From c172ab92b425612178fe80bcfeed88446606b288 Mon Sep 17 00:00:00 2001
From: Igor Ferreira <me@igorcferreira.dev>
Date: Fri, 9 Sep 2022 18:38:35 +0200
Subject: [PATCH 1/2] Include new class to control presentation and improve
 code syntax

---
 Sources/domain/PresentationController.swift | 59 +++++++++++++++++++++
 1 file changed, 59 insertions(+)
 create mode 100644 Sources/domain/PresentationController.swift

diff --git a/Sources/domain/PresentationController.swift b/Sources/domain/PresentationController.swift
new file mode 100644
index 0000000..f53dc77
--- /dev/null
+++ b/Sources/domain/PresentationController.swift
@@ -0,0 +1,59 @@
+//
+//  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))
+    }
+}

From fd781bc5dbfe3a46b192925caaf88045fe3eb8de Mon Sep 17 00:00:00 2001
From: Igor Ferreira <me@igorcferreira.dev>
Date: Fri, 9 Sep 2022 18:38:50 +0200
Subject: [PATCH 2/2] Take advantage of new class

---
 Sources/GIFImage.swift | 52 ++++++++++++------------------------------
 1 file changed, 14 insertions(+), 38 deletions(-)

diff --git a/Sources/GIFImage.swift b/Sources/GIFImage.swift
index 0ceb97b..3d694e4 100644
--- a/Sources/GIFImage.swift
+++ b/Sources/GIFImage.swift
@@ -1,7 +1,5 @@
 import SwiftUI
 
-private let kDefaultGIFFrameInterval: TimeInterval = 1.0 / 24.0
-
 /// `GIFImage` is a `View` that loads a `Data` object from a source into `CoreImage.CGImageSource`, parse the image source
 /// into frames and stream them based in the "Delay" key packaged on which frame item. The view will use the `ImageLoader` from the environment
 /// to convert the fetch the `Data`
@@ -9,8 +7,7 @@ public struct GIFImage: View {
     public let source: GIFSource
     public let placeholder: RawImage
     public let errorImage: RawImage?
-    public let frameRate: FrameRate
-    private let action: (GIFSource) async throws -> Void
+    private let presentationController: PresentationController
 
     @Environment(\.imageLoader) var imageLoader
     @State @MainActor private var frame: RawImage?
@@ -74,8 +71,14 @@ public struct GIFImage: View {
         self._loop = loop
         self.placeholder = placeholder
         self.errorImage = errorImage
-        self.frameRate = frameRate
-        self.action = loopAction
+        
+        self.presentationController = PresentationController(
+            source: source,
+            frameRate: frameRate,
+            animate: animate,
+            loop: loop,
+            action: loopAction
+        )
     }
 
     public var body: some View {
@@ -97,39 +100,12 @@ public struct GIFImage: View {
     }
     
     @Sendable private func load() {
-        guard animate else { return }
         presentationTask?.cancel()
-        presentationTask = Task {
-            do {
-                repeat {
-                    for try await imageFrame in try await imageLoader.load(source: source) {
-                        try await update(imageFrame)
-                        if !animate { break }
-                    }
-                    try await action(source)
-                } while(self.loop && self.animate)
-            } catch {
-                if !(error is CancellationError) {
-                    await setFrame(errorImage ?? placeholder)
-                }
-            }
-        }
-    }
-
-    @Sendable private func update(_ imageFrame: ImageFrame) async throws {
-        await setFrame(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))
+        presentationTask = Task { await presentationController.start(
+            imageLoader: imageLoader,
+            fallbackImage: errorImage ?? placeholder,
+            frameUpdate: setFrame(_:)
+        )}
     }
     
     @MainActor