微信小程序之自定义tabbar

0. 官方指南

# 由于微信小程序的异步机制，页面跳转会出现随机事件
# 目的： 解决认证跳转过程的不友好体验
https://developers.weixin.qq.com/miniprogram/dev/framework/ability/custom-tabbar.html

1. app.json文件的处理

1. 添加："custom": true,使用自定义的tabbar
2. 将非tabbar的内容删除，删除的示例是发布，如下：

"tabBar": {
"custom": true,
"selectedColor": "#CD5C5C",
"list": [
  {
    "pagePath": "pages/home/home",
    "text": "首页",
    "iconPath": "static/tabbar/ic_menu_choice_nor.png",
    "selectedIconPath": "static/tabbar/ic_menu_choice_pressed.png"
  },
  {
    "pagePath": "pages/auction/auction",
    "text": "拍卖",
    "iconPath": "static/tabbar/ic_menu_me_nor.png",
    "selectedIconPath": "static/tabbar/ic_menu_me_pressed.png"
  },
  {
    "pagePath": "pages/message/message",
    "text": "消息",
    "iconPath": "static/tabbar/ic_menu_me_nor.png",
    "selectedIconPath": "static/tabbar/ic_menu_me_pressed.png"
  },
  {
    "pagePath": "pages/index/index",
    "text": "我的",
    "iconPath": "static/tabbar/ic_menu_me_nor.png",
    "selectedIconPath": "static/tabbar/ic_menu_me_pressed.png"
  }
]

},

2. 创建组件目录

-component
	-tabBar
		-tabbar.js
		-tabbar.json
		-tabbar.wxml
		-tabbar.wxss

3. js文件解读：

// component/tabbar/tabbar.js
var app = getApp()
Component({
  /**
   * 组件的属性列表：selected--标记tabbar的index，
   */
  properties: {
	selected: {
	  type: Number,
	  value: 0
	}
  },

  /**
   * 组件的初始数据
   */
  data: {
	color: "#7A7E83",
	"selectedColor": "#CD5C5C",
	"list": [
	  {
		"pagePath": "/pages/home/home",
		"text": "首页",
		"iconPath": "/static/tabbar/ic_menu_choice_nor.png",
		"selectedIconPath": "/static/tabbar/ic_menu_choice_pressed.png"
	  },
	  {
		"pagePath": "/pages/auction/auction",
		"text": "拍卖",
		"iconPath": "/static/tabbar/ic_menu_me_nor.png",
		"selectedIconPath": "/static/tabbar/ic_menu_me_pressed.png"
	  },
	  {
		"text": "发布",
	  },
	  {
		"pagePath": "/pages/message/message",
		"text": "消息",
		"iconPath": "/static/tabbar/ic_menu_me_nor.png",
		"selectedIconPath": "/static/tabbar/ic_menu_me_pressed.png"
	  },
	  {
		"pagePath": "/pages/index/index",
		"text": "我的",
		"iconPath": "/static/tabbar/ic_menu_me_nor.png",
		"selectedIconPath": "/static/tabbar/ic_menu_me_pressed.png"
	  }
	]
  },

  /**
   * 组件的方法列表
   * switchTab：跳转到tabbar页面，即首页，拍卖，消息，我的，四个自定义tabbar页面
   * navigateTo：只能跳转到非tabbar页面，示例是发布页面："/pages/publish/publish"
   */
  methods: {

	switchTab(e) {
	  var data = e.currentTarget.dataset
	  var url = data.path;
	  console.log(url)
	  if (url) {
		wx.switchTab({ url });
	  } else {
		if (app.globalData.userinfo) {
		  wx.navigateTo({
			url: "/pages/publish/publish",
		  })
		} else {
		  wx.navigateTo({
			url: '/pages/login/login',
		  })
		}
	  }
	}
  }
})

3. js文件解读：

# component：true       ---即表示使用自定义tabbar
{
"component": true,
"usingComponents": {}
}

wxml 文件示例

# wx:for 循环list列表，生成自定义的tabbar标签

# 三元运算表达式：判断tabbar标签是否选中
	- src="{{selected === index ? item.selectedIconPath : item.iconPath}}"

<!--miniprogram/custom-tab-bar/index.wxml-->
<cover-view class="tab-bar">
  <cover-view class="tab-bar-border"></cover-view>

  
  <cover-view wx:for="{{list}}" wx:key="index" class="tab-bar-item" data-path="{{item.pagePath}}"  bindtap="switchTab">

	<block wx:if="{{ index === 2}}">
	  <cover-view class="pub">{{item.text}}</cover-view>
	</block>

	<block wx:else>
	  <cover-image src="{{selected === index ? item.selectedIconPath : item.iconPath}}"></cover-image>
	  <cover-view style="color: {{selected === index ? selectedColor : color}}">{{item.text}}</cover-view>
	</block>
	
  </cover-view>
</cover-view>

4. wxss 文件示例

.tab-bar {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  height: 48px;
  background: white;
  display: flex;
  padding-bottom: env(safe-area-inset-bottom);
  z-index:998
}

.tab-bar-border {
  background-color: rgba(0, 0, 0, 0.33);
  position: absolute;
  left: 0;
  top: 0;
   100%;
  height: 1px;
  transform: scaleY(0.5);
}

.tab-bar-item {
  flex: 1;
  text-align: center;
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
}

.tab-bar-item cover-image {
   27px;
  height: 27px;
}

.tab-bar-item cover-view {
  font-size: 10px;
}


.pub{
  background-color: #fa3d;
  height: 80rpx;
   80rpx;
  border-radius: 50%;

  display: flex;
  flex-direction: row;
  justify-content: center;
  align-items: center;
}

5. 应用实例：home页面(tabbar)

# 两步骤即可
	- selected：即为tabbar.js 文件中的properties属性列表，
	- selected: 标记tabbar的index，

1. home.json: "tabbar": "/component/tabBar/tabBar"

	- {
	  "usingComponents": {
		"tabbar": "/component/tabBar/tabBar"
	  },
	  "enablePullDownRefresh": true
	}
	
2. home.wxml: 

	- <tabbar selected="{{0}}"></tabbar>
	- ......

6. 对于非tabbar的发布，不用做任何操作