1 <! DOCTYPE html> 2 <html> 3 <head> 4 <title>Clock</title> 5 </head> 6 <style> 7 canvas{ 8 border:1px solid red; 9 } 10 </style> 11 <body onload="move();"> 12 <canvas width=500 height=400 id="c">浏览器暂不支持该功能</canvas> 13 </body> 14 <script> 15 //画表盘的函数 16 function drawcycle(){ 17 var cxt=document.getElementById("c").getContext("2d"); 18 //画圆盘 19 cxt.fillStyle=‘gray‘; 20 cxt.beginPath(); 21 cxt.arc(250,200,120,0,Math.PI*2,false); 22 cxt.closePath(); 23 cxt.fill(); 24 //画指针心 25 cxt.fillStyle=‘black‘; 26 cxt.beginPath(); 27 cxt.arc(250,200,5,0,Math.PI*2,false); 28 cxt.closePath(); 29 cxt.fill(); 30 //画刻度 31 cxt.fillStyle=‘black‘; 32 cxt.beginPath() 33 cxt.fillRect(248,81,4,10); 34 cxt.fillRect(360,198,10,4); 35 cxt.fillRect(248,310,4,10); 36 cxt.fillRect(130,198,10,4); 37 cxt.closePath(); 38 //画线条观测刻度位置是否端正 39 cxt.moveTo(250,80); 40 cxt.lineTo(250,320); 41 cxt.moveTo(130,200); 42 cxt.lineTo(370,200); 43 cxt.stroke();*/ 44 } 45 //变量alphe代表秒针初始状态所在位置角度 46 var alphe=Math.PI/2; 47 //变量bata代表分针初始状态所在位置角度 48 var bata=Math.PI/2; 49 //变量gama代表时针初始状态所在角度 50 var gama=Math.PI/2; 51 //秒针，分针，时针长度定义 52 var second_len=105; 53 var minite_len=75; 54 var hour_len=55; 55 //画针的函数 56 function drawpaint(){ 57 //画布的宽高 58 var width=500; 59 var height=400; 60 //秒针初始位置 61 var second_start_width=250; 62 var second_start_height=95; 63 //分针初始化 64 var minite_start_width=0; 65 var minite_start_height=0; 66 //时针初始化 67 var hour_start_width=0; 68 var hour_start_height=0; 69 var cxt=document.getElementById("c").getContext("2d"); 70 cxt.clearRect(0,0,width,height); 71 drawcycle(); 72 cxt.fillStyle=‘black‘; 73 //画秒针 74 cxt.moveTo(250,200); 75 var del=Math.PI/30; 76 alphe=alphe-del; 77 second_start_width +=second_len*Math.cos(alphe); 78 second_start_height =200-second_len*Math.sin(alphe); 79 cxt.lineTo(second_start_width,second_start_height); 80 cxt.stroke(); 81 //画分针 82 cxt.moveTo(250,200); 83 //分针一秒转过的角度 84 var del_min=Math.PI/1800; 85 bata=bata-del_min; 86 minite_start_width =250+minite_len*Math.cos(bata); 87 minite_start_height =200-minite_len*Math.sin(bata); 88 cxt.lineTo(minite_start_width,minite_start_height); 89 cxt.stroke(); 90 //cxt.fillRect(248,110,4,90); 91 //画时针 92 cxt.moveTo(250,200); 93 //时针一秒转过的角度 94 var del_hou=Math.PI/108000; 95 gama=gama-del_hou; 96 hour_start_width =250+hour_len*Math.cos(gama); 97 hour_start_height =200-hour_len*Math.sin(gama); 98 cxt.lineTo(hour_start_width,hour_start_height); 99 cxt.stroke(); 100 //cxt.fillRect(247,130,6,70);*/ 101 } 102 function move(){ 103 setInterval(‘drawpaint()‘,1000); 104 } 105 </script> 106 </html>
- 实现思路：首先要有绘图的画布，既要用到canvas画布，其次要绘出表盘的图案，最后要画出针的位置，这里注意到不管是时针还是分针亦或是秒针，他们的圆心始终是重叠的，唯一要关注的就是画线的终点坐标，这里就要有一定的几何图案的分析能力。
- 运行效果：
