add route/component transition animation and an option to disable it

app/src/App.vue

@@ -1,20 +1,25 @@
 <template>
   <div id="app" class="container">
+    <!-- HEADER -->
     <header>
       <b-navbar>
         <b-navbar-brand :to="{ name: 'home' }" exact exact-active-class="active">
           <img alt="Yunohost logo" src="./assets/logo.png">
         </b-navbar-brand>
+
         <b-navbar-nav class="ml-auto">
           <li class="nav-item">
-            <b-button href="/yunohost/sso"
+            <b-button
+              href="/yunohost/sso"
               variant="primary" size="sm" block
             >
               {{ $t('user_interface_link') }} <icon iname="user" />
             </b-button>
           </li>
+
           <li class="nav-item" v-show="connected">
-            <b-button @click.prevent="logout" to="/logout"
+            <b-button
+              @click.prevent="logout"
               variant="outline-dark" block size="sm"
             >
               {{ $t('logout') }} <icon iname="sign-out" />
@@ -24,12 +29,17 @@
       </b-navbar>
     </header>
 
-    <breadcrumb v-if="$route.meta.breadcrumb" />
+    <!-- MAIN -->
+    <breadcrumb />
 
     <main id="main">
-      <router-view />
+      <transition v-if="transitions" :name="transitionName">
+        <router-view class="animated" />
+      </transition>
+      <router-view v-else class="static" />
     </main>
 
+    <!-- FOOTER -->
     <footer>
       <nav>
         <b-nav class="justify-content-center">
@@ -70,8 +80,25 @@ import { mapGetters } from 'vuex'
 export default {
   name: 'App',
 
+  data () {
+    return {
+      transitionName: null
+    }
+  },
+
   computed: {
-    ...mapGetters(['connected', 'yunohost'])
+    ...mapGetters(['connected', 'yunohost', 'transitions'])
+  },
+
+  watch: {
+    // Set the css class to animate the components transition
+    '$route' (to, from) {
+      if (!this.transitions) return
+      // Use the breadcrumb array length as a direction indicator
+      const toDepth = to.meta.breadcrumb.length
+      const fromDepth = from.meta.breadcrumb.length
+      this.transitionName = toDepth < fromDepth ? 'slide-right' : 'slide-left'
+    }
   },
 
   methods: {
@@ -139,4 +166,30 @@ export default {
     }
   }
 }
+
+main {
+  position: relative;
+
+  // Routes transition
+  .animated {
+    transition: all .15s ease-in-out;
+  }
+  .slide-left-enter, .slide-right-leave-active {
+    position: absolute;
+    width: 100%;
+    top: 0;
+    transform: translate(100vw, 0);
+  }
+  .slide-left-leave-active, .slide-right-enter {
+    position: absolute;
+    width: 100%;
+    top: 0;
+    transform: translate(-100vw, 0);
+  }
+  // hack to hide last transition provoqued by the <router-view> element change
+  // while disabling the transitions in ToolWebAdmin
+  .static ~ .animated {
+    display: none;
+  }
+}
 </style>

app/src/components/globals/Breadcrumb.vue

@@ -1,14 +1,14 @@
 <template>
-  <b-breadcrumb>
+  <b-breadcrumb v-if="breadcrumb && breadcrumb.length">
     <b-breadcrumb-item to="/">
       <span class="sr-only">{{ $t('home') }}</span>
       <icon iname="home" />
     </b-breadcrumb-item>
+
     <b-breadcrumb-item
-      v-for="(route, index) in breadcrumb"
-      :key="index"
+      v-for="(route, index) in breadcrumb" :key="index"
       :to="{name: route.name}"
-      :active="index == lastIndex ? true : false"
+      :active="index === lastIndex"
     >
       {{ route.text }}
     </b-breadcrumb-item>
@@ -18,11 +18,14 @@
 <script>
 export default {
   name: 'Breadcrumb',
+
   computed: {
     params: function () {
       return this.$route.params
     },
+
     breadcrumb: function () {
+      if (!this.$route.meta.breadcrumb) return null
       return this.$route.meta.breadcrumb.map(({ name, trad, param }) => {
         let text = ''
         // if a traduction key string has been given and we also need to pass
@@ -37,6 +40,7 @@ export default {
         return { name, text }
       })
     },
+
     lastIndex: function () {
       return this.breadcrumb.length - 1
     }

