html5 canvas做的图表插件
浏览数：31 /
时间：2015年06月09日
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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