cowboy.java

J2ME核心类及MIDlet类 MIDP用户界面对象 图形处理及低级事件处理 多线程编程 I/O及网络编程 数据库RMS编程 浮点数编程 多媒体及GAME API编程 安全、加密及

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

public class Cowboy extends Sprite {

	static int WIDTH = 32;
	static int HEIGHT = 48;

	static int[] FRAME_SEQUENCE = { 3, 2, 1, 2 }; //图片序列
	
	int myInitialX;
	int myInitialY;

	int myNoJumpInt = -6;

	int myIsJumping = myNoJumpInt;  // 当前的跳动状态

	int myScoreThisJump = 0; // 本次得分

	/**
	 * 构造方法
	 */
	public Cowboy(int initialX, int initialY) throws Exception {
		super(Image.createImage("/icons/cowboy.png"), 
		WIDTH, HEIGHT);
		myInitialX = initialX;
		myInitialY = initialY;
		// 定义参考点在中间，以使得左右转向时显得自然
		defineReferencePixel(WIDTH/2, 0);
		setRefPixelPosition(myInitialX, myInitialY);
		// 设定动画序列
		setFrameSequence(FRAME_SEQUENCE);
	}

	/**
	 * 根据是碰撞来判定是否得分
	 */
	int checkCollision(Tumbleweed tumbleweed) {
		int retVal = 0;
		if(collidesWith(tumbleweed, true)) {
			retVal = 1;
			tumbleweed.reset();
		}
		return(retVal);
	}

	/**
	 * 重置
	 */
	void reset() {
		myIsJumping = myNoJumpInt;
		setRefPixelPosition(myInitialX, myInitialY);
		setFrameSequence(FRAME_SEQUENCE);
		myScoreThisJump = 0;
		// 用设定变形的方式使其面向左
		setTransform(TRANS_NONE);
	}

	/**
	 * 步进，改变其变形及位置
	 */
	void advance(int tickCount, boolean left) {
		if(left) {
			setTransform(TRANS_MIRROR);
			move(-1, 0);
		} else {
			setTransform(TRANS_NONE);
			move(1, 0);
		}
		if(tickCount % 3 == 0) { // 使其略慢一些
			if(myIsJumping == myNoJumpInt) {
				nextFrame();
			} else {
				myIsJumping++;
				if(myIsJumping < 0) {
					setRefPixelPosition(getRefPixelX(), 
						getRefPixelY() - (2<<(-myIsJumping)));
				} else {
					if(myIsJumping != -myNoJumpInt - 1) {
						setRefPixelPosition(getRefPixelX(), 
							getRefPixelY() + (2<<myIsJumping));
					} else {
						myIsJumping = myNoJumpInt;
						setRefPixelPosition(getRefPixelX(), myInitialY);
						setFrameSequence(FRAME_SEQUENCE);
						myScoreThisJump = 0;
					}
				}
			}
		}
	}

	/**
	 * 跳
	 */
	void jump() {
		if(myIsJumping == myNoJumpInt) {
			myIsJumping++;
			// 从走的图形变为Jump的图形
			setFrameSequence(null);
			setFrame(0);
		}
	}

	/**
	 * 加分
	 */
	int increaseScoreThisJump() {
		if(myScoreThisJump == 0) {
			myScoreThisJump++;
		} else {
			myScoreThisJump *= 2;
		}
		return(myScoreThisJump);
	}

}