Refactory the indicator API on WebImage, using the same design pattern like SwiftUI, return some View

Example/Podfile.lock

@@ -8,10 +8,10 @@ PODS:
   - libwebp/mux (1.0.3):
     - libwebp/demux
   - libwebp/webp (1.0.3)
-  - SDWebImage (5.2.3):
-    - SDWebImage/Core (= 5.2.3)
-  - SDWebImage/Core (5.2.3)
-  - SDWebImageSwiftUI (0.4.2):
+  - SDWebImage (5.2.5):
+    - SDWebImage/Core (= 5.2.5)
+  - SDWebImage/Core (5.2.5)
+  - SDWebImageSwiftUI (0.5.2):
     - SDWebImage (~> 5.1)
   - SDWebImageWebPCoder (0.2.5):
     - libwebp (~> 1.0)
@@ -33,8 +33,8 @@ EXTERNAL SOURCES:
 
 SPEC CHECKSUMS:
   libwebp: 057912d6d0abfb6357d8bb05c0ea470301f5d61e
-  SDWebImage: 46a7f73228f84ce80990c786e4372cf4db5875ce
-  SDWebImageSwiftUI: b91be76ecb0cdf74c18f6cd92aae8f19a9ded02d
+  SDWebImage: 4eabf2fa6695c95c47724214417a9c036c965e4a
+  SDWebImageSwiftUI: 3a3e3aa707aeedf024af6f9c718177f681edf9de
   SDWebImageWebPCoder: 947093edd1349d820c40afbd9f42acb6cdecd987
 
 PODFILE CHECKSUM: 3fb06a5173225e197f3a4bf2be7e5586a693257a

Example/SDWebImageSwiftUIDemo/ContentView.swift

@@ -96,8 +96,8 @@ struct ContentView: View {
                         } else {
                             #if os(macOS) || os(iOS) || os(tvOS)
                             WebImage(url: URL(string:url))
-                            .indicator(.activity)
                             .resizable()
+                            .indicator(.activity)
                             .scaledToFit()
                             .frame(width: CGFloat(100), height: CGFloat(100), alignment: .center)
                             .animation(.easeInOut(duration: 0.5))

Example/SDWebImageSwiftUIDemo/DetailView.swift

@@ -57,19 +57,17 @@ struct DetailView: View {
             } else {
                 #if os(macOS) || os(iOS) || os(tvOS)
                 WebImage(url: URL(string:url), options: [.progressiveLoad])
-                .indicator(.progress)
                 .resizable()
+                .indicator(.progress)
                 .scaledToFit()
                 #else
                 WebImage(url: URL(string:url), options: [.progressiveLoad])
-                .indicator(
-                    Indicator { isAnimating, progress in
-                        ProgressBar(value: progress)
-                        .foregroundColor(.blue)
-                        .frame(maxHeight: 6)
-                    }
-                )
                 .resizable()
+                .indicator { isAnimating, progress in
+                    ProgressBar(value: progress)
+                    .foregroundColor(.blue)
+                    .frame(maxHeight: 6)
+                }
                 .scaledToFit()
                 #endif
             }

README.md

@@ -73,8 +73,8 @@ var body: some View {
         .onSuccess { image, cacheType in
             // Success
         }
-        .indicator(.activity) // Activity Indicator
         .resizable()
+        .indicator(.activity) // Activity Indicator
         .scaledToFit()
         .frame(width: 300, height: 300, alignment: .center)
 }

SDWebImageSwiftUI/Classes/ImageViewWrapper.swift

@@ -65,7 +65,7 @@ public class ProgressIndicatorWrapper : PlatformView {
     #if os(macOS)
     public override func layout() {
         super.layout()
-        wrapped.setFrameOrigin(CGPoint(x: (self.bounds.width - wrapped.frame.width) / 2, y: (self.bounds.height - wrapped.frame.height) / 2))
+        wrapped.setFrameOrigin(CGPoint(x: round(self.bounds.width - wrapped.frame.width) / 2, y: round(self.bounds.height - wrapped.frame.height) / 2))
     }
     #else
     public override func layoutSubviews() {

SDWebImageSwiftUI/Classes/Indicator/Indicator.swift

@@ -10,23 +10,52 @@ import Foundation
 import SwiftUI
 
 /// A  type to build the indicator
-public struct Indicator {
-    var builder: (Binding<Bool>, Binding<CGFloat>) -> AnyView
+public struct Indicator<T> where T : View {
+    var builder: (Binding<Bool>, Binding<CGFloat>) -> T
 
