如何使用Chart.js显示折线图数据集点标签？

我终于找到了解决这个问题的方法。

我意识到我可以访问DOM中的图表对象：

Trends.datasets

在这五个数据集中，每个数据集中都有一个包含x和y位置的点对象：

Trends.datasets[0..4].points

因此，我利用Chart.js中的全局配置函数通过回调解析了这些要点：

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

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

我发现我必须使用onAnimationCompletewith，responsive: true因为在调整大小事件中点标签会被清除掉。

在回调中找到要点后，我只需在画布上写下想要的标签即可。

我对代码的补充是：

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

随着增加的功能：

    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);
                    }
                });
            });         
         }

因此，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);
                    }
                });
            });         
        }

这是jsfiddle上的原始有问题的版本：http : //jsfiddle.net/s9eannLh

[更新的链接]这是jsfiddle的更新解决方案：https ://jsfiddle.net/s9eannLh/82/

谢谢大家！