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，每个数据集中都有一个包含 x 和 y 位置的尖头对象：
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onAnimationComplete with responsive: true因为点标签会在调整大小事件时被擦除。
一旦我在回调中找到了点，我只需将我想要的标签写到画布上即可。
我对代码的添加是：
var options = {
onAnimationProgress: function() { drawDatasetPointsLabels() },
onAnimationComplete: function() { drawDatasetPointsLabels() }
}
增加功能后：
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);
}
});
});
}
这是完整的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 上原始的有问题的版本：http://jsfiddle.net/s9eannLh
[更新的链接]这是 jsfiddle 上更新的解决方案：https://jsfiddle.net/s9eannLh/82/
谢谢大家！
