Parabola.js
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/**
* founder : zzf
* Creation time : 2015/1/20
* note :
* role :
*/
if (!window.requestAnimationFrame) {
window.requestAnimationFrame = function(callback){
return setTimeout(callback, 16);
};
}
var Parabola = (function(){
var params = {}, moveStyle = "margin", testDiv = document.createElement("div");
var a = 0, b = 0, c = 0;//根据两点坐标以及曲率确定运动曲线函数（也就是确定a, b的值） 公式： y = a*x*x + b*x + c;
var exports = {};
var flagMove = true;//是否执行运动的标志量
var config = {
addview : "",
setview : "",
speed: 166.67, // 每帧移动的像素大小，每帧（对于大部分显示屏）大约16~17毫秒
curvature: 0.001, // 实际指焦点到准线的距离，你可以抽象成曲率，这里模拟扔物体的抛物线，因此是开口向下的
progress: function() {},
complete: function() {}
};
var rectElement = {}, rectTarget = {};
var centerElement = {}, centerTarget = {};// 移动元素的中心点位置，目标元素的中心点位置
var coordElement = {}, coordTarget = {};// 目标元素的坐标位置
var methods = {
compatibility : function(){
/* 确定移动的方式
* IE6-IE8 是margin位移
* IE9+使用transform
*/
if ("oninput" in testDiv) {
["", "ms", "webkit"].forEach(function(prefix) {
var transform = prefix + (prefix? "T": "t") + "ransform";
if (transform in testDiv.style) {
moveStyle = transform;
}
});
}
},
error : function(){
alert("请绑定对象");
},
setevent : function(){
// 标注当前元素的坐标
exports.mark = function() {
if (flagMove == false) return this;
if (typeof coordElement.x == "undefined") this.position();
config.addview.setAttribute("data-center", [coordElement.x, coordElement.y].join());
config.setview.setAttribute("data-center", [coordTarget.x, coordTarget.y].join());
return this;
}
exports.position = function() {
if (flagMove == false) return this;
var scrollLeft = document.documentElement.scrollLeft || document.body.scrollLeft,
scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
// 初始位置
if (moveStyle == "margin") {
config.addview.style.marginLeft = "0px";
} else {
config.addview.style[moveStyle] = "translate(0, 0)";
}
// 四边缘的坐标
rectElement = config.addview.getBoundingClientRect();
rectTarget = config.setview.getBoundingClientRect();
var _addview = $(config.addview), _setview = $(config.setview);
rectElement = {
width: _addview.outerWidth(),
height: _addview.outerHeight(),
left: _addview.offset().left - document.body.scrollLeft,
right: _addview.offset().left - document.body.scrollLeft + _addview.outerWidth(),
top: _addview.offset().top - document.body.scrollTop,
bottom: _addview.offset().top - document.body.scrollTop + _addview.outerHeight()
};
rectTarget = {
width: _setview.outerWidth(),
height: _setview.outerHeight(),
left: _setview.offset().left - document.body.scrollLeft,
right: _setview.offset().left - document.body.scrollLeft + _setview.outerWidth(),
top: _setview.offset().top - document.body.scrollTop,
bottom: _setview.offset().top - document.body.scrollTop + _setview.outerHeight()
}
// 移动元素的中心点坐标
centerElement = {
x: rectElement.left + (rectElement.right - rectElement.left) / 2 + scrollLeft,
y: rectElement.top + (rectElement.bottom - rectElement.top) / 2 + scrollTop
};
// 目标元素的中心点位置
centerTarget = {
x: rectTarget.left + (rectTarget.right - rectTarget.left) / 2 + scrollLeft,
y: rectTarget.top + (rectTarget.bottom - rectTarget.top) / 2 + scrollTop
};
// 转换成相对坐标位置
coordElement = {
x: 0,
y: 0
};
coordTarget = {
x: -1 * (centerElement.x - centerTarget.x),
y: -1 * (centerElement.y - centerTarget.y)
};
/*
* 因为经过(0, 0), 因此c = 0
* 于是：
* y = a * x*x + b*x;
* y1 = a * x1*x1 + b*x1;
* y2 = a * x2*x2 + b*x2;
* 利用第二个坐标：
* b = (y2+ a*x2*x2) / x2
*/
// 于是
b = (coordTarget.y - a * coordTarget.x * coordTarget.x) / coordTarget.x;
return this;
};
// 按照这个曲线运动
exports.move = function() {
// 如果曲线运动还没有结束，不再执行新的运动
if (flagMove == false) return this;
var startx = 0, rate = coordTarget.x > 0? 1: -1;
var step = function() {
// 切线 y'=2ax+b
var tangent = 2 * a * startx + b; // = y / x
// y*y + x*x = speed
// (tangent * x)^2 + x*x = speed
// x = Math.sqr(speed / (tangent * tangent + 1));
startx = startx + rate * Math.sqrt(config.speed / (tangent * tangent + 1));
// 防止过界
if ((rate == 1 && startx > coordTarget.x) || (rate == -1 && startx < coordTarget.x)) {
startx = coordTarget.x;
}
var x = startx, y = a * x * x + b * x;
// 标记当前位置，这里有测试使用的嫌疑，实际使用可以将这一行注释
config.addview.setAttribute("data-center", [Math.round(x), Math.round(y)].join());
// x, y目前是坐标，需要转换成定位的像素值
if (moveStyle == "margin") {
config.addview.style.marginLeft = x + "px";
config.addview.style.marginTop = y + "px";
} else {
config.addview.style[moveStyle] = "translate("+ [x + "px", y + "px"].join() +")";
}
if (startx !== coordTarget.x) {
config.progress(x, y);
window.requestAnimationFrame(step);
} else {
// 运动结束，回调执行
config.addview.style.visibility = "hidden";
config.complete();
flagMove = true;
}
};
window.requestAnimationFrame(step);
flagMove = false;
return this;
};
// 初始化方法
exports.init = function() {
this.position().mark().move();
};
},
events : function(){
config.btnview.click(function(event){
var joinBtn = $('.joincart');
var offset = joinBtn.offset();
config.addview.style.marginTop = '0px';
config.addview.style.marginLeft = '0px';
config.addview.style.marginRight = '0px';
config.addview.style.marginBottom = '0px';
config.addview.style.left = offset.left + joinBtn.outerWidth()/2 - 30 + "px";
config.addview.style.top = offset.top + "px";
config.addview.style.visibility = "visible";
// 需要重定位
exports.position().move();
return false;
});
}
};
exports = {
mark: function() { return this; },
position: function() { return this; },
move: function() { return this; },
init: function() { return this; },
start : function(options){
$.extend(config, options);//对象合并
if(! config.addview || ! config.setview){
this.error();
return false;
};
config.addview = document.querySelector(config.addview);
config.setview = document.querySelector(config.setview);
config.btnview = $(config.btnview);
methods.compatibility();
a = config.curvature;
if(1 == config.addview.nodeType && 1 == config.setview.nodeType){
methods.setevent();
};
methods.events();
}
};
return exports;
})();