Avoid dispatching range changed events if there's nothing to be gained.

src/components/timeline-core.ts

@@ -595,13 +595,22 @@ export class FrigateCardTimelineCore extends LitElement {
       this.view &&
       !MediaQueriesClassifier.areRecordingQueries(this.view.query)
     ) {
-      (
-        await this._createViewWithEventMediaQuery(
+      const newView = await this._createViewWithEventMediaQuery(
           this._createEventMediaQuerys({ window: this._timeline.getWindow() }),
         )
-      )
-        ?.mergeInContext(this._setWindowInContext())
-        ?.dispatchChangeEvent(this);
+
+      // Specifically avoid dispatching new results on range change unless there
+      // is something to be gained by doing so. Example usecase: On initial view
+      // load in mini timeline mode, the first 50 events are fetched -- the
+      // first drag of the timeline should not dispatch new results unless
+      // something is actually useful (as otherwise it creates a visible
+      // 'flicker' for the user as the viewer reloads all the media).
+      const newResults = newView?.queryResults;
+      if (newView && newResults && !this.view.queryResults?.isSupersetOf(newResults)) {
+        newView
+          ?.mergeInContext(this._setWindowInContext())
+          ?.dispatchChangeEvent(this);
+      }
     }
   }
 

src/utils/basic.ts

@@ -181,4 +181,13 @@ export const dayToDate = (day: string): Date => {
   // Must provide the hour:minute:second on parsing or Javascript will assume
   // *UTC* midnight.
   return new Date(`${day}T00:00:00`);
-}
+};
+
+export const isSuperset = (superset: Set<unknown>, subset: Set<unknown>) => {
+  for (const item of subset) {
+    if (!superset.has(item)) {
+      return false;
+    }
+  }
+  return true;
+};

src/view/media-queries-results.ts

@@ -1,4 +1,5 @@
 import clone from 'lodash-es/clone.js';
+import { isSuperset } from '../utils/basic.js';
 import { ViewMedia } from './media.js';
 
 export class MediaQueriesResults {
@@ -21,6 +22,28 @@ export class MediaQueriesResults {
     return clone(this);
   }
 
+  public isSupersetOf(that: MediaQueriesResults): boolean {
+    if (!this._results || !that._results) {
+      return false;
+    }
+
+    const thisMediaIDs = new Set(this._results.map((media) => media.getID()));
+    const thatMediaIDs = new Set(that._results.map((media) => media.getID()));
+
+    if (
+      !thisMediaIDs ||
+      !thatMediaIDs ||
+      // If either media sets contain a null identifier (i.e. a media item with
+      // no ID) we must assume this is not a subset as multiple media items may
+      // reduce to the same null identifier above.
+      thisMediaIDs.has(null) ||
+      thatMediaIDs.has(null)
+    ) {
+      return false;
+    }
+    return isSuperset(thisMediaIDs, thatMediaIDs);
+  }
+
   public getResults(): ViewMedia[] | null {
     return this._results;
   }

src/view/view.ts

@@ -1,7 +1,6 @@
 // Minor / later:
 //  - TODO: ts-prune https://camchenry.com/blog/deleting-dead-code-in-typescript
 //  - TODO: Changing camera in live view, timeline stays the same.
-//  - TODO: Timeline initial load, then drag, appears to reset?
 // Gallery:
 //  - TODO: Filter panel expands from right can occasionally 'stick' open.