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