CSS 3/HTML 5 - pie chart questions and help

See the attached file. I have a simple pie chart on a canvas, but I can't seem to get the percentages (the ones in text) to appear correctly next to their respective "slices" of pie.

Also, I was hoping for some kind of "fill" effect or animation that fills each slice. Any suggestions or help here would be awesome, too. I'm still trying learn HTML5 and CSS3 and am stuck on this one.
piechart.html
saturationAsked:
Who is Participating?
 
Robert SchuttConnect With a Mentor Software EngineerCommented:
Here's a start:
<html>
<head>
<style>
body {
   background: #333;
}

#canvas {
   display: block;
   width: 600px;
   margin: 100px auto;
   background: #555555;
}

@font-face {
   font-family: "bebas";
   src: url("http://thecodeplayer.com/uploads/fonts/BebasNeue.otf");
}

</style>

<script>

var canvas, context, W, H;

   // Variables
   var degrees = 0;
   var new_degrees = 0;
   var color = "yellow";
   var bgcolor = "#222";

   var barfill = 0;
   var new_barfill = 0;

   var difference = 0;
   var text;
   var animation_loop_gauge, animation_loop_bar, redraw_loop;

   var data = [120, 100, 140];
   var labels = ["120", "100", "140"];
   var colors = ["pink", "orange", "skyblue"];
   var radius;


window.onload = function(){

   // Canvas initialization
   canvas = document.getElementById("canvas");
   //var ctx = canvas.getContext("2d"); // removed - not used

   // Dimensions
   W = canvas.width;
   H = canvas.height;

   // Start the drawing
   //drawGauge();

   /////////////////////////////////
   // PIE CHART FUNCTIONS
   ////////////////////////////////
   //canvas = document.getElementById("canvas"); // removed - duplicate
   context = canvas.getContext("2d");

   for (var i=0; i < data.length; i++) {
      drawSegment(canvas, context, i);
   }

   function degreesToRadians(degrees) {
     return (degrees * Math.PI)/180;
   }

   function sumTo(a, i) {
     var sum = 0;
     for (var j = 0; j < i; j++) {
       sum += a[j];
     }
     return sum;
   }

   function drawSegment(canvas, context, i) {
     context.save();
     var centerX = Math.floor(canvas.width / 2);
     var centerY = Math.floor(canvas.height / 2);
     radius = 50;

     var startingAngle = degreesToRadians(sumTo(data, i));
     var arcSize = degreesToRadians(data[i]);
     var endingAngle = startingAngle + arcSize;

     context.beginPath();
     context.moveTo(centerX, centerY);
       //ctx.arc(W-200, H-200, 40, 0, Math.PI*2, false);
     context.arc(centerX, centerY, radius, startingAngle, endingAngle, false);
     context.closePath();

     context.fillStyle = colors[i];
     context.fill();
     context.restore();

     drawSegmentLabel(canvas, context, i);
   }

   function drawSegmentLabel(canvas, context, i) {
      context.save();
      var x = Math.floor(canvas.width / 2);
      var y = Math.floor(canvas.height / 2);
      var angle = degreesToRadians(sumTo(data, i));

      context.translate(x, y);
      //context.rotate(angle);
      var dx = Math.cos(angle+degreesToRadians(data[i]/2)) * (radius + 30); // Math.floor(canvas.width * 0.1) - 5;
      var dy = Math.sin(angle+degreesToRadians(data[i]/2)) * (radius + 30); // Math.floor(canvas.height * 0.18);

      context.textAlign = "right";
      context.font = "20px bebas";
      context.fillStyle = colors[i];
      //context.fillText(labels[i] + "%", dx, dy);
      var labelval = String(Math.round(data[i]*100/sumTo(data, data.length)));
      context.fillText(labelval + "%", dx + 10 * labelval.length, dy + 10);
      context.restore();
   }
}

</script>

</head>

<body>

<canvas id="canvas" width="600" height="300">Your browser does not support the canvas element.</canvas>

</body>
</html>

Open in new window

0
 
Scott Fell, EE MVEDeveloper & EE ModeratorCommented:
Instead of reinventing the wheel, there are plenty of great js and jquery charting options that can get you going very quickly.

http://www.chartjs.org/

http://www.flotcharts.org/
http://www.flotcharts.org/flot/examples/series-pie/index.html

http://www.fusioncharts.com/
http://www.highcharts.com/

Would these make your life easier or do you want to continue on your current solution?
0
 
saturationAuthor Commented:
Was really wanting to create my own from scratch. Any help?
0
Cloud Class® Course: Microsoft Windows 7 Basic

This introductory course to Windows 7 environment will teach you about working with the Windows operating system. You will learn about basic functions including start menu; the desktop; managing files, folders, and libraries.

