Add more view modifiers (#838)

1. ThemeProgressViewModifier to replace content with a progress view
while a condition is active
2. ThemeEmptyContentModifier to replace content with a message if an
empty condition is met
3. Replace .opacity(bool ? 1.0 : 0.0) with .opaque(bool)

Reuse:

- 1 in PaywallView and DonateView
- 2 in ProfileContainerView

Passepartout/Library/Sources/AppUIMain/Views/About/DonateView.swift

@@ -51,16 +51,8 @@ struct DonateView: View {
     private var errorHandler: ErrorHandler = .default()
 
     var body: some View {
-        Form {
-            if isFetchingProducts {
-                ProgressView()
-                    .id(UUID())
-            } else if !availableProducts.isEmpty {
         donationsView
-                    .disabled(purchasingIdentifier != nil)
-            }
-        }
-        .themeForm()
+            .themeProgress(if: isFetchingProducts)
             .navigationTitle(title)
             .alert(
                 title,
@@ -80,8 +72,8 @@ private extension DonateView {
         Strings.Views.Donate.title
     }
 
-    @ViewBuilder
     var donationsView: some View {
+        Form {
 #if os(macOS)
             Section {
                 Text(Strings.Views.Donate.Sections.Main.footer)
@@ -99,6 +91,9 @@ private extension DonateView {
             }
             .themeSection(footer: Strings.Views.Donate.Sections.Main.footer)
         }
+        .themeForm()
+        .disabled(purchasingIdentifier != nil)
+    }
 
     func thankYouActions() -> some View {
         Button(Strings.Global.ok) {

Passepartout/Library/Sources/AppUIMain/Views/App/InstalledProfileView.swift

@@ -62,8 +62,8 @@ struct InstalledProfileView: View, Routable {
 }
 
 private extension InstalledProfileView {
-    var installedOpacity: CGFloat {
-        profile != nil ? 1.0 : 0.0
+    var isOpaque: Bool {
+        profile != nil
     }
 
     var cardView: some View {
@@ -102,7 +102,7 @@ private extension InstalledProfileView {
             StatusText(
                 theme: theme,
                 tunnel: tunnel,
-                opacity: installedOpacity
+                isOpaque: isOpaque
             )
         }
     }
@@ -115,7 +115,7 @@ private extension InstalledProfileView {
             nextProfileId: $nextProfileId,
             interactiveManager: interactiveManager,
             errorHandler: errorHandler,
-            opacity: installedOpacity,
+            isOpaque: isOpaque,
             flow: flow
         )
     }
@@ -160,13 +160,13 @@ private struct StatusText: View {
     @ObservedObject
     var tunnel: ExtendedTunnel
 
-    let opacity: Double
+    let isOpaque: Bool
 
     var body: some View {
         ConnectionStatusText(tunnel: tunnel)
             .font(.body)
             .foregroundStyle(tunnel.statusColor(theme))
-            .opacity(opacity)
+            .opaque(isOpaque)
     }
 }
 
@@ -189,7 +189,7 @@ private struct ToggleButton: View {
     @ObservedObject
     var errorHandler: ErrorHandler
 
-    let opacity: Double
+    let isOpaque: Bool
 
     let flow: ProfileFlow?
 
@@ -209,7 +209,7 @@ private struct ToggleButton: View {
         // TODO: #584, necessary to avoid cell selection
         .buttonStyle(.plain)
         .foregroundStyle(tunnel.statusColor(theme))
-        .opacity(opacity)
+        .opaque(isOpaque)
     }
 }
 

Passepartout/Library/Sources/AppUIMain/Views/App/ProfileContainerView.swift

@@ -113,15 +113,8 @@ private struct ContainerModifier: ViewModifier {
 
     func body(content: Content) -> some View {
         debugChanges()
-        return ZStack {
-            content
-                .opacity(profileManager.hasProfiles ? 1.0 : 0.0)
-
-            if !profileManager.hasProfiles {
-                Text(Strings.Views.Profiles.Folders.noProfiles)
-                    .themeEmptyMessage()
-            }
-        }
+        return content
+            .themeEmptyContent(if: !profileManager.hasProfiles, message: Strings.Views.Profiles.Folders.noProfiles)
             .searchable(text: $search)
             .onChange(of: search) {
                 profileManager.search(byName: $0)

Passepartout/Library/Sources/AppUIMain/Views/App/ProfileRowView.swift

@@ -79,7 +79,7 @@ struct ProfileRowView: View, Routable {
 private extension ProfileRowView {
     var markerView: some View {
         ThemeImage(header.id == nextProfileId ? .pending : statusImage)
-            .opacity(header.id == nextProfileId || header.id == tunnel.currentProfile?.id ? 1.0 : 0.0)
+            .opaque(header.id == nextProfileId || header.id == tunnel.currentProfile?.id)
             .frame(width: 24.0)
     }
 

Passepartout/Library/Sources/AppUIMain/Views/Provider/iOS/VPNProviderServerView+iOS.swift

@@ -178,7 +178,7 @@ private extension VPNProviderServerView.ServersSubview {
         } label: {
             HStack {
                 ThemeImage(.marked)
-                    .opacity(server.id == selectedServerId ? 1.0 : 0.0)
+                    .opaque(server.id == selectedServerId)
                 VStack(alignment: .leading) {
                     if let area = server.provider.area {
                         Text(area)

Passepartout/Library/Sources/AppUIMain/Views/Provider/macOS/VPNProviderServerView+macOS.swift

