Chart.js docs

原文链接：http://www.bootcss.com/p/chart.js/docs/

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 src="Chart.js"></script>

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。

<canvas id="myChart" width="400" height="400"></canvas>

//Get the context of the canvas element we want to select

var ctx = document.getElementById("myChart").getContext("2d");

var myNewChart = new Chart(ctx).PolarArea(data);

我们还可以用jQuery获取canvas的context。首先从jQuery集合中获取我们需要的DOM节点，然后在这个DOM节点上调用 getContext("2d") 方法。

//Get context with jQuery - using jQuery's .get() method.

var ctx = $("#myChart").get(0).getContext("2d");

//This will get the first returned node in the jQuery collection.

var myNewChart = new Chart(ctx);

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。下面这个案例中，我们将展示如何绘制一幅极地区域图（Polar area chart）。

new Chart(ctx).PolarArea(data,options);

We call a method of the name of the chart we want to create. We pass in the data for that chart type, and the options for that chart as parameters. Chart.js will merge the options you pass in with the default options for that chart type.

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

new Chart(ctx).Line(data,options);

数据结构

var data = {

	labels : ["January","February","March","April","May","June","July"],

	datasets : [

		{

			fillColor : "rgba(220,220,220,0.5)",

			strokeColor : "rgba(220,220,220,1)",

			pointColor : "rgba(220,220,220,1)",

			pointStrokeColor : "#fff",

			data : [65,59,90,81,56,55,40]

		},

		{

			fillColor : "rgba(151,187,205,0.5)",

			strokeColor : "rgba(151,187,205,1)",

			pointColor : "rgba(151,187,205,1)",

			pointStrokeColor : "#fff",

			data : [28,48,40,19,96,27,100]

		}

	]

}

The line chart requires an array of labels for each of the data points. This is show on the X axis.

The data for line charts is broken up into an array of datasets. Each dataset has a colour for the fill, a colour for the line and colours for the points and strokes of the points. These colours are strings just like CSS. You can use RGBA, RGB, HEX or HSL notation.

图表参数

Line.defaults = {

	//Boolean - If we show the scale above the chart data

	scaleOverlay : false,

	//Boolean - If we want to override with a hard coded scale

	scaleOverride : false,

	//** Required if scaleOverride is true **

	//Number - The number of steps in a hard coded scale

	scaleSteps : null,

	//Number - The value jump in the hard coded scale

	scaleStepWidth : null,

	//Number - The scale starting value

	scaleStartValue : null,

	//String - Colour of the scale line

	scaleLineColor : "rgba(0,0,0,.1)",

	//Number - Pixel width of the scale line

	scaleLineWidth : 1,

	//Boolean - Whether to show labels on the scale

	scaleShowLabels : false,

	//Interpolated JS string - can access value

	scaleLabel : "<%=value%>",

	//String - Scale label font declaration for the scale label

	scaleFontFamily : "'Arial'",

	//Number - Scale label font size in pixels

	scaleFontSize : 12,

	//String - Scale label font weight style

	scaleFontStyle : "normal",

	//String - Scale label font colour

	scaleFontColor : "#666",	

	///Boolean - Whether grid lines are shown across the chart

	scaleShowGridLines : true,

	//String - Colour of the grid lines

	scaleGridLineColor : "rgba(0,0,0,.05)",

	//Number - Width of the grid lines

	scaleGridLineWidth : 1,	

	//Boolean - Whether the line is curved between points

	bezierCurve : true,

	//Boolean - Whether to show a dot for each point

	pointDot : true,

	//Number - Radius of each point dot in pixels

	pointDotRadius : 3,

	//Number - Pixel width of point dot stroke

	pointDotStrokeWidth : 1,

	//Boolean - Whether to show a stroke for datasets

	datasetStroke : true,

	//Number - Pixel width of dataset stroke

	datasetStrokeWidth : 2,

	//Boolean - Whether to fill the dataset with a colour

	datasetFill : true,

	//Boolean - Whether to animate the chart

	animation : true,

	//Number - Number of animation steps

	animationSteps : 60,

	//String - Animation easing effect

	animationEasing : "easeOutQuart",

	//Function - Fires when the animation is complete

	onAnimationComplete : null

}

柱状图（Bar chart）

简介

A bar chart is a way of showing data as bars.

It is sometimes used to show trend data, and the comparison of multiple data sets side by side.

