code: boolean tryCaptureViewForDrag(View toCapture, int pointerId) {
          if (toCapture == mCapturedView && mActivePointerId == pointerId) {
              // Already done!
              return true;
          }
          if (toCapture != null && mCallback.tryCaptureView(toCapture, pointerId)) {
              mActivePointerId = pointerId;
              captureChildView(toCapture, pointerId);
              return true;
          }
          return false;
      }
docs: Attempt to capture the view with the given pointer ID. The callback will be involved.
  This will put us into the "dragging" state. If we've already captured this view with
  this pointer this method will immediately return true without consulting the callback.
  
  @param toCapture View to capture
  @param pointerId Pointer to capture with
  @return true if capture was successful