 
Scott Fell, EE MVEDeveloper & EE ModeratorCommented:
I only use the chart libraries.  Others have made my life easier so I can concentrate on other aspects of my applications.    Let's see if there is any other input.
0
 
saturationAuthor Commented:
Awesome, Robert--that's looking good. I'll give you the points and ask about animation in a second question. Thanks!
0
 
saturationAuthor Commented:
Perfect.
0
 
Robert SchuttSoftware EngineerCommented:
Here's a version that does some animation.
<html>
<head>
<style>
body {
   background: #333;
}

#canvas {
   display: block;
   width: 600px;
   margin: 100px auto;
   background: #555555;
}

@font-face {
   font-family: "bebas";
   src: url("http://thecodeplayer.com/uploads/fonts/BebasNeue.otf");
}

</style>

<script>

var canvas, context, W, H, animSpeed = 50, animPerc = 0;

   // Variables
   var degrees = 0;
   var new_degrees = 0;
   var color = "yellow";
   var bgcolor = "#222";

   var barfill = 0;
   var new_barfill = 0;

   var difference = 0;
   var text;
   var animation_loop_gauge, animation_loop_bar, redraw_loop;

   var data = [120, 100, 140];
   var labels = ["120", "100", "140"];
   var colors = ["pink", "orange", "skyblue"];
   var radius;


window.onload = function(){

   // Canvas initialization
   canvas = document.getElementById("canvas");

   // Dimensions
   W = canvas.width;
   H = canvas.height;

   // Start the drawing
   //drawGauge();

   /////////////////////////////////
   // PIE CHART FUNCTIONS
   ////////////////////////////////
   context = canvas.getContext("2d");

   for (var i=0; i < data.length; i++) {
      drawSegment(canvas, context, i);
   }

   setTimeout(anim, animSpeed);
}

function degreesToRadians(degrees) {
  return (degrees * Math.PI)/180;
}

function sumTo(a, i) {
  var sum = 0;
  for (var j = 0; j < i; j++) {
    sum += a[j];
  }
  return sum;
}

function drawSegment(canvas, context, i) {
  context.save();
  var centerX = Math.floor(canvas.width / 2);
  var centerY = Math.floor(canvas.height / 2);
  radius = 50;

  var startingAngle = degreesToRadians(sumTo(data, i));
  var arcSize = degreesToRadians(data[i]);
  var endingAngle = startingAngle + arcSize * animPerc / 100;

  context.beginPath();
  context.moveTo(centerX, centerY);
  context.arc(centerX, centerY, radius, startingAngle, endingAngle, false);
  context.closePath();

  context.fillStyle = colors[i];
  context.fill();
  context.restore();

  drawSegmentLabel(canvas, context, i);
}

function drawSegmentLabel(canvas, context, i) {
   context.save();
   var x = Math.floor(canvas.width / 2);
   var y = Math.floor(canvas.height / 2);
   var angle = degreesToRadians(sumTo(data, i));

   context.translate(x, y);
   //context.rotate(angle);
   var dx = Math.cos(angle+degreesToRadians(data[i]/2)) * (radius + 30);
   var dy = Math.sin(angle+degreesToRadians(data[i]/2)) * (radius + 30);

   context.textAlign = "right";
   context.font = "20px bebas";
   context.fillStyle = colors[i];
   //context.fillText(labels[i] + "%", dx, dy);
   var labelval = String(Math.round(data[i]*100/sumTo(data, data.length)));
   context.fillText(labelval + "%", dx + 10 * labelval.length, dy + 10);
   context.restore();
}

function anim() {
   if (animPerc < 100) {
      animPerc += 5;
      context.clearRect(0, 0, canvas.width, canvas.height);
      for (var i=0; i < data.length; i++) {
         drawSegment(canvas, context, i);
      }

      setTimeout(anim, animSpeed);
   }
}

</script>

</head>

<body>

<canvas id="canvas" width="600" height="300">Your browser does not support the canvas element.</canvas>

</body>
</html>

Open in new window

0
 
Robert SchuttSoftware EngineerCommented:
oops... I was already working on that, you had included that in your post so I thought I would add it ;-)
0
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

All Courses

From novice to tech pro — start learning today.