Impl WinUIBackend ScrollView, fix ScrollView layout calculations

ScrollView had some layout bugs affecting all backends.

Examples/Sources/NotesExample/ContentView.swift

@@ -28,79 +28,6 @@ class NotesState: Observable, Codable {
     var error: String?
 }
 
-struct OnChangeOfView<Value: Equatable, Child: View>: View {
-    var state = OnChangeOfViewState()
-
-    var currentValue: Value
-    var onChange: (Value) -> Void
-    var child: Child
-    var notifyInitial: Bool
-
-    class OnChangeOfViewState: Observable {
-        var value: Value?
-    }
-
-    init(
-        _ value: Value,
-        _ onChange: @escaping (Value) -> Void,
-        _ notifyInitial: Bool,
-        _ child: Child
-    ) {
-        self.currentValue = value
-        self.onChange = onChange
-        self.notifyInitial = notifyInitial
-        self.child = child
-    }
-
-    var body: some View {
-        if state.value != currentValue {
-            let isInitial = state.value != nil
-            state.value = currentValue
-            if !isInitial || notifyInitial {
-                onChange(currentValue)
-            }
-        }
-        return child
-    }
-}
-
-struct OnAppearView<Child: View>: View {
-    var state = OnAppearViewState()
-    var onAppear: () -> Void
-    var child: Child
-
-    class OnAppearViewState: Observable {
-        var hasAppeared = false
-    }
-
-    init(_ onAppear: @escaping () -> Void, _ child: Child) {
-        self.onAppear = onAppear
-        self.child = child
-    }
-
-    var body: some View {
-        if !state.hasAppeared {
-            state.hasAppeared = true
-            onAppear()
-        }
-        return child
-    }
-}
-
-extension View {
-    func onChange<Value>(
-        of value: Value,
-        initial: Bool = false,
-        _ action: @escaping (Value) -> Void
-    ) -> OnChangeOfView<Value, Self> {
-        OnChangeOfView(value, action, initial, self)
-    }
-
-    func onAppear(perform action: @escaping () -> Void) -> OnAppearView<Self> {
-        OnAppearView(action, self)
-    }
-}
-
 struct ContentView: View {
     let notesFile = URL(fileURLWithPath: "notes.json")
 
@@ -149,9 +76,9 @@ struct ContentView: View {
                     state.selectedNoteId = note.id
                 }
             }
-            .onChange(of: state.notes) { notes in
+            .onChange(of: state.notes) {
                 do {
-                    let data = try JSONEncoder().encode(notes)
+                    let data = try JSONEncoder().encode(state.notes)
                     try data.write(to: notesFile)
                 } catch {
                     print("Error: \(error)")

Examples/Sources/NotesExample/NotesApp.swift

@@ -1,7 +1,10 @@
 import DefaultBackend
-import SwiftBundlerRuntime
 import SwiftCrossUI
 
+#if canImport(SwiftBundlerRuntime)
+    import SwiftBundlerRuntime
+#endif
+
 @main
 @HotReloadable
 struct NotesApp: App {

Examples/notes.json

@@ -0,0 +1 @@
+[{"content":"Welcome SwiftCrossNotes!","id":"D70F96BB-2153-4FC6-A79F-FD231B4F3523","title":"Hello, world!"},{"content":"- Carrots","id":"04864C37-38E3-4FC1-8BAF-C2BA41AAF8D9","title":"Shopping list"},{"title":"My note","id":"EAA92A96-E443-4374-AB35-41CD4BD99EBD","content":"I hope for world piss"}]

Sources/SwiftCrossUI/Views/ScrollView.swift

@@ -76,20 +76,14 @@ public struct ScrollView<Content: View>: TypeSafeView, View {
             scrollViewWidth = max(proposedSize.x, verticalScrollBarWidth)
             minimumWidth = verticalScrollBarWidth
         } else {
-            scrollViewWidth = max(
-                contentSize.size.x,
-                contentSize.minimumWidth + verticalScrollBarWidth
-            )
+            scrollViewWidth = contentSize.size.x + verticalScrollBarWidth
             minimumWidth = contentSize.minimumWidth + verticalScrollBarWidth
         }
         if axes.contains(.vertical) {
             scrollViewHeight = max(proposedSize.y, horizontalScrollBarHeight)
             minimumHeight = horizontalScrollBarHeight
         } else {
-            scrollViewHeight = max(
-                contentSize.size.y,
-                contentSize.minimumHeight + horizontalScrollBarHeight
-            )
+            scrollViewHeight = contentSize.size.y + horizontalScrollBarHeight
             minimumHeight = contentSize.minimumHeight + horizontalScrollBarHeight
         }
 
