code: @SuppressLint("NewApi")
  	private void peekDrawerInvalidate() {
  		if (mPeekScroller.computeScrollOffset()) {
  			final int oldX = (int) mOffsetPixels;
  			final int x = mPeekScroller.getCurrX();
  			if (x != oldX) {
  				setOffsetPixels(x);
  			}
  
  			if (!mPeekScroller.isFinished()) {
  				postOnAnimation(mPeekRunnable);
  				return;
  
  			} else if (mPeekDelay > 0) {
  				mPeekStartRunnable = new Runnable() {
  					@Override
  					public void run() {
  						startPeek();
  					}
  				};
  				postDelayed(mPeekStartRunnable, mPeekDelay);
  			}
  		}
  
  		completePeek();
  	}
docs: Callback when each frame in the peek drawer animation should be drawn.