/** * Create a window in which simple graphic elments can be drawn. * Also allow the programmer to easily get user mouse and keyboard inputs. * * @author Dr. Wayne Brown * * @version 1.0 July 2007 Original modification of textbook class * * @version 1.1 19 Sept 2007 Added additional user input for mouse and keyboard * * @version 1.2 31 Aug 2008 All graphics are drawn to an offscreen buffer. * Keyboard and Mouse input enhanced. * Documentation enhanced. * @version 1.3 3 June 2009 updated Javadoc (by Martin Carlisle) * now redraws when window minimized/restored * via MyCanvas class *============================================================================ * Original Documentation by Stuart Reges and Marty Stepp (textbook authors) * 07/01/2005 * The DrawingPanel class provides a simple interface for drawing persistent * images using a Graphics object. An internal BufferedImage object is used * to keep track of what has been drawn. A client of the class simply * constructs a DrawingPanel of a particular size and then draws on it with * the Graphics object, setting the background color if they so choose. * To ensure that the image is always displayed, a timer calls repaint at * regular intervals. * *============================================================================ * Changes made by Dr.Brown to the original code provided by the textbook: * 1) Draws to an "offscreen graphics" window that use user must * then copy to the screen. * 2) The GUI runs in a separate thread to allow for the * suspension and resumption of the application program * (so it can wait for mouse and key events). * 3) Removed the timer that refreshed the graphics image. *============================================================================ */ import java.awt.*; import java.awt.color.*; import java.awt.event.*; import java.awt.image.*; import java.awt.geom.*; import java.awt.EventQueue; import javax.imageio.*; import javax.swing.*; import javax.swing.event.*; public class DrawingPanel extends Thread implements MouseInputListener, KeyListener { public class MyCanvas extends Canvas { public void paint(Graphics g) { // this allows for a redraw when minimized/restored // may cause a not fully drawn image to be displayed // before "copyGraphicsToScreen" called g.drawImage(image, 0, 0, width, height, null ); } } public static final int LEFT_BUTTON = MouseEvent.BUTTON1; // 1 public static final int MIDDLE_BUTTON = MouseEvent.BUTTON2; // 2 public static final int RIGHT_BUTTON = MouseEvent.BUTTON3; // 3 private static final boolean PRETTY = true; // true to anti-alias private static final int STATUS_BAR_HEIGHT = 30; private static final int MAXIMUM_ACTIVE_KEYS = 20; public static final int NO_KEY_PRESSED = 0; public static final int ANY_KEY = 1; public static final int F1_KEY = KeyEvent.VK_F1; public static final int F2_KEY = KeyEvent.VK_F2; public static final int F3_KEY = KeyEvent.VK_F3; public static final int F4_KEY = KeyEvent.VK_F4; public static final int F5_KEY = KeyEvent.VK_F5; public static final int F6_KEY = KeyEvent.VK_F6; public static final int F7_KEY = KeyEvent.VK_F7; public static final int F8_KEY = KeyEvent.VK_F8; public static final int F9_KEY = KeyEvent.VK_F9; public static final int F10_KEY = KeyEvent.VK_F10; public static final int F11_KEY = KeyEvent.VK_F11; public static final int F12_KEY = KeyEvent.VK_F12; public static final int LEFT_ARROW_KEY = KeyEvent.VK_LEFT; public static final int RIGHT_ARROW_KEY = KeyEvent.VK_RIGHT; public static final int UP_ARROW_KEY = KeyEvent.VK_UP; public static final int DOWN_ARROW_KEY = KeyEvent.VK_DOWN; public static final int INSERT_KEY = KeyEvent.VK_INSERT; public static final int HOME_KEY = KeyEvent.VK_HOME; public static final int DELETE_KEY = KeyEvent.VK_DELETE; public static final int PAGE_UP_KEY = KeyEvent.VK_PAGE_UP; public static final int PAGE_DOWN_KEY = KeyEvent.VK_PAGE_DOWN; public static final int ESC_KEY = KeyEvent.VK_ESCAPE; public static final int TAB_KEY = KeyEvent.VK_TAB; public static final int SHIFT_KEY = KeyEvent.VK_SHIFT; public static final int ENTER_KEY = KeyEvent.VK_ENTER; private int width, height; // dimensions of window frame private JFrame frame; // overall window frame private Canvas canvas; // drawing canvas for window (inside panel) private BufferedImage image; // remembers drawing commands private Graphics2D canvasGraphics; // immediate graphics