Android自定义一个图形单点移动缩小的效果

public class MainActivity extends Activity {  View view;  public static final int DRAG = 1;  public static final int SCALE = 2;  int mode = 1;  int height = 10, width = 10;  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    getWindow().requestFeature(Window.FEATURE_NO_TITLE);    setContentView(R.layout.activity_main);    view = findViewById(R.id.view);  }  float length = 1;  // 重写  @Override  public boolean onTouchEvent(MotionEvent event) {    int x = (int) event.getX();    int y = (int) event.getY();    // 多指触控    switch (event.getAction() & event.getActionMasked()) {    case MotionEvent.ACTION_DOWN:      mode = DRAG;      break;    case MotionEvent.ACTION_POINTER_DOWN:      Log.e("TAG", "多指移动");      mode = SCALE;      // 两个手指开始的长度是多少呢？      length = calc(event);      break;    case MotionEvent.ACTION_UP:      length = 1;      break;    case MotionEvent.ACTION_MOVE:      if (mode == DRAG) {        // 1. 单个手指        FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(            width, height);        params.setMargins(x, y, 0, 0);        view.setLayoutParams(params);      } else {        // 2. 两个手指        float beilv = calc(event) / length;        width = (int) (view.getWidth() * beilv);        height = (int) (view.getHeight() * beilv);        Log.e("TAG", beilv + " " + width + " " + height);        FrameLayout.LayoutParams params = (LayoutParams) view            .getLayoutParams();        params.width = width;        params.height = height;        view.setLayoutParams(params);      }      break;    }    return true;  }  // 类 Ponint  public float calc(MotionEvent event) {    float x1 = event.getX();    float y1 = event.getY();    float x2 = event.getX(1);    float y2 = event.getY(1);    return (float) Math.sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));  }}