纯HTML5 Canvas实现的饼图

简介: 纯HTML5 Canvas实现的饼图

基本思路:

主要是利用HTML5 Canvas实现饼图绘制,绘制弧度的API主要是使用

context.arc与lineto两个API。

实现的功能有:

1. 支持标签Legend显示或者隐藏

2. 首次载入动画效果

3. 鼠标tooltip效果

4. 自定义饼图大小与是否添加文字

效果如下:


调用代码:

<html>
<head>
<meta http-equiv="X-UA-Compatible" content="chrome=IE8">
<script src="js/fishcomponent.js"></script>
<script src="js/pie.js"></script>
<title>My Demo 1</title>
  <script>
  window.onload = function() {
    var canvas = document.getElementById("pie_canvas");
    var seriesData = [{name:"apples", value:150, color:"RGBA(255,0,0,1)"},
                  {name:"orange", value:100, color:"RGBA(255,255,0,1)"},
                  {name:"banana", value:80, color:"RGBA(255,0,255,1)"},
                  {name:"peaches", value:60, color:"RGBA(0,255,255,1)"},
                  {name:"strawberries", value:40, color:"RGBA(0,127,255,1)"}]
    var config = {
        width : 600, 
        height: 400,
        series: seriesData,
        canvas: canvas,
        unit: "kg",
        title:"Fruit Sales",
        tooltips : {
          enable : true
        },
        animation :{
          enable: true
        },
          legend : {
            enable : true
          },
          text : {
            enable: true
          },
    };
    pieChart.initSettings(config);
    pieChart.render();
  }
  </script>
</head>
<body>
<h1>Pie Chart Demo</h1>
<div id="my_container" style="width:600px; height:500px;">
  <canvas id="pie_canvas"></canvas>
</div>
<div id="btn-group">
  <button type="button" id="clear-button">Clear Plot</button>
  <button type="button" id="refresh-button">Draw Plot</button>
</div>
</body>
</html>

饼图JS的代码:

var pieChart = {
    width: 600,
    height: 400,
    series: [],
    unit: "kg",
    chartCanvas: null,
    selectable : true,
    title: "Pie Chart",
    legend : {
      enable : true
    },
    edge : {
      width: 50,
      height: 50
    },
    animation: {
      enable: true,
      animCanvas : null,
      hh: 1, // trick is here!! for animation play
      pctx: null
    },
    tooltips: {
      enable: true,
      tooltipCanvas : null,
      ttContext: null,
      index: -1
    },
    circle : {
      cx: 0,
      cy: 0,
      radius: 0
      
    },
    text : {
      enable: false,
      content:[]
    },
    
    initSettings: function (config) {
      this.chartCanvas = config.canvas;
      this.chartCanvas.width = config.width;
      this.chartCanvas.height = config.height;
        this.width = config.width;
        this.height = config.height;
        this.series = config.series;
        this.title = config.title;
        this.unit = config.unit;
        if(config.tooltips != undefined) {
          this.tooltips.enable = config.tooltips.enable;          
        }
        if(config.animation != undefined) {
          this.animation.enable = config.animation.enable;          
        }
        if(config.legend != undefined) {
          this.legend.enable = config.legend.enable;          
        }
        if(config.text != undefined) {
          this.text.enable = config.text.enable;
        }
    },
    
    render : function() {
      // initialization circle
      this.circle.cx = this.width/2;
      this.circle.cy = this.height/2;
      this.circle.radius = Math.min(this.width/2, this.height/2) - Math.max(this.edge.width, this.edge.height);
      var ctx = null;
      if(this.animation.enable) {
        this.animation.animCanvas = document.createElement("canvas");
          this.animation.animCanvas.width = this.width;
          this.animation.animCanvas.height = this.height;
          ctx = this.animation.animCanvas.getContext("2d");
      } else {
        ctx = this.chartCanvas.getContext("2d");
        this.renderBorder(ctx);
      }
      
      if(this.circle.radius <= 0) {
        ctx.strokeText("Can not reader the chart, Circle is too small.");
        return;
      }
      
