Class DrawingPanel

java.lang.Object
  java.lang.Thread
      DrawingPanel

All Implemented Interfaces:

java.awt.event.KeyListener, java.awt.event.MouseListener, java.awt.event.MouseMotionListener, java.lang.Runnable, java.util.EventListener, javax.swing.event.MouseInputListener

public class DrawingPanel
extends java.lang.Thread
implements javax.swing.event.MouseInputListener, java.awt.event.KeyListener

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

java.lang.Thread.State, java.lang.Thread.UncaughtExceptionHandler

Field Summary

static int	ANY_KEY
static int	DELETE_KEY
static int	DOWN_ARROW_KEY
static int	ENTER_KEY
static int	ESC_KEY
static int	F1_KEY
static int	F10_KEY
static int	F11_KEY
static int	F12_KEY
static int	F2_KEY
static int	F3_KEY
static int	F4_KEY
static int	F5_KEY
static int	F6_KEY
static int	F7_KEY
static int	F8_KEY
static int	F9_KEY
static int	HOME_KEY
static int	INSERT_KEY
static int	LEFT_ARROW_KEY
static int	LEFT_BUTTON
static int	MIDDLE_BUTTON
static int	NO_KEY_PRESSED
static int	PAGE_DOWN_KEY
static int	PAGE_UP_KEY
static int	RIGHT_ARROW_KEY
static int	RIGHT_BUTTON
static int	SHIFT_KEY
static int	TAB_KEY
static int	UP_ARROW_KEY

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

DrawingPanel(int desiredWidth, int desiredHeight)
Construct a drawing panel of a given width and height enclosed in a window.

Method Summary

void	closeWindow() Close the DrawingPanel (actually closes the JFrame)
void	copyGraphicsToScreen() Copy the offscreen graphics buffer to the screen.
java.awt.Graphics2D	getGraphics() Obtain the Graphics object needed to draw on the DrawingPanel's offscreen graphics buffer.
int	getKeyHitCode() Returns a single "key code" for a key that was pressed and released.
int	getMouseButton() Get which mouse button was most recently clicked.
int	getMouseClickX(int whichButton) Get the x coordinate of the mouse's location when the most recent mouse click of the specified button occurred.
int	getMouseClickY(int whichButton) Get the y coordinate of the mouse's location when the most recent mouse click of the specified button occurred.
int	getMouseX() Get the current x coordinate of the mouse.
int	getMouseY() Get the current y coordinate of the mouse.
int	getRGB(int x, int y) Return an integer representation of the color at a specified pixel location.
boolean	isMouseButtonDown(int whichButton) Determine if a specific mouse button is down at the time of the method call.
boolean	keyHasBeenHit(int whichKeyCode) Has the specified key been hit (pressed and released)?
boolean	keyIsDown(int whichKeyCode) Is the specified key down at this moment in time?
void	keyPressed(java.awt.event.KeyEvent e) Callback method for "key pressed" events (never call explicitly).
void	keyReleased(java.awt.event.KeyEvent e) Callback method for "key release" events (never call explicitly).
void	keyTyped(java.awt.event.KeyEvent e) Callback method for "key typed" events (never used - never call explicitly).
static java.awt.image.BufferedImage	loadBitmap(java.lang.String filename) Load a bitmap image into memory.
void	mouseClicked(java.awt.event.MouseEvent e) MouseInputListener Callback (application never calls this method)
boolean	mouseClickHasOccurred(int whichButton) Determine if a mouse click has occurred.
void	mouseDragged(java.awt.event.MouseEvent e) MouseInputListener Callback (application never calls this method)
void	mouseEntered(java.awt.event.MouseEvent e) MouseInputListener Callback (application never calls this method)
void	mouseExited(java.awt.event.MouseEvent e) MouseInputListener Callback (application never calls this method)
void	mouseMoved(java.awt.event.MouseEvent e) MouseInputListener Callback (application never calls this method)
void	mousePressed(java.awt.event.MouseEvent e) MouseInputListener Callback (application never calls this method)
void	mouseReleased(java.awt.event.MouseEvent e) MouseInputListener Callback (application never calls this method)
int	numberOfKeysActive() Return the number of keys that are currently being pressed on the keyboard.
void	run() Run the GUI drawing panel in a separate thread so that the application that is drawing to the window can be paused and restarted (never called by an application).
void	saveGraphics(java.lang.String filename) Save the current graphics (in the offscreen buffer) to a file.
void	setBackground(java.awt.Color c) Clears the DrawingPanel's graphics window to the specified color.
void	setRGB(int x, int y, int RGB) Set the color at a specified pixel location.
void	setWindowTitle(java.lang.String name) Set the windows name -- which appears in the window's header.
void	sleep(int millis) Make your application "sleep" for the specified number of milliseconds.
void	waitForKeyHit() Wait for the user to hit a key on the keyboard -- your application goes to sleep until a key is pressed and released on the keyboard.
void	waitForKeyPressed() Wait for the user to press a key on the keyboard -- your application goes to sleep until a key is pressed.
void	waitForMouseClick(int whichButton) Wait for a mouse click on a specific mouse button (your application goes to sleep until the specific mouse button has been clicked (pressed and released)).

