html让图片自动旋转360 html5 canvas 360图片旋转制作抽奖转盘代码

特效描述：html5canvas 360图片旋转 抽奖转盘代码。60图片旋转制作抽奖转盘代码

代码结构

1. HTML代码

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 = 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();