html canvas - drawing circle with animation & number

Question

i'm totally new in javascript and css3. What I would like to achieve is to have an animation of drawing circle (in fact four of them). Everything should work like that: 1. animation of circle #1 and after animation put number 78 inside 2. animation of circle #2 and after animation put number 460 inside 3. the same but with number 20 inside 4. same but with 15 inside.

I've find a piece of code here: http://jsfiddle.net/uhVj6/100/

    // requestAnimationFrame Shim
(function() {
  var requestAnimationFrame = window.requestAnimationFrame || window.mozRequestAnimationFrame ||
                              window.webkitRequestAnimationFrame || window.msRequestAnimationFrame;
  window.requestAnimationFrame = requestAnimationFrame;
})();


var canvas = document.getElementById('myCanvas');
 var context = canvas.getContext('2d');
 var x = canvas.width / 2;
 var y = canvas.height / 2;
 var radius = 75;
 var endPercent = 101;
 var curPerc = 0;
 var counterClockwise = false;
 var circ = Math.PI * 2;
 var quart = Math.PI / 2;

 context.lineWidth = 10;
 context.strokeStyle = '#ad2323';
 context.shadowOffsetX = 0;
 context.shadowOffsetY = 0;


 function animate(current) {
     context.clearRect(0, 0, canvas.width, canvas.height);
     context.beginPath();
     context.arc(x, y, radius, -(quart), ((circ) * current) - quart, false);
     context.stroke();
     curPerc++;
     if (curPerc < endPercent) {
         requestAnimationFrame(function () {
             animate(curPerc / 100)
         });
     }
 }

 animate();

and I added few lines. But being honest I have to idea how to load four of them (one by one with animation) and then show those numbers inside (usually numbers puted in

show under the circle.

Any ideas? thank you!

Answer 1

Here's how I'd do it :

(function() {
    var requestAnimationFrame = window.requestAnimationFrame || window.mozRequestAnimationFrame || window.webkitRequestAnimationFrame || window.msRequestAnimationFrame;
    window.requestAnimationFrame = requestAnimationFrame;
}());

var canvas  = document.getElementById('myCanvas');
var context = canvas.getContext('2d');
var circles = [];

createCircle(100,100,'78', function() {
    createCircle(270,100,'460', function() {
        createCircle(440,100,'20', function() {
            createCircle(610,100,'15', null);
        });
    });
});

function createCircle(x,y,text,callback) {
     var radius = 75;
     var endPercent = 101;
     var curPerc = 0;
     var counterClockwise = false;
     var circ = Math.PI * 2;
     var quart = Math.PI / 2;

     context.lineWidth = 10;
     context.strokeStyle = '#ad2323';
     context.shadowOffsetX = 0;
     context.shadowOffsetY = 0;

     function doText(context,x,y,text) {
        context.lineWidth = 1;
        context.fillStyle = "#ad2323";
        context.lineStyle = "#ad2323";
        context.font      = "28px sans-serif";
        context.fillText(text, x-15, y+5);
     }
     function animate(current) {
         context.lineWidth = 10;
         context.clearRect(0, 0, canvas.width, canvas.height);
         context.beginPath();
         context.arc(x, y, radius, -(quart), ((circ) * current) - quart, false);
         context.stroke();
         curPerc++;
         if (circles.length) {
             for (var i=0; i<circles.length; i++) {
                 context.lineWidth = 10;
                 context.beginPath();
                 context.arc(circles[i].x, circles[i].y, radius, -(quart), ((circ) * circles[i].curr) - quart, false);
                 context.stroke();
                 doText(context,circles[i].x,circles[i].y,circles[i].text);
             }
         }
         if (curPerc < endPercent) {
             requestAnimationFrame(function () {
                 animate(curPerc / 100)
             });
         }else{
             var circle = {x:x,y:y,curr:current,text:text};
             circles.push(circle);
             doText(context,x,y,text);
             if (callback) callback.call();
         }
     }

     animate();
}

FIDDLE