From 84d379b08264b9c663e36ce7e33ae61d92d6b824 Mon Sep 17 00:00:00 2001
From: Philipp Rudiger <prudiger@anaconda.com>
Date: Tue, 25 Jun 2024 15:38:17 +0200
Subject: [PATCH] Do not trigger ScrollButton event unless clicked (#6938)

---
 panel/layout/feed.py   |  2 +-
 panel/models/column.ts | 19 ++++++++++++++++---
 panel/models/feed.ts   | 22 +---------------------
 3 files changed, 18 insertions(+), 25 deletions(-)

diff --git a/panel/layout/feed.py b/panel/layout/feed.py
index 58144e2fdc..fc711ee4f2 100644
--- a/panel/layout/feed.py
+++ b/panel/layout/feed.py
@@ -195,7 +195,7 @@ def _process_event(self, event: ScrollButtonClick) -> None:
         n_visible = self.visible_range[-1] - self.visible_range[0]
         with edit_readonly(self):
             # plus one to center on the last object
-            self.visible_range = (max(n - n_visible + 1, 0), n)
+            self.visible_range = (min(max(n - n_visible + 1, 0), n), n)
 
         with param.discard_events(self):
             # reset the buffers and loaded objects
diff --git a/panel/models/column.ts b/panel/models/column.ts
index 5dbca25a72..a050e67c69 100644
--- a/panel/models/column.ts
+++ b/panel/models/column.ts
@@ -1,6 +1,14 @@
-import {Column as BkColumn, ColumnView as BkColumnView} from "@bokehjs/models/layouts/column"
-import * as DOM from "@bokehjs/core/dom"
+import {ModelEvent} from "@bokehjs/core/bokeh_events"
+import {div} from "@bokehjs/core/dom"
 import type * as p from "@bokehjs/core/properties"
+import type {EventCallback} from "@bokehjs/model"
+import {Column as BkColumn, ColumnView as BkColumnView} from "@bokehjs/models/layouts/column"
+
+export class ScrollButtonClick extends ModelEvent {
+  static {
+    this.prototype.event_name = "scroll_button_click"
+  }
+}
 
 export class ColumnView extends BkColumnView {
   declare model: Column
@@ -62,7 +70,7 @@ export class ColumnView extends BkColumnView {
 
   override render(): void {
     super.render()
-    this.scroll_down_button_el = DOM.createElement("div", {class: "scroll-button"})
+    this.scroll_down_button_el = div({class: "scroll-button"})
     this.shadow_el.appendChild(this.scroll_down_button_el)
     this.el.addEventListener("scroll", () => {
       this.record_scroll_position()
@@ -70,6 +78,7 @@ export class ColumnView extends BkColumnView {
     })
     this.scroll_down_button_el.addEventListener("click", () => {
       this.scroll_to_latest()
+      this.model.trigger_event(new ScrollButtonClick())
     })
   }
 
@@ -118,4 +127,8 @@ export class Column extends BkColumn {
       view_latest: [Bool, false],
     }))
   }
+
+  on_click(callback: EventCallback<ScrollButtonClick>): void {
+    this.on_event(ScrollButtonClick, callback)
+  }
 }
diff --git a/panel/models/feed.ts b/panel/models/feed.ts
index 6a4521fdea..c2231724f3 100644
--- a/panel/models/feed.ts
+++ b/panel/models/feed.ts
@@ -2,14 +2,6 @@ import {Column, ColumnView} from "./column"
 import type * as p from "@bokehjs/core/properties"
 import {build_views} from "@bokehjs/core/build_views"
 import type {UIElementView} from "@bokehjs/models/ui/ui_element"
-import {ModelEvent} from "@bokehjs/core/bokeh_events"
-import type {EventCallback} from "@bokehjs/model"
-
-export class ScrollButtonClick extends ModelEvent {
-  static {
-    this.prototype.event_name = "scroll_button_click"
-  }
-}
 
 export class FeedView extends ColumnView {
   declare model: Feed
@@ -89,21 +81,13 @@ export class FeedView extends ColumnView {
     return created
   }
 
-  override scroll_to_latest(emit_event: boolean = true): void {
-    if (emit_event) {
-      this.model.trigger_event(new ScrollButtonClick())
-    }
-    super.scroll_to_latest()
-  }
-
   override trigger_auto_scroll(): void {
     const limit = this.model.auto_scroll_limit
     const within_limit = this.distance_from_latest <= limit
     if (limit == 0 || !within_limit) {
       return
     }
-
-    this.scroll_to_latest(false)
+    this.scroll_to_latest()
   }
 }
 
@@ -132,8 +116,4 @@ export class Feed extends Column {
       visible_children: [List(Str), []],
     }))
   }
-
-  on_click(callback: EventCallback<ScrollButtonClick>): void {
-    this.on_event(ScrollButtonClick, callback)
-  }
 }