小编这次要给大家分享的是js如何实现抽奖转盘,文章内容丰富,感兴趣的小伙伴可以来了解一下,希望大家阅读完这篇文章之后能够有所收获。
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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

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
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 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('');
};
} catch (e) {
return function (tagName) {
return document.createElement('<' + tagName + ' xmlns="urn:schemas-microsoft.com:vml" class="rvml">');
};
}
})();
}
})(jQuery); 看完这篇关于js如何实现抽奖转盘的文章,如果觉得文章内容写得不错的话,可以把它分享出去给更多人看到。