前言

导航栏是指位于页面顶部或者侧边区域的，在页眉横幅图片上边或下边的一排水平导航按钮，它起着链接站点或者软件内的各个页面的作用。

小程序原生导航栏的限制

• 除了胶囊按钮以外，原生导航栏只会出现返回按钮和当用户打开的小程序最底层页面是非首页时，默认展示的“返回首页”按钮 。
• 原生导航栏的标题文字的颜色只有黑白。
• 布局无法改变，不能做定制。

在做自定义导航栏栏之前得去掉原生导航栏，去掉方法如下：

• 将需要自定义navigationBar页面的page.json的navigationBarTitleText去掉。
• 加上"navigationStyle"："custom"，这样原生的导航栏就已经消失，甚至后退键也不会出现需要自定义。

一、自定义导航栏功能的实现

1.组件的封装

"use strict";
var app = getApp();

Component({
  options: {
    // 多插槽支持
    multipleSlots: true
    // ,addGlobalClass: true
  },
properties: {
  'ext-class': {
    type: String,
    value: ''
  },
    loading: {
      type: Boolean,
      value: false
    },
    active: {
      type: Boolean,
      value: false
      // ,observer: '_showChange'
    }  
  },
  data: {},
attached: function attached() {
  // 组件被加载时，计算ios、android两个平台的尺寸差异
  var _this = this;        
  //动态计算导航栏尺寸
  var isSupport = !!wx.getMenuButtonBoundingClientRect;
  var rect = wx.getMenuButtonBoundingClientRect ? wx.getMenuButtonBoundingClientRect() : null;
  wx.getSystemInfo({
      success: function success(res) {
        var ios = !!(res.system.toLowerCase().search('ios') + 1);
        var statusBarHeight=res.statusBarHeight;
        var topBarHeight=ios ? (44 + statusBarHeight) : (48 + statusBarHeight);

        _this.setData({
            ios: ios,
            topBarHeight:topBarHeight,
            statusBarHeight:statusBarHeight,
            innerWidth: isSupport ? 'width:' + rect.left + 'px' : '',
            innerPaddingRight: isSupport ? 'padding-right:' + (res.windowWidth - rect.left) + 'px' : '',
            leftWidth: isSupport ? 'width:' + (res.windowWidth - rect.left) + 'px' : ''
        }); 
        // 这是为了在外面注入wxss变量，这个设计并不太好
        // _this.triggerEvent('getBarInfo', {topBarHeight,statusBarHeight});               
      }
  });

    //back箭头处理的显示
    var pages=getCurrentPages()      
    if(pages.length>1){
      this.setData({showBack:true})
    }
  },
  methods: {
    // _showChange: function _showChange(active) {           
    //   var displayStyle = 'opacity: ' + (active ? '1' : '0') + ';-webkit-transition:opacity 0.5s;transition:opacity 0.5s;';           
    //   this.setData({
    //       displayStyle: displayStyle
    //   });
    // },
    //双击返回顶部
    doubleClick(e) {
      if (this.timeStamp && (e.timeStamp - this.timeStamp < 300)) {
        this.timeStamp = 0
        wx.pageScrollTo({
          scrollTop: 0,
          duration: 300
        })
      } else {
        this.timeStamp = e.timeStamp
      }
    }
  }
});

{
  "styleIsolation": "apply-shared",
  "component": true,
  "usingComponents": {}
}

<view class="weui-navigation-bar {{ext-class}}" bindtouchstart="doubleClick">
	<!-- 标题栏 -->
<view class="{{active ? 'navigator-active' : 'navigator-normal'}} weui-navigation-bar__inner {{ios ? 'ios' : 'android'}}" style="padding-top: {{statusBarHeight}}px;{{innerPaddingRight}};{{innerWidth}};">

		<view class='weui-navigation-bar__left' style="{{leftWidth}}">
			<slot name="left"></slot>
		</view>

		<view class='weui-navigation-bar__center'>
			<view wx:if="{{loading}}" class="weui-navigation-bar__loading"></view>
      <block wx:if="{{active}}">
			  <slot name="center"></slot>
      </block>
		</view>
	</view>
</view>

/* 微信小程序wxss中使用var变量 */
page {
  --height: 44px;
  --right: 190rpx;
}

.weui-navigation-bar {
  overflow: hidden
}
/* 
ios、android两个平台导航栏的高度不一样
ios 44px
android 48px
 */
.weui-navigation-bar .android {
  --height: 48px;
  --right: 222rpx
}

.weui-navigation-bar__placeholder {
  height: var(--height);
  background: #F8F8F8;
  position: relative;
  z-index: 50
}


