js抽奖转盘实现方法分析
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2022-03-07 13:44:00
本文实例讲述了js抽奖转盘实现方法。分享给大家供大家参考，具体如下：html 这里.left 固定了圆的宽度和高度，还有canvas也设置了固定宽高 绘制圆心的坐标也就出来了 (203,203)抽奖转...
本文实例讲述了js抽奖转盘实现方法。分享给大家供大家参考，具体如下：
html 这里.left 固定了圆的宽度和高度，还有canvas也设置了固定宽高 绘制圆心的坐标也就出来了 (203,203)
抽奖转盘是由一个大圆和一个内圆完成 ；大圆负责绘制上奖品 ，内圆负责确定指针的位置，指针直接使用图片，决定位置确定
<div class="left"> <div class="turnplate" style="background:#1bacff;border-radius: 50%"> <canvas class="item" id="wheelcanvas" width="406px" height="406px"></canvas> <img class="pointer" src="sp2/point.png"/> </div> </div>
外圆留空多少的问题
ps里查看间距是多少，此处圆心(203,203) 大圆的半径就是203-10 =193
这个数值在下图里设置
js
<script type="text/javascript">
var turnplate={
restaraunts:[], //大转盘奖品名称
colors:[], //大转盘奖品区块对应背景颜色
outsideradius:193, //大转盘外圆的半径 192
textradius:155, //大转盘奖品位置距离圆心的距离
insideradius:68, //大转盘内圆的半径
startangle:0, //开始角度
brotate:false //false:停止;ture:旋转
};
$(document).ready(function(){
//动态添加大转盘的奖品与奖品区域背景颜色
turnplate.restaraunts = ["50元代金券", "升职加薪", "100元代金券", "财源滚滚", "200元代金券", "爱情甜蜜 ", "500元代金券", "变美变帅"];
turnplate.colors = ["#1b62ca", "#1bacff", "#1b62ca", "#1bacff","#1b62ca", "#1bacff", "#1b62ca", "#1bacff"];
var rotatetimeout = function (){
$('#wheelcanvas').rotate({
angle:0,
animateto:2160,
duration:8000,
callback:function (){
alert('网络超时，请检查您的网络设置！');
}
});
};
//旋转转盘 item:奖品位置; txt：提示语;
var rotatefn = function (item, txt){
var angles = item * (360 / turnplate.restaraunts.length) - (360 / (turnplate.restaraunts.length*2));
if(angles<270){
angles = 270 - angles;
}else{
angles = 360 - angles + 270;
}
$('#wheelcanvas').stoprotate();
$('#wheelcanvas').rotate({
angle:0,
animateto:angles+1800,
duration:8000,
callback:function (){
alert(txt);
turnplate.brotate = !turnplate.brotate;
}
});
};
$('.pointer').click(function (){
if(turnplate.brotate)return;
turnplate.brotate = !turnplate.brotate;
//获取随机数(奖品个数范围内)
var item = rnd(1,turnplate.restaraunts.length);
//奖品数量等于10,指针落在对应奖品区域的中心角度[252, 216, 180, 144, 108, 72, 36, 360, 324, 288]
rotatefn(item, turnplate.restaraunts[item-1]);
/* switch (item) {
case 1:
rotatefn(252, turnplate.restaraunts[0]);
break;
case 2:
rotatefn(216, turnplate.restaraunts[1]);
break;
case 3:
rotatefn(180, turnplate.restaraunts[2]);
break;
case 4:
rotatefn(144, turnplate.restaraunts[3]);
break;
case 5:
rotatefn(108, turnplate.restaraunts[4]);
break;
case 6:
rotatefn(72, turnplate.restaraunts[5]);
break;
case 7:
rotatefn(36, turnplate.restaraunts[6]);
break;
case 8:
rotatefn(360, turnplate.restaraunts[7]);
break;
case 9:
rotatefn(324, turnplate.restaraunts[8]);
break;
case 10:
rotatefn(288, turnplate.restaraunts[9]);
break;
} */
console.log(item);
});
});
function rnd(n, m){
var random = math.floor(math.random()*(m-n+1)+n);
return random;
}
//页面所有元素加载完毕后执行drawroulettewheel()方法对转盘进行渲染
window.onload=function(){
drawroulettewheel();
};
function drawroulettewheel() {
var canvas = document.getelementbyid("wheelcanvas");
if (canvas.getcontext) {
//根据奖品个数计算圆周角度
var arc = math.pi / (turnplate.restaraunts.length/2);//圆周率/ 奖品数量除以2
var ctx = canvas.getcontext("2d");
//在给定矩形内清空一个矩形
ctx.clearrect(0,0,422,422);
//strokestyle 属性设置或返回用于笔触的颜色、渐变或模式
