1 files changed, 82 insertions, 5 deletions

diff --git a/src/components/timeline/timeline.js b/src/components/timeline/timeline.js
index 5a7f7a78..cba46daf 100644
--- a/src/components/timeline/timeline.js
+++ b/src/components/timeline/timeline.js
@@ -2,7 +2,13 @@ import Status from '../status/status.vue'
 import timelineFetcher from '../../services/timeline_fetcher/timeline_fetcher.service.js'
 import Conversation from '../conversation/conversation.vue'
 import TimelineMenu from '../timeline_menu/timeline_menu.vue'
-import { throttle, keyBy } from 'lodash'
+import { debounce, throttle, keyBy } from 'lodash'
+import { library } from '@fortawesome/fontawesome-svg-core'
+import { faCircleNotch } from '@fortawesome/free-solid-svg-icons'
+
+library.add(
+  faCircleNotch
+)
 
 export const getExcludedStatusIdsByPinning = (statuses, pinnedStatusIds) => {
   const ids = []
@@ -33,7 +39,9 @@ const Timeline = {
     return {
       paused: false,
       unfocused: false,
-      bottomedOut: false
+      bottomedOut: false,
+      virtualScrollIndex: 0,
+      blockingClicks: false
     }
   },
   components: {
@@ -63,8 +71,10 @@ const Timeline = {
       }
     },
     classes () {
+      let rootClasses = !this.embedded ? ['panel', 'panel-default'] : []
+      if (this.blockingClicks) rootClasses = rootClasses.concat(['-blocked', '_misclick-prevention'])
       return {
-        root: ['timeline'].concat(!this.embedded ? ['panel', 'panel-default'] : []),
+        root: rootClasses,
         header: ['timeline-heading'].concat(!this.embedded ? ['panel-heading'] : []),
         body: ['timeline-body'].concat(!this.embedded ? ['panel-body'] : []),
         footer: ['timeline-footer'].concat(!this.embedded ? ['panel-footer'] : [])
@@ -78,6 +88,16 @@ const Timeline = {
     },
     pinnedStatusIdsObject () {
       return keyBy(this.pinnedStatusIds)
+    },
+    statusesToDisplay () {
+      const amount = this.timeline.visibleStatuses.length
+      const statusesPerSide = Math.ceil(Math.max(3, window.innerHeight / 80))
+      const min = Math.max(0, this.virtualScrollIndex - statusesPerSide)
+      const max = Math.min(amount, this.virtualScrollIndex + statusesPerSide)
+      return this.timeline.visibleStatuses.slice(min, max).map(_ => _.id)
+    },
+    virtualScrollingEnabled () {
+      return this.$store.getters.mergedConfig.virtualScrolling
     }
   },
   created () {
@@ -85,7 +105,7 @@ const Timeline = {
     const credentials = store.state.users.currentUser.credentials
     const showImmediately = this.timeline.visibleStatuses.length === 0
 
-    window.addEventListener('scroll', this.scrollLoad)
+    window.addEventListener('scroll', this.handleScroll)
 
     if (store.state.api.fetchers[this.timelineName]) { return false }
 
@@ -104,14 +124,24 @@ const Timeline = {
       this.unfocused = document.hidden
     }
     window.addEventListener('keydown', this.handleShortKey)
+    setTimeout(this.determineVisibleStatuses, 250)
   },
   destroyed () {
-    window.removeEventListener('scroll', this.scrollLoad)
+    window.removeEventListener('scroll', this.handleScroll)
     window.removeEventListener('keydown', this.handleShortKey)
     if (typeof document.hidden !== 'undefined') document.removeEventListener('visibilitychange', this.handleVisibilityChange, false)
     this.$store.commit('setLoading', { timeline: this.timelineName, value: false })
   },
   methods: {
+    stopBlockingClicks: debounce(function () {
+      this.blockingClicks = false
+    }, 1000),
+    blockClicksTemporarily () {
+      if (!this.blockingClicks) {
+        this.blockingClicks = true
+      }
+      this.stopBlockingClicks()
+    },
     handleShortKey (e) {
       // Ignore when input fields are focused
       if (['textarea', 'input'].includes(e.target.tagName.toLowerCase())) return
@@ -123,6 +153,7 @@ const Timeline = {
         this.$store.commit('queueFlush', { timeline: this.timelineName, id: 0 })
         this.fetchOlderStatuses()
       } else {
+        this.blockClicksTemporarily()
         this.$store.commit('showNewStatuses', { timeline: this.timelineName })
         this.paused = false
       }
@@ -146,6 +177,48 @@ const Timeline = {
         }
       })
     }, 1000, this),
+    determineVisibleStatuses () {
+      if (!this.$refs.timeline) return
+      if (!this.virtualScrollingEnabled) return
+
+      const statuses = this.$refs.timeline.children
+      const cappedScrollIndex = Math.max(0, Math.min(this.virtualScrollIndex, statuses.length - 1))
+
+      if (statuses.length === 0) return
+
+      const height = Math.max(document.body.offsetHeight, window.pageYOffset)
+
+      const centerOfScreen = window.pageYOffset + (window.innerHeight * 0.5)
+
+      // Start from approximating the index of some visible status by using the
+      // the center of the screen on the timeline.
+      let approxIndex = Math.floor(statuses.length * (centerOfScreen / height))
+      let err = statuses[approxIndex].getBoundingClientRect().y
+
+      // if we have a previous scroll index that can be used, test if it's
+      // closer than the previous approximation, use it if so
+
+      const virtualScrollIndexY = statuses[cappedScrollIndex].getBoundingClientRect().y
+      if (Math.abs(err) > virtualScrollIndexY) {
+        approxIndex = cappedScrollIndex
+        err = virtualScrollIndexY
+      }
+
+      // if the status is too far from viewport, check the next/previous ones if
+      // they happen to be better
+      while (err < -20 && approxIndex < statuses.length - 1) {
+        err += statuses[approxIndex].offsetHeight
+        approxIndex++
+      }
+      while (err > window.innerHeight + 100 && approxIndex > 0) {
+        approxIndex--
+        err -= statuses[approxIndex].offsetHeight
+      }
+
+      // this status is now the center point for virtual scrolling and visible
+      // statuses will be nearby statuses before and after it
+      this.virtualScrollIndex = approxIndex
+    },
     scrollLoad (e) {
       const bodyBRect = document.body.getBoundingClientRect()
       const height = Math.max(bodyBRect.height, -(bodyBRect.y))
@@ -155,6 +228,10 @@ const Timeline = {
         this.fetchOlderStatuses()
       }
     },
+    handleScroll: throttle(function (e) {
+      this.determineVisibleStatuses()
+      this.scrollLoad(e)
+    }, 200),
     handleVisibilityChange () {
       this.unfocused = document.hidden
     }