From 27772946c2b87061aa1bb278e680d29e7f538c1f Mon Sep 17 00:00:00 2001
From: frank10000 <740427741@qq.com>
Date: Tue, 16 Oct 2018 10:56:01 +0800
Subject: [PATCH] perf[tagsView]: refactor the moveToTarget function (#1195)

* fix[tagsView]:fixed visited view move to currentTag

* edit the scroll regular friendly

* tweak
---
 src/components/ScrollPane/index.vue      | 54 ++++++++++++++++++++----
 src/views/layout/components/TagsView.vue |  4 +-
 2 files changed, 47 insertions(+), 11 deletions(-)

diff --git a/src/components/ScrollPane/index.vue b/src/components/ScrollPane/index.vue
index d4d75aee..89998e80 100644
--- a/src/components/ScrollPane/index.vue
+++ b/src/components/ScrollPane/index.vue
@@ -5,7 +5,7 @@
 </template>
 
 <script>
-const padding = 15 // tag's padding
+const tagAndTagSpacing = 4 // tagAndTagSpacing
 
 export default {
   name: 'ScrollPane',
@@ -20,18 +20,54 @@ export default {
       const $scrollWrapper = this.$refs.scrollContainer.$refs.wrap
       $scrollWrapper.scrollLeft = $scrollWrapper.scrollLeft + eventDelta / 4
     },
-    moveToTarget($target) {
+    moveToTarget(currentTag) {
       const $container = this.$refs.scrollContainer.$el
       const $containerWidth = $container.offsetWidth
       const $scrollWrapper = this.$refs.scrollContainer.$refs.wrap
-      const $targetLeft = $target.offsetLeft
-      const $targetWidth = $target.offsetWidth
-      if ($targetLeft > $containerWidth) {
-        // tag in the right
-        $scrollWrapper.scrollLeft = $targetLeft - $containerWidth + $targetWidth + padding
+      const tagList = this.$parent.$refs.tag
+
+      let firstTag = null
+      let lastTag = null
+      let prevTag = null
+      let nextTag = null
+
+      // find first tag and last tag
+      if (tagList.length > 0) {
+        firstTag = tagList[0]
+        lastTag = tagList[tagList.length - 1]
+      }
+
+      // find preTag and nextTag
+      for (let i = 0; i < tagList.length; i++) {
+        if (tagList[i] === currentTag) {
+          if (i === 0) {
+            nextTag = tagList[i].length > 1 && tagList[i + 1]
+          } else if (i === tagList.length - 1) {
+            prevTag = tagList[i].length > 1 && tagList[i - 1]
+          } else {
+            prevTag = tagList[i - 1]
+            nextTag = tagList[i + 1]
+          }
+          break
+        }
+      }
+
+      if (firstTag === currentTag) {
+        $scrollWrapper.scrollLeft = 0
+      } else if (lastTag === currentTag) {
+        $scrollWrapper.scrollLeft = $scrollWrapper.scrollWidth - $containerWidth
       } else {
-        // tag in the left
-        $scrollWrapper.scrollLeft = $targetLeft - padding
+        // the tag's offsetLeft after of nextTag
+        const afterNextTagOffsetLeft = nextTag.$el.offsetLeft + nextTag.$el.offsetWidth + tagAndTagSpacing
+
+        // the tag's offsetLeft before of prevTag
+        const beforePrevTagOffsetLeft = prevTag.$el.offsetLeft - tagAndTagSpacing
+
+        if (afterNextTagOffsetLeft > $scrollWrapper.scrollLeft + $containerWidth) {
+          $scrollWrapper.scrollLeft = afterNextTagOffsetLeft - $containerWidth
+        } else if (beforePrevTagOffsetLeft < $scrollWrapper.scrollLeft) {
+          $scrollWrapper.scrollLeft = beforePrevTagOffsetLeft
+        }
       }
     }
   }
diff --git a/src/views/layout/components/TagsView.vue b/src/views/layout/components/TagsView.vue
index 6d878e6a..0aa1c895 100644
--- a/src/views/layout/components/TagsView.vue
+++ b/src/views/layout/components/TagsView.vue
@@ -75,8 +75,8 @@ export default {
       const tags = this.$refs.tag
       this.$nextTick(() => {
         for (const tag of tags) {
-          if (tag.to.path === this.$route.path) {
-            this.$refs.scrollPane.moveToTarget(tag.$el)
+          if (tag.to === this.$route.fullPath) {
+            this.$refs.scrollPane.moveToTarget(tag)
 
             // when query is different then update
             if (tag.to.fullPath !== this.$route.fullPath) {