From 49c8d1b47d99852725bbd832c12dce8a90172aa7 Mon Sep 17 00:00:00 2001
From: Kristaps Fabians Geikins <fabians@speckle.systems>
Date: Thu, 4 Sep 2025 09:43:48 +0300
Subject: [PATCH] feat(fe2): saved views panel keepalive (#5370)

* feat(fe2): saved views panel keepalive

* Remove KeepAlive. Add throttle

---------

Co-authored-by: andrewwallacespeckle <andrew@speckle.systems>
---
 .../components/viewer/controls/Left.vue       | 17 +++++++-----
 .../components/viewer/models/Panel.vue        |  6 ++---
 .../components/viewer/saved-views/Panel.vue   |  7 ++++-
 .../frontend-2/lib/common/composables/dom.ts  | 26 ++++++++++++++++++-
 4 files changed, 44 insertions(+), 12 deletions(-)

diff --git a/packages/frontend-2/components/viewer/controls/Left.vue b/packages/frontend-2/components/viewer/controls/Left.vue
index b8f8bd498..92147ad3b 100644
--- a/packages/frontend-2/components/viewer/controls/Left.vue
+++ b/packages/frontend-2/components/viewer/controls/Left.vue
@@ -139,9 +139,10 @@
       ]"
       :style="`width: ${widthClass};`"
     >
-      <KeepAlive v-show="activePanel === 'models'">
-        <ViewerModelsPanel v-model:sub-view="modelsSubView" />
-      </KeepAlive>
+      <ViewerModelsPanel
+        v-show="activePanel === 'models'"
+        v-model:sub-view="modelsSubView"
+      />
       <KeepAlive v-show="resourceItems.length !== 0 && activePanel === 'filters'">
         <ViewerFiltersPanel />
       </KeepAlive>
@@ -154,10 +155,12 @@
         :summary="summary"
       />
       <ViewerDataviewerPanel v-if="activePanel === 'devMode'" />
-      <ViewerSavedViewsPanel
-        v-if="isSavedViewsEnabled && activePanel === 'savedViews'"
-        @close="activePanel = 'none'"
-      />
+      <KeepAlive>
+        <ViewerSavedViewsPanel
+          v-if="isSavedViewsEnabled && activePanel === 'savedViews'"
+          @close="activePanel = 'none'"
+        />
+      </KeepAlive>
     </div>
   </aside>
 </template>
diff --git a/packages/frontend-2/components/viewer/models/Panel.vue b/packages/frontend-2/components/viewer/models/Panel.vue
index 691f3eba1..d247047db 100644
--- a/packages/frontend-2/components/viewer/models/Panel.vue
+++ b/packages/frontend-2/components/viewer/models/Panel.vue
@@ -126,7 +126,7 @@ import {
   useTreeManagement,
   type UnifiedVirtualItem
 } from '~~/lib/viewer/composables/tree'
-import { useVirtualList, useDebounceFn } from '@vueuse/core'
+import { useVirtualList, useDebounceFn, useThrottleFn } from '@vueuse/core'
 
 type ModelItem = NonNullable<Get<ViewerLoadedResourcesQuery, 'project.models.items[0]'>>
 
@@ -373,7 +373,7 @@ const handleSelectionChange = useDebounceFn(
 )
 
 // Simple scroll tracking - just switch headers
-const handleScroll = (e: Event) => {
+const handleScroll = useThrottleFn((e: Event) => {
   const container = e.target as HTMLElement
   if (!container) return
 
@@ -400,7 +400,7 @@ const handleScroll = (e: Event) => {
       versionId: currentHeader.versionId
     }
   }
-}
+}, 16)
 
 watch(selectedObjects, handleSelectionChange, { deep: true })
 
diff --git a/packages/frontend-2/components/viewer/saved-views/Panel.vue b/packages/frontend-2/components/viewer/saved-views/Panel.vue
index 10574732b..298fafe83 100644
--- a/packages/frontend-2/components/viewer/saved-views/Panel.vue
+++ b/packages/frontend-2/components/viewer/saved-views/Panel.vue
@@ -78,7 +78,10 @@
         </ViewerButtonGroupButton>
       </ViewerButtonGroup>
     </div>
-    <div class="text-body-sm flex-1 min-h-0 overflow-y-auto simple-scrollbar">
+    <div
+      ref="groupsScrollArea"
+      class="text-body-sm flex-1 min-h-0 overflow-y-auto simple-scrollbar"
+    >
       <ViewerSavedViewsPanelGroups
         :views-type="selectedViewsType"
         :search="searchMode ? search || undefined : undefined"
@@ -111,6 +114,7 @@ import { useCreateSavedView } from '~/lib/viewer/composables/savedViews/manageme
 import { useInjectedViewerState } from '~/lib/viewer/composables/setup'
 import { ViewsType, viewsTypeLabels } from '~/lib/viewer/helpers/savedViews'
 import { useDebouncedTextInput } from '@speckle/ui-components'
+import { useKeepAliveScrollState } from '~/lib/common/composables/dom'
 
 graphql(`
   fragment ViewerSavedViewsPanel_Project on Project {
@@ -155,6 +159,7 @@ const searchMode = ref(false)
 const showCreateGroupDialog = ref(false)
 
 const { getTooltipProps } = useSmartTooltipDelay()
+useKeepAliveScrollState(useTemplateRef('groupsScrollArea'))
 
 const canCreateViewOrGroup = computed(
   () => project.value?.permissions.canCreateSavedView
diff --git a/packages/frontend-2/lib/common/composables/dom.ts b/packages/frontend-2/lib/common/composables/dom.ts
index 60edcc27e..f7c829371 100644
--- a/packages/frontend-2/lib/common/composables/dom.ts
+++ b/packages/frontend-2/lib/common/composables/dom.ts
@@ -1,6 +1,7 @@
 import { TIME_MS, timeoutAt } from '@speckle/shared'
-import { until } from '@vueuse/core'
+import { until, useScroll } from '@vueuse/core'
 import DOMPurify from 'dompurify'
+import type { ShallowRef } from 'vue'
 
 const purify = async (source: string) => {
   let purify: DOMPurify.DOMPurifyI
@@ -55,3 +56,26 @@ export function usePurifiedHtml(
     purifiedHtml: computed(() => asyncData.data.value || '')
   }
 }
+
+/**
+ * KeepAlive loses scroll position - use this to cache and restore the position
+ * upon reactivation
+ */
+export const useKeepAliveScrollState = (el: ShallowRef<HTMLElement | null>) => {
+  const scrollTracker = useScroll(el, {
+    throttle: 100
+  })
+
+  const retainedX = ref(scrollTracker.x.value)
+  const retainedY = ref(scrollTracker.y.value)
+
+  onDeactivated(() => {
+    retainedX.value = scrollTracker.x.value
+    retainedY.value = scrollTracker.y.value
+  })
+
+  onActivated(() => {
+    scrollTracker.x.value = retainedX.value
+    scrollTracker.y.value = retainedY.value
+  })
+}