From 9bdcaa5eaaf08783edf53224ae2dc23009490bef Mon Sep 17 00:00:00 2001
From: Robert McRackan <rmcrackan@metabolon.com>
Date: Fri, 13 May 2022 16:30:46 -0400
Subject: [PATCH] only call notifyPropertyChanged if actually set to new value

---
 .../grid/AsyncNotifyPropertyChanged.cs        |  2 +
 Source/LibationWinForms/grid/GridEntry.cs     | 48 ++++++++++++++-----
 2 files changed, 39 insertions(+), 11 deletions(-)

diff --git a/Source/LibationWinForms/grid/AsyncNotifyPropertyChanged.cs b/Source/LibationWinForms/grid/AsyncNotifyPropertyChanged.cs
index 9cc1bd39..87d3a52c 100644
--- a/Source/LibationWinForms/grid/AsyncNotifyPropertyChanged.cs
+++ b/Source/LibationWinForms/grid/AsyncNotifyPropertyChanged.cs
@@ -8,6 +8,8 @@ namespace LibationWinForms
 	{
 		public event PropertyChangedEventHandler PropertyChanged;
 
+		// per standard INotifyPropertyChanged pattern:
+		// https://docs.microsoft.com/en-us/dotnet/desktop/wpf/data/how-to-implement-property-change-notification
 		public void NotifyPropertyChanged([CallerMemberName] string propertyName = "")
 			=> this.UIThreadAsync(() => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName)));
 	}
diff --git a/Source/LibationWinForms/grid/GridEntry.cs b/Source/LibationWinForms/grid/GridEntry.cs
index 0d20ef1f..a1aa999f 100644
--- a/Source/LibationWinForms/grid/GridEntry.cs
+++ b/Source/LibationWinForms/grid/GridEntry.cs
@@ -41,8 +41,11 @@ namespace LibationWinForms
 			get => _cover;
 			private set
 			{
-				_cover = value;
-				NotifyPropertyChanged();
+				if (_cover != value)
+				{
+					_cover = value;
+					NotifyPropertyChanged();
+				}
 			}
 		}
 
@@ -172,16 +175,25 @@ namespace LibationWinForms
 			switch (itemName)
 			{
 				case nameof(udi.Tags):
-					Book.UserDefinedItem.Tags = udi.Tags;
-					NotifyPropertyChanged(nameof(DisplayTags));
+					if (Book.UserDefinedItem.Tags != udi.Tags)
+                    {
+                        Book.UserDefinedItem.Tags = udi.Tags;
+						NotifyPropertyChanged(nameof(DisplayTags));
+					}
 					break;
 				case nameof(udi.BookStatus):
-					Book.UserDefinedItem.BookStatus = udi.BookStatus;
-					NotifyPropertyChanged(nameof(Liberate));
+					if (Book.UserDefinedItem.BookStatus != udi.BookStatus)
+                    {
+                        Book.UserDefinedItem.BookStatus = udi.BookStatus;
+						NotifyPropertyChanged(nameof(Liberate));
+					}
 					break;
 				case nameof(udi.PdfStatus):
-					Book.UserDefinedItem.PdfStatus = udi.PdfStatus;
-					NotifyPropertyChanged(nameof(Liberate));
+					if (Book.UserDefinedItem.PdfStatus != udi.PdfStatus)
+                    {
+                        Book.UserDefinedItem.PdfStatus = udi.PdfStatus;
+						NotifyPropertyChanged(nameof(Liberate));
+					}
 					break;
 			}
 		}
@@ -211,9 +223,23 @@ namespace LibationWinForms
 
 		private void UpdateLiberatedStatus(bool notify = true)
 		{
-			_bookStatus = LibraryCommands.Liberated_Status(LibraryBook.Book);
-			_pdfStatus = LibraryCommands.Pdf_Status(LibraryBook.Book);
-			if (notify)
+			var changed = false;
+
+			var newBookStatus = LibraryCommands.Liberated_Status(LibraryBook.Book);
+			if (_bookStatus != newBookStatus)
+			{
+				_bookStatus = newBookStatus;
+				changed = true;
+			}
+
+			var newPdfStatus = LibraryCommands.Pdf_Status(LibraryBook.Book);
+			if (_pdfStatus != newPdfStatus)
+			{
+				_pdfStatus = newPdfStatus;
+				changed = true;
+			}
+
+			if (changed && notify)
 				NotifyPropertyChanged(nameof(Liberate));
 		}