Methods inherited from class java.lang.Thread

activeCount, checkAccess, countStackFrames, currentThread, destroy, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

LEFT_BUTTON

public static final int LEFT_BUTTON

See Also:

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MIDDLE_BUTTON

public static final int MIDDLE_BUTTON

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RIGHT_BUTTON

public static final int RIGHT_BUTTON

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NO_KEY_PRESSED

public static final int NO_KEY_PRESSED

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ANY_KEY

public static final int ANY_KEY

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F1_KEY

public static final int F1_KEY

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F2_KEY

public static final int F2_KEY

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F3_KEY

public static final int F3_KEY

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F4_KEY

public static final int F4_KEY

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F5_KEY

public static final int F5_KEY

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F6_KEY

public static final int F6_KEY

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F7_KEY

public static final int F7_KEY

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F8_KEY

public static final int F8_KEY

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F9_KEY

public static final int F9_KEY

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F10_KEY

public static final int F10_KEY

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F11_KEY

public static final int F11_KEY

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F12_KEY

public static final int F12_KEY

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LEFT_ARROW_KEY

public static final int LEFT_ARROW_KEY

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RIGHT_ARROW_KEY

public static final int RIGHT_ARROW_KEY

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UP_ARROW_KEY

public static final int UP_ARROW_KEY

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DOWN_ARROW_KEY

public static final int DOWN_ARROW_KEY

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INSERT_KEY

public static final int INSERT_KEY

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HOME_KEY

public static final int HOME_KEY

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DELETE_KEY

public static final int DELETE_KEY

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PAGE_UP_KEY

public static final int PAGE_UP_KEY

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PAGE_DOWN_KEY

public static final int PAGE_DOWN_KEY

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ESC_KEY

public static final int ESC_KEY

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TAB_KEY

public static final int TAB_KEY

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SHIFT_KEY

public static final int SHIFT_KEY

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ENTER_KEY

public static final int ENTER_KEY

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Constructor Detail

DrawingPanel

public DrawingPanel(int desiredWidth,
                    int desiredHeight)

Construct a drawing panel of a given width and height enclosed in a window.

Parameters:

desiredWidth - width of panel

desiredHeight - height of panel

Method Detail

run

public void run()

Run the GUI drawing panel in a separate thread so that the application that is drawing to the window can be paused and restarted (never called by an application).

Specified by:

run in interface java.lang.Runnable

Overrides:

run in class java.lang.Thread

setWindowTitle

public void setWindowTitle(java.lang.String name)

Set the windows name -- which appears in the window's header.

