fix gif caching

Pocket Poster/Packages/GIFImage/Sources/domain/CGImageSourceFrameSequence.swift

@@ -0,0 +1,46 @@
+//
+//  File.swift
+//  
+//
+//  Created by Igor Ferreira on 05/04/2022.
+//
+
+import Foundation
+import ImageIO
+
+public actor CGImageSourceFrameSequence: AsyncSequence {
+    public typealias Element = ImageFrame
+
+    public enum LoadError: Error {
+        case invalidData
+        case emptyData
+    }
+
+    public let source: CGImageSource
+
+    public init(data: Data) throws {
+        guard let source = CGImageSourceCreateWithData(data as CFData, nil) else {
+            throw LoadError.invalidData
+        }
+
+        switch CGImageSourceGetStatus(source) {
+        case .statusComplete: break
+        case .statusReadingHeader: break
+        case .statusIncomplete: throw LoadError.emptyData
+        case .statusInvalidData: throw LoadError.invalidData
+        case .statusUnexpectedEOF: throw LoadError.invalidData
+        case .statusUnknownType: throw LoadError.invalidData
+        @unknown default: throw LoadError.invalidData
+        }
+
+        self.init(source: source)
+    }
+
+    public init(source: CGImageSource) {
+        self.source = source
+    }
+
+    nonisolated public func makeAsyncIterator() -> CGImageSourceIterator {
+        CGImageSourceIterator(source: source)
+    }
+}

Pocket Poster/Packages/GIFImage/Sources/domain/CGImageSourceIterator.swift

@@ -0,0 +1,36 @@
+//
+//  File.swift
+//  
+//
+//  Created by Igor Ferreira on 05/04/2022.
+//
+
+import Foundation
+import ImageIO
+
+public actor CGImageSourceIterator: AsyncIteratorProtocol {
+
+    public let frameCount: Int
+    public let source: CGImageSource
+    public private(set) var currentFrame: Int
+
+    public init(source: CGImageSource) {
+        self.source = source
+        self.frameCount = CGImageSourceGetCount(source)
+        self.currentFrame = 0
+    }
+
+    public func next() async throws -> ImageFrame? {
+        guard currentFrame < frameCount else {
+            return nil
+        }
+
+        let frame: ImageFrame? = if let image = CGImageSourceCreateImageAtIndex(source, currentFrame, nil) {
+            ImageFrame(image: image, interval: source.intervalAtIndex(currentFrame))
+        } else {
+            nil
+        }
+        currentFrame += 1
+        return frame
+    }
+}

Pocket Poster/Packages/GIFImage/Sources/domain/ImageLoader.swift

@@ -0,0 +1,80 @@
+//
+//  File.swift
+//  
+//
+//  Created by Igor Ferreira on 05/04/2022.
+//
+
+import Foundation
+
+/// Object responsible to load a `GIFSource` into a `ImageFrame` stream.
+public struct ImageLoader {
+    public let session: URLSession
+    public let cache: URLCache
+    public let fileManager: FileManager
+
+    public init(session: URLSession = .shared, cache: URLCache = .shared, fileManager: FileManager = .default) {
+        self.session = session
+        self.cache = cache
+        self.fileManager = fileManager
+    }
+
+    public func load(source: GIFSource) async throws -> CGImageSourceFrameSequence {
+        let data = try await source.loadData(session: session, cache: cache, fileManager: fileManager)
+        return try data.imageAsyncSequence()
+    }
+}
+
+private extension GIFSource {
+    func loadData(session: URLSession, cache: URLCache, fileManager: FileManager) async throws -> Data {
+        switch self {
+        case let .static(data): data
+        case .remote(let url), .remoteURL(let url): try await url.loadData(session: session, cache: cache)
+        case let .remoteRequest(request): try await request.loadData(session: session, cache: cache)
+        case let .local(filePath): try await filePath.loadData(fileManager: fileManager)
+        }
+    }
+}
+
+private extension String {
+    func loadData(fileManager: FileManager) async throws -> Data {
+        guard fileManager.fileExists(atPath: self) else {
+            throw URLError(.fileDoesNotExist)
+        }
+        guard let data = fileManager.contents(atPath: self) else {
+            throw URLError(.cannotOpenFile)
+        }
+        return data
+    }
+}
+
+private extension URL {
+    func loadData(session: URLSession, cache: URLCache) async throws -> Data {
+        let request = URLRequest(url: self)
+        return try await request.loadData(session: session, cache: cache)
+    }
+}
+
+private extension URLRequest {
+    func loadData(session: URLSession, cache: URLCache) async throws -> Data {
+        if let cache = cache.cachedResponse(for: self) {
+            return cache.data
+        }
+
+        let (data, response) = try await session.data(for: self)
+        guard let httpResponse = response as? HTTPURLResponse else {
+            throw URLError(.badServerResponse)
+        }
+        guard httpResponse.isSuccess else {
+            throw URLError(.init(rawValue: httpResponse.statusCode))
+        }
+        cache.storeCachedResponse(CachedURLResponse(response: response, data: data), for: self)
+        return data
+    }
+}
+
+private extension HTTPURLResponse {
+    var isSuccess: Bool {
+        200..<300 ~= statusCode
+    }
+}

Pocket Poster/Packages/GIFImage/Sources/domain/PresentationController.swift

@@ -0,0 +1,65 @@
+//
+//  File.swift
+//  
+//
+//  Created by Igor Ferreira on 9/9/22.
+//
+
+import Foundation
+import SwiftUI
+
+private let kDefaultGIFFrameInterval: TimeInterval = 1.0 / 24.0
+
+struct PresentationController {
+    let source: GIFSource
+    let frameRate: FrameRate
+    let action: (GIFSource) async throws -> Void
+    @Binding var animate: Bool
+    @Binding var loop: Bool
+    
+    init(
+        source: GIFSource,
+        frameRate: FrameRate,
+        animate: Binding<Bool>,
+        loop: Binding<Bool>,
+        action: @Sendable @escaping (GIFSource) async throws -> Void = { _ in }
+    ) {
+        self.source = source
+        self.action = action
+        self.frameRate = frameRate
+        self._animate = animate
+        self._loop = loop
+    }
+    
+    func start(imageLoader: ImageLoader, fallbackImage: RawImage, frameUpdate: (RawImage) async -> Void) async {
+        do {
+            repeat {
+                for try await imageFrame in try await imageLoader.load(source: source) {
+                    try await update(imageFrame, frameUpdate: frameUpdate)
+                    if !animate { break }
+                }
+                try await action(source)
+            } while(self.loop && self.animate)
+        } catch {
+            if !(error is CancellationError) {
+                await frameUpdate(fallbackImage)
+            }
+        }
+    }
+    
+    private func update(_ imageFrame: ImageFrame, frameUpdate: (RawImage) async -> Void) async throws {
+        await frameUpdate(RawImage.create(with: imageFrame.image))
+        let calculatedInterval = imageFrame.interval ?? kDefaultGIFFrameInterval
+        let interval: Double
+        switch frameRate {
+        case .static(let fps):
+            interval = (1.0 / Double(fps))
+        case .limited(let fps):
+            let intervalLimit = (1.0 / Double(fps))
+            interval = max(calculatedInterval, intervalLimit)
+        case .dynamic:
+            interval = imageFrame.interval ?? kDefaultGIFFrameInterval
+        }
+        try await Task.sleep(nanoseconds: UInt64(interval * 1_000_000_000.0))
+    }
+}