HTML画布 - 动态绘制圆形并显示数字

Question

我完全不懂JavaScript和CSS3。我想实现的是绘制四个圆形的动画。整个过程应该如下： 1. 圆圈#1的动画，动画完成后在内部放置数字78 2. 圆圈#2的动画，动画完成后在内部放置数字460 3. 同上，但内部数字是20 4. 同上，但内部数字是15。

我找到了一个代码段： 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();

我添加了几行代码。但说实话，我不知道如何加载其中的四个（一个接一个地带有动画），然后在内部显示这些数字（通常放在

中的数字会显示在圆圈下面）。

有什么想法吗？谢谢！

- Paweł Skaba

---

jQuery在哪里？看起来对我来说就是普通的JavaScript。 - putvande

帖子已编辑。抱歉犯了错误。在jQuery部分找到了相关文章。 - Paweł Skaba

Answer 1

以下是我的方法：

(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

- adeneo