arctest.java

java教程第八章事例

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

public class ArcTest extends MIDlet implements CommandListener, ItemStateListener{

	Display display;
	MyCanvas myCanvas;
	ChoiceGroup setFilled;
	Form form;
	Gauge setStartAngle, setAngle;
	Gauge setWidth, setHeight;
	Command okCmd;

	public ArcTest(){
		display = Display.getDisplay(this);
		myCanvas = new MyCanvas();
		form = new Form("选择弧形类型");
		setStartAngle = new Gauge("起始角度", true, 360, 0);
		setAngle = new Gauge("展开角度", true, 360, 90);
		setWidth = new Gauge("宽度", true, myCanvas.getWidth()/2, myCanvas.getWidth()/4);
		setHeight = new Gauge("高度", true, myCanvas.getHeight()/2, myCanvas.getWidth()/4);
		okCmd = new Command("确定", Command.OK, 1);
		setFilled = new ChoiceGroup("Filled", List.EXCLUSIVE);
		setFilled.append("FALSE", null);
		setFilled.append("TRUE", null);
		form.append(setFilled);
		form.append(setStartAngle);
		form.append(setAngle);
		form.append(setWidth);
		form.append(setHeight);
		form.addCommand(okCmd);
		form.setCommandListener(this);
		form.setItemStateListener(this);
	}


	public void startApp(){
		display.setCurrent(myCanvas);
	}

	public void pauseApp(){

	}


	public void destroyApp(boolean unconditional){

	}

	public void commandAction(Command c, Displayable d){

		if(c == okCmd){
			int index = setFilled.getSelectedIndex();
			myCanvas.isFilled = (index == 0? false: true);
			myCanvas.arcWidth = setWidth.getValue();
			myCanvas.arcHeight = setHeight.getValue();
			myCanvas.startAngle = setStartAngle.getValue();
			myCanvas.angle = setAngle.getValue();
		}
		myCanvas.repaint();
		display.setCurrent(myCanvas);
	}

	public void itemStateChanged(Item item){
		if(item == setWidth){
			setWidth.setLabel("高度"+setWidth.getValue());
		}
		else if(item == setHeight){
			setHeight.setLabel("宽度"+ setHeight.getValue());
		}
		else if(item == setStartAngle){
			setStartAngle.setLabel("起始角度："+setStartAngle.getValue());
		}
		else if(item == setAngle){
			setAngle.setLabel("展开角度："+setAngle.getValue());
		}

	}

	class MyCanvas extends Canvas implements CommandListener{

		int arcWidth;
		int arcHeight;
		int startAngle, angle;
		int x, y;
		int mode;
		boolean isFilled;
		Command exitCmd;
		Command changeCmd;

		public MyCanvas(){
			x = getWidth()/4;
			y = getHeight()/4;
			arcWidth = getWidth()/2;
			arcHeight = getHeight()/2;
			startAngle = 0;
			angle = 180;
			isFilled = false;
			exitCmd = new Command("退出", Command.EXIT, 1);
			changeCmd = new Command("改变", Command.SCREEN, 1);
			addCommand(exitCmd);
			addCommand(changeCmd);
			setCommandListener(this);
		}

		public void paint(Graphics g){

			g.setColor(0xFFFFFF);
			g.fillRect(0, 0, getWidth(), getHeight());
			g.setColor(0);
			if(isFilled){
				g.fillArc(x, y, arcWidth, arcHeight, startAngle, angle);
			}
			else{
				g.drawArc(x, y, arcWidth, arcHeight, startAngle, angle);
			}
		}

		public void commandAction(Command c, Displayable d){

			if(c == exitCmd){
				destroyApp(true);
				notifyDestroyed();
			}
			else if(c == changeCmd){
				display.setCurrent(form);
			}
		}
	}
}