prio 为屏幕的像素数绘画比例 wx.canvasToTempFilePath({       x: 0,       y: that.data.startH2,       width: wid,       height: that.data.endH2,       destWidth: wid *prio,       destHeight: that.data.endH2 * prio,       quality: 1.0,       canvasId: 'cover-preview',       success: function (res) {         //res.tempFilePath即为生成的图片路径         console.log(res.tempFilePath)       }     }) 导出的图片模糊，哪个大神指导一下怎么解决这个问题