如何使用Chart.js显示折线图数据集点标签？

Question

我有设计要求显示包含5个趋势数据数据集的折线图。沿着笔划线的每个数据值需要在其各自的数据点显示数据值标签。

不幸的是，我在Charts.js中找不到满足此要求的选项。

是否有可以帮助我的解决方法？

我也把它发布在小提琴上：http://jsfiddle.net/s9eannLh/

非常感谢！

    var data = {
                labels: ["","Jun 2013","Jul 2013","Aug 2013","Sep 2013","Oct 2013","Nov 2013","Dec 2013","Jan 2014","Feb 2014","Mar 2014","Apr 2014","May 2014"],
                datasets: [
                    {
                        label: "hemoglobin_1",
                        title: "test",
                        fillColor: "transparent",
                        strokeColor: "#65204c",
                        pointColor: "#65204c",
                        pointHighlightStroke: "#FFF",
                        data: [null,5.7,5.7,5.8,5.7,5.8,5.7,5.9,6.7,6.7,6.5,6.4,6.4]
                    },
                    {
                        label: "hemoglobin_2",
                        fillColor: "transparent",
                        strokeColor: "#ed7141",
                        pointColor: "#ed7141",
                        pointHighlightStroke: "#FFF",
                        data: [null,15.5,15.5,15.6,15.2,15.6,15.1,15.8,17,17.4,16.8,16.4,16.4]
                    },                    
                    {
                        label: "hemoglobin_3",
                        fillColor: "transparent",
                        strokeColor: "#de4760",
                        pointColor: "#de4760",
                        pointHighlightStroke: "#FFF",
                        data: [null,37.1,37,37.2,37.6,36.9,37.6,36.8,37.6,38,37.5,39.1,37.5]
                    },
                    {
                        label: "hemoglobin_4",
                        fillColor: "transparent",
                        strokeColor: "#fdcf7e",
                        pointColor: "#fdcf7e",                          
                        pointHighlightStroke: "#FFF",
                        data: [null,29.9,30.4,29.5,29.6,30.2,29.4,29.8,26.9,27,28.5,26.8,28.5]
                     },                                        
                    {
                        label: "hemoglobin_5",
                        fillColor: "transparent",
                        strokeColor: "#a33a59",
                        pointColor: "#a33a59",
                        pointHighlightStroke: "#FFF",
                        data: [null,11.8,11.4,11.9,11.9,11.5,12.2,11.7,11.8,10.9,10.7,11.3,11.3]
                    }
                ]
            };

            var options = {
                responsive: true,
                scaleOverride: true,
                scaleSteps: 10,
                scaleStepWidth: 5,
                scaleStartValue: 0,
                showTooltips: false,
                pointDot: true,
                pointDotRadius : 6,
                datasetStrokeWidth : 3,
                bezierCurve : false,
                scaleShowHorizontalLines: false,
                scaleGridLineWidth : 2,
                scaleGridLineColor : "#EEEEEE",
                scaleLineWidth: 3,
                scaleLineColor: "#000000",
                scaleFontFamily: '"Gotham Book",sans-serif',
                scaleFontSize: 18
            }

            var ctx = $("#myChart").get(0).getContext("2d");
            var Trends = new Chart(ctx).Line(data, options);

Answer 1

我终于找到了这个问题的解决方案。

我意识到我可以访问DOM中的图表对象：

Trends.datasets

在五个数据集中的每个数据集中都有一个包含x＆amp;的点对象。我的职位：

Trends.datasets[0..4].points

因此，我使用Chart.js中的全局配置函数通过回调解析了这些点：

    // Function - Will fire on animation progression.
     onAnimationProgress: function(){},

   // Function - Will fire on animation completion.
    onAnimationComplete: function(){}

我发现我必须将onAnimationComplete与responsive: true一起使用，因为点标签会在调整大小事件中消失。

一旦我在回调中找到了积分，我就会把我想要的标签写在画布上。

我对代码的补充是：

var options = {
    onAnimationProgress: function() { drawDatasetPointsLabels() },
    onAnimationComplete: function() { drawDatasetPointsLabels() }
}

增加功能：

    function drawDatasetPointsLabels() {
            ctx.font = '.9rem "Gotham Book",sans-serif';
            ctx.fillStyle = '#AAA';
            ctx.textAlign="center";
            $(Trends.datasets).each(function(idx,dataset){
                $(dataset.points).each(function(pdx,pointinfo){
                    // First dataset is shifted off the scale line. 
                    // Don't write to the canvas for the null placeholder.
                    if ( pointinfo.value !== null ) { 
                        ctx.fillText(pointinfo.value,pointinfo.x,pointinfo.y - 15);
                    }
                });
            });         
         }

