code: private static float computeFocus(float viewSize, float drawableSize, float currentTranslation, float focusCoordinate) {
  		if(currentTranslation > 0 && focusCoordinate < currentTranslation) {
  			return currentTranslation;
  		} else if(currentTranslation < viewSize - drawableSize && focusCoordinate > currentTranslation + drawableSize) {
  			return drawableSize + currentTranslation;
  		}
  
  		return focusCoordinate;
  	}
docs: If our focal point is outside the image, we will project it to our image bounds