javascript - 如何通过单击 Chart.js v2 Canvas 外部的自定义按钮来导航工具提示弹出窗口？

Question

关于 Chart.js v2 库下移动可用性的讨论，

我们可以在雷达图表中模拟那些“得分点”的点击事件吗？ 我问这个是因为， 通过单击图表中的这些点以通过返回的索引触发外部交互，桌面 View 和平板电脑 View 对于“得分”导航来说看起来相当不错。

一个流行的例子是

$('#ChartV2').click(function(e) {
            var activePoints = myRadarChart.getElementsAtEvent(e);                  
            var firstPoint = activePoints[0];
            console.log(firstPoint);
            if (firstPoint !== undefined){
               alert(firstPoint._index); 
               //so then we can use 
              // index to hide show results in the  html elements out of canvas , etc
            }

});

但是如果你查看移动 View ， 在responsive:true下，图表会通过自动调整大小而变小， 因此雷达图中的点对于移动点击来说可能非常小，
与标签一样，所有内容都会变得更小并且更难以点击。

是否可以自定义，让用户导航这些“得分点” (最初是通过手动点击 Canvas 触发的)

可以间接触发吗 外部“上一个”、“下一个”导航按钮 位于雷达图的左侧和右侧 例如那些 slider /轮播导航按钮？

Answer 1

您可以通过利用图表实例方法来做到这一点

<小时/>

脚本

var myRadarChart = new Chart(ctx, {
    ...

(function (chart) {
    var helpers = Chart.helpers;

    var currentDatasetIndex;
    var currentPointIndex;

    $('#ChartV2').click(function (e) {
        // try getting an element close to the click
        var activePoints = chart.getElementAtEvent(e);
        var firstPoint = activePoints[0];

        if (firstPoint === undefined) {
            // otherwise pick the first visible element
            helpers.each(chart.data.datasets, function (dataset, datasetIndex) {
                if (firstPoint === undefined && this.isDatasetVisible(datasetIndex)) {
                    var meta = this.getDatasetMeta(datasetIndex);
                    firstPoint = meta.data[0];
                }
            }, chart);
        }

        // need this check as we may have 0 visible elements
        if (firstPoint !== undefined) {
            currentDatasetIndex = firstPoint._datasetIndex;
            currentPointIndex = firstPoint._index;
            $('#prev, #next').removeAttr('disabled');
            updateView();
        }
    });

    $('#prev').click(function () {
        // we add (n - 1) and do a modulo n to move one step back in an n element array.
        if (currentPointIndex === 0)
            currentDatasetIndex = (currentDatasetIndex + chart.data.datasets.length - 1) % chart.data.datasets.length;
        currentPointIndex = (currentPointIndex + chart.data.labels.length - 1) % chart.data.labels.length;
        updateView();
    });

    $('#next').click(function () {
        currentPointIndex = (currentPointIndex + 1) % chart.data.labels.length;
        if (currentPointIndex === 0)
            currentDatasetIndex = (currentDatasetIndex + 1) % chart.data.datasets.length;
        updateView();
    });


    // this (hoisted) function will update the text and show the tooltip
    function updateView() {
        $('#value').text(
            chart.data.datasets[currentDatasetIndex].label + ' : ' +
            chart.data.labels[currentPointIndex] + ' : ' +
            chart.data.datasets[currentDatasetIndex].data[currentPointIndex]);

        // we mess around with an internal variable here - this may not work with a new version
        chart.tooltip._active = [ chart.getDatasetMeta(currentDatasetIndex).data[currentPointIndex] ];
        chart.tooltip.update();
        chart.render();
    }

}(myRadarChart));

如果您只想在小屏幕上使用此功能，只需向上面的图表点击处理程序添加屏幕尺寸检查，并使用媒体查询隐藏按钮和标签。

<小时/>

fiddle - http://jsfiddle.net/uxqL6rwf/