     /// Create a indicator with builder
     /// - Parameter builder: A builder to build indicator
     /// - Parameter isAnimating: A Binding to control the animation. If image is during loading, the value is true, else (like start loading) the value is false.
     /// - Parameter progress: A Binding to control the progress during loading. If no progress can be reported, the value is 0.
     /// Associate a indicator when loading image with url
-    public init<T>(@ViewBuilder builder: @escaping (_ isAnimating: Binding<Bool>, _ progress: Binding<CGFloat>) -> T) where T : View {
-        self.builder = { isAnimating, progress in
-            AnyView(builder(isAnimating, progress))
+    public init(@ViewBuilder builder: @escaping (_ isAnimating: Binding<Bool>, _ progress: Binding<CGFloat>) -> T) {
+        self.builder = builder
+    }
+}
+
+/// A implementation detail View with indicator
+/// SwiftUI View Modifier construced by using a internal View type which modify the `body`
+/// It use type system to represent the view hierarchy, and Swift `some View` syntax to hide the type detail for users
+struct IndicatorView<T, Content> : View where T : View, Content : View {
+    @ObservedObject var imageManager: ImageManager
+
+    var indicator: Indicator<T>
+    var content: Content
+
+    var body: some View {
+        if (imageManager.image != nil) && !imageManager.isLoading {
+            // Disable Indiactor
+            return AnyView(content)
+        } else {
+            // Enable indicator
+            return AnyView(
+                ZStack {
+                    content
+                    indicator.builder($imageManager.isLoading, $imageManager.progress)
+                }
+            )
         }
     }
+
+    public init(_ view: Content, indicator: Indicator<T>, imageManager: ImageManager) {
+        self.content = view
+        self.indicator = indicator
+        self.imageManager = imageManager
+    }
 }
 
 #if os(macOS) || os(iOS) || os(tvOS)
-extension Indicator {
+extension Indicator where T == ActivityIndicator {
     /// Activity Indicator
     public static var activity: Indicator {
         Indicator { isAnimating, _ in
@@ -41,7 +70,9 @@ extension Indicator {
             ActivityIndicator(isAnimating, style: style)
         }
     }
-
+}
+
+extension Indicator where T == ProgressIndicator {
     /// Progress Indicator
     public static var progress: Indicator {
         Indicator { isAnimating, progress in

SDWebImageSwiftUI/Classes/Indicator/ProgressIndicator.swift

@@ -67,6 +67,9 @@ public struct ProgressIndicator: PlatformViewRepresentable {
         view.style = .bar
         view.isDisplayedWhenStopped = false
         view.controlSize = .small
+        view.frame = CGRect(x: 0, y: 0, width: 160, height: 0) // Width from `UIProgressView` default width
+        view.sizeToFit()
+        view.autoresizingMask = [.maxXMargin, .minXMargin, .maxYMargin, .minYMargin]
         return nsView
     }
 

SDWebImageSwiftUI/Classes/WebImage.swift

@@ -16,14 +16,8 @@ public struct WebImage : View {
     var context: [SDWebImageContextOption : Any]?
 
     var configurations: [(Image) -> Image] = []
-    var indicator: Indicator?
 
     @ObservedObject var imageManager: ImageManager
-    @State var progress: CGFloat = 0
-    @State var isLoading: Bool = false
-    var isFinished: Bool {
-        !isLoading && (imageManager.image != nil)
-    }
 
     /// Create a web image with url, placeholder, custom options and context.
     /// - Parameter url: The image url
@@ -52,7 +46,7 @@ public struct WebImage : View {
             // this can ensure we load the image, SDWebImage take care of the duplicated query
             self.imageManager.load()
         }
-        let view = configurations.reduce(image) { (previous, configuration) in
+        return configurations.reduce(image) { (previous, configuration) in
             configuration(previous)
         }
         .onAppear {
@@ -63,41 +57,6 @@ public struct WebImage : View {
         .onDisappear {
             self.imageManager.cancel()
         }
-        // Convert Combine.Publisher to Binding
-        .onReceive(imageManager.$isLoading) { isLoading in
-            // only Apple Watch complain that "Modifying state during view update, this will cause undefined behavior."
-            // Use dispatch to workaround, Thanks Apple :)
-            #if os(watchOS)
-            DispatchQueue.main.async {
-                self.isLoading = isLoading
-            }
-            #else
-            self.isLoading = isLoading
-            #endif
-        }
-        .onReceive(imageManager.$progress) { progress in
-            #if os(watchOS)
-            DispatchQueue.main.async {
-                self.progress = progress
-            }
-            #else
-            self.progress = progress
-            #endif
-        }
-        if let indicator = indicator {
-            if isFinished {
-                return AnyView(view)
-            } else {
-                return AnyView(
-                    ZStack {
-                        view
-                        indicator.builder($isLoading, $progress)
-                    }
-                )
-            }
-        } else {
-            return AnyView(view)
-        }
     }
 }
 
@@ -174,10 +133,14 @@ extension WebImage {
 
     /// Associate a indicator when loading image with url
     /// - Parameter indicator: The indicator type, see `Indicator`
-    public func indicator(_ indicator: Indicator?) -> WebImage {
-        var result = self
-        result.indicator = indicator
-        return result
+    public func indicator<T>(_ indicator: Indicator<T>) -> some View where T : View {
+        return IndicatorView(self, indicator: indicator, imageManager: imageManager)
+    }
+
+    /// Associate a indicator when loading image with url, convenient method with block
+    /// - Parameter indicator: The indicator type, see `Indicator`
+    public func indicator<T>(@ViewBuilder builder: @escaping (_ isAnimating: Binding<Bool>, _ progress: Binding<CGFloat>) -> T) -> some View where T : View {
+        return indicator(Indicator(builder: builder))
     }
 }