From 9338c81f4a68d217a70ffeefc4faab130d965df5 Mon Sep 17 00:00:00 2001
From: Henry Jameson <me@hjkos.com>
Date: Fri, 8 Nov 2019 21:25:13 +0200
Subject: [PATCH] replace sanity button with loading on scroll

---
 src/components/emoji_picker/emoji_picker.js  | 81 ++++++++++----------
 src/components/emoji_picker/emoji_picker.vue | 17 +---
 2 files changed, 44 insertions(+), 54 deletions(-)

diff --git a/src/components/emoji_picker/emoji_picker.js b/src/components/emoji_picker/emoji_picker.js
index a31adb63..92abf7a2 100644
--- a/src/components/emoji_picker/emoji_picker.js
+++ b/src/components/emoji_picker/emoji_picker.js
@@ -1,9 +1,12 @@
 import { set } from 'vue'
 import Checkbox from '../checkbox/checkbox.vue'
 
-const LOAD_EMOJI_BY = 50
-const LOAD_EMOJI_INTERVAL = 100
-const LOAD_EMOJI_SANE_AMOUNT = 500
+// At widest, approximately 20 emoji are visible in a row,
+// loading 3 rows, could be overkill for narrow picker
+const LOAD_EMOJI_BY = 60
+
+// When to start loading new batch emoji, in pixels
+const LOAD_EMOJI_MARGIN = 64
 
 const filterByKeyword = (list, keyword = '') => {
   return list.filter(x => x.displayText.includes(keyword))
@@ -34,10 +37,22 @@ const EmojiPicker = {
     Checkbox
   },
   methods: {
+    onStickerUploaded (e) {
+      this.$emit('sticker-uploaded', e)
+    },
+    onStickerUploadFailed (e) {
+      this.$emit('sticker-upload-failed', e)
+    },
     onEmoji (emoji) {
       const value = emoji.imageUrl ? `:${emoji.displayText}:` : emoji.replacement
       this.$emit('emoji', { insertion: value, keepOpen: this.keepOpen })
     },
+    onScroll (e) {
+      const target = (e && e.target) || this.$refs['emoji-groups']
+      this.updateScrolledClass(target)
+      this.scrolledGroup(target)
+      this.triggerLoadMore(target)
+    },
     highlight (key) {
       const ref = this.$refs['group-' + key]
       const top = ref[0].offsetTop
@@ -47,9 +62,7 @@ const EmojiPicker = {
         this.$refs['emoji-groups'].scrollTop = top + 1
       })
     },
-    scrolledGroup (e) {
-      const target = (e && e.target) || this.$refs['emoji-groups']
-      const top = target.scrollTop + 5
+    updateScrolledClass (target) {
       if (target.scrollTop <= 5) {
         this.groupsScrolledClass = 'scrolled-top'
       } else if (target.scrollTop >= target.scrollTopMax - 5) {
@@ -57,6 +70,26 @@ const EmojiPicker = {
       } else {
         this.groupsScrolledClass = 'scrolled-middle'
       }
+    },
+    triggerLoadMore (target) {
+      const ref = this.$refs['group-end-custom'][0]
+      const bottom = ref.offsetTop + ref.offsetHeight
+
+      const scrollerBottom = target.scrollTop + target.clientHeight
+      const scrollerTop = target.scrollTop
+
+      // Loads more emoji when they come into view
+      const approachingBottom = bottom - scrollerBottom < LOAD_EMOJI_MARGIN
+      // Always load when at the very top in case there's no scroll space yet
+      const atTop = scrollerTop < 5
+      // Don't load when looking at unicode category
+      const bottomAboveViewport = bottom < scrollerTop
+      if (!bottomAboveViewport && (approachingBottom || atTop)) {
+        this.loadEmoji()
+      }
+    },
+    scrolledGroup (target) {
+      const top = target.scrollTop + 5
       this.$nextTick(() => {
         this.emojisView.forEach(group => {
           const ref = this.$refs['group-' + group.id]
@@ -66,56 +99,34 @@ const EmojiPicker = {
         })
       })
     },
-    loadEmojiInsane () {
-      this.customEmojiLoadAllConfirmed = true
-      this.continueEmojiLoad()
-    },
     loadEmoji () {
       const allLoaded = this.customEmojiBuffer.length === this.filteredEmoji.length
-      const saneLoaded = this.customEmojiBuffer.length >= LOAD_EMOJI_SANE_AMOUNT &&
-            !this.customEmojiLoadAllConfirmed
 
