code: public void setSaturation(float saturation) {
  		mBarPointerPosition = Math.round((mSatToPosFactor * saturation))
  				+ mBarPointerHaloRadius;
  		calculateColor(mBarPointerPosition);
  		mBarPointerPaint.setColor(mColor);
  		if (mPicker != null) {
  			mPicker.setNewCenterColor(mColor);
  			mPicker.changeValueBarColor(mColor);
  			mPicker.changeOpacityBarColor(mColor);
  		}
  		invalidate();
  	}
docs: Set the pointer on the bar. With the opacity value.
  
  @param saturation float between 0 and 1