判断控件是不是在屏幕可见范围

<pre>
public class MainActivity extends AppCompatActivity {
private NestedScrollView mScrollView;
private TextView mTextView;
private int mScreenHeight;
private int mScreenWeight;
private Rect mRect;
private boolean isReady;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    WindowManager windowManager = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
    Point point = new Point();
    windowManager.getDefaultDisplay().getSize(point);
    mScreenHeight = point.y;
    mScreenWeight = point.x;
    initViews();
}
private void initViews() {
    mScrollView= (NestedScrollView) findViewById(R.id.nested_scroll);
    mTextView= (TextView) findViewById(R.id.text4);
    mRect = new Rect(0,0,mScreenWeight,mScreenHeight );
    mScrollView.setOnScrollChangeListener(new NestedScrollView.OnScrollChangeListener() {
        @Override
        public void onScrollChange(NestedScrollView v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
            if(mTextView.getLocalVisibleRect(mRect)){
                if (isReady) {
                    isReady=false;
                    System.out.println("控件在屏幕显示范围内");
                }
            }else{
                if (!isReady){
                    isReady=true;
                    System.out.println("控件在屏幕显示范围外");
                }
            }
        }
    });

}}
</pre>