context for painting private Graphics2D offscreenGraphics; // buffered graphics context for painting private JLabel statusBar; // status bar showing mouse position private long createTime; private Thread application; private boolean [] mouseClicked; private int [] mouseClickedX; private int [] mouseClickedY; private int mostRecentMouseButton; private int currentMouseX; private int currentMouseY; private int waitingForButton; private boolean [] buttonDown; // uses indexes of 1, 2, 3 for buttons private int [] activeKeys; private boolean [] keyHasBeenRetreivedByApplication; private boolean [] keyIsDown; private int numberActiveKeys; private int indexOfKeyToReturn; private boolean waitingForKeyHit; private boolean waitingForKeyPressed; //---------------------------------------------------------------------------- /** * Construct a drawing panel of a given width and height enclosed in a window. * @param desiredWidth width of panel * @param desiredHeight height of panel */ public DrawingPanel(int desiredWidth, int desiredHeight) { // Keep a reference to the user application so that it can be suspended to // wait for mouse and keyboard events. width = desiredWidth; height = desiredHeight; application = Thread.currentThread(); // Start the drawing panel in its own thread this.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). */ public void run() { // Construct a buffered image (an offscreen image that is stored in RAM) image = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB); offscreenGraphics = image.createGraphics(); offscreenGraphics.setColor( Color.BLACK ); // Create a AWT canvas object that can be drawn on - the offscreen image will // be drawn onto this canvas canvas = new MyCanvas(); canvas.setPreferredSize(new Dimension(width, height)); canvas.setBounds(0, 0, width, height); canvas.setBackground( Color.WHITE ); canvas.addMouseListener(this); canvas.addMouseMotionListener(this); canvas.addKeyListener(this); canvasGraphics = (Graphics2D) canvas.getGraphics(); // Create a swing label to display the location of the cursor statusBar = new JLabel(" "); statusBar.setBorder(BorderFactory.createLineBorder(Color.BLACK)); statusBar.setBackground(Color.WHITE); statusBar.setForeground(Color.BLACK); statusBar.setBounds(0, STATUS_BAR_HEIGHT, width, 20); // Create the window frame = new JFrame(); frame.setTitle("Drawing Panel"); frame.setResizable(false); frame.setLayout( new BorderLayout() ); frame.getContentPane().add(canvas, "North"); frame.getContentPane().add(statusBar, "South"); frame.pack(); frame.setFocusable(true); frame.setVisible(true); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.toFront(); // Initialize the mouse states // Store information about mouse clicks for each button separately mouseClicked = new boolean[4]; mouseClickedX = new int[4]; mouseClickedY = new int[4]; buttonDown = new boolean[4]; for (int j=0; j<4; j++) { mouseClicked[j] = false; mouseClickedX[j] = 0; mouseClickedY[j] = 0; buttonDown[j] = false; } // Store general information about the state of the mouse mostRecentMouseButton = -1; currentMouseX = -1; currentMouseY = -1; waitingForButton = -1; // Initialize the key (keyboard) states activeKeys = new int[MAXIMUM_ACTIVE_KEYS]; keyHasBeenRetreivedByApplication = new boolean[MAXIMUM_ACTIVE_KEYS]; keyIsDown = new boolean[MAXIMUM_ACTIVE_KEYS]; numberActiveKeys = 0; indexOfKeyToReturn = -1; waitingForKeyHit = false; waitingForKeyPressed = false; // Wait for one second to give the swing library time to create the GUI // and get it on the screen. This makes sure that the AWT canvas // exists on the screen by the time the application tries to display // graphics to it. sleep(1000); // Make the canvas have the focus so that events are immediately sent to it. canvas.requestFocus(); } //---------------------------------------------------------------------------- /** * Set the windows name -- which appears in the window's header. * @param name title of window */ public void setWindowTitle(String name) { frame.setTitle(name); } //---------------------------------------------------------------------------- /** * Close the DrawingPanel (actually closes the JFrame) */ public void closeWindow() { frame.dispose(); } //============================================================================ // Implement all the MouseInputListener methods //============================================================================ //---------------------------------------------------------------------------- /** * MouseInputListener Callback (application never calls this method) */ public void mouseMoved(MouseEvent e) { currentMouseX = e.getX(); currentMouseY = e.getY(); statusBar.setText("(" + currentMouseX + ", " + currentMouseY + ")"); } //---------------------------------------------------------------------------- /** * MouseInputListener Callback (application never calls this method) */ public void mouseEntered(MouseEvent e) { mouseMoved(e); } //---------------------------------------------------------------------------- /** * MouseInputListener Callback (application never calls this method) */ public void mouseExited(MouseEvent e) { statusBar.setText(" "); } //---------------------------------------------------------------------------- /** * MouseInputListener Callback (application never calls this method) */ public void mousePressed(MouseEvent e) { mostRecentMouseButton = e.getButton(); buttonDown[mostRecentMouseButton] = true; } //---------------------------------------------------------------------------- /** * MouseInputListener Callback (application never calls this method) */ public void mouseReleased(MouseEvent e) { mostRecentMouseButton = e.getButton(); buttonDown[mostRecentMouseButton] = false; mouseClicked[mostRecentMouseButton] = true; mouseClickedX[mostRecentMouseButton] = e.getX(); mouseClickedY[mostRecentMouseButton] = e.getY(); } //---------------------------------------------------------------------------- /** * MouseInputListener Callback (application never calls this method) */ public void mouseDragged(MouseEvent e) { mouseMoved(e); } //---------------------------------------------------------------------------- /** * MouseInputListener Callback (application never calls this method) */ public void mouseClicked(MouseEvent e) { int whichButton = e.getButton(); // get the mouse click information and save it for retreival later mouseClicked[whichButton] = true; mouseClickedX[whichButton] = e.getX(); mouseClickedY[whichButton] = e.getY(); mostRecentMouseButton = whichButton; //System.out.println("Recognized click button " + whichButton); if ( waitingForButton == whichButton ) { // The application is waiting for this button waitingForButton = -1; //System.out.println("mouse click = " + mouseButton + " x = " + mouseX + " y = " + mouseY); // Resume the application synchronized(application) { application.notify(); } } } //============================================================================ // Implement the "KeyListener" methods //============================================================================ //---------------------------------------------------------------------------- /** * Internal method to search for a key to see if it is in the "active key" list * (applications will never call this method). * @param keyCode integer value of key */ private int findKeyCodeIndexInList(int keyCode) { for (int j=0; j= 0) { keyIsDown[index] = false; if ( keyHasBeenRetreivedByApplication[index] ) removeActiveKey(index); } // Debugging //printActiveKeys("After keyReleased event: ) // If the application is waiting for a key hit, wake the application up if (waitingForKeyHit) { waitingForKeyHit = false; synchronized(application) { application.notify(); // stop waiting } } } //---------------------------------------------------------------------------- /** * Callback method for "key typed" events (never used - never call explicitly). */ public void keyTyped(KeyEvent e) { } //============================================================================ // Implement the "DrawingPanel's" methods //============================================================================ //---------------------------------------------------------------------------- /** * 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. */ // public Graphics2D getGraphics() { return offscreenGraphics; } //---------------------------------------------------------------------------- /** * Clears the DrawingPanel's graphics window to the specified color. All previously * drawn graphics are erased. * @param c new background color */ public void setBackground(Color c) { // remember the current color so it can be restored Color currentColor = offscreenGraphics.getColor(); offscreenGraphics.setColor(c); offscreenGraphics.fillRect(0,0,width,height); // restore