@@ -68,7 +68,7 @@ extension VPNProviderServerView {
             return Table(servers) {
                 TableColumn("") { server in
                     ThemeImage(.marked)
-                        .opacity(server.id == selectedServerId ? 1.0 : 0.0)
+                        .opaque(server.id == selectedServerId)
                 }
                 .width(10.0)
 

Passepartout/Library/Sources/AppUITV/Views/Profile/ProfileView.swift

@@ -77,7 +77,7 @@ struct ProfileView: View, TunnelInstallationProviding {
                     ZStack {
                         listView
                             .padding(.horizontal)
-                            .opacity(interactiveManager.isPresented ? 0.0 : 1.0)
+                            .opaque(!interactiveManager.isPresented)
 
                         if interactiveManager.isPresented {
                             interactiveView

Passepartout/Library/Sources/CommonUtils/Views/View+Extensions.swift

@@ -38,6 +38,10 @@ extension View {
             self
         }
     }
+
+    public func opaque(_ condition: Bool) -> some View {
+        opacity(condition ? 1.0 : 0.0)
+    }
 }
 
 extension ViewModifier {

Passepartout/Library/Sources/UILibrary/Theme/UI/Theme+Modifiers.swift

@@ -24,10 +24,10 @@
 //
 
 import CommonLibrary
+import CommonUtils
 #if canImport(LocalAuthentication)
 import LocalAuthentication
 #endif
-import CommonUtils
 import SwiftUI
 
 // MARK: Shortcuts
@@ -143,6 +143,14 @@ extension View {
         modifier(ThemeAnimationModifier(value: value, category: category))
     }
 
+    public func themeProgress(if isProgressing: Bool) -> some View {
+        modifier(ThemeProgressViewModifier(isProgressing: isProgressing))
+    }
+
+    public func themeEmptyContent(if isEmpty: Bool, message: String) -> some View {
+        modifier(ThemeEmptyContentModifier(isEmpty: isEmpty, message: message))
+    }
+
 #if !os(tvOS)
     public func themeWindow(width: CGFloat, height: CGFloat) -> some View {
         modifier(ThemeWindowModifier(size: .init(width: width, height: height)))
@@ -349,6 +357,39 @@ struct ThemeAnimationModifier<T>: ViewModifier where T: Equatable {
     }
 }
 
+struct ThemeProgressViewModifier: ViewModifier {
+    let isProgressing: Bool
+
+    func body(content: Content) -> some View {
+        ZStack {
+            if isProgressing {
+                ThemeProgressView()
+            }
+            content
+                .opaque(!isProgressing)
+        }
+    }
+}
+
+struct ThemeEmptyContentModifier: ViewModifier {
+    let isEmpty: Bool
+
+    let message: String
+
+    func body(content: Content) -> some View {
+        ZStack {
+            content
+                .opaque(!isEmpty)
+
+            if isEmpty {
+                Text(message)
+                    .themeEmptyMessage()
+                    .opaque(isEmpty)
+            }
+        }
+    }
+}
+
 #if !os(tvOS)
 
 struct ThemeWindowModifier: ViewModifier {

Passepartout/Library/Sources/UILibrary/Theme/UI/Theme+Views.swift

@@ -225,6 +225,17 @@ public struct ThemeSecureField: View {
     }
 }
 
+public struct ThemeProgressView: View {
+    public init() {
+    }
+
+    public var body: some View {
+        ProgressView()
+            .frame(maxWidth: .infinity, maxHeight: .infinity)
+            .id(UUID())
+    }
+}
+
 #if !os(tvOS)
 
 public struct ThemeMenuImage: View {

Passepartout/Library/Sources/UILibrary/Views/Paywall/PaywallView.swift

@@ -59,20 +59,8 @@ struct PaywallView: View {
     private var errorHandler: ErrorHandler = .default()
 
     var body: some View {
-        Form {
-            if isFetchingProducts {
-                ProgressView()
-                    .id(UUID())
-            } else if !recurringProducts.isEmpty {
-                Group {
-                    productsView
-                    subscriptionFeaturesView
-                    restoreView
-                }
-                .disabled(purchasingIdentifier != nil)
-            }
-        }
-        .themeForm()
+        paywallView
+            .themeProgress(if: isFetchingProducts)
             .toolbar(content: toolbarContent)
             .alert(
                 Strings.Global.purchase,
@@ -92,6 +80,16 @@ private extension PaywallView {
         Strings.Global.purchase
     }
 
+    var paywallView: some View {
+        Form {
+            productsView
+            subscriptionFeaturesView
+            restoreView
+        }
+        .themeForm()
+        .disabled(purchasingIdentifier != nil)
+    }
+
     var subscriptionFeatures: [AppFeature] {
         AppFeature.allCases.sorted {
             $0.localizedDescription.lowercased() < $1.localizedDescription.lowercased()

Passepartout/Library/Sources/UILibrary/Views/UI/FavoriteToggle.swift

@@ -48,7 +48,7 @@ public struct FavoriteToggle<ID>: View where ID: Hashable {
             }
         } label: {
             ThemeImage(selection.contains(value) ? .favoriteOn : .favoriteOff)
-                .opacity(opacity)
+                .opaque(opaque)
         }
 #if os(macOS)
         .onHover {
@@ -59,11 +59,11 @@ public struct FavoriteToggle<ID>: View where ID: Hashable {
 }
 
 private extension FavoriteToggle {
-    var opacity: Double {
+    var opaque: Bool {
 #if os(macOS)
-        selection.contains(value) || value == hover ? 1.0 : 0.0
+        selection.contains(value) || value == hover
 #else
-        1.0
+        true
 #endif
     }
 }