This time I will bring you parabola.js to implement parabola and add to shopping cart functions, parabola.js to implement parabola and add to shopping cart functions What are the precautions, the following is a practical case, let’s take a look one time.
parabola.js
var funParabola = function (element, target, options) {
/*
* 网页模拟现实需要一个比例尺
* 如果按照1像素就是1米来算，显然不合适，因为页面动不动就几百像素
* 页面上，我们放两个物体，200~800像素之间，我们可以映射为现实世界的2米到8米，也就是100:1
* 不过，本方法没有对此有所体现，因此不必在意
*/
var defaults = {
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 params = {};
options = options || {};
for (var key in defaults) {
params[key] = options[key] || defaults[key];
}
var exports = {
mark: function () {
return this;
},
position: function () {
return this;
},
move: function () {
return this;
},
init: function () {
return this;
}
};
/* 确定移动的方式
* IE6-IE8 是margin位移
* IE9+使用transform
*/
var moveStyle = "margin", testp = document.createElement("p");
if ("oninput" in testp) {
["", "ms", "webkit"].forEach(function (prefix) {
var transform = prefix + (prefix ? "T" : "t") + "ransform";
if (transform in testp.style) {
moveStyle = transform;
}
});
}
// 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 a = params.curvature, b = 0, c = 0;
// 是否执行运动的标志量
var flagMove = true;
if (element && target && element.nodeType == 1 && target.nodeType == 1) {
var rectElement = {}, rectTarget = {};
// 移动元素的中心点位置，目标元素的中心点位置
var centerElement = {}, centerTarget = {};
// 目标元素的坐标位置
var coordElement = {}, coordTarget = {};
// 标注当前元素的坐标
exports.mark = function () {
if (flagMove == false) return this;
if (typeof coordElement.x == "undefined") this.position();
element.setAttribute("data-center", [coordElement.x, coordElement.y].join());
target.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") {
element.style.marginLeft = element.style.marginTop = "0px";
} else {
element.style[moveStyle] = "translate(0, 0)";
}
// 四边缘的坐标
rectElement = element.getBoundingClientRect();
rectTarget = target.getBoundingClientRect();
// 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(params.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
element.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") {
element.style.marginLeft = x + "px";
element.style.marginTop = y + "px";
} else {
element.style[moveStyle] = "translate(" + [x + "px", y + "px"].join() + ")";
}
if (startx !== coordTarget.x) {
params.progress(x, y);
window.requestAnimationFrame(step);
} else {
// 运动结束，回调执行
params.complete();
flagMove = true;
}
};
window.requestAnimationFrame(step);
flagMove = false;
return this;
};
// 初始化方法
exports.init = function () {
this.position().mark().move();
};
}
return exports;
};Implementation
// body <p class="container">  <center>点击加入购物车查看效果</center> <!--动画图片--> <p class="img-element" id="imgElement">  </p> <!--购物车--> <p class="shop-cart" id="shopCart"></p> <span class="shop-cart-num">0</span> <p class="add-shop-cart"><!--加入购物车--></p> </p>
// script
// 起始位置元素
var imgElement = document.querySelector('#imgElement'),
// 终点位置元素
shopCartElement = document.querySelector('#shopCart'),
// 购物车数量
proNum = 0;
// 初始化抛物线动画
var myParabola = funParabola(imgElement, shopCartElement, {
speed: 100,// 每帧移动的像素大小
curvature: 0.005,// 实际指焦点到准线的距离
complete: function () {
imgElement.style.visibility = "hidden";
$('.shop-cart-num').text(++proNum);
}
});
// 绑定加入购物车事件
$('.add-shop-cart').click(function () {
// 重置位置
$('#imgElement').css({ left: '70px', bottom: '25px', visibility: 'visible' });
myParabola.position().move();
});I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the PHP Chinese website!
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