-      if (allLoaded || saneLoaded) {
+      if (allLoaded) {
         return
       }
 
       this.customEmojiBufferSlice += LOAD_EMOJI_BY
-      this.customEmojiTimeout = window.setTimeout(this.loadEmoji, LOAD_EMOJI_INTERVAL)
     },
     startEmojiLoad (forceUpdate = false) {
       const bufferSize = this.customEmojiBuffer.length
-      const bufferPrefilledSane = bufferSize === LOAD_EMOJI_SANE_AMOUNT && !this.customEmojiLoadAllConfirmed
       const bufferPrefilledAll = bufferSize === this.filteredEmoji.length
-      if ((bufferPrefilledSane || bufferPrefilledAll) && !forceUpdate) {
+      if (bufferPrefilledAll && !forceUpdate) {
         return
       }
-      if (this.customEmojiTimeout) {
-        window.clearTimeout(this.customEmojiTimeout)
-      }
-
       this.customEmojiBufferSlice = LOAD_EMOJI_BY
-      this.customEmojiTimeout = window.setTimeout(this.loadEmoji, LOAD_EMOJI_INTERVAL)
-    },
-    continueEmojiLoad () {
-      this.customEmojiTimeout = window.setTimeout(this.loadEmoji, LOAD_EMOJI_INTERVAL)
     },
     toggleStickers () {
       this.showingStickers = !this.showingStickers
     },
     setShowStickers (value) {
       this.showingStickers = value
-    },
-    onStickerUploaded (e) {
-      this.$emit('sticker-uploaded', e)
-    },
-    onStickerUploadFailed (e) {
-      this.$emit('sticker-upload-failed', e)
     }
   },
   watch: {
     keyword () {
       this.customEmojiLoadAllConfirmed = false
-      this.scrolledGroup()
+      this.onScroll()
       this.startEmojiLoad(true)
     }
   },
@@ -129,10 +140,6 @@ const EmojiPicker = {
       }
       return 0
     },
-    saneAmount () {
-      // for UI
-      return LOAD_EMOJI_SANE_AMOUNT
-    },
     filteredEmoji () {
       return filterByKeyword(
         this.$store.state.instance.customEmoji || [],
@@ -142,10 +149,6 @@ const EmojiPicker = {
     customEmojiBuffer () {
       return this.filteredEmoji.slice(0, this.customEmojiBufferSlice)
     },
-    askForSanity () {
-      return this.customEmojiBuffer.length >= LOAD_EMOJI_SANE_AMOUNT &&
-        !this.customEmojiLoadAllConfirmed
-    },
     emojis () {
       const standardEmojis = this.$store.state.instance.emoji || []
       const customEmojis = this.customEmojiBuffer
diff --git a/src/components/emoji_picker/emoji_picker.vue b/src/components/emoji_picker/emoji_picker.vue
index 43da6aa2..9998131d 100644
--- a/src/components/emoji_picker/emoji_picker.vue
+++ b/src/components/emoji_picker/emoji_picker.vue
@@ -47,7 +47,7 @@
           ref="emoji-groups"
           class="emoji-groups"
           :class="groupsScrolledClass"
-          @scroll="scrolledGroup"
+          @scroll="onScroll"
         >
           <div
             v-for="group in emojisView"
@@ -73,6 +73,7 @@
                 :src="emoji.imageUrl"
               >
             </span>
+            <span :ref="'group-end-' + group.id"/>
           </div>
         </div>
         <div class="keep-open">
@@ -80,20 +81,6 @@
             {{ $t('emoji.keep_open') }}
           </Checkbox>
         </div>
-        <div
-          v-if="askForSanity"
-          class="too-many-emoji"
-        >
-          <div class="alert warning hint">
-            {{ $t('emoji.load_all_hint', { saneAmount } ) }}
-          </div>
-          <button
-            class="btn btn-default"
-            @click.prevent="loadEmojiInsane"
-          >
-            {{ $t('emoji.load_all', { emojiAmount: filteredEmoji.length } ) }}
-          </button>
-        </div>
       </div>
       <div
         v-if="showingStickers"