private boolean topCanBounce() {
   boolean b1 = mBrwView.getScrollYWrap() == 0;
   if (b1) {
     return true;
   } else {
     return false;
   }
 }
 private boolean bottomCanBounce() {
   float nowScale = mBrwView.getScaleWrap();
   int h1 = (int) (mBrwView.getContentHeight() * nowScale);
   int h2 = mBrwView.getScrollYWrap() + mBrwView.getHeightWrap();
   if (h1 <= h2 + 5) {
     return true;
   } else {
     return false;
   }
 }