      // draw each arc according to data series 
      var sum = 0;
      var nums = this.series.length;
      for(var i=0; i<nums; i++) {
        sum += this.series[i].value;
      }
      
      // draw title
      ctx.font = '18pt Calibri';
      ctx.fillText(this.title, this.width/2 - this.edge.width, 30);
      ctx.save();
      var deltaArc = 0;
      for(var i=0; i<nums; i++) {
        var precent = this.series[i].value/sum;
        this.renderPie(ctx, i, precent, deltaArc);
        deltaArc += 2*Math.PI * precent;
      }
      ctx.restore();
      
      // add blur shadow
      ctx.save();
      ctx.shadowColor = "black";
      ctx.shadowOffsetX = 0;
      ctx.shadowOffsetY = 0;
      ctx.shadowBlur = 10;
      ctx.beginPath();
      ctx.arc(this.circle.cx, this.circle.cy, this.circle.radius, 0, Math.PI * 2, false);
      ctx.closePath();
      ctx.lineWidth = 1;
      ctx.strokeStyle = "RGBA(127,127,127,1)";
      ctx.stroke();
      ctx.restore();
      
      // render legend
      ctx.save();
      this.renderLegend(ctx, sum);
      ctx.restore();
      
      // play animation
      if(this.animation.enable) {
        var parent = this;
        this.animation.pctx = this.chartCanvas.getContext("2d");
        this.renderBorder(this.animation.pctx);
        setTimeout(function() {parent.playAnimation(parent);}, 1000/20);            
      }
    },
    
    showTooltips : function(loc, ctx) {
      if(!this.tooltips.enable) {
        return;
      }
      var dx = loc.x - this.width/2;
      var dy = loc.y - this.height/2;
      var dis = Math.floor(Math.sqrt(dx * dx + dy * dy));
      if(dis <= this.circle.radius) {
        // draw tool tip text
        var angle = Math.atan2(dy,dx);
        if(angle <= 0) {
          // if[-Math.PI, 0], make it[Math.PI, 2*Math.PI]
          angle = angle + 2*Math.PI;
        }
        
          var sum = 0;
          var nums = this.series.length;
          for(var s=0; s<nums; s++) {
            sum += this.series[s].value;
          }
          
          var deltaArc = 0;
          var index = 0;
          for(var i=0; i<nums; i++) {
            var precent = this.series[i].value/sum;
            deltaArc += 2*Math.PI * precent;
            if(angle<=deltaArc) {
              index = i;
              break;
            }
          }
        if(this.tooltips.tooltipCanvas == null) {
          this.tooltips.tooltipCanvas = document.createElement("canvas");
          this.tooltips.ttContext = this.tooltips.tooltipCanvas.getContext("2d");
            this.tooltips.tooltipCanvas.width = 150;
            this.tooltips.tooltipCanvas.height = 100;
        } 
        
        // only draw once
        // if(index == this.tooltips.index){
        //  return;
        // }
        this.clearTooltips(ctx);
        
        this.tooltips.index = index;
        var m_context = this.tooltips.ttContext;
        m_context.save();
        m_context.clearRect(0, 0, this.tooltips.tooltipCanvas.width, this.tooltips.tooltipCanvas.height);
        m_context.lineWidth = 2;
        m_context.strokeStyle = this.series[index].color;
        m_context.fillStyle="RGBA(255,255,255,0.7)";
        // m_context.strokeRect(2, 2, this.tooltips.tooltipCanvas.width-4, this.tooltips.tooltipCanvas.height-4);
        // m_context.fillRect(2,2,this.tooltips.tooltipCanvas.width-4, this.tooltips.tooltipCanvas.height-4);
        m_context.roundRect(2,2,this.tooltips.tooltipCanvas.width-4, this.tooltips.tooltipCanvas.height-4, 5, true, true);
      m_context.font="14px Arial";
      m_context.fillStyle="RGBA(0,0,0,1)";
      m_context.fillText("Index: " + (index + 1), 5, 20);
      m_context.fillText(this.series[index].name + ": " + this.series[index].value + this.unit, 5, 40);
      m_context.fillText(this.series[index].precent, 5, 60);
      m_context.restore();
      
