js地區轉盤抽獎插件

<script type="text/javascript">
var colors = ["#B8D430", "#3AB745", "#029990", "#3501CB","#2E2C75", "#673A7E", "#CC0071", "#F80120","#F35B20", "#FB9A00", "#FFCC00", "#FEF200"];  
var restaraunts = ["北京", "上海", "天津", "南京","杭州", "深圳", "武漢", "濟南","重慶", "大連", "合肥", "鄭洲"];   
var startAngle = 0;
var arc = Math.PI / 6;
var spinTimeout = null;    
var spinArcStart = 10;  
var spinTime = 0;  
var spinTimeTotal = 0;    
var ctx;    
function draw() {    
  drawRouletteWheel();  
}    
function drawRouletteWheel() {    
  var canvas = document.getElementById("wheelcanvas");    
  if (canvas.getContext) {      
      var outsideRadius = 200;      
      var textRadius = 160;      
      var insideRadius = 125;            
      ctx = canvas.getContext("2d");      
      ctx.clearRect(0,0,500,500);
      ctx.strokeStyle = "black";      
      ctx.lineWidth = 2;            
      ctx.font = 'bold 12px sans-serif';            
      for(var i = 0; i < 12; i++) {       
          var angle = startAngle + i * arc;        
          ctx.fillStyle = colors[i];                
          ctx.beginPath();        
          ctx.arc(250, 250, outsideRadius, angle, angle + arc, false);        
          ctx.arc(250, 250, insideRadius, angle + arc, angle, true);        
          ctx.stroke();        
          ctx.fill();                
          ctx.save();       
          ctx.shadowOffsetX = -1;        
          ctx.shadowOffsetY = -1;        
          ctx.shadowBlur    = 0;        
          ctx.shadowColor   = "rgb(220,220,220)";        
          ctx.fillStyle = "black";        
          ctx.translate(250 + Math.cos(angle + arc / 2) * textRadius, 250 + Math.sin(angle + arc / 2) * textRadius);        
          ctx.rotate(angle + arc / 2 + Math.PI / 2);        
          var text = restaraunts[i];        
          ctx.fillText(text, -ctx.measureText(text).width / 2, 0);        
          ctx.restore();      
          }             
          //Arrow
          ctx.fillStyle = "black";      
          ctx.beginPath();      
          ctx.moveTo(250 - 4, 250 - (outsideRadius + 5));      
          ctx.lineTo(250 + 4, 250 - (outsideRadius + 5));      
          ctx.lineTo(250 + 4, 250 - (outsideRadius - 5)); 
          ctx.lineTo(250 + 9, 250 - (outsideRadius - 5));      
          ctx.lineTo(250 + 0, 250 - (outsideRadius - 13));     
          ctx.lineTo(250 - 9, 250 - (outsideRadius - 5));      
          ctx.lineTo(250 - 4, 250 - (outsideRadius - 5));      
          ctx.lineTo(250 - 4, 250 - (outsideRadius + 5));      
          ctx.fill();    
          } 
}    
function spin() {    
    spinAngleStart = Math.random() * 10 + 10;    
    spinTime = 0;    
    spinTimeTotal = Math.random() * 3 + 4 * 1000;   
    rotateWheel();  
}    
function rotateWheel() {    
    spinTime += 30;    
    if(spinTime >= spinTimeTotal) {      
        stopRotateWheel();      
        return;    
    }    
    var spinAngle = spinAngleStart - easeOut(spinTime, 0, spinAngleStart, spinTimeTotal);    
    startAngle += (spinAngle * Math.PI / 180);
    drawRouletteWheel();    spinTimeout = setTimeout('rotateWheel()', 30); 
}    
function stopRotateWheel() {    
    clearTimeout(spinTimeout);    
    var degrees = startAngle * 180 / Math.PI + 90;    
    var arcd = arc * 180 / Math.PI;    
    var index = Math.floor((360 - degrees % 360) / arcd);    ctx.save();
    ctx.font = 'bold 30px sans-serif';    
    var text = restaraunts[index]    
    ctx.fillText(text, 250 - ctx.measureText(text).width / 2, 250 + 10);    ctx.restore();  
}    
function easeOut(t, b, c, d) {    
    var ts = (t/=d)*t;    
    var tc = ts*t;    
    return b+c*(tc + -3*ts + 3*t);  
}    
draw();
</script>