所以这里是整个代码源以及提供解决方案的新代码：

    var data = {
                labels: ["","Jun 2013","Jul 2013","Aug 2013","Sep 2013","Oct 2013","Nov 2013","Dec 2013","Jan 2014","Feb 2014","Mar 2014","Apr 2014","May 2014"],
                datasets: [
                    {
                        label: "hemoglobin_1",
                        fillColor: "transparent",
                        strokeColor: "#65204c",
                        pointColor: "#65204c",
                        pointHighlightStroke: "#FFF",
                        data: [null,5.7,5.7,5.8,5.7,5.8,5.7,5.9,6.7,6.7,6.5,6.4,6.4]
                    },
                    {
                        label: "hemoglobin_2",
                        fillColor: "transparent",
                        strokeColor: "#ed7141",
                        pointColor: "#ed7141",
                        pointHighlightStroke: "#FFF",
                        data: [null,15.5,15.5,15.6,15.2,15.6,15.1,15.8,17,17.4,16.8,16.4,16.4]
                    },                    
                    {
                        label: "hemoglobin_3",
                        fillColor: "transparent",
                        strokeColor: "#de4760",
                        pointColor: "#de4760",
                        pointHighlightStroke: "#FFF",
                        data: [null,37.1,37,37.2,37.6,36.9,37.6,36.8,37.6,38,37.5,39.1,37.5]
                    },
                    {
                        label: "hemoglobin_4",
                        fillColor: "transparent",
                        strokeColor: "#fdcf7e",
                        pointColor: "#fdcf7e",                          
                        pointHighlightStroke: "#FFF",
                        data: [null,29.9,30.4,29.5,29.6,30.2,29.4,29.8,26.9,27,28.5,26.8,28.5]
                     },                                        
                    {
                        label: "hemoglobin_5",
                        fillColor: "transparent",
                        strokeColor: "#a33a59",
                        pointColor: "#a33a59",
                        pointHighlightStroke: "#FFF",
                        data: [null,11.8,11.4,11.9,11.9,11.5,12.2,11.7,11.8,10.9,10.7,11.3,11.3]
                    }
                ]
            };

    var options = {
                responsive: true,
                scaleOverride: true,
                scaleSteps: 10,
                scaleStepWidth: 5,
                scaleStartValue: 0,
                showTooltips: false,
                pointDot: true,
                pointDotRadius : 6,
                datasetStrokeWidth : 3,
                bezierCurve : false,
                scaleShowHorizontalLines: false,
                scaleGridLineWidth : 2,
                scaleGridLineColor : "#EEEEEE",
                scaleLineWidth: 3,
                scaleLineColor: "#000000",
                scaleFontFamily: '"Gotham Book",sans-serif',
                scaleFontSize: 18,
                onAnimationProgress: function() { drawDatasetPointsLabels() },
                onAnimationComplete: function() { drawDatasetPointsLabels() }                    
            }
            var ctx = $("#myChart").get(0).getContext("2d");
            var Trends = new Chart(ctx).Line(data, options);            

        function drawDatasetPointsLabels() {
            ctx.font = '.9rem "Gotham Book",sans-serif';
            ctx.fillStyle = '#AAA';
            ctx.textAlign="center";
            $(Trends.datasets).each(function(idx,dataset){
                // First dataset is shifted off the scale line. 
                // Don't write to the canvas for the null placeholder.
                $(dataset.points).each(function(pdx,pointinfo){
                    if ( pointinfo.value !== null ) {
                        ctx.fillText(pointinfo.value,pointinfo.x,pointinfo.y - 15);
                    }
                });
            });         
        }

以下是jsfiddle的原始问题版本：http://jsfiddle.net/s9eannLh

[更新链接] 以下是jsfiddle的更新解决方案：https://jsfiddle.net/s9eannLh/82/

全部谢谢！

Answer 2

以下是基于github上提供的示例的方法。它看起来与您的解决方案类似......

// Define a plugin to provide data labels
Chart.plugins.register({
    afterDatasetsDraw: function(chart, easing) {
        // To only draw at the end of animation, check for easing === 1
        var ctx = chart.ctx;
        chart.data.datasets.forEach(function (dataset, i) {
            var meta = chart.getDatasetMeta(i);
            if (!meta.hidden) {
                meta.data.forEach(function(element, index) {
                    // Draw the text in black, with the specified font
                    ctx.fillStyle = 'rgb(0, 0, 0)';
                    var fontSize = 16;
                    var fontStyle = 'normal';
                    var fontFamily = 'Helvetica Neue';
                    ctx.font = Chart.helpers.fontString(fontSize, fontStyle, fontFamily);
                    // Just naively convert to string for now
                    var dataString = dataset.data[index].toString();
                    // Make sure alignment settings are correct
                    ctx.textAlign = 'center';
                    ctx.textBaseline = 'middle';
                    var padding = 5;
                    var position = element.tooltipPosition();
                    ctx.fillText(dataString, position.x, position.y - (fontSize / 2) - padding);
                });
            }
        });
    }
});

来自代码： NUnit - Is it possible to check in the TearDown whether the test succeeded?

