Class TGCanvas

java.lang.Object
  java.awt.Component
      TGCanvas

All Implemented Interfaces:

java.awt.event.FocusListener, java.awt.event.KeyListener, java.awt.event.MouseListener, java.awt.event.MouseMotionListener, java.awt.image.ImageObserver, java.awt.MenuContainer, java.io.Serializable, java.util.EventListener

public class TGCanvas
extends java.awt.Component
implements java.awt.event.FocusListener, java.awt.event.KeyListener, java.awt.event.MouseListener, java.awt.event.MouseMotionListener

This class is an implementation of a graphics canvas window for TG. All graphics (pixels painted) are maintained in an Image for redisplay in the event of resizing.

Other features of TGCanvas are:

- the coordinate space is the traditional mathematics; [0,0] is in the middle of the graphics window.

- KeyListener method invocations are handled and may be passed on.

- MouseListener.mouseReleased() and MouseMotionListener.mouseMoved() are captured and can be passed on.

- higher-level functionality (i.e., flood-fill provided).

- in-memory Image maintained with buffered operations to improve graphics display performance.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class java.awt.Component

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

Field Summary

static int	AQUA
static int	BLACK The SETPENCOLOR command's input is a built-in color number or an RGB value.
static int	BLUE
static int	BROWN
static int	CHOCOLATE
static int	CYAN
static int	EAST Turtle heading for the positive X axis.
static int	FOREST
static int	GOLD
static int	GRAY
static int	GREEN
static int	KHAKI
static int	LAWNGREEN
static int	LIGHTBLUE
static int	LIGHTGRAY
static int	LIME
static java.awt.Color[]	LOGO_COLORS All derivations of Logo have a basic, minimum set of colors that are specified by numbers.
static int	MAGENTA
static int	MAX_LOGO_COLOR The maximum value for a Logo color which require conversion to RGB colors used by Java.
static int	NAVY
static int	NORTH Turtle heading for the positive Y axis.
static int	OLIVE
static int	ORANGE
static int	PALEGREEN
static int	PERU
static int	PINK
static int	PURPLE
static int	RED
static int	SALMON
static int	SKYBLUE
static int	SOUTH Turtle heading for the negative Y axis.
static int	STEELBLUE
static int	TAN
static int	VIOLET
static int	WEST Turtle heading for the negative X axis.
static int	WHEAT
static int	WHITE
static int	YELLOW

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

Constructor Summary

TGCanvas()
Instantiate a turtle graphics canvas with initial width of 700 turtle steps and a height of 400 turtle steps.

TGCanvas(int width, int height)
Instantiate a turtle graphics canvas of a specified width and height.

Method Summary

void	addGraphOp(TGGraphicsOp grafOp) Append a graphics operation, a TGGraphicsOp object, to the queue of outstanding operations.
void	addKeyHandler(TGKeyHandler kh) Add an object which implements TGKeyHandler to the list of those that want a callback when a key is pressed while the graphics canvas has focus.
void	addMouseHandler(TGMouseHandler mh) Add an object which implements TGMouseHandler to the list of those that want a callback.
void	addSprite(Sprite sprite) Add a new Sprite, start displaying its image on the graphics canvas.
int	canvasHeight() Return the height of the graphics canvas.
int	canvasWidth() Return the width of the graphics canvas.
void	clean() Clean graphics off of the display.
void	focusGained(java.awt.event.FocusEvent e) Invoked when this Component gets focus.
void	focusLost(java.awt.event.FocusEvent e) Invoked when this Component loses focus.
int	getBackgroundColor() Return the background Logo color number.
java.awt.image.BufferedImage	getPicture() Return the contents of the graphics canvas overlaid with existing Sprite images as a composite BufferedImage.
int[]	getPixels(TGPoint topLeft, int width, int height) Return an array of pixel RGB values.
void	keyPressed(java.awt.event.KeyEvent ke) Invoked when a key has been pressed.
void	keyReleased(java.awt.event.KeyEvent ke) Invoked when a key has been released.
void	keyTyped(java.awt.event.KeyEvent ke) Invoked when a key has been typed.
void	loadPicture(java.awt.Image pictureImage) Load the provided array of pixels into the background.
static java.awt.Color	logoColorToJavaColor(int logoColor) Convert a Logo color to a Java Color object.
static int	logoColorToRGB(int logoColor) Convert a Logo color to a Java RGB int with the alpha component maintained.
void	mouseClicked(java.awt.event.MouseEvent me) Invoked when a mouse button has been clicked (pressed and released) on this Component.
void	mouseDragged(java.awt.event.MouseEvent me) Invoked when a mouse button is held down on TGCanvas and the mouse is moved.
void	mouseEntered(java.awt.event.MouseEvent me) Invoked when the mouse enters a Component.
void	mouseExited(java.awt.event.MouseEvent me) Invoked when the mouse exits a Component.
void	mouseMoved(java.awt.event.MouseEvent me) Invoked when the mouse is moved around on the TGCanvas without any buttons in a depressed state.
void	mousePressed(java.awt.event.MouseEvent me) Invoked when a mouse button has been pressed while on a Component.
void	mouseReleased(java.awt.event.MouseEvent me) Invoked when a mouse button has been released on TGCanvas.
int	mousex() Return the TurtleSpace x-coordinate of the mouse when it was last clicked.
int	mousey() Return the TurtleSpace y-coordinate of the mouse when it was last clicked.
void	paint(java.awt.Graphics g) Paints this Component.
void	removeKeyHandler(TGKeyHandler kh) Remove an object from TGCanvas' list of those wanting their keyPressed() method invoked when TGCanvas receives this Event.
void	removeMouseHandler(TGMouseHandler mh) Remove an object from TGCanvas' list of those wanting their mouseClicked() and mouseMoved() methods invoked when we receive these Events.
void	removeSprite(Sprite sprite) Remove the specified Sprite from the list of sprites whose images are displayed on the graphics canvas.
static int	rgbToLogoColor(int rgbValue) Return a Logo pen color number given an ARGB or RGB value.
void	setbg(int logoColor) Set the background color of the graphics canvas.
void	setBounds(int x, int y, int width, int height) Moves and resizes this Component.
void	setSize(int width, int height) Resizes this Component to have the specified width and height.
void	update(java.awt.Graphics gfx) Update the displayed image of this Component.

