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Example code for generating histogram (bar chart) effect in html5

不言Original: 2018-06-05 14:54:384310browse

The editor below will share with you an example code for generating a histogram (bar chart) effect in HTML5. The editor thinks it’s pretty good, so I’d like to share it with you now and give you a reference. Let’s follow the editor to take a look

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<html>
<canvas id="a_canvas" width="1000" height="700"></canvas>
<script>
    (function (){    
        window.addEventListener("load", function(){    
          var data = [1000,1300,2000,3000,2000,2000,1000,1500,2000,5000,1000,1000];    
          var xinforma = [&#39;1月&#39;,&#39;2月&#39;,&#39;3月&#39;,&#39;4月&#39;,&#39;5月&#39;,&#39;6月&#39;,&#39;7月&#39;,&#39;8月&#39;,&#39;9月&#39;,&#39;10月&#39;,&#39;11月&#39;,&#39;12月&#39;];    
          // 获取上下文    
          var a_canvas = document.getElementById(&#39;a_canvas&#39;);    
          var context = a_canvas.getContext("2d");    
          // 绘制背景    
          var gradient = context.createLinearGradient(0,0,0,300);    
         // gradient.addColorStop(0,"#e0e0e0");    
          //gradient.addColorStop(1,"#ffffff");    
          context.fillStyle = gradient;    
          context.fillRect(0,0,a_canvas.width,a_canvas.height);    
          var realheight = a_canvas.height-15;    
          var realwidth = a_canvas.width-40;    
          // 描绘边框    
          var grid_cols = data.length + 1;    
          var grid_rows = 4;    
          var cell_height = realheight / grid_rows;    
          var cell_width = realwidth / grid_cols;    
          context.lineWidth = 1;    
          context.strokeStyle = "#a0a0a0";    
          // 结束边框描绘    
          context.beginPath();    
          // 准备画横线    
          /*for(var row = 1; row <= grid_rows; row++){    
            var y = row * cell_height;    
            context.moveTo(0,y);    
            context.lineTo(a_canvas.width, y);    
          }*/    
            //划横线    
            context.moveTo(0,realheight);    
            context.lineTo(realwidth,realheight);    
            //画竖线    
          context.moveTo(0,20);    
           context.lineTo(0,realheight);    
          context.lineWidth = 1;    
          context.strokeStyle = "black";    
          context.stroke();    
          var max_v =0;    
          for(var i = 0; i<data.length; i++){    
            if (data[i] > max_v) { max_v =data[i]};    
          }    
          max_vmax_v = max_v * 1.1;    
          // 将数据换算为坐标    
          var points = [];    
          for( var i=0; i < data.length; i++){    
            var v= data[i];    
            var px = cell_width *　(i +1);    
            var py = realheight - realheight*(v / max_v);    
            //alert(py);    
            points.push({"x":px,"y":py});    
          }    
          //绘制坐标图形    
          for(var i in points){    
            var p = points[i];    
            context.beginPath();    
            context.fillStyle="green";    
            context.fillRect(p.x,p.y,15,realheight-p.y);    
            context.fill();    
          }    
          //添加文字    
          for(var i in points)    
          {  var p = points[i];    
            context.beginPath();    
            context.fillStyle="black";    
            context.fillText(data[i], p.x + 1, p.y - 15);    
             context.fillText(xinforma[i],p.x + 1,realheight+12);    
             context.fillText(&#39;月份&#39;,realwidth,realheight+12);    
             context.fillText(&#39;资金量&#39;,0,10);    
              }    
        },false);    
      })();    
</script>
</html>

html5 generation Histogram (bar chart) detailed code

Running results:

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Example code for generating histogram (bar chart) effect in html5

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