html2canvas 转换图片出现锯齿，提升图片质量

html2canvas(this.$refs['point-detail-info'], {
                        backgroundColor: 'transparent',// 设置背景透明
                        dpi: window.devicePixelRatio * 4,
                        scale: 4,
                        width: document.body.clientWidth,
                        heigth: document.body.clientHeight,
                    }).then(canvas2 => {
                          // TODO 
                     })