      // make tool-tip rectangle is always visible 
      if((loc.x + this.tooltips.tooltipCanvas.width)> this.width) {
        loc.x = loc.x - this.tooltips.tooltipCanvas.width;
      }
      if((loc.y - this.tooltips.tooltipCanvas.height) <= 0) {
        loc.y = loc.y + this.tooltips.tooltipCanvas.height;
      }
      ctx.drawImage(this.tooltips.tooltipCanvas, 0, 0, this.tooltips.tooltipCanvas.width, this.tooltips.tooltipCanvas.height, 
          loc.x, loc.y-this.tooltips.tooltipCanvas.height, this.tooltips.tooltipCanvas.width, this.tooltips.tooltipCanvas.height);  
      } else {
        this.tooltips.index = -1;
        this.clearTooltips(ctx);
      }
    },
    
    clearTooltips : function(ctx) {
    ctx.clearRect(0,0,this.width, this.height);
    this.renderBorder(ctx);
    ctx.drawImage(this.animation.animCanvas, 0, 0, this.width, this.height, 0, 0, this.width, this.height); 
    },
    
    renderBorder : function(ctx) {
    ctx.save();
    ctx.fillStyle="white";
    ctx.strokeStyle="black";
    ctx.fillRect(0, 0, this.width, this.height);
    ctx.strokeRect(0, 0, this.width, this.height);
    ctx.restore();
    },
    
    renderPie : function(ctx, index, precent, deltaArc) {
      var endAngle = deltaArc + 2*Math.PI*precent;
      ctx.beginPath();
      ctx.arc(this.circle.cx, this.circle.cy, this.circle.radius, deltaArc, endAngle, false);
      ctx.moveTo(this.circle.cx, this.circle.cy);
      ctx.lineTo(this.circle.cx + this.circle.radius * Math.cos(deltaArc), this.circle.cy + this.circle.radius * Math.sin(deltaArc));
      ctx.lineTo(this.circle.cx + this.circle.radius * Math.cos(endAngle), this.circle.cy + this.circle.radius * Math.sin(endAngle));
      ctx.lineTo(this.circle.cx, this.circle.cy);
      ctx.closePath();
      ctx.fillStyle = this.series[index].color;
      ctx.fill();
      
      // render text content
      if(this.text.enable) {        
        var halfEndAngle = deltaArc + Math.PI*precent;
        var hx = this.circle.cx + this.circle.radius * Math.cos(halfEndAngle);
        var hy = this.circle.cy + this.circle.radius * Math.sin(halfEndAngle);
        ctx.beginPath();
        ctx.moveTo(hx, hy);
        var linePos = (hx < this.circle.cx) ? (hx - this.edge.width) : (hx + this.edge.width);
        ctx.lineTo(linePos, hy);
        ctx.closePath();
        ctx.strokeStyle="black";
        ctx.stroke();
        var textPos = (hx < this.circle.cx) ? (hx - this.edge.width*2) : (hx + this.edge.width);
        precent = Math.round (precent*100) / 100;
        var size = this.text.content.length;
        var tipStr = (size > index) ? this.text.content[index] : this.series[index].name + ": " + (precent * 100).toFixed(0) + "%";
        ctx.font = '10pt Calibri';
        ctx.fillStyle="black";
        ctx.fillText(tipStr, textPos, hy);
      }
    },
    
    renderLegend : function(ctx, sum) {
      if(!this.legend.enable) return;
      var nums = this.series.length;
      ctx.font = '10pt Calibri';
      var pos = (this.width/2 > (this.circle.radius+50)) ? 50 : (this.circle.cx - this.circle.radius);
      for(var i=0; i<nums; i++) {
        var x = this.series[i].value/sum;
        x = Math.round (x*100) / 100;
        var tipStr =  this.series[i].name + ": " + (x * 100).toFixed(0) + "%";
        this.series[i].precent = tipStr;
        ctx.fillStyle = this.series[i].color;
        ctx.fillRect(pos - 40, 20*i+10, 10, 10);
          ctx.fillStyle = "black";
        ctx.fillText(tipStr, pos - 25, 20*i+20);
      }     
    },
    
