TTFConfig 设置distanceFieldEnabled后Size宽度取值变大

Cocos2d-x
#1

TTFConfig config;
config.fontFilePath = font;
config.fontSize = 18;
config.glyphs = GlyphCollection::DYNAMIC;
config.customGlyphs = nullptr;
config.distanceFieldEnabled = true

Label* _text = Label::createWithTTF(config, _str);

_text->getContentSize();

取出的宽度可以达到40多？按理说应该变小才对啊？
设置为false时取值正常