ctx.strokestyle = "#ffbe04";
//font 属性设置或返回画布上文本内容的当前字体属性
ctx.font = '16px microsoft yahei';
// 绘制圆 （弧形）
for(var i = 0; i < turnplate.restaraunts.length; i++) {
var angle = turnplate.startangle + i * arc;
ctx.fillstyle = turnplate.colors[i];
ctx.beginpath();
//arc(x,y,r,起始角,结束角,绘制方向) 方法创建弧/曲线（用于创建圆或部分圆）
ctx.arc(203, 203, turnplate.outsideradius, angle, angle + arc, false);//绘制外圆
ctx.arc(203, 203, turnplate.insideradius, angle + arc, angle, true);//绘制内圆
ctx.stroke();
ctx.fill();
//锁画布(为了保存之前的画布状态)
ctx.save();
//----绘制奖品开始----
ctx.fillstyle = "#fff";/*奖品文字颜色*/
var text = turnplate.restaraunts[i];
var line_height = 17;
//translate方法重新映射画布上的 (0,0) 位置
ctx.translate(211 + math.cos(angle + arc / 2) * turnplate.textradius, 211 + math.sin(angle + arc / 2) * turnplate.textradius);
//rotate方法旋转当前的绘图
ctx.rotate(angle + arc / 2 + math.pi / 2);
/** 下面代码根据奖品类型、奖品名称长度渲染不同效果，如字体、颜色、图片效果。(具体根据实际情况改变) **/
if(text.indexof("m")>0){//流量包
var texts = text.split("m");
for(var j = 0; j<texts.length; j++){
ctx.font = j == 0?'bold 20px microsoft yahei':'16px microsoft yahei';
if(j == 0){
ctx.filltext(texts[j]+"m", -ctx.measuretext(texts[j]+"m").width / 2, j * line_height);
}else{
ctx.filltext(texts[j], -ctx.measuretext(texts[j]).width / 2, j * line_height);
}
}
}else if(text.indexof("m") == -1 && text.length>6){//奖品名称长度超过一定范围
text = text.substring(0,6)+"||"+text.substring(6);
var texts = text.split("||");
for(var j = 0; j<texts.length; j++){
ctx.filltext(texts[j], -ctx.measuretext(texts[j]).width / 2, j * line_height);
}
}else{
//在画布上绘制填色的文本。文本的默认颜色是黑色
//measuretext()方法返回包含一个对象，该对象包含以像素计的指定字体宽度
ctx.filltext(text, -ctx.measuretext(text).width / 2, 0);
}
//添加对应图标
if(text.indexof("闪币")>0){
var img= document.getelementbyid("shan-img");
img.onload=function(){
ctx.drawimage(img,-15,10);
};
ctx.drawimage(img,-15,10);
}else if(text.indexof("谢谢参与")>=0){
var img= document.getelementbyid("sorry-img");
img.onload=function(){
ctx.drawimage(img,-15,10);
};
ctx.drawimage(img,-15,10);
}
//把当前画布返回（调整）到上一个save()状态之前
ctx.restore();
//----绘制奖品结束----
}
}
}
</script>
引用jquery
在加载以下js
/* ????????????? www.datouwang.com */
(function($) {
var supportedcss,styles=document.getelementsbytagname("head")[0].style,tocheck="transformproperty webkittransform otransform mstransform moztransform".split(" ");
for (var a=0;a<tocheck.length;a++) if (styles[tocheck[a]] !== undefined) supportedcss = tocheck[a];
// bad eval to preven google closure to remove it from code o_o
// after compresion replace it back to var ie = 'v' == '\v'
var ie = eval('"v"=="\v"');
jquery.fn.extend({
rotate:function(parameters)
{
if (this.length===0||typeof parameters=="undefined") return;
if (typeof parameters=="number") parameters={angle:parameters};
var returned=[];
for (var i=0,i0=this.length;i<i0;i++)
{
var element=this.get(i);
if (!element.wilq32 || !element.wilq32.photoeffect) {
var paramclone = $.extend(true, {}, parameters);
var newrotobject = new wilq32.photoeffect(element,paramclone)._rootobj;
returned.push($(newrotobject));
}
else {
element.wilq32.photoeffect._handlerotation(parameters);
}
}
return returned;
},
getrotateangle: function(){
