Add MMMFilteredLoadableImage

MMMLoadable.podspec

@@ -6,7 +6,7 @@
 Pod::Spec.new do |s|
 
   s.name = "MMMLoadable"
-  s.version = "2.1.1"
+  s.version = "2.2.0"
   s.summary = "A simple model for async calculations"
   s.description = "#{s.summary}."
   s.homepage = "https://github.com/mediamonks/#{s.name}"

Sources/MMMLoadable/MMMFilteredLoadableImage.swift

@@ -0,0 +1,55 @@
+//
+// Starbucks App.
+// Copyright (c) 2024 MediaMonks. All rights reserved.
+// 
+
+#if canImport(CoreImage)
+
+import CoreImage
+
+/// A simple proxy filtering the contents of another loadable image with CoreImage filters.
+public final class MMMFilteredLoadableImage: MMMLoadableProxy, MMMLoadableImage {
+
+	private let upstreamImage: MMMLoadableImage
+	private let filters: [CIFilter]
+
+	public init(_ image: MMMLoadableImage, _ filters: [CIFilter]) {
+		self.upstreamImage = image
+		self.filters = filters
+		super.init()
+		self.loadable = image
+	}
+
+	public override func proxyDidChange() {
+		if
+			upstreamImage.isContentsAvailable, let uiImage = upstreamImage.image,
+			let ciImage = uiImage.ciImage ?? uiImage.cgImage.flatMap(CIImage.init(cgImage:))
+		{
+			// TODO: it would be great to move it out of the main thread of course.
+			let outputImage = filters.reduce(ciImage) { inputImage, filter in
+				filter.setValue(inputImage, forKey: kCIInputImageKey)
+				return filter.outputImage ?? inputImage
+			}
+			self.image = UIImage(ciImage: outputImage)
+		} else {
+			self.image = nil
+		}
+	}
+
+	public override var isContentsAvailable: Bool { image != nil }
+
+	public override var loadableState: MMMLoadableState {
+		set { self.loadableState = newValue }
+		get {
+			if super.loadableState == .didSyncSuccessfully && !isContentsAvailable {
+				.didFailToSync
+			} else {
+				super.loadableState
+			}
+		}
+	}
+
+	public private(set) var image: UIImage?
+}
+
+#endif