使用案例

new Chart(ctx).Bar(data,options);

数据结构

var data = {

	labels : ["January","February","March","April","May","June","July"],

	datasets : [

		{

			fillColor : "rgba(220,220,220,0.5)",

			strokeColor : "rgba(220,220,220,1)",

			data : [65,59,90,81,56,55,40]

		},

		{

			fillColor : "rgba(151,187,205,0.5)",

			strokeColor : "rgba(151,187,205,1)",

			data : [28,48,40,19,96,27,100]

		}

	]

}

The bar chart has the a very similar data structure to the line chart, and has an array of datasets, each with colours and an array of data. Again, colours are in CSS format.

We have an array of labels too for display. In the example, we are showing the same data as the previous line chart example.

图表参数

Bar.defaults = {

	//Boolean - If we show the scale above the chart data

	scaleOverlay : false,

	//Boolean - If we want to override with a hard coded scale

	scaleOverride : false,

	//** Required if scaleOverride is true **

	//Number - The number of steps in a hard coded scale

	scaleSteps : null,

	//Number - The value jump in the hard coded scale

	scaleStepWidth : null,

	//Number - The scale starting value

	scaleStartValue : null,

	//String - Colour of the scale line

	scaleLineColor : "rgba(0,0,0,.1)",

	//Number - Pixel width of the scale line

	scaleLineWidth : 1,

	//Boolean - Whether to show labels on the scale

	scaleShowLabels : false,

	//Interpolated JS string - can access value

	scaleLabel : "<%=value%>",

	//String - Scale label font declaration for the scale label

	scaleFontFamily : "'Arial'",

	//Number - Scale label font size in pixels

	scaleFontSize : 12,

	//String - Scale label font weight style

	scaleFontStyle : "normal",

	//String - Scale label font colour

	scaleFontColor : "#666",	

	///Boolean - Whether grid lines are shown across the chart

	scaleShowGridLines : true,

	//String - Colour of the grid lines

	scaleGridLineColor : "rgba(0,0,0,.05)",

	//Number - Width of the grid lines

	scaleGridLineWidth : 1,	

	//Boolean - If there is a stroke on each bar

	barShowStroke : true,

	//Number - Pixel width of the bar stroke

	barStrokeWidth : 2,

	//Number - Spacing between each of the X value sets

	barValueSpacing : 5,

	//Number - Spacing between data sets within X values

	barDatasetSpacing : 1,

	//Boolean - Whether to animate the chart

	animation : true,

	//Number - Number of animation steps

	animationSteps : 60,

	//String - Animation easing effect

	animationEasing : "easeOutQuart",

	//Function - Fires when the animation is complete

	onAnimationComplete : null

}

雷达图或蛛网图（Radar chart）

简介

A radar chart is a way of showing multiple data points and the variation between them.

They are often useful for comparing the points of two or more different data sets

使用案例

new Chart(ctx).Radar(data,options);

数据结构

var data = {

	labels : ["Eating","Drinking","Sleeping","Designing","Coding","Partying","Running"],

	datasets : [

		{

			fillColor : "rgba(220,220,220,0.5)",

			strokeColor : "rgba(220,220,220,1)",

			pointColor : "rgba(220,220,220,1)",

			pointStrokeColor : "#fff",

			data : [65,59,90,81,56,55,40]

		},

		{

			fillColor : "rgba(151,187,205,0.5)",

			strokeColor : "rgba(151,187,205,1)",

			pointColor : "rgba(151,187,205,1)",

			pointStrokeColor : "#fff",

			data : [28,48,40,19,96,27,100]

		}

	]

}

For a radar chart, usually you will want to show a label on each point of the chart, so we include an array of strings that we show around each point in the chart. If you do not want this, you can either not include the array of labels, or choose to hide them in the chart options.

For the radar chart data, we have an array of datasets. Each of these is an object, with a fill colour, a stroke colour, a colour for the fill of each point, and a colour for the stroke of each point. We also have an array of data values.

