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html5 canvas做的图表插件

2014-05-13 23:12 405 查看
用highchart的时候发现它是用svg来画图的，那么用canvas来做怎么样的。

以前做AS图表插件的时候，绘制图画主要用容器的Graphics对象来绘制，而canvas的context和Graphics一样，都可以用来绘制图形。

然后就试着用canvas做了这样一个东西。



具体实现如下，个人表达能力有问题，各位看官还是看源码吧，如下：

<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>LineChart</title>

</head>

<body>
<div id="lineChart" style="width: 900px;height: 600px;border: #c9302c"></div>
<script src="jquery-1.8.2.min.js"></script>
<script src="ChartTest1.js"></script>
<script type="text/javascript">
$("#lineChart").lineChart("init");
</script>
</body>
</html>


ChartTest1.js源码如下：

/**
* Created by jackyWHJ on 14-2-26.
*/
(function($) {

var canvas,context;
var stepXArr=[],stepYArr=[],xStepWidth=0;
var xAxisHeight = 0 ,yAxisWidth = 0;
var heightVal = 0;//高度值对应数据比例

/**
* 画X轴
* */
var drawXAxis = function (xAxisData) {
context.beginPath();
//画X轴横线
context.moveTo(yAxisWidth - 6, canvas.height - xAxisHeight);
context.lineTo(canvas.width-yAxisWidth,canvas.height - xAxisHeight);
//画刻度、加标签
var len = xAxisData.length;
xStepWidth = (canvas.width-2*yAxisWidth)/len;
for(var i = 0;i < len;i++){
//画刻度，默认刻度高度为6个像素
context.moveTo(yAxisWidth + (i+1)*xStepWidth, canvas.height - xAxisHeight);
context.lineTo(yAxisWidth + (i+1)*xStepWidth,canvas.height - xAxisHeight + 6);
//画标签，默认字体为14个像素
context.font = 'normal normal bold 14px 微软雅黑';
//字体居中在刻度中间
context.fillText(xAxisData[i],
yAxisWidth + (i+0.5)*xStepWidth - xAxisData[i].length*14/2,
canvas.height - xAxisHeight + 24);
//缓存刻度位置，用于画网格
stepXArr.push(yAxisWidth + (i+1)*xStepWidth);
}

context.stroke();
}

/**
* 画Y轴
* */
var drawYAxis = function(yMax,step) {
context.beginPath();
//画X轴横线
context.moveTo(yAxisWidth, xAxisHeight);
context.lineTo(yAxisWidth,canvas.height - xAxisHeight + 6);
//画刻度、加标签
var tickWidth = (canvas.height - 2*xAxisHeight )/step;
heightVal = (canvas.height - 2*xAxisHeight )/yMax;
for(var i = 0;i <= step;i++){
//画刻度，默认刻度高度为6个像素
context.moveTo(yAxisWidth, canvas.height - xAxisHeight - tickWidth * i);
context.lineTo(yAxisWidth - 6,canvas.height - xAxisHeight - tickWidth * i);
//画标签，默认字体为14个像素
context.font = 'normal normal 14px 微软雅黑';
//字体居中在刻度中间
context.fillText(yMax/step * i,
yAxisWidth -  50,
canvas.height - xAxisHeight - tickWidth * i + 7);
//缓存刻度位置，用于画网格
stepYArr.push(canvas.height - xAxisHeight - tickWidth * i);
}
context.stroke();
}

/**
* 画网格
* */
var drawGrid = function() {
context.save();

context.strokeStyle = "#6e6e6e";
context.fillStyle = '#ffffff';
context.lineWidth = 0.5;

//画横线
var j = 0,stepX = (canvas.width - 2*yAxisWidth)/10,stepY = (canvas.height - 2*xAxisHeight)/10;
//10个像素位为单位,6个像素画线，4个像素空出来，成为虚线
for (var i = 0,len = stepYArr.length; i < len; i ++) {
context.beginPath();
for(j = 0;j < stepX;j++){
context.moveTo(yAxisWidth + j*10, stepYArr[i]);
context.lineTo(yAxisWidth + j*10 + 6,  stepYArr[i]);
}
context.stroke();
}

