From b7c90a420604166cfd1a508419820d8535c73217 Mon Sep 17 00:00:00 2001
From: Nolan Lawson <nolan@nolanlawson.com>
Date: Wed, 2 May 2018 21:32:43 -0700
Subject: [PATCH] add animation for navigation bar indicator (#257)

---
 routes/_components/Layout.html                |  2 +
 routes/_components/Nav.html                   | 39 ++------
 routes/_components/NavItem.html               | 89 ++++++++++++++++---
 routes/_store/computations/computations.js    |  2 +
 .../computations/instanceComputations.js      | 13 ---
 routes/_store/computations/navComputations.js | 85 ++++++++++++++++++
 routes/_store/observers/navObservers.js       | 21 +++++
 routes/_store/observers/observers.js          |  2 +
 8 files changed, 200 insertions(+), 53 deletions(-)
 create mode 100644 routes/_store/computations/navComputations.js
 create mode 100644 routes/_store/observers/navObservers.js

diff --git a/routes/_components/Layout.html b/routes/_components/Layout.html
index e173fa50..a22b5d8a 100644
--- a/routes/_components/Layout.html
+++ b/routes/_components/Layout.html
@@ -29,6 +29,8 @@
         firstTime = false
         this.refs.container.focus()
       }
+      let { page } = this.get()
+      this.store.set({currentPage: page})
     },
     store: () => store
   }
diff --git a/routes/_components/Nav.html b/routes/_components/Nav.html
index f3eabb5f..b9b9e1fa 100644
--- a/routes/_components/Nav.html
+++ b/routes/_components/Nav.html
@@ -1,37 +1,16 @@
 <nav class="main-nav">
 	<ul class="main-nav-ul">
-		<li class="main-nav-li">
-      <NavItem {page} name="home" href="/" svg="#pinafore-logo" label="Home" />
-		</li>
-		<li class="main-nav-li">
-      <NavItem {page} name="notifications" href="/notifications" svg="#fa-bell" label="Notifications" />
-		</li>
-    {#if $pinnedPage === '/local'}
+    {#each $navPages as navPage (navPage.name)}
       <li class="main-nav-li">
-        <NavItem {page} name="local" href="/local" svg="#fa-users" label="Local" />
+        <NavItem
+          {page}
+          name={navPage.name}
+          href={navPage.href}
+          svg={navPage.svg}
+          label={navPage.label}
+        />
       </li>
-    {:elseif $pinnedPage === '/federated'}
-      <li class="main-nav-li">
-        <NavItem {page} name="federated" href="/federated" svg="#fa-globe" label="Federated" />
-      </li>
-    {:elseif $pinnedPage === '/favorites'}
-      <li class="main-nav-li">
-        <NavItem {page} name="favorites" href="/favorites" svg="#fa-star" label="Favorites" />
-      </li>
-    {:elseif $pinnedPage.startsWith('/lists/')}
-      <li class="main-nav-li">
-        <NavItem {page} name="lists" href={$pinnedPage} svg="#fa-bars" label={$pinnedListTitle} />
-      </li>
-    {/if}
-		<li class="main-nav-li">
-      <NavItem {page} name="community" href="/community" svg="#fa-comments" label="Community" />
-		</li>
-    <li class="main-nav-li">
-      <NavItem {page} name="search" href="/search" svg="#fa-search" label="Search" />
-    </li>
-	  <li class="main-nav-li">
-      <NavItem {page} name="settings" href="/settings" svg="#fa-gear" label="Settings" />
-		</li>
+    {/each}
 	</ul>
 </nav>
 
diff --git a/routes/_components/NavItem.html b/routes/_components/NavItem.html
index a08d1ce7..c94ffc39 100644
--- a/routes/_components/NavItem.html
+++ b/routes/_components/NavItem.html
@@ -3,28 +3,41 @@
    aria-current={selected}
    on:click="onClick(event)"
    {href} >
-  {#if name === 'notifications'}
+  <div class="nav-icon-and-label">
+    {#if name === 'notifications'}
     <div class="nav-link-svg-wrapper">
       <svg class="nav-link-svg">
         <use xlink:href={svg} />
       </svg>
       {#if $hasNotifications}
-        <span class="nav-link-notifications" aria-hidden="true">
+      <span class="nav-link-notifications" aria-hidden="true">
           {$numberOfNotifications}
         </span>
       {/if}
     </div>
-  {:else}
+    {:else}
     <svg class="nav-link-svg">
       <use xlink:href={svg} />
     </svg>
-  {/if}
-  <span class="nav-link-label">{label}</span>
+    {/if}
+    <span class="nav-link-label">{label}</span>
+  </div>
+  <div class="nav-indicator"
+       nav-indicator-key={name}
+       ref:indicator
+  ></div>
 </a>
 <style>
   .main-nav-link {
-    border-bottom: 1px solid var(--nav-a-border);
     text-decoration: none;
+    display: flex;
+    justify-content: center;
+    align-items: center;
+    flex: 1;
+    flex-direction: column;
+  }
+
+  .nav-icon-and-label {
     padding: 15px 20px;
     display: flex;
     justify-content: center;
@@ -62,18 +75,38 @@
   }
 