.weui-navigation-bar__inner {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 5001;
  height: var(--height);
  display: flex;
  align-items: center;
  padding-right: var(--right);
  width: calc(100% - var(--right))
}

.weui-navigation-bar__inner.navigation-bar-border {
  /* border-bottom: 2rpx solid #ddd; */
}

.weui-navigation-bar__inner .weui-navigation-bar__left {
  position: relative;
  width: var(--right);
  padding-left: 15px;
  box-sizing: border-box;
  display: -webkit-box;
  display: -webkit-flex;
  display: flex;
  align-items: center;
  -webkit-box-pack: center;
}

.weui-navigation-bar__inner .weui-navigation-bar__left .btn-back {
  width: 12px;
  height: 24px;
}

.weui-navigation-bar__inner .weui-navigation-bar__left .btn-back image {
  width: 100%;
  height: 100%;
}

.weui-navigation-bar__left .btn-home {
  width: 20px;
  height: 20px;
}

.weui-navigation-bar__left .btn-back+.btn-home {
  margin-left: 50rpx;
}

.weui-navigation-bar__left .btn-home image {
  width: 100%;
  height: 100%;
}

.weui-navigation-bar__inner .weui-navigation-bar__left .weui-navigation-bar__btn_goback:active {
  opacity: .5
}


.weui-navigation-bar__inner .weui-navigation-bar__center {
  font-size: 17px;
  text-align: center;
  position: relative;
  flex: 1;
  display: -webkit-box;
  display: -webkit-flex;
  display: flex;
  align-items: center;
  -webkit-box-pack: center;
  -webkit-justify-content: center;
  justify-content: center;
  overflow: hidden;
}

.weui-navigation-bar__center text {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  margin-top: -2px;
}

.weui-navigation-bar__inner .weui-navigation-bar__loading {
  width: 20px;
  height: 20px;
  margin-right: 5px;
  content: " ";
  animation: loading-animate 1s steps(12, end) infinite;
  background: transparent url(data:image/svg+xml;base64,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) no-repeat;
  background-size: 100%;
}

@keyframes loading-animate {
  0% {
    transform: rotate3d(0, 0, 1, 0deg);
  }

  100% {
    transform: rotate3d(0, 0, 1, 360deg);
  }
}



/* 激活显示的状态, 非透明，有背景色 */
.navigator-active {
  -webkit-transition: opacity 0.5s;
  transition: opacity 0.5s;
  background: #FFF;
  color: #3c3c3c;
}

.navigator-normal {
  -webkit-transition: opacity 0.5s;
  transition: opacity 0.5s;
  background: transparent;
  color: white;
}

2.使用

<navigation-bar 
  ext-class="page-navigator-bar"
  active="{{active}}"
  loading="{{loading}}">
    <view class="left" slot="left">
      <icon bindtap="goBack" class="iconfont icon-back"></icon>
      <icon bindtap="goHome" class="iconfont icon-home"></icon>
    </view>
    <view slot="center">
      <view>自定义导航标题</view>
    </view>
</navigation-bar>

Page({
  data: {
    loading: false,
    active: true
  },
  //点击back事件处理
  goBack: function () {
    wx.navigateBack();
    this.triggerEvent('back');
  },
  //返回首页
  goHome:function(){
    wx.reLaunch({
      url: '/pages/index/index'
    })
  },
})

@font-face {
  font-family: 'iconfont';  /* project id 1716930 */
  src: url('//at.alicdn.com/t/font_1716930_0fs7vun2ngmn.eot');
  src: url('//at.alicdn.com/t/font_1716930_0fs7vun2ngmn.eot?#iefix') format('embedded-opentype'),
  url('//at.alicdn.com/t/font_1716930_0fs7vun2ngmn.woff2') format('woff2'),
  url('//at.alicdn.com/t/font_1716930_0fs7vun2ngmn.woff') format('woff'),
  url('//at.alicdn.com/t/font_1716930_0fs7vun2ngmn.ttf') format('truetype'),
  url('//at.alicdn.com/t/font_1716930_0fs7vun2ngmn.svg#iconfont') format('svg');
}
.iconfont{
  font-family: 'iconfont';
}
.icon-back::after{
  content: '\e604';
  font-size: 22px;
}
.icon-home::after{
  content: '\e6f3';
  font-size: 22px;
}
.left icon:last-child{
  padding-left: 20rpx;
}

.page-navigator-bar .navigator-normal .icon-back{
  color: white;
}
.page-navigator-bar .navigator-normal .icon-home{
  color: white;
}
.page-navigator-bar .navigator-active .icon-back{
  color: black;
}
.page-navigator-bar .navigator-active .icon-home{
  color: black;
}