//画竖线
for (var i = 0,len = stepXArr.length; i < len; i ++) {
context.beginPath();
for(j = 0;j < stepY;j++){
context.moveTo(stepXArr[i],xAxisHeight + j*10 );
context.lineTo(stepXArr[i],xAxisHeight + j*10+6);
}
context.stroke();
}
context.restore();
}

/**
* 画线条
* */
var drawLine = function(lineData){
//循环数据源画线条
context.beginPath();
context.fillStyle = '#000000';
context.lineWidth = 2;
context.moveTo(stepXArr[0] - xStepWidth/2 ,canvas.height - xAxisHeight - lineData[0]*heightVal);
for (var i = 1,len = lineData.length; i < len; i ++) {
context.lineTo(stepXArr[i] - xStepWidth/2 ,canvas.height - xAxisHeight - lineData[i]*heightVal);
}
context.stroke();
//画圆点
for (var i = 0,len = lineData.length; i < len; i ++) {
context.beginPath();
context.fillStyle = 'rgba(' + (Math.random()*255).toFixed(0) + ', ' +
(Math.random()*255).toFixed(0) + ', ' +
(Math.random()*255).toFixed(0) + ', 1.0)';
context.arc(stepXArr[i] - xStepWidth/2 ,canvas.height - xAxisHeight - lineData[i]*heightVal,
7, 0, Math.PI*2, true);
context.fill();
}
}
/**
* 画柱子
* */
var drawBar = function(barData,colorArr){
var barWidth = xStepWidth/2;//定义柱子宽度
//循环数据源画矩形
for (var i = 0,len = barData.length; i < len; i ++) {
context.beginPath();
context.fillStyle = colorArr[i];
context.fillRect(stepXArr[i] - xStepWidth/2 - barWidth/2,canvas.height - xAxisHeight - barData[i]*heightVal,
barWidth,barData[i]*heightVal);
context.fill();
}
}

var methods = {
init: function(options) {

// 在每个元素上执行方法
return this.each(function() {
var $this = $(this);

// 尝试去获取settings，如果不存在，则返回“undefined”
var settings = $this.data("lineChart");

// 如果获取settings失败，则根据options和default创建它
if (typeof settings === "undefined") {

var defaults = {
width:850,
height:450,
xAxis:["苹果","香蕉","梨","番茄","龙眼"],
lineData:[350,200,300,245,150],
barData:[350,134,120,51,90],
colorArr:['#ae303e','#913730','#D49797','0x538FD3','#A34e5d'],
onSomeEvent: function() {
}
};

settings = $.extend({}, defaults, options);

// 保存我们新创建的settings
$this.data("lineChart", settings);
} else {
//如果我们获取了settings，则将它和options进行合并（这不是必须的，你可以选择不这样做）
settings = $.extend({}, settings, options);

// 如果你想每次都保存options，可以添加下面代码：
// $this.data("lineChart", settings);
}
canvas = document.createElement("canvas");
canvas.width = settings.width;
canvas.height = settings.height;
canvas.style.cssText = 'margin:0 auto;';
$this.append(canvas);
context = canvas.getContext('2d');
xAxisHeight = settings.height/8 ,yAxisWidth = settings.width/8;
drawXAxis(settings.xAxis);
drawYAxis(400,10);
drawGrid();
drawBar(settings.barData,settings.colorArr);
drawLine(settings.lineData);
});
},
destroy: function(options) {
// 在每个元素中执行代码
return $(this).each(function() {
var $this = $(this);

// 执行代码

// 删除元素对应的数据
$this.removeData("lineChart");
});
},
val: function(options) {
// 这里的代码通过.eq(0)来获取选择器中的第一个元素的，我们或获取它的HTML内容作为我们的返回值
var someValue = this.eq(0).html();

// 返回值
return someValue;
}
};

$.fn.lineChart = function() {
var method = arguments[0];
if (methods[method]) {
method = methods[method];
arguments = Array.prototype.slice.call(arguments, 1);
} else if (typeof method === "object" || !method) {
method = methods.init;
} else {
$.error("Method" + method + "does not exist on jQuery.pluginName");
return this;
}
return method.apply(this, arguments);
};
})(jQuery);


　
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