var ret = [];
for (var i=0,i0=this.length;i<i0;i++)
{
var element=this.get(i);
if (element.wilq32 && element.wilq32.photoeffect) {
ret[i] = element.wilq32.photoeffect._angle;
}
}
return ret;
},
stoprotate: function(){
for (var i=0,i0=this.length;i<i0;i++)
{
var element=this.get(i);
if (element.wilq32 && element.wilq32.photoeffect) {
cleartimeout(element.wilq32.photoeffect._timer);
}
}
}
});
// library agnostic interface
wilq32=window.wilq32||{};
wilq32.photoeffect=(function(){
if (supportedcss) {
return function(img,parameters){
img.wilq32 = {
photoeffect: this
};
this._img = this._rootobj = this._eventobj = img;
this._handlerotation(parameters);
}
} else {
return function(img,parameters) {
// make sure that class and id are also copied - just in case you would like to refeer to an newly created object
this._img = img;
this._rootobj=document.createelement('span');
this._rootobj.style.display="inline-block";
this._rootobj.wilq32 =
{
photoeffect: this
};
img.parentnode.insertbefore(this._rootobj,img);
if (img.complete) {
this._loader(parameters);
} else {
var self=this;
// todo: remove jquery dependency
jquery(this._img).bind("load", function()
{
self._loader(parameters);
});
}
}
}
})();
wilq32.photoeffect.prototype={
_setupparameters : function (parameters){
this._parameters = this._parameters || {};
if (typeof this._angle !== "number") this._angle = 0 ;
if (typeof parameters.angle==="number") this._angle = parameters.angle;
this._parameters.animateto = (typeof parameters.animateto==="number") ? (parameters.animateto) : (this._angle);
this._parameters.step = parameters.step || this._parameters.step || null;
this._parameters.easing = parameters.easing || this._parameters.easing || function (x, t, b, c, d) { return -c * ((t=t/d-1)*t*t*t - 1) + b; }
this._parameters.duration = parameters.duration || this._parameters.duration || 1000;
this._parameters.callback = parameters.callback || this._parameters.callback || function(){};
if (parameters.bind && parameters.bind != this._parameters.bind) this._bindevents(parameters.bind);
},
_handlerotation : function(parameters){
this._setupparameters(parameters);
if (this._angle==this._parameters.animateto) {
this._rotate(this._angle);
}
else {
this._animatestart();
}
},
_bindevents:function(events){
if (events && this._eventobj)
{
// unbinding previous events
if (this._parameters.bind){
var oldevents = this._parameters.bind;
for (var a in oldevents) if (oldevents.hasownproperty(a))
// todo: remove jquery dependency
jquery(this._eventobj).unbind(a,oldevents[a]);
}
this._parameters.bind = events;
for (var a in events) if (events.hasownproperty(a))
// todo: remove jquery dependency
jquery(this._eventobj).bind(a,events[a]);
}
},
_loader:(function()
{
if (ie)
return function(parameters)
{
var width=this._img.width;
var height=this._img.height;
this._img.parentnode.removechild(this._img);
this._vimage = this.createvmlnode('image');
this._vimage.src=this._img.src;
this._vimage.style.height=height+"px";
this._vimage.style.width=width+"px";
this._vimage.style.position="absolute"; // fixes ie problem - its only rendered if its on absolute position!
