From cbbdad3a10a1b3d406551e0f515c8b8716d78544 Mon Sep 17 00:00:00 2001
From: Drew Weymouth <dweymouth@gmail.com>
Date: Fri, 21 Feb 2025 07:58:56 -0800
Subject: [PATCH] add debouncing for gridview loading

---
 ui/widgets/gridview.go     | 47 ++++++++++++++++++++++++++++++++++----
 ui/widgets/gridviewitem.go |  7 +++---
 2 files changed, 46 insertions(+), 8 deletions(-)

diff --git a/ui/widgets/gridview.go b/ui/widgets/gridview.go
index ae30699e..5855654a 100644
--- a/ui/widgets/gridview.go
+++ b/ui/widgets/gridview.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"strconv"
 	"sync"
+	"time"
 
 	"fyne.io/fyne/v2/lang"
 
@@ -19,6 +20,17 @@ import (
 	"fyne.io/fyne/v2/widget"
 )
 
+var (
+	gridViewUpdateCounter = util.NewEventCounter(70)
+
+	emptyItem = GridViewItemModel{
+		ID:        "dummy",
+		Name:      "—",
+		Secondary: []string{"—"},
+		Suffix:    "—",
+	}
+)
+
 const batchFetchSize = 6
 
 type BatchingIterator[M any] struct {
@@ -340,16 +352,41 @@ func (g *GridView) doUpdateItemCard(itemIdx int, card *GridViewItem) {
 	}
 	card.ItemIndex = itemIdx
 	g.itemForIndex[itemIdx] = card
+	g.stateMutex.Unlock()
+
 	card.ShowSuffix = g.ShowSuffix
+	card.Cover.Im.PlaceholderIcon = g.Placeholder
 	if !card.NeedsUpdate(item) {
 		// nothing to do
-		g.stateMutex.Unlock()
 		return
 	}
-	card.Cover.Im.PlaceholderIcon = g.Placeholder
-	g.stateMutex.Unlock()
-	card.Update(&item)
-	card.ImgLoader.Load(item.CoverArtID)
+
+	if gridViewUpdateCounter.NumEventsSince(time.Now().Add(-150*time.Millisecond)) > 64 {
+		if card.itemID != emptyItem.ID {
+			card.Update(&emptyItem)
+			card.ImgLoader.Load("")
+		}
+		if card.NextUpdateModel == nil {
+			// queue to run later
+			go func() {
+				<-time.After(10 * time.Millisecond)
+				fyne.Do(func() {
+					if card.NextUpdateModel != nil {
+						gridViewUpdateCounter.Add()
+						card.Update(card.NextUpdateModel)
+						card.ImgLoader.Load(card.NextUpdateModel.CoverArtID)
+					}
+					card.NextUpdateModel = nil
+				})
+			}()
+		}
+		card.NextUpdateModel = &item
+	} else {
+		card.NextUpdateModel = nil
+		gridViewUpdateCounter.Add()
+		card.Update(&item)
+		card.ImgLoader.Load(item.CoverArtID)
+	}
 
 	// if user has scrolled near the bottom, fetch more
 	if itemIdx > g.lenItems()-10 {
diff --git a/ui/widgets/gridviewitem.go b/ui/widgets/gridviewitem.go
index 04a1f00c..af5d8916 100644
--- a/ui/widgets/gridviewitem.go
+++ b/ui/widgets/gridviewitem.go
@@ -308,9 +308,10 @@ type GridViewItem struct {
 	focusRect     *canvas.Rectangle
 
 	// updated by GridView
-	Cover     *coverImage
-	ImgLoader util.ThumbnailLoader
-	ItemIndex int
+	Cover           *coverImage
+	ImgLoader       util.ThumbnailLoader
+	ItemIndex       int
+	NextUpdateModel *GridViewItemModel
 
 	OnPlay              func()
 	OnFavorite          func(bool)