Html5绘制时钟

Html5绘制时钟

最近在对Html5比较感兴趣，就用空闲时间做一些小例子进行练习，今天绘制一个走动的时钟，具体如下图所示：

具体思路在上图已有说明，代码如下：

 <script type="text/javascript">

         //绘制圆形的弧度，ctx 为绘制环境，x,y为绘制中心，r为绘制半径，st为起始弧度，end为结束弧度

         function circle(ctx, x, y, r, st, end, w) {

             ctx.lineWidth = w;

             ctx.beginPath();

             ctx.moveTo(x, y);

             ctx.arc(x, y, r, st, end, true);

             ctx.stroke();

         }

         //画一个白色的圆，用以覆盖

         function circle0(ctx, x, y, r, st, end) {

             ctx.fillStyle = "#ffffff";

             ctx.beginPath();

             ctx.arc(x, y, r, st, end, true);

             ctx.fill();

         }

         function circle1(ctx, x, y, r, st, end, w) {

             ctx.strokeStyle = "gray";

             ctx.lineWidth = w;

             ctx.beginPath();

             ctx.arc(x, y, r, st, end, true);

             ctx.stroke();

         }

         //绘制时钟用的线

         function line(ctx, x1, y1, x2, y2, w) {

             if (w == 1) {

                 ctx.strokeStyle = "red";

             } else if (w == 2) {

                 ctx.strokeStyle = "blue";

             } else {

                 ctx.strokeStyle = "black";

             }

             ctx.lineWidth = w;

             ctx.beginPath();

             ctx.moveTo(x1, y1);

             ctx.lineTo(x2, y2);

             ctx.stroke();

         }

         function drawClock() {

             var c = document.getElementById("myCanvas");

             var ctx = c.getContext("2d");

             ctx.clearRect(0, 0, c.width, c.height);

             //绘制一个钟表

             var cX = 300;

             var cY = 200;

             var radius = 100;

             //绘制分与秒的刻度

             for (var i = 0; i < 60; i++) {

                 circle(ctx, cX, cY, radius, i * 6 * Math.PI / 180, (i + 1) * 6 * Math.PI / 180, 1);

             }

             circle0(ctx, cX, cY, radius * 9 / 10, 0, 2 * Math.PI, true);

             //绘制时刻度

             for (var i = 0; i < 12; i++) {

                 circle(ctx, cX, cY, radius, i * 30 * Math.PI / 180, (i + 1) * 30 * Math.PI / 180, 2);

             }

             circle0(ctx, cX, cY, radius * 8 / 10, 0, 2 * Math.PI, true);

             //外围再画一圈

             circle1(ctx, cX, cY, radius * 11 / 10, 0, 2 * Math.PI, 1);

             ctx.save();

             ctx.fillStyle = "black";

             ctx.font = "10px Arial";

             //在钟表的周围画上数字

             for (var i = 0; i < 12; i++) {

                 var fX = cX + Math.cos((i + 1) * 5 * 6 * Math.PI / 180 - Math.PI / 2) * radius * 7.5 / 10;

                 var fY = cY + Math.sin((i + 1) * 5 * 6 * Math.PI / 180 - Math.PI / 2) * radius * 7.5 / 10;

                 ctx.fillText((i + 1), fX, fY);

             }

             var date = new Date();

             var second = date.getSeconds();

             var minute = date.getMinutes();

             var hour = date.getHours();

             hour = hour % 12; //采用12小时制

             var secondX = cX + Math.cos(second * 6 * Math.PI / 180 - Math.PI / 2) * radius * 9 / 10;

             var secondY = cY + Math.sin(second * 6 * Math.PI / 180 - Math.PI / 2) * radius * 9 / 10;

             var minuteX = cX + Math.cos(minute * 6 * Math.PI / 180 - Math.PI / 2) * radius * 8 / 10;

             var minuteY = cY + Math.sin(minute * 6 * Math.PI / 180 - Math.PI / 2) * radius * 8 / 10;

             //小时为了准确起见，应该要加上分的弧度

             var hourX = cX + Math.cos(hour * 30 * Math.PI / 180 + (minute * 6 * Math.PI / 180) / 12 - Math.PI / 2) * radius * 6.5 / 10;

             var hourY = cY + Math.sin(hour * 30 * Math.PI / 180 + (minute * 6 * Math.PI / 180) / 12 - Math.PI / 2) * radius * 6.5 / 10;

             //画秒针，红色

             line(ctx, cX, cY, secondX, secondY, 1);

             //画分针，蓝色

             line(ctx, cX, cY, minuteX, minuteY, 2);

             //画时针，黑色

             line(ctx, cX, cY, hourX, hourY, 3);

             ctx.fillStyle = "black";

             ctx.font = "15px Arial";

             ctx.fillText("CurrentTime is : " + date.toLocaleString(), 150, 450);

             ctx.save();

         }

         window.onload = function () {

             //循环，1s一次，且要在加载完才可以开始，否则会出现找不到对象的异常

             setInterval(drawClock, 1000);

         }

     </script>