图表

Radar.defaults = {

	//Boolean - If we show the scale above the chart data

	scaleOverlay : false,

	//Boolean - If we want to override with a hard coded scale

	scaleOverride : false,

	//** Required if scaleOverride is true **

	//Number - The number of steps in a hard coded scale

	scaleSteps : null,

	//Number - The value jump in the hard coded scale

	scaleStepWidth : null,

	//Number - The centre starting value

	scaleStartValue : null,

	//Boolean - Whether to show lines for each scale point

	scaleShowLine : true,

	//String - Colour of the scale line

	scaleLineColor : "rgba(0,0,0,.1)",

	//Number - Pixel width of the scale line

	scaleLineWidth : 1,

	//Boolean - Whether to show labels on the scale

	scaleShowLabels : false,

	//Interpolated JS string - can access value

	scaleLabel : "<%=value%>",

	//String - Scale label font declaration for the scale label

	scaleFontFamily : "'Arial'",

	//Number - Scale label font size in pixels

	scaleFontSize : 12,

	//String - Scale label font weight style

	scaleFontStyle : "normal",

	//String - Scale label font colour

	scaleFontColor : "#666",

	//Boolean - Show a backdrop to the scale label

	scaleShowLabelBackdrop : true,

	//String - The colour of the label backdrop

	scaleBackdropColor : "rgba(255,255,255,0.75)",

	//Number - The backdrop padding above & below the label in pixels

	scaleBackdropPaddingY : 2,

	//Number - The backdrop padding to the side of the label in pixels

	scaleBackdropPaddingX : 2,

	//Boolean - Whether we show the angle lines out of the radar

	angleShowLineOut : true,

	//String - Colour of the angle line

	angleLineColor : "rgba(0,0,0,.1)",

	//Number - Pixel width of the angle line

	angleLineWidth : 1,			

	//String - Point label font declaration

	pointLabelFontFamily : "'Arial'",

	//String - Point label font weight

	pointLabelFontStyle : "normal",

	//Number - Point label font size in pixels

	pointLabelFontSize : 12,

	//String - Point label font colour

	pointLabelFontColor : "#666",

	//Boolean - Whether to show a dot for each point

	pointDot : true,

	//Number - Radius of each point dot in pixels

	pointDotRadius : 3,

	//Number - Pixel width of point dot stroke

	pointDotStrokeWidth : 1,

	//Boolean - Whether to show a stroke for datasets

	datasetStroke : true,

	//Number - Pixel width of dataset stroke

	datasetStrokeWidth : 2,

	//Boolean - Whether to fill the dataset with a colour

	datasetFill : true,

	//Boolean - Whether to animate the chart

	animation : true,

	//Number - Number of animation steps

	animationSteps : 60,

	//String - Animation easing effect

	animationEasing : "easeOutQuart",

	//Function - Fires when the animation is complete

	onAnimationComplete : null

}

极地区域图（Polar area chart）

简介

Polar area charts are similar to pie charts, but each segment has the same angle - the radius of the segment differs depending on the value.

This type of chart is often useful when we want to show a comparison data similar to a pie chart, but also show a scale of values for context.

使用案例

new Chart(ctx).PolarArea(data,options);

数据结构

var data = [

	{

		value : 30,

		color: "#D97041"

	},

	{

		value : 90,

		color: "#C7604C"

	},

	{

		value : 24,

		color: "#21323D"

	},

	{

		value : 58,

		color: "#9D9B7F"

	},

	{

		value : 82,

		color: "#7D4F6D"

	},

	{

		value : 8,

		color: "#584A5E"

	}

]

As you can see, for the chart data you pass in an array of objects, with a value and a colour. The value attribute should be a number, while the color attribute should be a string. Similar to CSS, for this string you can use HEX notation, RGB, RGBA or HSL.

图表

These are the default chart options. By passing in an object with any of these attributes, Chart.js will merge these objects and the graph accordingly. Explanations of each option are commented in the code below.

PolarArea.defaults = {

	//Boolean - Whether we show the scale above or below the chart segments

	scaleOverlay : true,

	//Boolean - If we want to override with a hard coded scale

	scaleOverride : false,

	//** Required if scaleOverride is true **

	//Number - The number of steps in a hard coded scale

	scaleSteps : null,

	//Number - The value jump in the hard coded scale

	scaleStepWidth : null,

	//Number - The centre starting value

	scaleStartValue : null,

	//Boolean - Show line for each value in the scale

	scaleShowLine : true,

	//String - The colour of the scale line

	scaleLineColor : "rgba(0,0,0,.1)",

	//Number - The width of the line - in pixels

	scaleLineWidth : 1,

	//Boolean - whether we should show text labels

	scaleShowLabels : true,

	//Interpolated JS string - can access value

	scaleLabel : "<%=value%>",

	//String - Scale label font declaration for the scale label

	scaleFontFamily : "'Arial'",

	//Number - Scale label font size in pixels

	scaleFontSize : 12,

	//String - Scale label font weight style

	scaleFontStyle : "normal",

	//String - Scale label font colour

	scaleFontColor : "#666",

	//Boolean - Show a backdrop to the scale label

	scaleShowLabelBackdrop : true,

	//String - The colour of the label backdrop

	scaleBackdropColor : "rgba(255,255,255,0.75)",

	//Number - The backdrop padding above & below the label in pixels

	scaleBackdropPaddingY : 2,

	//Number - The backdrop padding to the side of the label in pixels

	scaleBackdropPaddingX : 2,

	//Boolean - Stroke a line around each segment in the chart

	segmentShowStroke : true,

	//String - The colour of the stroke on each segement.

