever a step has been completed.
`void`	`drawLine(double x1, double y1, double x2, double y2, java.awt.Color color)` Draw a line on teh canvas, given the start coordinates, end coordinates, and color.
`void`	`drawTurtle(Turtle turtle, double x, double y, double heading)` Draw the given turtle on this canvas, using its color and pen state.
`static Canvas`	`getCanvas()` Only one canvas ever exists in the program.
`boolean`	`isAlive(Turtle t)` Check whether this turtle is alive.
`void`	`removeTurtle(Turtle turtle)` Remove a turtle from the master list of turtles.
`void`	`setScale(double setting)` The applet should also call this to tell the turtles how to draw.
`void`	`setStepper(Stepper stepper)` Attach this canvas to a stepper.
`void`	`update(java.awt.Graphics g)` Draw all the living turtles in the given graphics context.

Methods inherited from class java.awt.Panel

addNotify, getAccessibleContext

Methods inherited from class java.awt.Container

add, add, add, add, add, addContainerListener, addImpl, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, countComponents, deliverEvent, doLayout, findComponentAt, findComponentAt, getAlignmentX, getAlignmentY, getComponent, getComponentAt, getComponentAt, getComponentCount, getComponents, getContainerListeners, getFocusTraversalKeys, getFocusTraversalPolicy, getInsets, getLayout, getListeners, getMaximumSize, getMinimumSize, getPreferredSize, insets, invalidate, isAncestorOf, isFocusCycleRoot, isFocusCycleRoot, isFocusTraversalPolicySet, layout, list, list, locate, minimumSize, paint, paintComponents, paramString, preferredSize, print, printComponents, processContainerEvent, processEvent, remove, remove, removeAll, removeContainerListener, removeNotify, setFocusCycleRoot, setFocusTraversalKeys, setFocusTraversalPolicy, setFont, setLayout, transferFocusBackward, transferFocusDownCycle, validate, validateTree

Methods inherited from class java.awt.Component

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

Methods inherited from class java.lang.Object

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

Method Detail

addTurtle

public void addTurtle(Turtle turtle)

Add a turtle to the master list of turtles, so that it will be drawn and will be considered alive.

Parameters:: turtle - Turtle to add.

clear

public void clear()

Remove all turtles. Used when the simulation is reset.

didStep

public void didStep()

A Turtle should call this whenever a step has been completed. If there is a stepper being used, it will have a chance to pause.

drawLine

public void drawLine(double x1,
                     double y1,
                     double x2,
                     double y2,
                     java.awt.Color color)

Draw a line on teh canvas, given the start coordinates, end coordinates, and color.

Parameters:: x1 - x coordinate of start point; y1 - y coordinate of start point; x2 - x coordinate of end point; y2 - y coordinate of end point; color - Color to draw with

drawTurtle

public void drawTurtle(Turtle turtle,
                       double x,
                       double y,
                       double heading)

Draw the given turtle on this canvas, using its color and pen state.

Parameters:: turtle - Turtle to draw; x - x coordinate of that turtle; y - y coordinate of that turtle; heading - Heading of that turtle

getCanvas

public static Canvas getCanvas()

Only one canvas ever exists in the program. This method will return it.

Returns:: The Canvas.

isAlive

public boolean isAlive(Turtle t)

Check whether this turtle is alive.

Parameters:: t - Turtle to look for.
Returns:: Whether this turtle is alive, true or false.

removeTurtle

public void removeTurtle(Turtle turtle)

Remove a turtle from the master list of turtles. It is no longer considered alive. Any further commands to it should result in a DeadTurtleException.

Parameters:: turtle - Turtle to remove.

setScale

public void setScale(double setting)

The applet should also call this to tell the turtles how to draw. It gives the origin in screen coordinates, and the scale factor (how many pixels is one step of the turtle).

Parameters:: setting - A number from 0 to 4 describing the scale. The default is 2.

setStepper

public void setStepper(Stepper stepper)

Attach this canvas to a stepper. This will permit pausing or stopping after each step.

Parameters:: stepper - Stepper to attach.

update

public void update(java.awt.Graphics g)

Draw all the living turtles in the given graphics context.