refactor: Create a generic ViewGeometry component

Mail/Components/BottomBarView.swift

@@ -16,17 +16,10 @@
  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+import MailCore
 import MailResources
 import SwiftUI
 
-struct BottomSafeAreaKey: PreferenceKey {
-    static var defaultValue: CGFloat = .zero
-
-    static func reduce(value: inout CGFloat, nextValue: () -> CGFloat) {
-        value = nextValue()
-    }
-}
-
 struct BottomBar<Items: View>: ViewModifier {
     let isVisible: Bool
     @ViewBuilder var items: () -> Items
@@ -59,19 +52,16 @@ struct BottomBarView<Items: View>: View {
             items()
             Spacer(minLength: 8)
         }
-        .padding(.top, 8)
-        .padding(.bottom, hasBottomSafeArea ? 4 : 8)
+        .padding(.top, UIConstants.bottomBarVerticalPadding)
+        .padding(.bottom, hasBottomSafeArea ? UIConstants.bottomBarSmallVerticalPadding : UIConstants.bottomBarVerticalPadding)
         .background(MailResourcesAsset.backgroundTabBarColor.swiftUIColor)
         .overlay(alignment: .top) {
             Divider()
                 .frame(height: 1)
                 .overlay(Color(uiColor: .systemGray3))
         }
         .overlay {
-            GeometryReader { proxy in
-                Color.clear
-                    .preference(key: BottomSafeAreaKey.self, value: proxy.safeAreaInsets.bottom)
-            }
+            ViewGeometry(key: BottomSafeAreaKey.self, property: \.safeAreaInsets.bottom)
         }
         .onPreferenceChange(BottomSafeAreaKey.self) { value in
             hasBottomSafeArea = value > 0

Mail/Utils/GeometryReaderHelpers.swift

@@ -0,0 +1,47 @@
+/*
+ Infomaniak Mail - iOS App
+ Copyright (C) 2022 Infomaniak Network SA
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+import SwiftUI
+
+struct ViewWidthKey: PreferenceKey {
+    static var defaultValue: CGFloat = .zero
+
+    static func reduce(value: inout CGFloat, nextValue: () -> CGFloat) {
+        value = max(value, nextValue())
+    }
+}
+
+struct BottomSafeAreaKey: PreferenceKey {
+    static var defaultValue: CGFloat = .zero
+
+    static func reduce(value: inout CGFloat, nextValue: () -> CGFloat) {
+        value = nextValue()
+    }
+}
+
+struct ViewGeometry<K>: View where K: PreferenceKey {
+    let key: K.Type
+    let property: KeyPath<GeometryProxy, K.Value>
+
+    var body: some View {
+        GeometryReader { proxy in
+            Color.clear
+                .preference(key: key, value: proxy[keyPath: property])
+        }
+    }
+}

Mail/Views/Thread/MessageHeaderDetailView.swift

@@ -25,23 +25,6 @@ import RealmSwift
 import SwiftUI
 import WrappingHStack
 
-struct ViewWidthKey: PreferenceKey {
-    static var defaultValue: CGFloat = .zero
-
-    static func reduce(value: inout CGFloat, nextValue: () -> CGFloat) {
-        value = max(value, nextValue())
-    }
-}
-
-struct ViewGeometry: View {
-    var body: some View {
-        GeometryReader { geometry in
-            Color.clear
-                .preference(key: ViewWidthKey.self, value: geometry.size.width)
-        }
-    }
-}
-
 struct MessageHeaderDetailView: View {
     @ObservedRealmObject var message: Message
 
@@ -109,7 +92,7 @@ struct RecipientLabel: View {
         HStack(alignment: .top) {
             Text(title)
                 .textStyle(.bodySmallSecondary)
-                .background(ViewGeometry())
+                .background(ViewGeometry(key: ViewWidthKey.self, property: \.size.width))
                 .frame(width: labelWidth, alignment: .leading)
             VStack(alignment: .leading, spacing: 4) {
                 ForEach(recipients, id: \.self) { recipient in

MailCore/UI/UIConstants.swift

@@ -98,6 +98,9 @@ public enum UIConstants {
     public static let buttonsRadius: CGFloat = 16
     public static let buttonsIconSize: CGFloat = 16
 
+    public static let bottomBarVerticalPadding: CGFloat = 8
+    public static let bottomBarSmallVerticalPadding: CGFloat = 4
+
     public static let bottomSheetHorizontalPadding: CGFloat = 24
 
     public static let componentsMaxWidth: CGFloat = 496