   .main-nav-link.selected {
-    border-bottom: 1px solid var(--nav-a-selected-border);
     background: var(--nav-a-selected-bg);
   }
 
   .main-nav-link.selected:hover {
-    border-bottom: 1px solid var(--nav-a-selected-border-hover);
     background: var(--nav-a-selected-bg-hover);
   }
 
+  .nav-indicator {
+    width: 100%;
+    height: 1px;
+    background: var(--nav-a-border);
+    transform-origin: left;
+  }
+
+  .nav-indicator.animate {
+    transition: transform 333ms ease-in-out;
+  }
+
+  .main-nav-link:hover .nav-indicator {
+    background: var(--nav-a-border-hover);
+  }
+
+  .main-nav-link.selected .nav-indicator {
+    background: var(--nav-a-selected-border);
+  }
+
+  .main-nav-link.selected:hover .nav-indicator {
+    background: var(--nav-a-selected-border-hover);
+  }
+
   .main-nav-link:hover {
     background-color: var(--nav-a-bg-hover);
-    border-bottom: 1px solid var(--nav-a-border-hover);
     text-decoration: none;
   }
 
@@ -106,7 +139,7 @@
       width: 25px;
       height: 25px;
     }
-    .main-nav-link {
+    .nav-icon-and-label {
       padding: 20px 0;
     }
     .nav-link-notifications {
@@ -118,8 +151,44 @@
 <script>
   import { store } from '../_store/store'
   import { smoothScrollToTop } from '../_utils/smoothScrollToTop'
+  import { on, emit } from '../_utils/eventBus'
+  import { mark, stop } from '../_utils/marks'
+  import { doubleRAF } from '../_utils/doubleRAF'
 
   export default {
+    oncreate () {
+      let { name } = this.get()
+      let indicator = this.refs.indicator
+      on('animateNavPart1', this, ({fromPage, toPage}) => {
+        if (fromPage !== name) {
+          return
+        }
+        mark('animateNavPart1 gBCR')
+        let fromRect = indicator.getBoundingClientRect()
+        stop('animateNavPart1 gBCR')
+        emit('animateNavPart2', {fromRect, fromPage, toPage})
+      })
+      on('animateNavPart2', this, ({fromPage, fromRect, toPage}) => {
+        if (toPage !== name) {
+          return
+        }
+        mark('animateNavPart2 gBCR')
+        let toRect = indicator.getBoundingClientRect()
+        stop('animateNavPart2 gBCR')
+        let translateX = fromRect.left - toRect.left
+        let scaleX = fromRect.width / toRect.width
+        indicator.style.transform = `translateX(${translateX}px) scaleX(${scaleX})`
+        let onTransitionEnd = () => {
+          indicator.removeEventListener('transitionend', onTransitionEnd)
+          indicator.classList.remove('animate')
+        }
+        indicator.addEventListener('transitionend', onTransitionEnd)
+        doubleRAF(() => {
+          indicator.classList.add('animate')
+          indicator.style.transform = ''
+        })
+      })
+    },
     store: () => store,
     computed: {
       selected: ({ page, name }) => page === name,
diff --git a/routes/_store/computations/computations.js b/routes/_store/computations/computations.js
index a322ac60..9e360bfc 100644
--- a/routes/_store/computations/computations.js
+++ b/routes/_store/computations/computations.js
@@ -1,7 +1,9 @@
 import { instanceComputations } from './instanceComputations'
 import { timelineComputations } from './timelineComputations'
+import { navComputations } from './navComputations'
 