Parameters:

name - title of window

closeWindow

public void closeWindow()

Close the DrawingPanel (actually closes the JFrame)

mouseMoved

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

MouseInputListener Callback (application never calls this method)

Specified by:

mouseMoved in interface java.awt.event.MouseMotionListener

mouseEntered

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

MouseInputListener Callback (application never calls this method)

Specified by:

mouseEntered in interface java.awt.event.MouseListener

mouseExited

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

MouseInputListener Callback (application never calls this method)

Specified by:

mouseExited in interface java.awt.event.MouseListener

mousePressed

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

MouseInputListener Callback (application never calls this method)

Specified by:

mousePressed in interface java.awt.event.MouseListener

mouseReleased

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

MouseInputListener Callback (application never calls this method)

Specified by:

mouseReleased in interface java.awt.event.MouseListener

mouseDragged

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

MouseInputListener Callback (application never calls this method)

Specified by:

mouseDragged in interface java.awt.event.MouseMotionListener

mouseClicked

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

MouseInputListener Callback (application never calls this method)

Specified by:

mouseClicked in interface java.awt.event.MouseListener

keyPressed

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

Callback method for "key pressed" events (never call explicitly). Known problem: if multiple keys are being held down simultaneously, the operating system does not always generate new key pressed events for new keys pressed.

Specified by:

keyPressed in interface java.awt.event.KeyListener

keyReleased

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

Callback method for "key release" events (never call explicitly).

Specified by:

keyReleased in interface java.awt.event.KeyListener

keyTyped

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

Callback method for "key typed" events (never used - never call explicitly).

Specified by:

keyTyped in interface java.awt.event.KeyListener

getGraphics

public java.awt.Graphics2D getGraphics()

Obtain the Graphics object needed to draw on the DrawingPanel's offscreen graphics buffer. Make sure you call copyGraphicsToScreen() after all your drawing methods have been called to copy the offscreen graphics to the screen.

setBackground

public void setBackground(java.awt.Color c)

Clears the DrawingPanel's graphics window to the specified color. All previously drawn graphics are erased.

Parameters:

c - new background color

copyGraphicsToScreen

public void copyGraphicsToScreen()

Copy the offscreen graphics buffer to the screen. No graphics are visible until this method is called.

sleep

public void sleep(int millis)

Make your application "sleep" for the specified number of milliseconds.

Parameters:

millis - # of milliseconds

waitForMouseClick

public void waitForMouseClick(int whichButton)

Wait for a mouse click on a specific mouse button (your application goes to sleep until the specific mouse button has been clicked (pressed and released)).

Parameters:

whichButton - which mouse button you want to wait for (DrawingPanel.LEFT_BUTTON, DrawingPanel.MIDDLE_BUTTON, or DrawingPanel.RIGHT_BUTTON).

mouseClickHasOccurred

public boolean mouseClickHasOccurred(int whichButton)

Determine if a mouse click has occurred. Calling this method always resets the status of the specified button to "unclicked." If you want the location of the click, immediately call getMouseClickX(whichButton) and/or getMouseClickY(whichButton)

Parameters:

whichButton - which mouse button you want to check for a click (DrawingPanel.LEFT_BUTTON, DrawingPanel.MIDDLE_BUTTON, or DrawingPanel.RIGHT_BUTTON).

Returns:

true if a mouse click using the specified button has occurred since the last call to this method, false otherwise.

isMouseButtonDown

public boolean isMouseButtonDown(int whichButton)

Determine if a specific mouse button is down at the time of the method call.

Parameters:

whichButton - which mouse button you want to check the status of (DrawingPanel.LEFT_BUTTON, DrawingPanel.MIDDLE_BUTTON, or DrawingPanel.RIGHT_BUTTON).

Returns:

true if a mouse button is down, false otherwise.

getMouseButton

public int getMouseButton()

Get which mouse button was most recently clicked.

Returns:

button code (DrawingPanel.LEFT_BUTTON, DrawingPanel.MIDDLE_BUTTON, or DrawingPanel.RIGHT_BUTTON)

getMouseX

public int getMouseX()

Get the current x coordinate of the mouse.

Returns:

x coordinate of the mouse in pixels (left side of window is 0, right side is the (DrawingPanel's width - 1).

getMouseY

public int getMouseY()

Get the current y coordinate of the mouse.

