Fix the default image provider.

Author: gonzalezreal

Sources/MarkdownUI/Extensions/DefaultImageProvider.swift

@@ -10,8 +10,9 @@ public struct DefaultImageProvider: ImageProvider {
     self.urlSession = urlSession
   }
 
-  public func makeImage(url: URL?) -> some SwiftUI.View {
-    View(url: url, urlSession: self.urlSession).id(url)
+  public func makeImage(url: URL?) -> some View {
+    DefaultImageView(url: url, urlSession: self.urlSession)
+      .id(url)
   }
 }
 
@@ -23,118 +24,3 @@ extension ImageProvider where Self == DefaultImageProvider {
     .init()
   }
 }
-
-// MARK: - View
-
-extension DefaultImageProvider {
-  private struct View: SwiftUI.View {
-    @StateObject private var viewModel = ViewModel()
-
-    let url: URL?
-    let urlSession: URLSession
-
-    var body: some SwiftUI.View {
-      self.content.task {
-        await self.viewModel.onAppear(url: self.url, urlSession: self.urlSession)
-      }
-    }
-
-    @ViewBuilder private var content: some SwiftUI.View {
-      switch self.viewModel.state {
-      case .notRequested, .loading, .failure:
-        Color.clear
-          .frame(width: 0, height: 0)
-      case .success(let image, let size):
-        ResizeToFit(idealSize: size) {
-          image.resizable()
-        }
-      }
-    }
-  }
-}
-
-// MARK: - ViewModel
-
-extension DefaultImageProvider {
-  private final class ViewModel: ObservableObject {
-    enum State: Equatable {
-      case notRequested
-      case loading
-      case success(Image, CGSize)
-      case failure
-    }
-
-    @Published private(set) var state: State = .notRequested
-
-    private let cache = NSCache<NSURL, PlatformImage>()
-
-    @MainActor func onAppear(url: URL?, urlSession: URLSession) async {
-      guard case .notRequested = state else {
-        return
-      }
-
-      guard let url = url else {
-        self.state = .failure
-        return
-      }
-
-      self.state = .loading
-
-      do {
-        let image = try await self.image(with: url, urlSession: urlSession)
-        self.state = .success(.init(platformImage: image), image.size)
-      } catch {
-        self.state = .failure
-      }
-    }
-
-    private func image(with url: URL, urlSession: URLSession) async throws -> PlatformImage {
-      if let image = self.cache.object(forKey: url as NSURL) {
-        return image
-      }
-
-      let (data, response) = try await urlSession.data(from: url)
-
-      guard let statusCode = (response as? HTTPURLResponse)?.statusCode,
-        200..<300 ~= statusCode
-      else {
-        throw URLError(.badServerResponse)
-      }
-
-      guard let image = PlatformImage.decode(from: data) else {
-        throw URLError(.cannotDecodeContentData)
-      }
-
-      self.cache.setObject(image, forKey: url as NSURL)
-
-      return image
-    }
-  }
-}
-
-// MARK: - PlatformImage
-
-extension PlatformImage {
-  fileprivate static func decode(from data: Data) -> PlatformImage? {
-    #if os(iOS) || os(tvOS) || os(watchOS)
-      guard let image = UIImage(data: data) else {
-        return nil
-      }
-      return image
-    #elseif os(macOS)
-      guard let bitmapImageRep = NSBitmapImageRep(data: data) else {
-        return nil
-      }
-
-      let image = NSImage(
-        size: NSSize(
-          width: bitmapImageRep.pixelsWide,
-          height: bitmapImageRep.pixelsHigh
-        )
-      )
-
-      image.addRepresentation(bitmapImageRep)
-      return image
-    #endif
-  }
-}

Sources/MarkdownUI/Extensions/DefaultImageView/DefaultImageLoader.swift

@@ -0,0 +1,56 @@
+import SwiftUI
+
+final class DefaultImageLoader {
+  static let shared = DefaultImageLoader()
+
+  private let cache = NSCache<NSURL, PlatformImage>()
+
+  private init() {}
+
+  func image(with url: URL, urlSession: URLSession) async throws -> PlatformImage {
+    if let image = self.cache.object(forKey: url as NSURL) {
+      return image
+    }
+
+    let (data, response) = try await urlSession.data(from: url)
+
+    guard let statusCode = (response as? HTTPURLResponse)?.statusCode,
+      200..<300 ~= statusCode
+    else {
+      throw URLError(.badServerResponse)
+    }
+
+    guard let image = PlatformImage.decode(from: data) else {
+      throw URLError(.cannotDecodeContentData)
+    }
+
+    self.cache.setObject(image, forKey: url as NSURL)
+
+    return image
+  }
+}
+
+extension PlatformImage {
+  fileprivate static func decode(from data: Data) -> PlatformImage? {
+    #if os(iOS) || os(tvOS) || os(watchOS)
+      guard let image = UIImage(data: data) else {
+        return nil
+      }
+      return image
+    #elseif os(macOS)
+      guard let bitmapImageRep = NSBitmapImageRep(data: data) else {
+        return nil
+      }
+
+      let image = NSImage(
+        size: NSSize(
+          width: bitmapImageRep.pixelsWide,
+          height: bitmapImageRep.pixelsHigh
+        )
+      )
+
+      image.addRepresentation(bitmapImageRep)
+      return image
+    #endif
+  }
+}

Sources/MarkdownUI/Extensions/DefaultImageView/DefaultImageView.swift

@@ -0,0 +1,23 @@
+import SwiftUI
+
+struct DefaultImageView: View {
+  @StateObject private var viewModel = DefaultImageViewModel()
+
+  let url: URL?
+  let urlSession: URLSession
+
+  var body: some View {
+    switch self.viewModel.state {
+    case .notRequested, .loading, .failure:
+      Color.clear
+        .frame(width: 0, height: 0)
+        .task {
+          await self.viewModel.task(url: self.url, urlSession: self.urlSession)
+        }
+    case .success(let image, let size):
+      ResizeToFit(idealSize: size) {
+        image.resizable()
+      }
+    }
+  }
+}

Sources/MarkdownUI/Extensions/DefaultImageView/DefaultImageViewModel.swift

@@ -0,0 +1,33 @@
+import SwiftUI
+
+final class DefaultImageViewModel: ObservableObject {
+  enum State: Equatable {
+    case notRequested
+    case loading
+    case success(Image, CGSize)
+    case failure
+  }
+
+  @Published private(set) var state: State = .notRequested
+  private let imageLoader: DefaultImageLoader = .shared
+
+  @MainActor func task(url: URL?, urlSession: URLSession) async {
+    guard case .notRequested = state else {
+      return
+    }
+
+    guard let url = url else {
+      self.state = .failure
+      return
+    }
+
+    self.state = .loading
+
+    do {
+      let image = try await self.imageLoader.image(with: url, urlSession: urlSession)
+      self.state = .success(.init(platformImage: image), image.size)
+    } catch {
+      self.state = .failure
+    }
+  }
+}