 export function computations (store) {
   instanceComputations(store)
   timelineComputations(store)
+  navComputations(store)
 }
diff --git a/routes/_store/computations/instanceComputations.js b/routes/_store/computations/instanceComputations.js
index b0718df5..e7eb3c12 100644
--- a/routes/_store/computations/instanceComputations.js
+++ b/routes/_store/computations/instanceComputations.js
@@ -47,17 +47,4 @@ export function instanceComputations (store) {
     ['currentInstanceData'],
     (currentInstanceData) => currentInstanceData && currentInstanceData.access_token
   )
-
-  store.compute(
-    'pinnedListTitle',
-    ['lists', 'pinnedPage'],
-    (lists, pinnedPage) => {
-      if (!pinnedPage.startsWith('/lists')) {
-        return
-      }
-      let listId = pinnedPage.split('/').slice(-1)[0]
-      let list = lists.find(_ => _.id === listId)
-      return list ? list.title : ''
-    }
-  )
 }
diff --git a/routes/_store/computations/navComputations.js b/routes/_store/computations/navComputations.js
new file mode 100644
index 00000000..f0ee1573
--- /dev/null
+++ b/routes/_store/computations/navComputations.js
@@ -0,0 +1,85 @@
+export function navComputations (store) {
+  store.compute(
+    'pinnedListTitle',
+    ['lists', 'pinnedPage'],
+    (lists, pinnedPage) => {
+      if (!pinnedPage.startsWith('/lists')) {
+        return
+      }
+      let listId = pinnedPage.split('/').slice(-1)[0]
+      let list = lists.find(_ => _.id === listId)
+      return list ? list.title : ''
+    }
+  )
+
+  store.compute(
+    'navPages',
+    ['pinnedPage', 'pinnedListTitle'],
+    (pinnedPage, pinnedListTitle) => {
+      let pinnedPageObject
+      if (pinnedPage === '/federated') {
+        pinnedPageObject = {
+          name: 'federated',
+          href: '/federated',
+          svg: '#fa-globe',
+          label: 'Federated'
+        }
+      } else if (pinnedPage === '/favorites') {
+        pinnedPageObject = {
+          name: 'favorites',
+          href: '/favorites',
+          svg: '#fa-star',
+          label: 'Favorites'
+        }
+      } else if (pinnedPage.startsWith('/lists/')) {
+        pinnedPageObject = {
+          name: 'lists',
+          href: pinnedPage,
+          svg: '#fa-bars',
+          label: pinnedListTitle
+        }
+      } else { // local
+        pinnedPageObject = {
+          name: 'local',
+          href: '/local',
+          svg: '#fa-users',
+          label: 'Local'
+        }
+      }
+
+      return [
+        {
+          name: 'home',
+          href: '/',
+          svg: '#pinafore-logo',
+          label: 'Home'
+        },
+        {
+          name: 'notifications',
+          href: '/notifications',
+          svg: '#fa-bell',
+          label: 'Notifications'
+        },
+        pinnedPageObject,
+        {
+          name: 'community',
+          href: '/community',
+          svg: '#fa-comments',
+          label: 'Community'
+        },
+        {
+          name: 'search',
+          href: '/search',
+          svg: '#fa-search',
+          label: 'Search'
+        },
+        {
+          name: 'settings',
+          href: '/settings',
+          svg: '#fa-gear',
+          label: 'Settings'
+        }
+      ]
+    }
+  )
+}
diff --git a/routes/_store/observers/navObservers.js b/routes/_store/observers/navObservers.js
new file mode 100644
index 00000000..4b0105de
--- /dev/null
+++ b/routes/_store/observers/navObservers.js
@@ -0,0 +1,21 @@
+import { emit } from '../../_utils/eventBus'
+
+export function navObservers (store) {
+  function pageIsInNav (store, page) {
+    let { navPages } = store.get()
+    return !!navPages.find(_ => _.name === page)
+  }
+
+  store.observe('currentPage', (currentPage, previousPage) => {
+    if (currentPage && previousPage &&
+        pageIsInNav(store, currentPage) &&
+        pageIsInNav(store, previousPage)) {
+      emit('animateNavPart1', {
+        fromPage: previousPage,
+        toPage: currentPage
+      })
+    }
+  }, {
+    init: false
+  })
+}
diff --git a/routes/_store/observers/observers.js b/routes/_store/observers/observers.js
index 1be4d923..304a201c 100644
--- a/routes/_store/observers/observers.js
+++ b/routes/_store/observers/observers.js
@@ -2,10 +2,12 @@ import { instanceObservers } from './instanceObservers'
 import { timelineObservers } from './timelineObservers'
 import { notificationObservers } from './notificationObservers'
 import { onlineObservers } from './onlineObservers'
+import { navObservers } from './navObservers'
 
 export function observers (store) {
   instanceObservers(store)
   timelineObservers(store)
   notificationObservers(store)
   onlineObservers(store)
+  navObservers(store)
 }