Chart.js
是一个简单、面向对象、为设计者和开发者准备的图表绘制工具库。
帮你用不同的方式让你的数据变得可视化。每种类型的图表都有动画效果，并且看上去非常棒，即便是在retina屏幕上。
基于HTML5 canvas技术，支持所有现代浏览器，并且针对IE7/8提供了降级替代方案。
不依赖任何外部工具库，轻量级（压缩之后仅有4.5k），并且提供了加载外部参数的方法。
下面是Chart.js的应用示例：
1引入Chart.js文件
首先我们需要在页面中引入Chart.js文件。此工具库在全局命名空间中定义了Chart变量
<script type="text/javascript" src="js/Chart.min.js"></script>
2 创建图表
为了创建图表，我们要实例化一个Chart对象。为了完成前面的步骤，首先需要需要传入一个绘制图表的2d context。以下是案例。
Html
<canvas id="canvas1" height="450" width="600"></canvas>
Js：
var ctx1 = new Chart(document.getElementById("canvas1").getContext("2d"));
var options = {scaleFontSize: 13, scaleFontColor: "#ffa45e"};
var myLineChart = ctx1.Line(LineChart, options);
当我们完成了在指定的canvas上实例化Chart对象之后，Chart.js会自动针对retina屏幕做缩放。
Chart对象设置完成后，我们就可以继续创建Chart.js中提供的具体类型的图表了
3 曲线图（Line chart）
简介
曲线图就是将数据标于曲线上的一种图表。
一般用于展示趋势数据，和比较两组数据集。
使用案例
数据结构
<canvas id="canvas1" height="450" width="600"></canvas>
var ctx1 = new Chart(document.getElementById("canvas1").getContext("2d"));
var options = {scaleFontSize: 13, scaleFontColor: "#ffa45e"};
// 线型图
var LineChart = {
labels: ["Ruby", "jQuery", "Java", "ASP.Net", "PHP"],
datasets: [{
fillColor: "rgba(151,249,190,0.5)",
strokeColor: "rgba(255,255,255,1)",
pointColor: "rgba(220,220,220,1)",
pointStrokeColor: "#fff",
data: [100, 200, 300, 400, 550]
}, {
fillColor: "rgba(252,147,65,0.5)",
strokeColor: "rgba(255,255,255,1)",
pointColor: "rgba(173,173,173,1)",
pointStrokeColor: "#fff",
data: [28, 68, 40, 19, 96]
}]
};
var myLineChart = ctx1.Line(LineChart, options);
4 条形图（Bar chart）
简介
条形图是将数据显示为条形图的一种方法。
它有时用来显示趋势数据，同时比较多个数据集。
使用案例
数据结构
<canvas id="canvas2" height="450" width="600"></canvas>
var ctx2 = new Chart(document.getElementById("canvas2").getContext("2d"));
var options = {scaleFontSize: 13, scaleFontColor: "#ffa45e"};
// 条形图
var BarChart = {
labels: ["Ruby", "jQuery", "Java", "ASP.Net", "PHP"],
datasets: [{
fillColor: "rgba(151,249,190,0.5)",
strokeColor: "rgba(255,255,255,1)",
data: [13, 20, 30, 40, 50]
}, {
fillColor: "rgba(252,147,65,0.5)",
strokeColor: "rgba(255,255,255,1)",
data: [28, 68, 40, 19, 96]
}]
};
var myBarChart = ctx2.Bar(BarChart, options);
5 饼图（Pie chart）
简介
饼图可能是最常用的图表。它们被划分为段，每个段的弧显示每一段数据的比例值。
他们擅长显示数据之间的关系比例。
使用案例
数据结构
<canvas id="canvas3" height="450" width="600"></canvas>
var ctx3 = new Chart(document.getElementById("canvas3").getContext("2d"));
var options = {scaleFontSize: 13, scaleFontColor: "#ffa45e"};
// 饼状图
var pieChart = [
{value: 40, color: "#fcc79c", highlight: "#AD0A56", label: "SCI"},
{value: 30, color: "#beefd2", highlight: "#AD0A56", label: "SSCI"},
{value: 90, color: "#ffddfb", highlight: "#AD0A56", label: "Others"},
];
var myPieChart = ctx3.Pie(pieChart);
6 环形图（Doughnut chart）
简介
环形图表与饼图相似，但它们有中心切割，因此形状更像油炸圈饼而不是馅饼！
他们善于展示数据之间的关系比例。
使用案例
数据结构
<canvas id="canvas4" height="450" width="600"></canvas>
var ctx4 = new Chart(document.getElementById("canvas4").getContext("2d"));
var options = {scaleFontSize: 13, scaleFontColor: "#ffa45e"};
// 环状图
var doughnutChart = [
