AnalysisSystemForRadionuclide_vue/src/utils/chartHelper.js

/**
 * 根据位置获取这个点在图表的哪个轴线上
 * @param offsetX
 * @param offsetY
 */
export function getXAxisAndYAxisByPosition(chart, offsetX, offsetY, seriesIndex = 0) {
    const pointInPixel = [offsetX, offsetY]
    if (
        chart.containPixel(
            {
                seriesIndex: 0
            },
            pointInPixel
        )
    ) {
        const [xAxis, yAxis] = chart.convertFromPixel({ seriesIndex }, pointInPixel)
        return [xAxis, yAxis]
    }
    return null
}

/**
 * 将图表导出为图片
 * @param {import("echarts").ECharts} chartInstance 
 * @param {'png' | 'jpeg' | 'svg'} type
 */
export function exportEchartImg(chartInstance, type = 'png', backgroundColor = '#022024') {
    const dataURL = chartInstance.getDataURL({
        type,
        pixelRatio: 2,
        backgroundColor
    });

    const link = document.createElement('a')
    link.style.display = 'none'
    link.href = dataURL
    link.setAttribute('download', 'export.png')
    document.body.appendChild(link)
    link.click()
    document.body.removeChild(link) //下载完成移除元素

}


/**
 * 按份数分割轴线
 * @param {Number} max 
 * @param {Number} min 
 * @param {Number} cnt 
 * @param {Number} maxBoundaryGap 
 */
export function splitAxis(max, min, cnt, maxBoundaryGap = 1.1) {
    const _min = Math.floor(min)
    const interval = Math.ceil((Math.ceil(max * maxBoundaryGap) - _min) / cnt)
    const _max = _min + interval * cnt

    return {
        min: _min,
        interval,
        max: _max
    }
}