最终效果图.png

场景描述：一般情况下，加入购物车的动画效果都会是上图的3的路线，在这篇文章里，我们来实现1和2路线的加入购物车的动效（3路线的动画效果网上有很多，具体可以参考这篇文章来实现：https://www.cnblogs.com/greengage/p/7815842.html
）。

实现方式：不管是上图中的哪一种效果，我们都是用CSS3里的cubic-bezier（三次贝塞尔曲线）来实现的。具体什么是三次贝塞尔曲线，可以参考这篇文章：https://www.bbsmax.com/A/RnJWwpbRJq/

实现流程：

1、获取屏幕的高度大小

 wx.getSystemInfo({//  获取页面的有关信息
      success: function (res) {
        wx.setStorageSync('systemInfo', res)
        var ww = res.windowWidth;
        var hh = res.windowHeight;
        that.globalData.ww = ww;
        that.globalData.hh = hh;
      }
    });

2、获取点击的位置（购物车的位置我们定为最上方或者最下方），定义移动距离

/*加入购物车动效*/
  _flyToCartEffect: function (events) {
    //获得当前点击的位置，距离可视区域左上角
    var touches = events.touches[0];
    var diff = {
      x: '25px',
      y: app.globalData.hh -touches.clientY-40 + 'px'//向下
      // y: 25- touches.clientY  + 'px'//向上

    },
      style = 'display: block;-webkit-transform:translate(' + diff.x + ',' + diff.y + ') rotate(350deg) scale(0)';  //移动距离
    this.setData({
      isFly: true,
      translateStyle: style
    });
    var that = this;
    setTimeout(() => {
      that.setData({
        isFly: false,
        translateStyle: '-webkit-transform: none;',  //恢复到最初状态
        isShake: true,
      });
      setTimeout(() => {
        var counts = that.data.cartTotalCounts + that.data.productCounts;
        that.setData({
          isShake: false,
          cartTotalCounts: counts
        });
      }, 200);
    }, 1000);
  },

3、在css里调用beizer函数

.fiexd-cart.animate{
  animation: aCartScale 200ms cubic-bezier(.17,.67,.83,.67);
  animation-fill-mode: backwards;
}

aCartScale是，在曲线的最后，实现了个购物车抖动的动画

@-webkit-keyframes aCartScale{
  0%{
    -webkit-transform: scale(1.1);
  }
  100% {
    -webkit-transform: scale(1);
  }
}

至此，流程全部介绍完毕，下面是全部的代码（里面可能有一些没用的css样式代码，读者可以自行根据需要删除）：

js代码：

var app = getApp();
Page({

  /**
   * 页面的初始数据
   */
  data: {
    isFly:false
  },

  /*添加到购物车*/
  onAddingToCartTap: function (events) {
    //防止快速点击
    if (this.data.isFly) {
      return;
    }
    this._flyToCartEffect(events);
  },
  /*加入购物车动效*/
  _flyToCartEffect: function (events) {
    //获得当前点击的位置，距离可视区域左上角
    var touches = events.touches[0];
    var diff = {
      x: '25px',
      y: app.globalData.hh -touches.clientY-40 + 'px'//向下
      // y: 25- touches.clientY  + 'px'//向上

    },
      style = 'display: block;-webkit-transform:translate(' + diff.x + ',' + diff.y + ') rotate(350deg) scale(0)';  //移动距离
    this.setData({
      isFly: true,
      translateStyle: style
    });
    var that = this;
    setTimeout(() => {
      that.setData({
        isFly: false,
        translateStyle: '-webkit-transform: none;',  //恢复到最初状态
        isShake: true,
      });
      setTimeout(() => {
        var counts = that.data.cartTotalCounts + that.data.productCounts;
        that.setData({
          isShake: false,
          cartTotalCounts: counts
        });
      }, 200);
    }, 1000);
  },

})

wxml代码：

<view class="container detail-container">
  <view class="fixed-btns-box" bindtap="onCartTap">
    <view class="fiexd-cart {{isShake?'animate':''}}">
      <image src="../../imgs/icon/cart@top.png"></image>
      <view wx:if="{{cartTotalCounts>0}}">{{cartTotalCounts}}</view>
    </view>
  </view>

  <view 
  style="position: fixed;right: 50rpx;bottom:100rpx;width: 100rpx;"
  class="add-cart-btn {{product.stock==0?'disabled':''}}" bindtap="onAddingToCartTap">
    <text style="width: 360rpx">加入分享</text>
    <image class="cart-icon" src="../../imgs/icon/cart.png"></image>
    <image id="small-top-img" class="small-top-img {{isFly?'animate':''}}" src="https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1575871576&di=dda9d07660c88bea6553c3279b0a8cf0&imgtype=jpg&er=1&src=http%3A%2F%2Fpic.pc6.com%2Fup%2F2011-9%2F2011926155953.jpg"
      mode="aspectFill" style="{{translateStyle}}"></image>
  </view>


  

  <view class="fixed-btns-box2" bindtap="onCartTap">
    <view class="fiexd-cart {{isShake?'animate':''}}">
      <image src="../../imgs/icon/cart@top.png"></image>
      <view wx:if="{{cartTotalCounts>0}}">{{cartTotalCounts}}</view>
    </view>
  </view>

</view>

wxss代码：

.detail-container {
  background-color:#F9F9F9
}
.detail-header-box,.detail-bottom-box{
  background-color: #fff;
}
.detail-topic-img{
  display: flex;
  justify-content: center;
}
.detail-topic-img image{
  width: 100%;
}

.fixed-btns-box{
  position: fixed;
  top:50rpx;
  right:12px;
  width: 80rpx;

}
.fixed-btns-box2{
  position: fixed;
  right:12px;
  width: 80rpx;
  bottom: 50rpx;

}
.fiexd-cart image{
  height: 64rpx;
  width: 64rpx;
}
.fiexd-cart view{
  font-size: 24rpx;
  background-color: #AB956D;
  color: white;
  position: absolute;
  right: 64rpx;
  top: 0rpx;
  height: 36rpx;
  width: 36rpx;
  line-height: 36rpx;
  border-radius: 36rpx;
  text-align: center;
}
.fiexd-cart.animate{
  animation: aCartScale 200ms cubic-bezier(.17,.67,.83,.67);
  animation-fill-mode: backwards;
}

@-webkit-keyframes aCartScale{
  0%{
    -webkit-transform: scale(1.1);
  }
  100% {
    -webkit-transform: scale(1);
  }
}



.product-counts,.add-cart-btn{
  height: 100%;
  display: flex;
  font-size: 24rpx;
  align-items: center;
  justify-content: center;
}
.product-counts{
  width: 50%;
}
.add-cart-btn{
  position: relative;
  flex: 1;
}
.add-cart-btn:active{
  color: #fff;
}
.add-cart-btn.disabled{
  color: #D5D5DB;
}



.small-top-img{
  height: 160rpx;
  width: 160rpx;
  right:6rpx;
  position: absolute;
  opacity: 0;
}
.small-top-img.animate{
  opacity: 1;
  -webkit-transition:all 1000ms cubic-bezier(0.175, 0.885, 0.32, 1.275);
}




.add-cart-btn .cart-icon{
  margin-left: 40rpx;
  height: 32rpx;
  width: 32rpx;
}


.disabled{
    pointer-events: none;
}