实施例： https://github.com/chartjs/Chart.js/blob/master/samples/advanced/data-labelling.html

您还可以定义内联到图表的插件，而不是全局...

var chart = new Chart(ctx, {
    plugins: [{
        afterDatasetsDraw: ...
    }]
});

Answer 3

万一有人像我最近那样来这里寻找东西，有一个新的插件可用。

https://github.com/chartjs/chartjs-plugin-datalabels

Answer 4

更新了@JBMcClure解决方案的代码：

        var data = {
            labels: ["","Jun 2013","Jul 2013","Aug 2013","Sep 2013","Oct 2013","Nov 2013","Dec 2013","Jan 2014","Feb 2014","Mar 2014","Apr 2014","May 2014"],
            datasets: [
                {
                    label: "hemoglobin_1",
                    fillColor: "transparent",
                    strokeColor: "#65204c",
                    pointColor: "#65204c",
                    pointHighlightStroke: "#FFF",
                    data: [null,5.7,5.7,5.8,5.7,5.8,5.7,5.9,6.7,6.7,6.5,6.4,6.4]
                },
                {
                    label: "hemoglobin_2",
                    fillColor: "transparent",
                    strokeColor: "#ed7141",
                    pointColor: "#ed7141",
                    pointHighlightStroke: "#FFF",
                    data: [null,15.5,15.5,15.6,15.2,15.6,15.1,15.8,17,17.4,16.8,16.4,16.4]
                },
                {
                    label: "hemoglobin_3",
                    fillColor: "transparent",
                    strokeColor: "#de4760",
                    pointColor: "#de4760",
                    pointHighlightStroke: "#FFF",
                    data: [null,37.1,37,37.2,37.6,36.9,37.6,36.8,37.6,38,37.5,39.1,37.5]
                },
                {
                    label: "hemoglobin_4",
                    fillColor: "transparent",
                    strokeColor: "#fdcf7e",
                    pointColor: "#fdcf7e",
                    pointHighlightStroke: "#FFF",
                    data: [null,29.9,30.4,29.5,29.6,30.2,29.4,29.8,26.9,27,28.5,26.8,28.5]
                },
                {
                    label: "hemoglobin_5",
                    fillColor: "transparent",
                    strokeColor: "#a33a59",
                    pointColor: "#a33a59",
                    pointHighlightStroke: "#FFF",
                    data: [null,11.8,11.4,11.9,11.9,11.5,12.2,11.7,11.8,10.9,10.7,11.3,11.3]
                }
            ]
        };

        var options = {
            type: 'line',
            data: data,
            options: {
                responsive: true,
                scaleOverride: true,
                scaleSteps: 10,
                scaleStepWidth: 5,
                scaleStartValue: 0,
                showTooltips: false,
                pointDot: true,
                pointDotRadius : 6,
                datasetStrokeWidth : 3,
                bezierCurve : false,
                scaleShowHorizontalLines: false,
                scaleGridLineWidth : 2,
                scaleGridLineColor : "#EEEEEE",
                scaleLineWidth: 3,
                scaleLineColor: "#000000",
                scaleFontFamily: '"Gotham Book",sans-serif',
                scaleFontSize: 18,
                onAnimationProgress: function() { drawDatasetPointsLabels() },
                onAnimationComplete: function() { drawDatasetPointsLabels() }
            }
        };
        var ctx = document.getElementById('myChart').getContext('2d');
        var Trends = new Chart(ctx, options);

        function drawDatasetPointsLabels() {
            ctx.font = '.9rem "Gotham Book",sans-serif';
            ctx.fontWeight = 'bold';
            ctx.fillStyle = '#AAA';
            ctx.textAlign="center";
            $(Trends.datasets).each(function(idx,dataset){
                $(dataset.points).each(function(pdx,pointinfo){
                    if ( pointinfo.value !== null ) {
                        ctx.fillText(pointinfo.value,pointinfo.x,pointinfo.y - 15);
                    }
                });
            });
        }

@JBMcClure这是一个更新的工作链接：

https://jsfiddle.net/s9eannLh/177/