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, 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, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeys, setFocusTraversalKeysEnabled, setFont, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setMaximumSize, setMinimumSize, setName, setPreferredSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle, validate

Methods inherited from class java.lang.Object

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

Field Detail

NORTH

public static final int NORTH

Turtle heading for the positive Y axis. The Logo turtle's heading in degrees does not match the standard mathematics notion of having the positive X axis as zero, with degrees increasing counter-clockwise. Logo has the positive Y axis as zero with degrees increasing clockwise. The use of abstract symbolic constants for north, east, south, and west help.

See Also:

Constant Field Values

EAST

public static final int EAST

Turtle heading for the positive X axis. The Logo turtle's heading in degrees does not match the standard mathematics notion of having the positive X axis as zero, with degrees increasing counter-clockwise. Logo has the positive Y axis as zero with degrees increasing clockwise. The use of abstract symbolic constants for north, east, south, and west help.

See Also:

Constant Field Values

SOUTH

public static final int SOUTH

Turtle heading for the negative Y axis. The Logo turtle's heading in degrees does not match the standard mathematics notion of having the positive X axis as zero, with degrees increasing counter-clockwise. Logo has the positive Y axis as zero with degrees increasing clockwise. The use of abstract symbolic constants for north, east, south, and west help.

See Also:

Constant Field Values

WEST

public static final int WEST

Turtle heading for the negative X axis. The Logo turtle's heading in degrees does not match the standard mathematics notion of having the positive X axis as zero, with degrees increasing counter-clockwise. Logo has the positive Y axis as zero with degrees increasing clockwise. The use of abstract symbolic constants for north, east, south, and west help.

See Also:

Constant Field Values

BLACK

public static final int BLACK

The SETPENCOLOR command's input is a built-in color number or an RGB value. Built-in colors numbers are in range of 0-31 with 0 for black.

See Also:

Constant Field Values

BLUE

public static final int BLUE

See Also:

Constant Field Values

GREEN

public static final int GREEN

See Also:

Constant Field Values

CYAN

public static final int CYAN

See Also:

Constant Field Values

RED

public static final int RED

See Also:

Constant Field Values

MAGENTA

public static final int MAGENTA

See Also:

Constant Field Values

YELLOW

public static final int YELLOW

See Also:

Constant Field Values

WHITE

public static final int WHITE

See Also:

Constant Field Values

BROWN

public static final int BROWN

See Also:

Constant Field Values

TAN

public static final int TAN

See Also:

Constant Field Values

FOREST

public static final int FOREST

See Also:

Constant Field Values

AQUA

public static final int AQUA

See Also:

Constant Field Values

SALMON

public static final int SALMON

See Also:

Constant Field Values

VIOLET

public static final int VIOLET

See Also:

Constant Field Values

ORANGE

public static final int ORANGE

See Also:

Constant Field Values

GRAY

public static final int GRAY

See Also:

Constant Field Values

NAVY

public static final int NAVY

See Also:

Constant Field Values

SKYBLUE

public static final int SKYBLUE

See Also:

Constant Field Values

LIME

public static final int LIME

See Also:

Constant Field Values

STEELBLUE

public static final int STEELBLUE

See Also:

Constant Field Values

CHOCOLATE

public static final int CHOCOLATE

See Also:

Constant Field Values

PURPLE

public static final int PURPLE

See Also:

Constant Field Values

GOLD

public static final int GOLD

See Also:

Constant Field Values

LIGHTGRAY

public static final int LIGHTGRAY

See Also:

Constant Field Values

PERU

public static final int PERU

See Also:

Constant Field Values

WHEAT

public static final int WHEAT

See Also:

Constant Field Values

PALEGREEN

public static final int PALEGREEN

See Also:

Constant Field Values

LIGHTBLUE

public static final int LIGHTBLUE

See Also:

Constant Field Values

KHAKI

public static final int KHAKI

See Also:

Constant Field Values

PINK

public static final int PINK

See Also:

Constant Field Values

LAWNGREEN

public static final int LAWNGREEN

See Also:

Constant Field Values

OLIVE

public static final int OLIVE

See Also:

Constant Field Values

MAX_LOGO_COLOR

public static final int MAX_LOGO_COLOR

The maximum value for a Logo color which require conversion to RGB colors used by Java.

See Also:

Constant Field Values

LOGO_COLORS

public static final java.awt.Color[] LOGO_COLORS

All derivations of Logo have a basic, minimum set of colors that are specified by numbers. jLogo supports a set of sixteen, compatible with Brian Harvey's Berkeley Logo.

Constructor Detail

TGCanvas

public TGCanvas()

Instantiate a turtle graphics canvas with initial width of 700 turtle steps and a height of 400 turtle steps.

TGCanvas

public TGCanvas(int width,
                int height)

Instantiate a turtle graphics canvas of a specified width and height.

Method Detail

focusGained

public void focusGained(java.awt.event.FocusEvent e)

Invoked when this Component gets focus. Note that this has happened, that the graphics canvas now gets keyboard and mouse events.

Specified by:

focusGained in interface java.awt.event.FocusListener

focusLost

public void focusLost(java.awt.event.FocusEvent e)

Invoked when this Component loses focus. Note that this has happened.

Specified by:

focusLost in interface java.awt.event.FocusListener

keyPressed

public void keyPressed(java.awt.event.KeyEvent ke)

Invoked when a key has been pressed.

Specified by:

keyPressed in interface java.awt.event.KeyListener

keyReleased

public void keyReleased(java.awt.event.KeyEvent ke)

Invoked when a key has been released.

Specified by:

keyReleased in interface java.awt.event.KeyListener

keyTyped

public void keyTyped(java.awt.event.KeyEvent ke)

Invoked when a key has been typed.

Specified by:

keyTyped in interface java.awt.event.KeyListener

mouseClicked

public void mouseClicked(java.awt.event.MouseEvent me)

Invoked when a mouse button has been clicked (pressed and released) on this Component.

Specified by:

mouseClicked in interface java.awt.event.MouseListener

mouseEntered

public void mouseEntered(java.awt.event.MouseEvent me)

Invoked when the mouse enters a Component.

Specified by:

mouseEntered in interface java.awt.event.MouseListener

mouseExited

public void mouseExited(java.awt.event.MouseEvent me)

Invoked when the mouse exits a Component.

Specified by:

mouseExited in interface java.awt.event.MouseListener

mousePressed

public void mousePressed(java.awt.event.MouseEvent me)

Invoked when a mouse button has been pressed while on a Component.

Specified by:

mousePressed in interface java.awt.event.MouseListener

mouseReleased

public void mouseReleased(java.awt.event.MouseEvent me)

Invoked when a mouse button has been released on TGCanvas.

Specified by:

mouseReleased in interface java.awt.event.MouseListener

mouseDragged

public void mouseDragged(java.awt.event.MouseEvent me)

Invoked when a mouse button is held down on TGCanvas and the mouse is moved.

Specified by:

mouseDragged in interface java.awt.event.MouseMotionListener

mouseMoved

public void mouseMoved(java.awt.event.MouseEvent me)

Invoked when the mouse is moved around on the TGCanvas without any buttons in a depressed state.

