tanksprite.java

J2ME 上的坦克大战的demo,欢迎大家用来学习使用

/**
 * Copyright_2006, Liao Xuefeng
 * Created on 2006-2-7
 */
package com.javaeedev.j2megame.tank;

import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.Image;
import javax.microedition.lcdui.game.Sprite;

public abstract class TankSprite extends Sprite {

    protected final GameMainCanvas canvas;

    // position in map:
    protected int x;
    protected int y;
    // target position in map:
    protected int target_x;
    protected int target_y;
    // direction defined as Canvas.UP, Canvas.DOWN, Canvas.LEFT, Canvas.RIGHT:
    protected int direction;

    private int lock = 0; // when lock==0, can fire

    public TankSprite(GameMainCanvas canvas, int x, int y, Image image, int direction) {
        super(image, 16, 16);
        this.canvas = canvas;
        this.target_x = this.x = x;
        this.target_y = this.y = y;
        updateKeyPosition();
        switch(direction) {
        case Canvas.DOWN:
            turnDown();
            break;
        case Canvas.LEFT:
            turnLeft();
            break;
        case Canvas.RIGHT:
            turnRight();
            break;
        default:
            turnUp();
        }
    }

    public Bullet fire() {
        if(lock>0) // cannot fire!
            return null;
        lock = 2;
        int fire_x = x*GameMap.TILE_WIDTH;
        int fire_y = y*GameMap.TILE_WIDTH;
        switch(direction) {
        case Canvas.DOWN:
            fire_y += GameMap.TILE_WIDTH*2;
        case Canvas.UP:
            fire_x += GameMap.TILE_WIDTH;
            break;
        case Canvas.RIGHT:
            fire_x += GameMap.TILE_WIDTH*2;
        case Canvas.LEFT:
            fire_y += GameMap.TILE_WIDTH;
            break;
        }
        return new Bullet(direction, fire_x, fire_y);
    }

    /**
     * stay in the same position.
     */
    public void stay() {
        if(lock>0)
            lock--;
        x = target_x;
        y = target_y;
        updateKeyPosition();
    }

    public boolean moveUp() {
        turnUp();
        if(canvas.getGameMap().canMoveUp(x, y, 2, 2)) {
            target_y = y-1;
            updateKeyPosition();
            return true;
        }
        return false;
    }

    public boolean moveDown() {
        turnDown();
        if(canvas.getGameMap().canMoveDown(x, y, 2, 2)) {
            target_y = y+1;
            updateKeyPosition();
            return true;
        }
        return false;
    }

    public boolean moveLeft() {
        turnLeft();
        if(canvas.getGameMap().canMoveLeft(x, y, 2, 2)) {
            target_x = x-1;
            updateKeyPosition();
            return true;
        }
        return false;
    }

    public boolean moveRight() {
        turnRight();
        if(canvas.getGameMap().canMoveRight(x, y, 2, 2)) {
            target_x = x+1;
            updateKeyPosition();
            return true;
        }
        return false;
    }

    public void moveStep(int frameId) {
        // frameId is from 1 to MAX_STEP_FRAMES:
        if(target_x==x && target_y==y)
            return; // no need move!
        updatePosition(frameId);
    }

    public int getMapX() {
        return x;
    }

    public int getMapY() {
        return y;
    }

    private void updateKeyPosition() {
        setPosition(x*GameMap.TILE_WIDTH, y*GameMap.TILE_WIDTH);
    }

    private void updatePosition(int frameId) {
        int curr_x = x*GameMap.TILE_WIDTH;
        int curr_y = y*GameMap.TILE_WIDTH;
        int distance = GameMainCanvas.STEP_WIDTH * frameId;
        switch(direction) {
        case Canvas.UP:
            curr_y -= distance;
            break;
        case Canvas.DOWN:
            curr_y += distance;
            break;
        case Canvas.LEFT:
            curr_x -= distance;
            break;
        case Canvas.RIGHT:
            curr_x += distance;
        }
        setPosition(curr_x, curr_y);
    }


    public void turnUp() {
        if(direction!=Canvas.UP) {
            direction = Canvas.UP;
            setFrame(0);
        }
    }

    public void turnDown() {
        if(direction!=Canvas.DOWN) {
            direction = Canvas.DOWN;
            setFrame(1);
        }
    }

    public void turnLeft() {
        if(direction!=Canvas.LEFT) {
            direction = Canvas.LEFT;
            setFrame(2);
        }
    }

    public void turnRight() {
        if(direction!=Canvas.RIGHT) {
            direction = Canvas.RIGHT;
            setFrame(3);
        }
    }

    public boolean moveTo(int direction) {
        switch(direction) {
        case Canvas.UP:
            return moveUp();
        case Canvas.DOWN:
            return moveDown();
        case Canvas.LEFT:
            return moveLeft();
        case Canvas.RIGHT:
            return moveRight();
        }
        // for other, such as 0, just return false:
        return false;
    }
}