    playAnimation : function(parent) {  
      if(parent.animation.hh < parent.height) {
        parent.animation.pctx.save();
        parent.animation.pctx.globalAlpha=0.5;
        parent.animation.pctx.clearRect(0,0,parent.width, parent.height);
        parent.renderBorder(parent.animation.pctx);
        parent.animation.pctx.drawImage(parent.animation.animCanvas, 0, 0, parent.width, this.animation.hh, 0, 0, parent.width, this.animation.hh);
        parent.animation.hh = parent.animation.hh + 10;
        parent.animation.pctx.restore();              
        setTimeout(function() {parent.playAnimation(parent);}, 1000/20); 
      } else {
        parent.animation.pctx.clearRect(0,0,parent.width, parent.height);
        parent.renderBorder(parent.animation.pctx);
        parent.animation.pctx.drawImage(parent.animation.animCanvas, 0, 0, parent.width, parent.height, 0, 0, parent.width, parent.height);
        
        // enable tool-tip functionality
          if(parent.animation.enable && parent.legend.enable) {
            parent.chartCanvas.addEventListener('mousemove', function(event) {
              var x = event.pageX;
              var y = event.pageY;
              var canvas = event.target;
              var bbox = canvas.getBoundingClientRect();
              var loc = { x: x - bbox.left * (canvas.width  / bbox.width),
                  y: y - bbox.top  * (canvas.height / bbox.height)};
              
              parent.showTooltips(loc, (parent.animation.enable ? parent.animation.pctx : ctx));
              }, false);
          }
      }
    },
    
};

源代码可以直接使用

相关文章
|
1月前
|
移动开发 前端开发 API
HTML5 Canvas渐进填充与透明
HTML5 Canvas渐进填充与透明
26 7
|
1月前
|
Web App开发 移动开发 JavaScript
基于VML与HTML5 Canva实现的跨浏览器饼图与折线图
基于VML与HTML5 Canva实现的跨浏览器饼图与折线图
22 5
|
1月前
|
移动开发 前端开发 API
HTML5 Canvas 填充与描边(Fill And Stroke)
HTML5 Canvas 填充与描边(Fill And Stroke)
54 3
|
1月前
|
移动开发 前端开发 JavaScript
HTML5 Canvas动画效果演示
HTML5 Canvas动画效果演示
29 5
|
1月前
|
移动开发 前端开发 HTML5
HTML5 Canvas阴影用法演示
HTML5 Canvas阴影用法演示
37 4
|
1月前
|
移动开发 前端开发 HTML5
HTML5 Canvas中实现绘制一个像素宽的细线
HTML5 Canvas中实现绘制一个像素宽的细线
20 3
|
1月前
|
移动开发 前端开发 JavaScript
HTML5 Canvas自定义圆角矩形与虚线(Rounded Rectangle and Dash Line)
HTML5 Canvas自定义圆角矩形与虚线(Rounded Rectangle and Dash Line)
22 3
|
1月前
|
移动开发 前端开发 JavaScript
HTML5 Canvas实现360度全景图
HTML5 Canvas实现360度全景图
21 1
|
1月前
|
移动开发 前端开发 JavaScript
浏览器端图表渲染技术SVG, VML HTML Canvas
浏览器端图表渲染技术SVG, VML HTML Canvas
16 0
|
移动开发 前端开发 API
《HTML5 Canvas游戏开发实战》——3.4 小结
本节书摘来自华章计算机《HTML5 Canvas游戏开发实战》一书中的第3章,第3.4节,作者:张路斌著, 更多章节内容可以访问云栖社区“华章计算机”公众号查看。
952 0