var num = 6// 奖品数量 var canvas = document.getElementById('canvas')var
btn = document.getElementById('btn')if(!canvas.getContext){
alert('抱歉！浏览器不支持。')return} // 获取绘图上下文 var ctx = canvas.getContext('2d')for
(var i = 1i <= numi++) { // 保存当前状态 ctx.save()// 开始一条新路径
ctx.beginPath()// 位移到圆心，下面需要围绕圆心旋转 ctx.translate(150, 150)// 从(0,
0)坐标开始定义一条新的子路径 ctx.moveTo(0, 0)// 旋转弧度,需将角度转换为弧度,使用 degrees * Math.PI/180
公式进行计算。 ctx.rotate(360 / num * i * Math.PI/180)// 绘制圆弧 ctx.arc(0, 0, 150, 0, 2
* Math.PI / num, false)if (i % 2 == 0) { ctx.fillStyle = '#ffb820'}else{
ctx.fillStyle = '#ffcb3f'} // 填充扇形 ctx.fill()// 绘制边框 ctx.lineWidth = 0.5
ctx.strokeStyle = '#f48d24'ctx.stroke()// 恢复前一个状态 ctx.restore()}
自己参考改吧<input type="button" value="开始旋转" onclick="spin()" style="float: left" />
<meta http-equiv="Content-Type" content="text/htmlcharset=utf-8" />
<canvas id="wheelcanvas" width="500" height="500"></canvas>
<script type="application/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", "武汉", "济南",
"重庆", "大连", "合肥", "郑洲"]
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 = 0i <12i++) {
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>
