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：

package caicai.animation;
import java.util.Random;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Paint.Style;
import android.util.Log;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceHolder.Callback;
import android.view.SurfaceView;

public class beisaierView extends SurfaceView implements Callback, Runnable {
    private Paint paint;// 画布
    private SurfaceHolder sfh; // 用于控制SurfaceView
    private Canvas canvas;// 画布
    private boolean flag;// 关闭线程标志
    private Thread th;// 新建线程
    private int[] x=null,y=null;//赛尔曲线的起点，操作点以及终止点
    private Path path;
    int num=0;

    public beisaierView(Context context) {
        super(context);
        sfh = this.getHolder();// 实例SurfaceHolder
        sfh.addCallback(this);// 为SurfaceView添加状态监听    
        x=new int[100];
        y=new int[100];
        x[0]=0;y[0]=0;
        path=new Path();
        paint = new Paint();//实例一个画笔
        paint.setColor(Color.WHITE);//设置画笔颜色为白色
        paint.setStyle(Style.STROKE);//设置画笔为轻敲类型
        paint.setStrokeWidth(5);
        paint.setAntiAlias(true);//画笔是否有锯齿
        setFocusable(true);//设置焦点
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        flag = true;
        //实例线程
        th = new Thread(this);
        //启动线程
        th.start();
    }

    public void mydraw() {
        try {
            canvas = sfh.lockCanvas();//锁定画布
            if (canvas != null) {
                canvas.drawRGB(0, 0, 0);//刷屏，或者叫重置画布
                drawQpath(canvas);
            } else {
                Log.i("tt", "获取不到画布");//释放画布
            }
        } catch (Exception e) {

        } finally {
            if (canvas != null)
                sfh.unlockCanvasAndPost(canvas);
        }
    }
    /**
     * 绘制贝赛尔曲线
     * 
     * @param canvas 主画布
     */
    private void drawQpath(Canvas canvas2) {
        path.reset();// 重置path
        path.moveTo(x[0], y[0]);// 贝赛尔曲线的起始点
        for(int i=1;i<num;i++){
            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）
    }

    /**
     * SurfaceView视图状态发生改变，响应此函数
     */
    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width,
            int height) {
        // TODO Auto-generated method stub

    }
    /**
     * SurfaceView视图消亡时，响应此函数
     */
    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        flag = false;//结束游戏，设置线程关闭标志为false

    }
    /**
     * 游戏逻辑
     */
    public void logic() {

    };

    @Override
    public void run() {
        while (flag) {
            long start = System.currentTimeMillis();
            mydraw();
            logic();
            long end = System.currentTimeMillis();
            try {
                if (end - start < 50) {
                    Thread.sleep(50 - (end - start));
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
    //获取点击坐标
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        x[num] = (int) event.getX();
        y[num] = (int) event.getY();
        num++;
        return true;
    }

}

package caicai.animation;

import android.app.Activity;
import android.os.Bundle;
import android.view.Window;
import android.view.WindowManager;

public class MainActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //设置全屏
        this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        //显示自定义的SurfaceView视图
        setContentView(new beisaierView(this));

    }
}

谢谢支持“趣淘鼓浪屿”（www.qtgly.com）