applet awt绘图实例 坐标图

[java]代码库

import java.awt.*;
import java.awt.event.*;
import java.applet.*;

public class ArcTest extends Applet implements WindowListener {
	ArcControls controls;

	public void init() { // Applet的入口方法
		setLayout(new BorderLayout());
		ArcCanvas c = new ArcCanvas();

		add("Center", c);
		add("South", controls = new ArcControls(c));
	}

	public void start() {
		controls.setEnabled(true); // 激活controls
	}

	public void stop() {
		controls.setEnabled(false);
	}

	public void windowActivated(WindowEvent e) {
	}

	// 重写WindowListener的方法
	public void windowClosed(WindowEvent e) {
	}

	// 重写WindowListener的方法
	public void windowClosing(WindowEvent e) {
		// 重写WindowListener的方法
		System.exit(0);
	}

	public void windowDeactivated(WindowEvent e) {
	}

	// 重写WindowListener的方法
	public void windowDeiconified(WindowEvent e) {
	}

	// 重写WindowListener的方法
	public void windowIconified(WindowEvent e) {
	}

	// 重写WindowListener的方法
	public void windowOpend(WindowEvent e) {
	}

	// 重写WindowListener的方法

	public static void main(String args[]) {
		Frame f = new Frame("ArcTest"); // 构造Frame
		ArcTest arcTest = new ArcTest(); // 构造arcTest
		arcTest.init();
		arcTest.start();
		f.add("Center", arcTest);
		f.setSize(300, 300);
		f.show();

		f.addWindowListener(arcTest);
	}

	@Override
	public void windowOpened(WindowEvent arg0) {
		// TODO Auto-generated method stub

	}
}

class ArcCanvas extends Canvas { // 类ArcCanvas
	int startAngle = 0;
	int endAngle = 45;
	boolean filled = false;
	Font font;

	public void paint(Graphics g) {
		// paint方法，该方法的作用是在Canvas上画图
		Rectangle r = getBounds();
		int hlines = r.height / 10;
		int vlines = r.width / 10;
		g.setColor(Color.pink);

		for (int i = 1; i <= hlines; i++) {
			g.drawLine(0, i * 10, r.width, i * 10);
		}
		for (int i = 1; i <= vlines; i++) {
			g.drawLine(i * 10, 0, i * 10, r.height);
		}
		g.setColor(Color.red);
		if (filled) {
			g.fillArc(0, 0, r.width - 1, r.height - 1, startAngle, endAngle);
		} else {
			g.drawArc(0, 0, r.width - 1, r.height - 1, startAngle, endAngle);
		}

		g.setColor(Color.black);
		g.setFont(font);
		g.drawLine(0, r.height / 2, r.width, r.height / 2);
		g.drawLine(r.width / 2, 0, r.width / 2, r.height);
		g.drawLine(0, 0, r.width, r.height);
		g.drawLine(r.width, 0, 0, r.height);
		int sx = 10;
		int sy = r.height - 28;
		g.drawString("S=" + startAngle, sx, sy);
		g.drawString("E=" + endAngle, sx, sy + 14);
	}

	public void redraw(boolean filled, int start, int end) { // 重画方法
		this.filled = filled;
		this.startAngle = start;
		this.endAngle = end;
		repaint();
		// 通过调用repaint()方法，从而最终调用paint方法完成重画
	}
}

class ArcControls extends Panel implements ActionListener { // ArcControls类
	TextField s;
	TextField e;
	ArcCanvas canvas;

	public ArcControls(ArcCanvas canvas) {
		Button b = null;
		this.canvas = canvas;
		add(s = new TextField("0", 4));
		add(e = new TextField("45", 4));
		b = new Button("Fill");
		b.addActionListener(this);
		add(b);
		b = new Button("Draw");
		b.addActionListener(this);
		add(b);
	}

	public void actionPerformed(ActionEvent ev) {
		// 实现接口ActionListener的方法
		String label = ev.getActionCommand();
		canvas.redraw(label.equals("Fill"),
				Integer.parseInt(s.getText().trim()),
				Integer.parseInt(e.getText().trim()));
	}
}