canvas instanceof MagicBrushCanvas 是怎么回事? const query = wx.createSelectorQuery().in(_this) query.select('#photo_canvas') .fields({ node: true, size: true }) 手机预览,控制台提示 canvas instanceof MagicBrushCanvas 是怎么回事?https://developers.weixin.qq.com/s/oSNjAsmI7UCr