Prevent saving when some file properties change

CHDataManagement/Model/Content.swift

@@ -47,6 +47,9 @@ final class Content: ObservableObject {
 
     var errorCallback: ((StorageError) -> Void)?
 
+    /// A cache of file sizes
+    private var fileSizes: [String: Int] = [:]
+
     init() {
         let settings = Settings.default
         self.settings = settings
@@ -196,4 +199,26 @@ final class Content: ObservableObject {
     func setLastSaveTimestamp() {
         self.lastSave = .now
     }
+
+    // MARK: File sizes
+
+    func size(of file: String) -> Int? {
+        fileSizes[file]
+    }
+
+    func cache(size: Int?, of file: String) {
+        fileSizes[file] = size
+    }
+
+    // MARK: Image dimensions
+
+    private var imageDimensions: [String: CGSize] = [:]
+
+    func dimensions(of image: String) -> CGSize? {
+        imageDimensions[image]
+    }
+
+    func cache(dimensions: CGSize?, of image: String) {
+        imageDimensions[image] = dimensions
+    }
 }

CHDataManagement/Model/FileResource.swift

@@ -48,12 +48,22 @@ final class FileResource: Item, LocalizedItem {
     var isAsset: Bool
 
     /// The dimensions of the image
-    @Published
+    var imageDimensions: CGSize? {
-    var imageDimensions: CGSize? = nil
+        get { content.dimensions(of: id) }
+        set {
+            content.cache(dimensions: newValue, of: id)
+            didChange(save: false)
+        }
+    }
 
     /// The size of the file in bytes
-    @Published
+    var fileSize: Int? {
-    var fileSize: Int? = nil
+        get { content.size(of: id) }
+        set {
+            content.cache(size: newValue, of: id)
+            didChange(save: false)
+        }
+    }
 
     var savedData: Data?
 

CHDataManagement/Model/Item/ChangeObservingItem.swift

@@ -8,7 +8,9 @@ class ChangeObservingItem: ObservableContentItem {
     /// A dummy property to force views to update when properties change
     @Published
     private var changeToggle = false
-    
+
+    private var shouldSave = true
+
     var cancellables = Set<AnyCancellable>()
     
     init(content: Content) {
@@ -19,9 +21,18 @@ class ChangeObservingItem: ObservableContentItem {
     
     // MARK: Change observation
     
-    func didChange() {
+    func didChange(save: Bool = true) {
         DispatchQueue.main.async {
+            self.shouldSave = save
             self.changeToggle.toggle()
+            self.shouldSave = true
         }
     }
+
+    func needsSaving() {
+        guard shouldSave else {
+            return
+        }
+        content.needsSave()
+    }
 }

CHDataManagement/Storage/ChangeObservableItem.swift

@@ -7,6 +7,17 @@ protocol ChangeObservableItem: ObservableObject {
     func needsSaving()
 }
 
+extension ChangeObservableItem {
+
+    func observeChanges() {
+        objectWillChange
+            .sink { [weak self] _ in
+                self?.needsSaving()
+            }
+            .store(in: &cancellables)
+    }
+}
+
 protocol ObservableContentItem: ChangeObservableItem {
 
     var content: Content { get }
@@ -18,14 +29,3 @@ extension ObservableContentItem {
         content.needsSave()
     }
 }
-
-extension ChangeObservableItem {
-
-    func observeChanges() {
-        objectWillChange
-            .sink { [weak self] _ in
-                self?.needsSaving()
-            }
-            .store(in: &cancellables)
-    }
-}