this._vimage.style.top = "0px";
this._vimage.style.left = "0px";
/* group minifying a small 1px precision problem when rotating object */
this._container = this.createvmlnode('group');
this._container.style.width=width;
this._container.style.height=height;
this._container.style.position="absolute";
this._container.setattribute('coordsize',width-1+','+(height-1)); // this -1, -1 trying to fix ugly problem with small displacement on ie
this._container.appendchild(this._vimage);
this._rootobj.appendchild(this._container);
this._rootobj.style.position="relative"; // fixes ie problem
this._rootobj.style.width=width+"px";
this._rootobj.style.height=height+"px";
this._rootobj.setattribute('id',this._img.getattribute('id'));
this._rootobj.classname=this._img.classname;
this._eventobj = this._rootobj;
this._handlerotation(parameters);
}
else
return function (parameters)
{
this._rootobj.setattribute('id',this._img.getattribute('id'));
this._rootobj.classname=this._img.classname;
this._width=this._img.width;
this._height=this._img.height;
this._widthhalf=this._width/2; // used for optimisation
this._heighthalf=this._height/2;// used for optimisation
var _widthmax=math.sqrt((this._height)*(this._height) + (this._width) * (this._width));
this._widthadd = _widthmax - this._width;
this._heightadd = _widthmax - this._height; // widthmax because maxwidth=maxheight
this._widthaddhalf=this._widthadd/2; // used for optimisation
this._heightaddhalf=this._heightadd/2;// used for optimisation
this._img.parentnode.removechild(this._img);
this._aspectw = ((parseint(this._img.style.width,10)) || this._width)/this._img.width;
this._aspecth = ((parseint(this._img.style.height,10)) || this._height)/this._img.height;
this._canvas=document.createelement('canvas');
this._canvas.setattribute('width',this._width);
this._canvas.style.position="relative";
this._canvas.style.left = -this._widthaddhalf + "px";
this._canvas.style.top = -this._heightaddhalf + "px";
this._canvas.wilq32 = this._rootobj.wilq32;
this._rootobj.appendchild(this._canvas);
this._rootobj.style.width=this._width+"px";
this._rootobj.style.height=this._height+"px";
this._eventobj = this._canvas;
this._cnv=this._canvas.getcontext('2d');
this._handlerotation(parameters);
}
})(),
_animatestart:function()
{
if (this._timer) {
cleartimeout(this._timer);
}
this._animatestarttime = +new date;
this._animatestartangle = this._angle;
this._animate();
},
_animate:function()
{
var actualtime = +new date;
var checkend = actualtime - this._animatestarttime > this._parameters.duration;
// todo: bug for animatedgif for static rotation ? (to test)
if (checkend && !this._parameters.animatedgif)
{
cleartimeout(this._timer);
}
else
{
if (this._canvas||this._vimage||this._img) {
var angle = this._parameters.easing(0, actualtime - this._animatestarttime, this._animatestartangle, this._parameters.animateto - this._animatestartangle, this._parameters.duration);
this._rotate((~~(angle*10))/10);
}
if (this._parameters.step) {
this._parameters.step(this._angle);
}
var self = this;
this._timer = settimeout(function()
{
self._animate.call(self);
}, 10);
}
// to fix bug that prevents using recursive function in callback i moved this function to back
if (this._parameters.callback && checkend){
this._angle = this._parameters.animateto;
this._rotate(this._angle);
this._parameters.callback.call(this._rootobj);
}
},
_rotate : (function()
{
var rad = math.pi/180;
if (ie)
return function(angle)
{
this._angle = angle;
this._container.style.rotation=(angle%360)+"deg";
}
else if (supportedcss)
return function(angle){
this._angle = angle;
this._img.style[supportedcss]="rotate("+(angle%360)+"deg)";
}
else
return function(angle)
{
this._angle = angle;
angle=(angle%360)* rad;
// clear canvas
this._canvas.width = this._width+this._widthadd;
this._canvas.height = this._height+this._heightadd;
// remember: all drawings are read from backwards.. so first function is translate, then rotate, then translate, translate..
this._cnv.translate(this._widthaddhalf,this._heightaddhalf); // at least center image on screen
this._cnv.translate(this._widthhalf,this._heighthalf); // we move image back to its orginal
this._cnv.rotate(angle); // rotate image
this._cnv.translate(-this._widthhalf,-this._heighthalf); // move image to its center, so we can rotate around its center
this._cnv.scale(this._aspectw,this._aspecth); // scale - if needed ;)
this._cnv.drawimage(this._img, 0, 0); // first - we draw image
}
})()
}
if (ie)
{
wilq32.photoeffect.prototype.createvmlnode=(function(){
document.createstylesheet().addrule(".rvml", "behavior:url(#default#vml)");
try {
!document.namespaces.rvml && document.namespaces.add("rvml", "urn:schemas-microsoft-com:vml");
return function (tagname) {
return document.createelement('<rvml:' + tagname + ' class="rvml">');
};
} catch (e) {
return function (tagname) {
return document.createelement('<' + tagname + ' xmlns="urn:schemas-microsoft.com:vml" class="rvml">');
};
}
})();
}
})(jquery);
感兴趣的朋友可以使用在线html/css/javascript代码运行工具：http://tools.jb51.net/code/htmljsrun 测试上述代码运行效果。
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