	segmentStrokeColor : "#fff",

	//Number - The width of the stroke value in pixels

	segmentStrokeWidth : 2,

	//Boolean - Whether to animate the chart or not

	animation : true,

	//Number - Amount of animation steps

	animationSteps : 100,

	//String - Animation easing effect.

	animationEasing : "easeOutBounce",

	//Boolean - Whether to animate the rotation of the chart

	animateRotate : true,

	//Boolean - Whether to animate scaling the chart from the centre

	animateScale : false,

	//Function - This will fire when the animation of the chart is complete.

	onAnimationComplete : null

}

饼图（Pie chart）

简介

Pie charts are probably the most commonly used chart there are. They are divided into segments, the arc of each segment shows a the proportional value of each piece of data.

They are excellent at showing the relational proportions between data.

使用案例

new Chart(ctx).Pie(data,options);

数据结构

var data = [

	{

		value: 30,

		color:"#F38630"

	},

	{

		value : 50,

		color : "#E0E4CC"

	},

	{

		value : 100,

		color : "#69D2E7"

	}

]

For a pie chart, you must pass in an array of objects with a value and a color property. The value attribute should be a number, Chart.js will total all of the numbers and calculate the relative proportion of each. The color attribute should be a string. Similar to CSS, for this string you can use HEX notation, RGB, RGBA or HSL.

图表

These are the default options for the Pie chart. Pass in an object with any of these attributes to override them.

Pie.defaults = {

	//Boolean - Whether we should show a stroke on each segment

	segmentShowStroke : true,

	//String - The colour of each segment stroke

	segmentStrokeColor : "#fff",

	//Number - The width of each segment stroke

	segmentStrokeWidth : 2,

	//Boolean - Whether we should animate the chart

	animation : true,

	//Number - Amount of animation steps

	animationSteps : 100,

	//String - Animation easing effect

	animationEasing : "easeOutBounce",

	//Boolean - Whether we animate the rotation of the Pie

	animateRotate : true,

	//Boolean - Whether we animate scaling the Pie from the centre

	animateScale : false,

	//Function - Will fire on animation completion.

	onAnimationComplete : null

}

环形图（Doughnut chart）

简介

Doughnut charts are similar to pie charts, however they have the centre cut out, and are therefore shaped more like a doughnut than a pie!

They are aso excellent at showing the relational proportions between data.

使用案例

new Chart(ctx).Doughnut(data,options);

数据结构

var data = [

	{

		value: 30,

		color:"#F7464A"

	},

	{

		value : 50,

		color : "#E2EAE9"

	},

	{

		value : 100,

		color : "#D4CCC5"

	},

	{

		value : 40,

		color : "#949FB1"

	},

	{

		value : 120,

		color : "#4D5360"

	}

]

For a doughnut chart, you must pass in an array of objects with a value and a color property. The value attribute should be a number, Chart.js will total all of the numbers and calculate the relative proportion of each. The color attribute should be a string. Similar to CSS, for this string you can use HEX notation, RGB, RGBA or HSL.

图表

These are the default options for the doughnut chart. Pass in an object with any of these attributes to override them.

Doughnut.defaults = {

	//Boolean - Whether we should show a stroke on each segment

	segmentShowStroke : true,

	//String - The colour of each segment stroke

	segmentStrokeColor : "#fff",

	//Number - The width of each segment stroke

	segmentStrokeWidth : 2,

	//The percentage of the chart that we cut out of the middle.

	percentageInnerCutout : 50,

	//Boolean - Whether we should animate the chart

	animation : true,

	//Number - Amount of animation steps

	animationSteps : 100,

	//String - Animation easing effect

	animationEasing : "easeOutBounce",

	//Boolean - Whether we animate the rotation of the Doughnut

	animateRotate : true,

	//Boolean - Whether we animate scaling the Doughnut from the centre

	animateScale : false,

	//Function - Will fire on animation completion.

	onAnimationComplete : null

}