是男人就下100层【第四层】——Crazy贪吃蛇（1）

贪吃蛇是一款非常经典的游戏，这些经典游戏给我们的童年添加了不少乐趣，今天開始我们来一步一步的在Android设备上实现一款贪吃蛇游戏，我也是第一次写这个游戏，有可能会写错，或者走弯路，可是终于希望能有一个好的结果，接下来我们一起来一步步的摸着石头开发吧。

一、建立一个project

二、自己定义View（贪吃蛇界面）

package com.example.crazysnake;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.View;

public class MySnake extends View {
	private Paint paint;
	private RectF rect;

	public MySnake(Context context, AttributeSet attrs) {
		super(context, attrs);
		paint = new Paint();
		rect = new RectF();
	}

	@Override
	protected void onDraw(Canvas canvas) {
		super.onDraw(canvas);
		rect.set(50, 50, 90, 90);
		paint.setColor(Color.RED);
		canvas.drawRect(rect, paint);
	}

}

布局文件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >
	<com.example.crazysnake.MySnake 
	    android:layout_width="match_parent"
	    android:layout_height="match_parent"/>
</LinearLayout>

执行效果：

我们在界面上绘制了一个小方块，这个就是我们完毕贪吃蛇的基础（就像我们要盖一座大楼的砖一样重要）

三、画一条彩蛇

先创建一个方块对象

package com.example.crazysnake;

public class Box {
	private int x;
	private int y;
	
	public Box(int x, int y) {
		super();
		this.x = x;
		this.y = y;
	}
	public int getX() {
		return x;
	}
	public void setX(int x) {
		this.x = x;
	}
	public int getY() {
		return y;
	}
	public void setY(int y) {
		this.y = y;
	}
}

绘制一排方块

package com.example.crazysnake;

import java.util.ArrayList;
import java.util.List;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.View;

public class MySnake extends View {
	private Paint paint;
	private RectF rect;
	
	private int boxSize = 30;
	
	private List<Box> boxs = new ArrayList<Box>();
	
	private static final int[] colors = {
		Color.RED,
		Color.BLUE, 
		Color.GREEN,
		Color.YELLOW
	};

	public MySnake(Context context, AttributeSet attrs) {
		super(context, attrs);
		paint = new Paint();
		rect = new RectF();
		initData();
	}
	
	private void initData(){
		Box box;
		for(int i=0; i<10; i++){
			box = new Box(i*boxSize, 0);
			boxs.add(box);
		}
	}

	@Override
	protected void onDraw(Canvas canvas) {
		super.onDraw(canvas);
		for(int i=0; i<boxs.size(); i++){
			paint.setColor(colors[i % colors.length]);
			rect.set(boxs.get(i).getX(), boxs.get(i).getY(), boxs.get(i).getX() + boxSize, boxSize);
			canvas.drawRect(rect, paint);
		}
	}
}

四、让这条彩蛇移动

重写onTouchEvent方法

	@Override
	public boolean onTouchEvent(MotionEvent event) {
		System.out.println("onTouch");
		switch (event.getAction()) {
		case MotionEvent.ACTION_DOWN:
			mDownX = event.getX();
			mDownY = event.getY();
			break;
		case MotionEvent.ACTION_UP:
			float disX = event.getX() - mDownX;
			float disY = event.getY() - mDownY;
			System.out.println("disX = " + disX);
			System.out.println("dixY = " + disY);
			if(Math.abs(disX) > Math.abs(disY)){
				if(disX > 0){
					System.out.println("right");
					move(Derectory.RIGHT);
				}else{
					move(Derectory.LEFT);
				}
			}else{
				if(disY > 0){
					
				}else{
					
				}
			}
			break;
		}
		return true;
	}

move方法来依据方向移动

	private void move(Derectory derectory){
		Box box;
		int bs = 0;
		switch (derectory) {
		case LEFT:
		case TOP:
			bs = - boxSize;
			break;
		case RIGHT:
		case BOTTOM:
			bs = boxSize;
			break;
		}
		
		if(derectory == Derectory.LEFT || derectory == Derectory.RIGHT){
			for(int i=0; i<boxs.size(); i++){
				box = boxs.get(i);
				box.setX(box.getX() + bs);
			}
		}else{
			for(int i=0; i<boxs.size(); i++){
				box = boxs.get(i);
				box.setY(box.getY() + bs);
			}
		}
		invalidate();
	}

