microtankcanvas.java

通过一个坦克的小例子介绍了j2me精灵类的用法

import java.io.IOException;

import javax.microedition.lcdui.*;
import javax.microedition.lcdui.game.*;

public class MicroTankCanvas extends GameCanvas implements Runnable {
    private volatile boolean mTrucking;

    private MicroTankSprite mTank;

    private TiledLayer mBoard;

    private LayerManager mLayerManager;

    public MicroTankCanvas() throws IOException {
        super(false);

        mTank = createTank();
        mTank.setPosition(0, 24);
        mBoard = createBoard();

        mLayerManager = new LayerManager();
        mLayerManager.append(mTank);
        mLayerManager.append(mBoard);
    }

    private MicroTankSprite createTank() throws IOException {
        Image image = Image.createImage("/tank.png");
        return new MicroTankSprite(image, 32, 32);
    }

    private TiledLayer createBoard() throws IOException {
        Image image = Image.createImage("/board.png");
        TiledLayer tiledLayer = new TiledLayer(10, 10, image, 16, 16);

        int[] map = { 1, 1, 1, 1, 11, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0, 0, 0, 0,
                0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 7, 1, 0, 0, 0, 0, 0, 1,
                1, 1, 1, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, 11, 0, 0, 0,
                0, 0, 0, 0, 7, 6, 0, 0, 0, 0, 0, 0, 0, 7, 6, 0, 0, 0 };

        for (int i = 0; i < map.length; i++) {
            int column = i % 10;
            int row = (i - column) / 10;
            tiledLayer.setCell(column, row, map[i]);
        }

        return tiledLayer;
    }

    public void start() {
        mTrucking = true;
        Thread t = new Thread(this);
        t.start();
    }

    public void run() {
        Graphics g = getGraphics();

        int timeStep = 80;

        while (mTrucking) {
            long start = System.currentTimeMillis();

            tick(); //
            input();  //
            render(g);  //

            long end = System.currentTimeMillis();
            int duration = (int) (end - start);
            debug(g, duration * 100 / timeStep);

            if (duration < timeStep) {
                try {
                    Thread.sleep(timeStep - duration);
                } catch (InterruptedException ie) {
                    stop();
                }
            }
        }
    }

    private void tick() {
        if (mTank.collidesWith(mBoard, true))
            mTank.undo();
    }

    private void input() {
        int keyStates = getKeyStates();
        if ((keyStates & LEFT_PRESSED) != 0)
            mTank.turn(-1);
        else if ((keyStates & RIGHT_PRESSED) != 0)
            mTank.turn(1);
        else if ((keyStates & UP_PRESSED) != 0)
            mTank.forward(2);
        else if ((keyStates & DOWN_PRESSED) != 0)
            mTank.forward(-2);
    }

    private void render(Graphics g) {
        int w = getWidth();
        int h = getHeight();

        g.setColor(0xffffff);
        g.fillRect(0, 0, w, h);

        int x = (w - 160) / 2;
        int y = (h - 160) / 2;

        mLayerManager.paint(g, x, y);

        g.setColor(0x000000);
        g.drawRect(x, y, 160, 160);

        flushGraphics();
    }

    private void debug(Graphics g, int percent) {
        int w = getWidth();
        int h = getHeight();

        StringBuffer sb = new StringBuffer();
        sb.append(Integer.toString(percent));
        sb.append('%');
        String s = sb.toString();

        Font font = g.getFont();
        int sw = font.stringWidth(s) + 2;
        int sh = font.getHeight();

        // Draw the render capacity.
        g.setColor(0xffffff);
        g.fillRect(w - sw, h - sh, sw, sh);
        g.setColor(0x000000);
        g.drawRect(w - sw, h - sh, sw, sh);
        g.drawString("" + percent + "%", w, h, Graphics.RIGHT
                | Graphics.BOTTOM);

        flushGraphics();
    }

    public void stop() {
        mTrucking = false;
    }
}