app/src/i18n/locales/en.json

@@ -354,7 +354,8 @@
         "cache": "Cache",
         "cache_description": "Consider disabling the cache if you plan on working with the CLI while also navigating in this web-admin.",
         "experimental": "Experimental mode",
-        "experimental_description": "Gives you access to experimental features. These are considered unstable and may break your system.<br> Enabled this only if you know what you are doing."
+        "experimental_description": "Gives you access to experimental features. These are considered unstable and may break your system.<br> Enabled this only if you know what you are doing.",
+        "transitions": "Page transition animations"
     },
     "tools_webadmin_settings": "Web-admin settings",
     "udp": "UDP",

app/src/router/routes.js

@@ -7,8 +7,20 @@ import { DomainList, DomainAdd, DomainInfo, DomainDns, DomainCert } from '@/view
 import { ServiceList, ServiceInfo } from '@/views/service'
 
 const routes = [
-  { name: 'home', path: '/', component: Home },
-  { name: 'login', path: '/login', component: Login, meta: { noAuth: true } },
+  {
+    name: 'home',
+    path: '/',
+    component: Home,
+    // Leave the empty breadcrumb as it is used by the animated transition to know which way to go
+    meta: { breadcrumb: [] }
+  },
+
+  {
+    name: 'login',
+    path: '/login',
+    component: Login,
+    meta: { noAuth: true, breadcrumb: [] }
+  },
 
   /* ───────────────╮
    │  POST INSTALL  │
@@ -17,6 +29,7 @@ const routes = [
     name: 'post-install',
     path: '/postinstall',
     component: () => import(/* webpackChunkName: "views/postinstall" */ '@/views/PostInstall'),
+    // Leave the breadcrumb
     meta: { noAuth: true }
   },
 

app/src/store/settings.js

@@ -12,6 +12,7 @@ export default {
     locale: localStorage.getItem('locale'),
     fallbackLocale: localStorage.getItem('fallbackLocale'),
     cache: localStorage.getItem('cache') !== 'false',
+    transitions: localStorage.getItem('transitions') !== 'false',
     experimental: localStorage.getItem('experimental') === 'true',
     supportedLocales: supportedLocales
   },
@@ -32,6 +33,11 @@ export default {
       state.cache = boolean
     },
 
+    'SET_TRANSITIONS' (state, boolean) {
+      localStorage.setItem('transitions', boolean)
+      state.transitions = boolean
+    },
+
     'SET_EXPERIMENTAL' (state, boolean) {
       localStorage.setItem('experimental', boolean)
       state.experimental = boolean
@@ -61,6 +67,7 @@ export default {
     locale: state => (state.locale),
     fallbackLocale: state => (state.fallbackLocale),
     cache: state => (state.cache),
+    transitions: state => (state.transitions),
     experimental: state => state.experimental,
 
     availableLocales: state => {

app/src/views/tool/ToolWebadmin.vue

@@ -39,11 +39,22 @@
         {{ $t('tools_webadmin.cache_description') }}
       </template>
     </b-form-group>
-
     <hr>
 
-    <!-- EXPERIMENTAL MODE -->
+    <!-- TRANSITIONS -->
     <b-form-group
+      label-cols="0" label-cols-lg="2"
+      :label="$t('tools_webadmin.transitions')" label-for="transitions" label-class="font-weight-bold"
+    >
+      <b-checkbox v-model="currentTransitions" id="transitions" switch>
+        {{ $t(currentTransitions ? 'enabled' : 'disabled') }}
+      </b-checkbox>
+    </b-form-group>
+    <hr>
+
+    <!-- EXPERIMENTAL MODE (dev environment only)-->
+    <b-form-group
+      v-if="isDev"
       label-cols="0" label-cols-lg="2" label-class="font-weight-bold"
       label-for="experimental"
     >
@@ -75,6 +86,7 @@ export default {
       'locale',
       'fallbackLocale',
       'cache',
+      'transitions',
       'experimental',
       'availableLocales'
     ]),
@@ -100,6 +112,19 @@ export default {
       }
     },
 
+    currentTransitions: {
+      get: function () { return this.transitions },
+      set: function (newValue) {
+        this.$store.commit('SET_TRANSITIONS', newValue)
+      }
+    },
+
+    // environment
+    isDev () {
+      return process.env.NODE_ENV === 'development'
+    },
+
+    // Only available in 'development' environment.
     currentExperimental: {
       get: function () { return this.experimental },
       set: function (newValue) {