color offscreenGraphics.setColor(currentColor); } //---------------------------------------------------------------------------- /** * Copy the offscreen graphics buffer to the screen. No graphics are visible * until this method is called. */ public void copyGraphicsToScreen() { Graphics2D myG = (Graphics2D) canvas.getGraphics(); myG.drawImage(image, 0, 0, width, height, null ); } //---------------------------------------------------------------------------- /** * Make your application "sleep" for the specified number of milliseconds. * @param millis # of milliseconds */ public void sleep(int millis) { synchronized(application) { try { application.sleep(millis); } catch (InterruptedException e) {} } } //---------------------------------------------------------------------------- /** * 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)). * * @param whichButton which mouse button you want to wait for * (DrawingPanel.LEFT_BUTTON, DrawingPanel.MIDDLE_BUTTON, or DrawingPanel.RIGHT_BUTTON). */ public void waitForMouseClick(int whichButton) { if (whichButton >= LEFT_BUTTON && whichButton <= RIGHT_BUTTON) { waitingForButton = whichButton; //System.out.println("Waiting for button " + whichButton + ". Application waiting."); synchronized(application) { try { application.wait(); } catch ( InterruptedException e) {}; } } } //---------------------------------------------------------------------------- /** * 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) * * @param whichButton which mouse button you want to check for a click * (DrawingPanel.LEFT_BUTTON, DrawingPanel.MIDDLE_BUTTON, or DrawingPanel.RIGHT_BUTTON). * * @return true if a mouse click using the specified button has occurred since the last call to this method, * false otherwise. */ public boolean mouseClickHasOccurred(int whichButton) { if (whichButton >= LEFT_BUTTON && whichButton <= RIGHT_BUTTON) { boolean status = mouseClicked[whichButton]; mouseClicked[whichButton] = false; return status; } return false; } //---------------------------------------------------------------------------- /** * Determine if a specific mouse button is down at the time of the method call. * * @param whichButton which mouse button you want to check the status of * (DrawingPanel.LEFT_BUTTON, DrawingPanel.MIDDLE_BUTTON, or DrawingPanel.RIGHT_BUTTON). * * @return true if a mouse button is down, false otherwise. */ public boolean isMouseButtonDown(int whichButton) { if (whichButton >= LEFT_BUTTON && whichButton <= RIGHT_BUTTON) return buttonDown[whichButton]; else return false; } //---------------------------------------------------------------------------- /** * Get which mouse button was most recently clicked. * * @return button code (DrawingPanel.LEFT_BUTTON, DrawingPanel.MIDDLE_BUTTON, or DrawingPanel.RIGHT_BUTTON) */ public int getMouseButton() { return mostRecentMouseButton; } //---------------------------------------------------------------------------- /** * Get the current x coordinate of the mouse. * * @return x coordinate of the mouse in pixels (left side of window is 0, right * side is the (DrawingPanel's width - 1). */ public int getMouseX() { return currentMouseX; } //---------------------------------------------------------------------------- /** * Get the current y coordinate of the mouse. * * @return y coordinate of the mouse in pixels (top of window is 0, bottom * is the (DrawingPanel's height - 1). */ public int getMouseY() { return currentMouseY; } //---------------------------------------------------------------------------- /** * 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. * * @return x coordinate of the mouse (in pixels) when the most recent mouse click for the specified button occurred. */ public int getMouseClickX(int whichButton) { if (whichButton >= LEFT_BUTTON && whichButton <= RIGHT_BUTTON) { return mouseClickedX[whichButton]; } else return -1; } //---------------------------------------------------------------------------- /** * 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. * * @return y coordinate of the mouse (in pixels) when the most recent mouse click for the specified button occurred. */ public int getMouseClickY(int whichButton) { if (whichButton >= LEFT_BUTTON && whichButton <= RIGHT_BUTTON) { return mouseClickedY[whichButton]; } else return -1; } //---------------------------------------------------------------------------- /** * 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. */ // public void waitForKeyHit() { waitingForKeyHit = true; synchronized(application) { try { application.wait(); } catch ( InterruptedException e) {}; } } //---------------------------------------------------------------------------- /** * Is the specified key down at this moment in time? * * @param whichKeyCode which key to check * * @return true if the specified key is down, false otherwise. */ public boolean keyIsDown(int whichKeyCode) { if (whichKeyCode == ANY_KEY) { // if any key is in the active buffer and down, then return true for (int j=0; j= 0) return keyIsDown[index]; } return false; } //---------------------------------------------------------------------------- /** * Has the specified key been hit (pressed and released)? * * @param whichKeyCode which key to check * * @return true if the specified key has been hit, false otherwise. */ public boolean keyHasBeenHit(int whichKeyCode) { if (whichKeyCode == ANY_KEY) { // if any key is in the active buffer and not down, then return true for (int j=0; j= 0) { if ( ! keyIsDown[index] && ! keyHasBeenRetreivedByApplication[index] ) { removeActiveKey( index ); return true; } } } return false; } //---------------------------------------------------------------------------- /** * Wait for the user to press a key on the keyboard -- your application goes to * sleep until a key is pressed. */ // public void waitForKeyPressed() { waitingForKeyPressed = true; synchronized(application) { try { application.wait(); } catch ( InterruptedException e) {}; } } //---------------------------------------------------------------------------- /** * 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. * * @return 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
      • *
    *
    • *
* */ public int getKeyHitCode() { int returnKeyCode = NO_KEY_PRESSED; // assume there are no active keys if (numberActiveKeys > 0) { // Debugging //printActiveKeys("Start of getKeyHitCode: " ); //System.out.println("indexOfKeyToReturn = " + indexOfKeyToReturn); // Make sure there is a valid index into the keys hit buffer if (indexOfKeyToReturn < 0 || indexOfKeyToReturn >= numberActiveKeys) indexOfKeyToReturn = 0; // Only return the active key if it has been released and it has not been // returned previously. if (! keyIsDown[indexOfKeyToReturn] && ! keyHasBeenRetreivedByApplication[indexOfKeyToReturn] ) { returnKeyCode = activeKeys[indexOfKeyToReturn]; removeActiveKey( indexOfKeyToReturn ); if (indexOfKeyToReturn >= numberActiveKeys) indexOfKeyToReturn = 0; } else indexOfKeyToReturn = (indexOfKeyToReturn + 1) % numberActiveKeys; } return returnKeyCode; } //---------------------------------------------------------------------------- /** * 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. * @return number of pressed keys */ public int numberOfKeysActive() { return numberActiveKeys; } //---------------------------------------------------------------------------- /** * Return an integer representation of the color at a specified pixel location. * @return integer RGB value */ public int getRGB(int x, int y) { try { return image.getRGB(x,y); } catch(Exception e) {return 0;} } //---------------------------------------------------------------------------- /** * Set the color at a specified pixel location. * @param x x coordinate * @param y y coordinate * @param RGB color */ public void setRGB(int x, int y, int RGB) { try { image.setRGB(x, y, RGB); } catch(Exception e) {} } /** * 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" * @param filename name of file */ public void saveGraphics(String filename) { String extension = filename.substring(filename.lastIndexOf(".") + 1); // write file try { ImageIO.write(image, extension, new java.io.File(filename)); } catch (java.io.IOException e) { System.err.println("Unable to save image:\n" + e); } } /** * Load a bitmap image into memory. * * @param filename the name of the bitmap image file (including the .bmp extension) * * @return a BufferedImage object */ public static BufferedImage loadBitmap(String filename) { // read file try { BufferedImage image = ImageIO.read( new java.io.File(filename) ); return image; } catch (java.io.IOException e) { System.err.println("Unable to read bitmap image:\n" + e); return null; } } }