贝塞尔曲线-android游戏开发

案例简介：通过贝塞尔曲线手指点击屏幕划出曲线来

主要内容：

path.reset();// 重置path
path.moveTo(x[0], y[0]);// 贝赛尔曲线的起始点

path.quadTo(x[i-1], y[i-1], x[i], y[i]);// 设置贝赛尔曲线的操作点以及终止点

canvas.drawPath(path, paint); // 绘制贝赛尔曲线（Path）

源码：

  1 package caicai.animation;
  2 import java.util.Random;
  3 
  4 import android.content.Context;
  5 import android.graphics.Bitmap;
  6 import android.graphics.BitmapFactory;
  7 import android.graphics.Canvas;
  8 import android.graphics.Color;
  9 import android.graphics.Paint;
 10 import android.graphics.Path;
 11 import android.graphics.Paint.Style;
 12 import android.util.Log;
 13 import android.view.MotionEvent;
 14 import android.view.SurfaceHolder;
 15 import android.view.SurfaceHolder.Callback;
 16 import android.view.SurfaceView;
 17 
 18 public class beisaierView extends SurfaceView implements Callback, Runnable {
 19     private Paint paint;// 画布
 20     private SurfaceHolder sfh; // 用于控制SurfaceView
 21     private Canvas canvas;// 画布
 22     private boolean flag;// 关闭线程标志
 23     private Thread th;// 新建线程
 24     private int[] x=null,y=null;//赛尔曲线的起点，操作点以及终止点
 25     private Path path;
 26     int num=0;
 27 
 28     public beisaierView(Context context) {
 29         super(context);
 30         sfh = this.getHolder();// 实例SurfaceHolder
 31         sfh.addCallback(this);// 为SurfaceView添加状态监听    
 32         x=new int[100];
 33         y=new int[100];
 34         x[0]=0;y[0]=0;
 35         path=new Path();
 36         paint = new Paint();//实例一个画笔
 37         paint.setColor(Color.WHITE);//设置画笔颜色为白色
 38         paint.setStyle(Style.STROKE);//设置画笔为轻敲类型
 39         paint.setStrokeWidth(5);
 40         paint.setAntiAlias(true);//画笔是否有锯齿
 41         setFocusable(true);//设置焦点
 42     }
 43 
 44     @Override
 45     public void surfaceCreated(SurfaceHolder holder) {
 46         flag = true;
 47         //实例线程
 48         th = new Thread(this);
 49         //启动线程
 50         th.start();
 51     }
 52 
 53     public void mydraw() {
 54         try {
 55             canvas = sfh.lockCanvas();//锁定画布
 56             if (canvas != null) {
 57                 canvas.drawRGB(0, 0, 0);//刷屏，或者叫重置画布
 58                 drawQpath(canvas);
 59             } else {
 60                 Log.i("tt", "获取不到画布");//释放画布
 61             }
 62         } catch (Exception e) {
 63 
 64         } finally {
 65             if (canvas != null)
 66                 sfh.unlockCanvasAndPost(canvas);
 67         }
 68     }
 69     /**
 70      * 绘制贝赛尔曲线
 71      * 
 72      * @param canvas 主画布
 73      */
 74     private void drawQpath(Canvas canvas2) {
 75         path.reset();// 重置path
 76         path.moveTo(x[0], y[0]);// 贝赛尔曲线的起始点
 77         for(int i=1;i<num;i++){
 78             path.quadTo(x[i-1], y[i-1], x[i], y[i]);    // 设置贝赛尔曲线的操作点以及终止点                
 79         }    
 80         canvas.drawPath(path, paint);    // 绘制贝赛尔曲线（Path）
 81     }
 82 
 83     /**
 84      * SurfaceView视图状态发生改变，响应此函数
 85      */
 86     @Override
 87     public void surfaceChanged(SurfaceHolder holder, int format, int width,
 88             int height) {
 89         // TODO Auto-generated method stub
 90 
 91     }
 92     /**
 93      * SurfaceView视图消亡时，响应此函数
 94      */
 95     @Override
 96     public void surfaceDestroyed(SurfaceHolder holder) {
 97         flag = false;//结束游戏，设置线程关闭标志为false
 98 
 99     }
100     /**
101      * 游戏逻辑
102      */
103     public void logic() {
104 
105     };
106 
107     @Override
108     public void run() {
109         while (flag) {
110             long start = System.currentTimeMillis();
111             mydraw();
112             logic();
113             long end = System.currentTimeMillis();
114             try {
115                 if (end - start < 50) {
116                     Thread.sleep(50 - (end - start));
117                 }
118             } catch (InterruptedException e) {
119                 e.printStackTrace();
120             }
121         }
122     }
123     //获取点击坐标
124     @Override
125     public boolean onTouchEvent(MotionEvent event) {
126         x[num] = (int) event.getX();
127         y[num] = (int) event.getY();
128         num++;
129         return true;
130     }
131 
132 }

beisaierView

 1 package caicai.animation;
 2 
 3 import android.app.Activity;
 4 import android.os.Bundle;
 5 import android.view.Window;
 6 import android.view.WindowManager;
 7 
 8 public class MainActivity extends Activity {
 9     /** Called when the activity is first created. */
10     @Override
11     public void onCreate(Bundle savedInstanceState) {
12         super.onCreate(savedInstanceState);
13         //设置全屏
14         this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
15         requestWindowFeature(Window.FEATURE_NO_TITLE);
16         //显示自定义的SurfaceView视图
17         setContentView(new beisaierView(this));
18 
19     }
20 }

MainActivity

谢谢支持“趣淘鼓浪屿”（www.qtgly.com）