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  • HTML5 移动开发 Canvas 9.4 表格 , 折线图

    表格

    <!DOCTYPE html>

    <html>
      <head>
        <meta charset='utf-8'>
      </head>
      <body>
        <canvas id="a_canvas" width="300" height="300"></canvas>

        <script type="text/javascript">
          (function (){

            window.addEventListener("load", function(){

              // 获取上下文
              var a_canvas = document.getElementById('a_canvas');
              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);

              
              // 描绘边框
              var grid_cols = 10;
              var grid_rows = 10;
              var cell_height = a_canvas.height / grid_rows;
              var cell_width = a_canvas.width / grid_cols;
              context.lineWidth = 1;
              context.strokeStyle = "#a0a0a0";

              // 结束边框描绘
              context.beginPath();
              // 准备画横线
              for (var col = 0; col <= grid_cols; col++) {
                var x = col * cell_width;
                context.moveTo(x,0);
                context.lineTo(x,a_canvas.height);
              }
              // 准备画竖线
              for(var row = 0; row <= grid_rows; row++){
                var y = row * cell_height;
                context.moveTo(0,y);
                context.lineTo(a_canvas.width, y);
              }
              context.stroke();
            },false);
          })();
        </script>

      </body>

     折线图

    <!DOCTYPE html>
    <html>
      <head>
        <meta charset='utf-8'>
      </head>
      <body>
        <canvas id="a_canvas" width="300" height="300"></canvas>

        <script type="text/javascript">
          (function (){

            window.addEventListener("load", function(){

              var data = [80,92,104,110,68,50,45,90,74,68,98,103];

              // 获取上下文
              var a_canvas = document.getElementById('a_canvas');
              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);

              
              // 描绘边框
              var grid_cols = data.length + 1;
              var grid_rows = 4;
              var cell_height = a_canvas.height / grid_rows;
              var cell_width = a_canvas.width / grid_cols;
              context.lineWidth = 1;
              context.strokeStyle = "#a0a0a0";

              // 结束边框描绘
              context.beginPath();
              // 准备画横线
              for (var col = 0; col <= grid_cols; col++) {
                var x = col * cell_width;
                context.moveTo(x,0);
                context.lineTo(x,a_canvas.height);
              }
              // 准备画竖线
              for(var row = 0; row <= grid_rows; row++){
                var y = row * cell_height;
                context.moveTo(0,y);
                context.lineTo(a_canvas.width, y);
              }
              context.lineWidth = 1;
              context.strokeStyle = "#c0c0c0";
              context.stroke();

              var max_v = 0;
              for(var i = 0; i<data.length; i++){
                if (data[i] > max_v) { max_v = data[i]};
              }

              max_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 = a_canvas.height - a_canvas.height*(v / max_v);
                points.push({"x":px,"y":py});
              }
              // 绘制折现
              context.beginPath();
              context.moveTo(points[0].x, points[0].y);
              for(var i= 1; i< points.length; i++){
                context.lineTo(points[i].x,points[i].y);
              }


              context.lineWidth = 2;
              context.strokeStyle = "#ee0000";
              context.stroke();

              //绘制坐标图形
              for(var i in points){
                var p = points[i];
                context.beginPath();
                context.arc(p.x,p.y,6,0,2*Math.PI);
                context.fillStyle = "#ee0000";
                context.fill();
              }
            },false);
          })();
        </script>
      </body>

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  • 原文地址:https://www.cnblogs.com/lxf1016/p/4702207.html
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