goodtechnique.java

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//: GoodTechnique.java
// Your first choice when overriding components
// should be to install listeners. The code is
// much safer, more modular and maintainable.
import java.awt.*;
import java.awt.event.*;

class Display {
	public static final int
		EVENT = 0, COMPONENT = 1,
		MOUSE = 2, MOUSE_MOVE = 3,
		FOCUS = 4, KEY = 5, ACTION = 6,
		LAST = 7;

	public String[] evnt;

	Display() {
		evnt = new String[LAST];
		for(int i = 0; i < LAST; i++)
			evnt[i] = new String();
	}
	
	public void show(Graphics g) {
		for(int i = 0; i < LAST; i++)
			g.drawString(evnt[i], 0, 10 * i + 10);
	}
}

class EnabledPanel extends Panel {
	Color c;
	int id;
	Display display = new Display();

	public EnabledPanel(int i, Color mc) {
		id = i;
		c = mc;
		setLayout(new BorderLayout());
		add(new MyButton(), BorderLayout.SOUTH);
		addComponentListener(new CL());
		addFocusListener(new FL());
		addKeyListener(new KL());
		addMouseListener(new ML());
		addMouseMotionListener(new MML());
	}

	// To eliminate flicker:
	public void update(Graphics g) {
		paint(g);
	}
	
	public void paint(Graphics g) {
		g.setColor(c);
		Dimension s = getSize();
		g.fillRect(0, 0, s.width, s.height);
		g.setColor(Color.black);
		display.show(g);
	}

	// Don't need to enable anything for this:
	public void processEvent(AWTEvent e) {
		display.evnt[Display.EVENT]= e.toString();
		repaint();
		super.processEvent(e);
	}

	class CL implements ComponentListener {
		public void componentMoved(ComponentEvent e){
			display.evnt[Display.COMPONENT] =
				"Component moved";
			repaint();
		}
		
		public void	componentResized(ComponentEvent e) {
			display.evnt[Display.COMPONENT] =
				"Component resized";
			repaint();
		}
	
		public void componentHidden(ComponentEvent e) {
			display.evnt[Display.COMPONENT] =
				"Component hidden";
			repaint();
		}
	
		public void componentShown(ComponentEvent e){
			display.evnt[Display.COMPONENT] =
				"Component shown";
			repaint();
		}
	}

	class FL implements FocusListener {
		public void focusGained(FocusEvent e) {
			display.evnt[Display.FOCUS] =
				"FOCUS gained";
			repaint();
		}
	
		public void focusLost(FocusEvent e) {
			display.evnt[Display.FOCUS] =
				"FOCUS lost";
			repaint();
		}
	}
	class KL implements KeyListener {
		public void keyPressed(KeyEvent e) {
			display.evnt[Display.KEY] =
				"KEY pressed: ";
			showCode(e);
		}

		public void keyReleased(KeyEvent e) {
			display.evnt[Display.KEY] =
				"KEY released: ";
			showCode(e);
		}

		public void keyTyped(KeyEvent e) {
			display.evnt[Display.KEY] =
				"KEY typed: ";
			showCode(e);
		}
	
		void showCode(KeyEvent e) {
			int code = e.getKeyCode();
			display.evnt[Display.KEY] +=
				KeyEvent.getKeyText(code);
			repaint();
		}
	}

	class ML implements MouseListener {
		public void mouseClicked(MouseEvent e) {
			requestFocus(); // Get FOCUS on click
			display.evnt[Display.MOUSE] =
				"MOUSE clicked";
			showMouse(e);
		}
	
		public void mousePressed(MouseEvent e) {
			display.evnt[Display.MOUSE] =
				"MOUSE pressed";
			showMouse(e);
		}
	
		public void mouseReleased(MouseEvent e) {
			display.evnt[Display.MOUSE] =
				"MOUSE released";
			showMouse(e);
		}
	
		public void mouseEntered(MouseEvent e) {
			display.evnt[Display.MOUSE] =
				"MOUSE entered";
			showMouse(e);
		}

		public void mouseExited(MouseEvent e) {
			display.evnt[Display.MOUSE] =
				"MOUSE exited";
			showMouse(e);
		}

		void showMouse(MouseEvent e) {
			display.evnt[Display.MOUSE] +=
				", x = " + e.getX() +
				", y = " + e.getY();
			repaint();
		}
	}

	class MML implements MouseMotionListener {
		public void mouseDragged(MouseEvent e) {
			display.evnt[Display.MOUSE_MOVE] =
				"MOUSE dragged";
			showMouse(e);
		}

		public void mouseMoved(MouseEvent e) {
			display.evnt[Display.MOUSE_MOVE] =
				"MOUSE moved";
			showMouse(e);
		}

		void showMouse(MouseEvent e) {
			display.evnt[Display.MOUSE_MOVE] +=
				", x = " + e.getX() +
				", y = " + e.getY();
			repaint();
		}
	}
}

class MyButton extends Button {
	int clickCounter;
	String label = "";

	public MyButton() {
		addActionListener(new AL());
	}

	public void paint(Graphics g) {
		g.setColor(Color.green);
		Dimension s = getSize();
		g.fillRect(0, 0, s.width, s.height);
		g.setColor(Color.black);
		g.drawRect(0, 0, s.width - 1, s.height - 1);
		drawLabel(g);
	}

	private void drawLabel(Graphics g) {
		FontMetrics fm = g.getFontMetrics();
		int width = fm.stringWidth(label);
		int height = fm.getHeight();
		int ascent = fm.getAscent();
		int leading = fm.getLeading();
		int horizMargin =
		(getSize().width - width)/2;
		int verMargin =
		(getSize().height - height)/2;
		g.setColor(Color.red);
		g.drawString(label, horizMargin,
		verMargin + ascent + leading);
	}

	class AL implements ActionListener {
		public void actionPerformed(ActionEvent e) {
			clickCounter++;
			label = "click #" + clickCounter +
				" " + e.toString();
			repaint();
		}
	}
}

public class GoodTechnique extends Frame {
	GoodTechnique() {
		setLayout(new GridLayout(2,2));
		add(new EnabledPanel(1, Color.cyan));
		add(new EnabledPanel(2, Color.lightGray));
		add(new EnabledPanel(3, Color.yellow));
	}

	public static void main(String[] args) {
		Frame f = new GoodTechnique();
		f.setTitle("Good Technique");
		f.addWindowListener(
		new WindowAdapter() {
			public void windowClosing(WindowEvent e){
				System.out.println(e);
				System.out.println("Window Closing");
				System.exit(0);
			}
		});
		f.setSize(700,700);
		f.setVisible(true);
	}
} ///:~