撕衣服小游戏原理

/*撕衣服原理：底层放无衣服人物，上层放穿衣服人物当触摸划过使上层划过像素变透明*/    public class MainActivity extends Activity {    private ImageView iv;    private Bitmap srcBM;    private Bitmap copyBM;    private Canvas canvas;    private Paint paint;    private Matrix matrix;    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        iv = (ImageView) findViewById(R.id.iv);        srcBM = BitmapFactory.decodeResource(getResources(), R.drawable.pre);        copyBM = Bitmap.createBitmap(srcBM.getWidth(),srcBM.getHeight(), srcBM.getConfig());        canvas = new Canvas(copyBM);        paint = new Paint();        matrix = new Matrix();        canvas.drawBitmap(srcBM, matrix, paint);        iv.setImageBitmap(copyBM);        iv.setOnTouchListener(new OnTouchListener() {            @Override            public boolean onTouch(View v, MotionEvent event) {                int action = event.getAction();                switch (action) {                case MotionEvent.ACTION_MOVE:                    int x = (int) event.getX();                    int y = (int) event.getY();                    for(int i = -15;i < 15;i++){                        for(int j = -10;j < 10;j++){                            copyBM.setPixel(x+i, y+j, Color.TRANSPARENT);                        }                    }                    iv.setImageBitmap(copyBM);                                      break;                }                return true;            }        });    }}