ImageProcessor to intercept the UIImage

AsyncImage.xcodeproj/project.pbxproj

@@ -21,6 +21,7 @@
 /* End PBXAggregateTarget section */
 
 /* Begin PBXBuildFile section */
+		1F6284DD29525A5E0060AAD8 /* ImageProcessor.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1F6284DC29525A5E0060AAD8 /* ImageProcessor.swift */; };
 		D4B7E90A2676204F006271B3 /* AsyncImageDemoApp.swift in Sources */ = {isa = PBXBuildFile; fileRef = D4B7E9092676204F006271B3 /* AsyncImageDemoApp.swift */; };
 		D4B7E90C2676204F006271B3 /* ContentView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D4B7E90B2676204F006271B3 /* ContentView.swift */; };
 		D4B7E90E26762050006271B3 /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = D4B7E90D26762050006271B3 /* Assets.xcassets */; };
@@ -78,6 +79,7 @@
 /* End PBXCopyFilesBuildPhase section */
 
 /* Begin PBXFileReference section */
+		1F6284DC29525A5E0060AAD8 /* ImageProcessor.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ImageProcessor.swift; sourceTree = "<group>"; };
 		"AsyncImage::AsyncImage::Product" /* AsyncImage.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; path = AsyncImage.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		"AsyncImage::AsyncImageTests::Product" /* AsyncImageTests.xctest */ = {isa = PBXFileReference; lastKnownFileType = file; path = AsyncImageTests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
 		D4B7E9072676204F006271B3 /* AsyncImageDemo.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = AsyncImageDemo.app; sourceTree = BUILT_PRODUCTS_DIR; };
@@ -207,6 +209,7 @@
 				OBJ_9 /* AsyncImage.swift */,
 				OBJ_10 /* ImageLoader.swift */,
 				OBJ_11 /* ImageService.swift */,
+				1F6284DC29525A5E0060AAD8 /* ImageProcessor.swift */,
 				D4B7E93F26774B8F006271B3 /* SessionDelegate.swift */,
 				D4B7E93126766DB2006271B3 /* DataTask.swift */,
 				OBJ_12 /* LRUCache.swift */,
@@ -351,6 +354,7 @@
 				D4B7E94026774B8F006271B3 /* SessionDelegate.swift in Sources */,
 				OBJ_26 /* AsyncImage.swift in Sources */,
 				OBJ_27 /* ImageLoader.swift in Sources */,
+				1F6284DD29525A5E0060AAD8 /* ImageProcessor.swift in Sources */,
 				OBJ_28 /* ImageService.swift in Sources */,
 				OBJ_29 /* LRUCache.swift in Sources */,
 			);

Sources/AsyncImage/AsyncImage.swift

@@ -37,17 +37,18 @@ public struct AsyncImage<Content: View>: View {
             .onDisappear { loader.cancelDownload() }
     }
 
-    public init(url: URL, scale: CGFloat = 1) where Content == Image {
-        loader = ImageLoader(url: url, scale: scale)
+    public init(url: URL, scale: CGFloat = 1, processor: ImageProcessor? = nil) where Content == Image {
+        loader = ImageLoader(url: url, scale: scale, processor: processor)
     }
 
     public init<I: View, P: View>(
         url: URL?,
         scale: CGFloat = 1,
+        processor: ImageProcessor? = nil,
         content: @escaping (Image) -> I,
         placeholder: @escaping () -> P
     ) where Content == _ConditionalContent<I, P> {
-        self.init(url: url, scale: scale) { phase in
+        self.init(url: url, scale: scale, processor: processor) { phase in
             if let image = phase.image {
                 content(image)
             } else {
@@ -59,10 +60,11 @@ public struct AsyncImage<Content: View>: View {
     public init(
         url: URL?,
         scale: CGFloat = 1,
+        processor: ImageProcessor? = nil,
         transaction: Transaction = Transaction(),
         @ViewBuilder content: @escaping (AsyncImagePhase) -> Content
     ) {
         self.content = content
-        loader = ImageLoader(url: url, scale: scale)
+        loader = ImageLoader(url: url, scale: scale, processor: processor)
     }
 }

Sources/AsyncImage/ImageLoader.swift

@@ -7,16 +7,16 @@ final class ImageLoader: ObservableObject {
     @Published var asyncImagePhase = AsyncImagePhase.empty
     let scale: CGFloat
     let url: URL?
+    let processor: ImageProcessor?
     var downloadTask: DownloadTask?
 
-    init(url: URL?, scale: CGFloat) {
+    init(url: URL?, scale: CGFloat, processor: ImageProcessor?) {
         self.url = url
         self.scale = scale
+        self.processor = processor
     }
 
-    deinit {
-        print(true)
-    }
+    deinit {}
 
     func loadImage() {
         guard let url = url, asyncImagePhase.image == nil else { return }
@@ -27,6 +27,11 @@ final class ImageLoader: ObservableObject {
                 guard let self = self else { return }
                 switch result {
                 case .success(let image):
+                    var image = image
+                    if let processor = self.processor {
+                        // Processing the fetched image here to keep the cached image untouched.
+                        image = processor.process(image: image)
+                    }
                     self.asyncImagePhase = .success(Image(uiImage: image))
                 case .failure(let error):
                     if error.isCanceled { return }

Sources/AsyncImage/ImageProcessor.swift

@@ -0,0 +1,12 @@
+//
+//  ImageProcessor.swift
+//  AsyncImage
+//
+//  Created by Fabian Thies on 20.12.22.
+//
+
+import UIKit
+
+public protocol ImageProcessor {
+    func process(image: UIImage) -> UIImage
+}