可视区域应用-android游戏开发

主要方法：
                //----设置矩形可视区域
                canvas.save();
                canvas.clipRect(20,20,50,50);
                canvas.drawBitmap(bmp, 0, 0, paint);
                canvas.restore();
                //----利用Path设置可视区域
                canvas.save();
                Path path=new Path();
                path.addCircle(100+30, 100+30, 30, Direction.CCW);
                canvas.clipPath(path);
                canvas.drawBitmap(bmp, 100, 100, paint);
                canvas.restore();
                //----利用Region设置可视区域
                canvas.save();
                Region region = new Region();
                region.op(new Rect(20,20+300,100,100+300), Region.Op.XOR);
                region.op(new Rect(40,20+300,80,150+300), Region.Op.XOR);
                canvas.clipRegion(region);
                canvas.drawBitmap(bmp, 0, 300, paint);
                canvas.restore();

案例运行结果：

案例源码：

package caicai.animation;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PaintFlagsDrawFilter;
import android.graphics.Path;
import android.graphics.Path.Direction;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.Region;
import android.util.Log;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceHolder.Callback;
import android.view.SurfaceView;

public class clipView 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 Bitmap bmp;// 位图

    // 设置画布绘图无锯齿
    private PaintFlagsDrawFilter pfd = new PaintFlagsDrawFilter(0,
            Paint.ANTI_ALIAS_FLAG);

    public clipView(Context context) {
        super(context);
        sfh = this.getHolder();// 实例SurfaceHolder
        sfh.addCallback(this);// 为SurfaceView添加状态监听
        paint = new Paint();// 实例一个画笔
        paint.setColor(Color.WHITE);// 设置画笔颜色为白色
        setFocusable(true);// 设置焦点
        bmp = BitmapFactory.decodeResource(getResources(), R.drawable.tanke);
    }

    @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.drawColor(Color.BLACK);
                //----设置矩形可视区域
                canvas.save();
                canvas.clipRect(20,20,50,50);
                canvas.drawBitmap(bmp, 0, 0, paint);
                canvas.restore();
                //----利用Path设置可视区域
                canvas.save();
                Path path=new Path();
                path.addCircle(100+30, 100+30, 30, Direction.CCW);
                canvas.clipPath(path);
                canvas.drawBitmap(bmp, 100, 100, paint);
                canvas.restore();
                //----利用Region设置可视区域
                canvas.save();
                Region region = new Region();
                region.op(new Rect(20,20+300,100,100+300), Region.Op.XOR);
                region.op(new Rect(40,20+300,80,150+300), Region.Op.XOR);
                canvas.clipRegion(region);
                canvas.drawBitmap(bmp, 0, 300, paint);
                canvas.restore();
                canvas.drawBitmap(bmp, 200, 300, paint);
            } else {
                Log.i("tt", "获取不到画布");// 释放画布
            }
        } catch (Exception e) {

        } finally {
            if (canvas != null)
                sfh.unlockCanvasAndPost(canvas);
        }
    }

    /**
     * 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

    }

    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) {
        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 clipView(this));

    }
}

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