上面代码中我们没有控制边界，须要加入推断边界条件的代码。

五、让蛇自己主动跑，我们来控制它

启动一个线程了让蛇自己主动跑

	private class SnakeThread extends Thread{
		private boolean stoped = false;
		@Override
		public void run() {
			while(!stoped){
				try {
					Thread.sleep(1000);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
				move();
				postInvalidate();
			}
		}
	}

所有代码例如以下：

package com.example.crazysnake;

import java.util.ArrayList;
import java.util.List;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

public class MySnake extends View {
	private Paint paint;
	private RectF rect;
	
	private int boxSize = 30;
	
	private SnakeThread snakeThread;
	
	private List<Box> boxs = new ArrayList<Box>();
	
	private static final int[] colors = {
		Color.RED,
		Color.BLUE, 
		Color.GREEN,
		Color.YELLOW
	};
	
	private enum Derectory{
		LEFT,
		RIGHT,
		TOP,
		BOTTOM;
	}
	
	private Derectory currentDerect = Derectory.RIGHT;

	public MySnake(Context context, AttributeSet attrs) {
		super(context, attrs);
		paint = new Paint();
		rect = new RectF();
		initData();
		startThread();
	}
	
	public void startThread(){
		if(snakeThread == null){
			snakeThread = new SnakeThread();
			snakeThread.start();
		}
	}
	
	private void initData(){
		Box box;
		for(int i=0; i<10; i++){
			box = new Box(i*boxSize, 0);
			boxs.add(box);
		}
	}
	
	private float mDownX;
	private float mDownY;
	@Override
	public boolean onTouchEvent(MotionEvent event) {
		System.out.println("onTouch");
		switch (event.getAction()) {
		case MotionEvent.ACTION_DOWN:
			mDownX = event.getX();
			mDownY = event.getY();
			break;
		case MotionEvent.ACTION_UP:
			float disX = event.getX() - mDownX;
			float disY = event.getY() - mDownY;
			System.out.println("disX = " + disX);
			System.out.println("dixY = " + disY);
			if(Math.abs(disX) > Math.abs(disY)){
				if(disX > 0){
					currentDerect = Derectory.RIGHT;
				}else{
					currentDerect = Derectory.LEFT;
				}
			}else{
				if(disY > 0){
					currentDerect = Derectory.BOTTOM;
				}else{
					currentDerect = Derectory.TOP;
				}
			}
			break;
		}
		return true;
	}
	
	private class SnakeThread extends Thread{
		private boolean stoped = false;
		@Override
		public void run() {
			while(!stoped){
				try {
					Thread.sleep(1000);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
				move();
				postInvalidate();
			}
		}
	}
	
	private void move(){
		Box box;
		if(boxs.get(0).getX() - boxSize < 0) {
			currentDerect = Derectory.RIGHT;
		}
		if(boxs.get(boxs.size() - 1).getX() + 2 * boxSize > getWidth()){
			currentDerect = Derectory.LEFT;
		}
		switch (currentDerect) {
		case LEFT:
			
			for(int i=0; i<boxs.size(); i++){
				box = boxs.get(i);
				box.setX(box.getX() - boxSize);
			}
			break;
		case RIGHT:
			
			for(int i=0; i<boxs.size(); i++){
				box = boxs.get(i);
				box.setX(box.getX() + boxSize);
			}
			break;
		case TOP:
			
			break;
		case BOTTOM:
			
			break;
		}
	}

	@Override
	protected void onDraw(Canvas canvas) {
		super.onDraw(canvas);
		for(int i=0; i<boxs.size(); i++){
			paint.setColor(colors[i % colors.length]);
			rect.set(boxs.get(i).getX(), boxs.get(i).getY(), boxs.get(i).getX() + boxSize, boxSize);
			canvas.drawRect(rect, paint);
		}
	}
}

今天先到这里吧，明天继续......^-^