Returns:

y coordinate of the mouse in pixels (top of window is 0, bottom is the (DrawingPanel's height - 1).

getMouseClickX

public int getMouseClickX(int whichButton)

Get the x coordinate of the mouse's location when the most recent mouse click of the specified button occurred. Call the mouseClickHasOccurred(whichButton) method to determine if a mouse click has occurred. If no mouse click has occurred, this method returns a bogus x coordinate.

Returns:

x coordinate of the mouse (in pixels) when the most recent mouse click for the specified button occurred.

getMouseClickY

public int getMouseClickY(int whichButton)

Get the y coordinate of the mouse's location when the most recent mouse click of the specified button occurred. Call the mouseClickHasOccurred(whichButton) method to determine if a mouse click has occurred. If no mouse click has occurred, this method returns a bogus y coordinate.

Returns:

y coordinate of the mouse (in pixels) when the most recent mouse click for the specified button occurred.

waitForKeyHit

public void waitForKeyHit()

Wait for the user to hit a key on the keyboard -- your application goes to sleep until a key is pressed and released on the keyboard.

keyIsDown

public boolean keyIsDown(int whichKeyCode)

Is the specified key down at this moment in time?

Parameters:

whichKeyCode - which key to check

Returns:

true if the specified key is down, false otherwise.

keyHasBeenHit

public boolean keyHasBeenHit(int whichKeyCode)

Has the specified key been hit (pressed and released)?

Parameters:

whichKeyCode - which key to check

Returns:

true if the specified key has been hit, false otherwise.

waitForKeyPressed

public void waitForKeyPressed()

Wait for the user to press a key on the keyboard -- your application goes to sleep until a key is pressed.

getKeyHitCode

public int getKeyHitCode()

Returns a single "key code" for a key that was pressed and released. If multiple keys are hit at the same time, the order of the keys returned is indeterminate. Key hits are bufferred. Therefore, if multiple keys are hit at the same time, subsequent calls to getKeyHitCode will return the other keys. A "key hit" will only be returned once.

Returns:

returns a key code for the latest key that was pressed and released by a user.

The integer values represents the key that was pressed (and not the upper or lower case of the key).

• For the digits, the codes are equivalent to the Unicode character '0' - '9'
• For the characters, the codes are equivalent to the Unicode characters 'A' - 'Z' (NOTE: CAPITAL LETTERS)
• For the function keys, use the named constants F1_KEY, ... F12_KEY
• For the other special keys, use:
  • DrawingPanel.LEFT_ARROW_KEY
  • DrawingPanel.RIGHT_ARROW_KEY
  • DrawingPanel.UP_ARROW_KEY
  • DrawingPanel.DOWN_ARROW_KEY
  • DrawingPanel.INSERT_KEY
  • DrawingPanel.HOME_KEY
  • DrawingPanel.DELETE_KEY
  • DrawingPanel.PAGE_UP_KEY
  • DrawingPanel.PAGE_DOWN_KEY
  • DrawingPanel.ESC_KEY
  • DrawingPanel.TAB_KEY
  • DrawingPanel.SHIFT_KEY
  • DrawingPanel.ENTER_KEY

numberOfKeysActive

public int numberOfKeysActive()

Return the number of keys that are currently being pressed on the keyboard.

If you call the getKeyCode() the number of times returned by this method, you will get the key codes for all keys currently being held down.

Returns:

number of pressed keys

getRGB

public int getRGB(int x,
                  int y)

Return an integer representation of the color at a specified pixel location.

Returns:

integer RGB value

setRGB

public void setRGB(int x,
                   int y,
                   int RGB)

Set the color at a specified pixel location.

Parameters:

x - x coordinate

y - y coordinate

RGB - color

saveGraphics

public void saveGraphics(java.lang.String filename)

Save the current graphics (in the offscreen buffer) to a file. The file name should have an appropriate image file extension, such as ".bmp" or ".jpg"

Parameters:

filename - name of file

loadBitmap

public static java.awt.image.BufferedImage loadBitmap(java.lang.String filename)

Load a bitmap image into memory.

Parameters:

filename - the name of the bitmap image file (including the .bmp extension)

Returns:

a BufferedImage object