Specified by:

mouseMoved in interface java.awt.event.MouseMotionListener

paint

public void paint(java.awt.Graphics g)

Paints this Component.

Something has occured that requires updating the graphics canvas. As an example, TGGraphicsOps have been queued to be performed, or a Sprite whose image is being displayed has moved or rotated, or the AWT has decided we need to redraw at least some subset of our pixels, e.g., partially covered stuff (by some other application on the desktop) has moved/gone away, etc...

Overrides:

paint in class java.awt.Component

setBounds

public void setBounds(int x,
                      int y,
                      int width,
                      int height)

Moves and resizes this Component. The new location of the top-left corner is specified by x and y. The new size is specified by width and height.

Overrides:

setBounds in class java.awt.Component

setSize

public void setSize(int width,
                    int height)

Resizes this Component to have the specified width and height.

Overrides:

setSize in class java.awt.Component

update

public void update(java.awt.Graphics gfx)

Update the displayed image of this Component.

Overridden in TGCanvas to eliminate Component.update()'s invocation of Graphics.clear().

Overrides:

update in class java.awt.Component

addGraphOp

public void addGraphOp(TGGraphicsOp grafOp)

Append a graphics operation, a TGGraphicsOp object, to the queue of outstanding operations.

addKeyHandler

public void addKeyHandler(TGKeyHandler kh)

Add an object which implements TGKeyHandler to the list of those that want a callback when a key is pressed while the graphics canvas has focus. The object's keyPressed() method is invoked.

addMouseHandler

public void addMouseHandler(TGMouseHandler mh)

Add an object which implements TGMouseHandler to the list of those that want a callback. A callback is performed when the graphics canvas has focus and

• a mouse button is clicked (the object's tgMouseClicked() method is invoked), or
• the mouse is moved (the object's tgMouseMoved() method is invoked).

addSprite

public void addSprite(Sprite sprite)

Add a new Sprite, start displaying its image on the graphics canvas.

canvasHeight

public int canvasHeight()

Return the height of the graphics canvas.

canvasWidth

public int canvasWidth()

Return the width of the graphics canvas.

clean

public void clean()

Clean graphics off of the display.

getBackgroundColor

public int getBackgroundColor()

Return the background Logo color number. Values zero through fifteen (inclusive) are fixed Logo colors (black, blue, etc...) other values are RGB numbers, with or without alpha values.

getPicture

public java.awt.image.BufferedImage getPicture()

Return the contents of the graphics canvas overlaid with existing Sprite images as a composite BufferedImage.

getPixels

public int[] getPixels(TGPoint topLeft,
                       int width,
                       int height)

Return an array of pixel RGB values. A rectangular area of the graphics canvas defined by a top-left corner (in TurtleSpace coordinates) and its width and height.

Since all drawing operations are queued to be performed by the paint() method, we must wait for all outstanding operations to complete before we grab pixels.

loadPicture

public void loadPicture(java.awt.Image pictureImage)

Load the provided array of pixels into the background.

*NOTE* a side-effect of changing the background color is that all current graphics is cleared.

logoColorToJavaColor

public static java.awt.Color logoColorToJavaColor(int logoColor)

Convert a Logo color to a Java Color object. If the alpha component is zero it is replaced with 0xFF - assumed to be an opaque color.

logoColorToRGB

public static int logoColorToRGB(int logoColor)

Convert a Logo color to a Java RGB int with the alpha component maintained.

mousex

public int mousex()

Return the TurtleSpace x-coordinate of the mouse when it was last clicked.

See Also:

mousey()

mousey

public int mousey()

Return the TurtleSpace y-coordinate of the mouse when it was last clicked.

See Also:

mousex()

removeKeyHandler

public void removeKeyHandler(TGKeyHandler kh)

Remove an object from TGCanvas' list of those wanting their keyPressed() method invoked when TGCanvas receives this Event.

removeMouseHandler

public void removeMouseHandler(TGMouseHandler mh)

Remove an object from TGCanvas' list of those wanting their mouseClicked() and mouseMoved() methods invoked when we receive these Events.

removeSprite

public void removeSprite(Sprite sprite)

Remove the specified Sprite from the list of sprites whose images are displayed on the graphics canvas.

rgbToLogoColor

public static int rgbToLogoColor(int rgbValue)

Return a Logo pen color number given an ARGB or RGB value.

setbg

public void setbg(int logoColor)

Set the background color of the graphics canvas.

*NOTE* a side-effect of changing the background color is that all current graphics is cleared.