{value: 60, color: "#fcc79e", highlight: "#AD0A56", label: "SCI"},
{value: 30, color: "#beefd2", highlight: "#AD0A56", label: "SSCI"},
{value: 50, color: "#ffddfb", highlight: "#AD0A56", label: "Others"},
{value: 120, color: "#cdecff", highlight: "#AD0A56", label: "TEST"},
{value: 90, color: "#fff5bc", highlight: "#AD0A56", label: "ADD"}
];
var myRingChart = ctx4.Doughnut(doughnutChart);
7 浏览器支持
所有现代浏览器和大部分手机浏览器都支持canvas
对于IE8及以下版本的浏览器，建议使用ExplorerCanvas。对于不支持canvas的IE会自动降级为VML格式。使用下面方法，excamvas.js可以在下面网址
http://www.bvbcode.com/cn/yk51lwhx-894917-down
<head>
<!--[if lte IE 8]>
<script src="excanvas.js"></script>
<![endif]-->
</head>
附，下面是完整的html代码：
<html>
<head>
<meta charset="utf-8">
<script type="text/javascript" src="js/Chart.min.js"></script>
</head>
<body>
<canvas id="canvas1" height="450" width="600"></canvas>
<canvas id="canvas2" height="450" width="600"></canvas>
<canvas id="canvas3" height="450" width="600"></canvas>
<canvas id="canvas4" height="450" width="600"></canvas>
<script type="text/javascript">
var ctx1 = new Chart(document.getElementById("canvas1").getContext("2d"));
var ctx2 = new Chart(document.getElementById("canvas2").getContext("2d"));
var ctx3 = new Chart(document.getElementById("canvas3").getContext("2d"));
var ctx4 = new Chart(document.getElementById("canvas4").getContext("2d"));
var options = {scaleFontSize: 13, scaleFontColor: "#ffa45e"};
// 线型图
var LineChart = {
labels: ["Ruby", "jQuery", "Java", "ASP.Net", "PHP"],
datasets: [{
fillColor: "rgba(151,249,190,0.5)",
strokeColor: "rgba(255,255,255,1)",
pointColor: "rgba(220,220,220,1)",
pointStrokeColor: "#fff",
data: [100, 200, 300, 400, 550]
}, {
fillColor: "rgba(252,147,65,0.5)",
strokeColor: "rgba(255,255,255,1)",
pointColor: "rgba(173,173,173,1)",
pointStrokeColor: "#fff",
data: [28, 68, 40, 19, 96]
}]
};
var myLineChart = ctx1.Line(LineChart, options);
// 条形图
var BarChart = {
labels: ["Ruby", "jQuery", "Java", "ASP.Net", "PHP"],
datasets: [{
fillColor: "rgba(151,249,190,0.5)",
strokeColor: "rgba(255,255,255,1)",
data: [13, 20, 30, 40, 50]
}, {
fillColor: "rgba(252,147,65,0.5)",
strokeColor: "rgba(255,255,255,1)",
data: [28, 68, 40, 19, 96]
}]
};
var myBarChart = ctx2.Bar(BarChart, options);
// 饼状图
var pieChart = [
{value: 40, color: "#fcc79c", highlight: "#AD0A56", label: "SCI"},
{value: 30, color: "#beefd2", highlight: "#AD0A56", label: "SSCI"},
{value: 90, color: "#ffddfb", highlight: "#AD0A56", label: "Others"},
];
var myPieChart = ctx3.Pie(pieChart);
// 环状图
var doughnutChart = [
{value: 60, color: "#fcc79e", highlight: "#AD0A56", label: "SCI"},
{value: 30, color: "#beefd2", highlight: "#AD0A56", label: "SSCI"},
{value: 50, color: "#ffddfb", highlight: "#AD0A56", label: "Others"},
{value: 120, color: "#cdecff", highlight: "#AD0A56", label: "TEST"},
{value: 90, color: "#fff5bc", highlight: "#AD0A56", label: "ADD"}
];
var myRingChart = ctx4.Doughnut(doughnutChart);
</script>
</body>
</html>
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