fix gif caching

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))
+    }
+}