@@ -102,9 +96,11 @@ public struct ScrollView<Content: View>: TypeSafeView, View {
         if !dryRun {
             let proposedContentSize = SIMD2(
                 hasHorizontalScrollBar
-                    ? contentSize.idealSize.x : (contentSize.size.x - verticalScrollBarWidth),
+                    ? contentSize.idealSize.x
+                    : min(contentSize.size.x, proposedSize.x - verticalScrollBarWidth),
                 hasVerticalScrollBar
-                    ? contentSize.idealSize.y : (contentSize.size.y - horizontalScrollBarHeight)
+                    ? contentSize.idealSize.y
+                    : min(contentSize.size.y, proposedSize.y - horizontalScrollBarHeight)
             )
 
             finalResult = children.child.update(

Sources/WinUIBackend/WinUIBackend.swift

@@ -37,7 +37,7 @@ public struct WinUIBackend: AppBackend {
     public let defaultPaddingAmount = 10
 
     public var scrollBarWidth: Int {
-        fatalError("TODO")
+        12
     }
 
     private class InternalState {
@@ -61,8 +61,9 @@ public struct WinUIBackend: AppBackend {
             // Toggle Switch has annoying default 'internal margins' (not Control
             // margins that we can set directly) that we can luckily get rid of by
             // overriding the relevant resource values.
-            application.resources.insert("ToggleSwitchPreContentMargin", 0.0 as Double)
-            application.resources.insert("ToggleSwitchPostContentMargin", 0.0 as Double)
+            _ = application.resources.insert("ToggleSwitchPreContentMargin", 0.0 as Double)
+            _ = application.resources.insert("ToggleSwitchPostContentMargin", 0.0 as Double)
+
             callback()
         }
         WinUIApplication.main()
@@ -219,7 +220,6 @@ public struct WinUIBackend: AppBackend {
     public func addChild(_ child: Widget, to container: Widget) {
         let container = container as! Canvas
         container.children.append(child)
-        try! container.updateLayout()
     }
 
     public func setPosition(ofChildAt index: Int, in container: Widget, to position: SIMD2<Int>) {
@@ -394,12 +394,10 @@ public struct WinUIBackend: AppBackend {
         let block = createTextView()
         updateTextView(block, content: text, environment: environment)
 
-        let allocation =
-            proposedFrame.map(WindowsFoundation.Size.init(_:))
-            ?? WindowsFoundation.Size(
-                width: .infinity,
-                height: .infinity
-            )
+        let allocation = WindowsFoundation.Size(
+            width: (proposedFrame?.x).map(Float.init(_:)) ?? .infinity,
+            height: .infinity
+        )
         try! block.measure(allocation)
 
         let computedSize = block.desiredSize
@@ -451,11 +449,42 @@ public struct WinUIBackend: AppBackend {
         internalState.buttonClickActions[ObjectIdentifier(button)] = action
     }
 
-    // public func createScrollContainer(for child: Widget) -> Widget {
-    //     let scrollViewer = ScrollViewer()
-    //     scrollViewer.content = child
-    //     return scrollViewer
-    // }
+    public func createScrollContainer(for child: Widget) -> Widget {
+        let scrollViewer = WinUI.ScrollViewer()
+        scrollViewer.content = child
+        child.horizontalAlignment =
+            __x_ABI_CMicrosoft_CUI_CXaml_CHorizontalAlignment_Left
+        child.verticalAlignment = __x_ABI_CMicrosoft_CUI_CXaml_CVerticalAlignment_Top
+        return scrollViewer
+    }
+
+    public func setScrollBarPresence(
+        ofScrollContainer scrollView: Widget,
+        hasVerticalScrollBar: Bool,
+        hasHorizontalScrollBar: Bool
+    ) {
+        let scrollViewer = scrollView as! WinUI.ScrollViewer
+
+        scrollViewer.isHorizontalRailEnabled = hasHorizontalScrollBar
+        scrollViewer.horizontalScrollMode =
+            hasHorizontalScrollBar
+            ? __x_ABI_CMicrosoft_CUI_CXaml_CControls_CScrollMode_Enabled
+            : __x_ABI_CMicrosoft_CUI_CXaml_CControls_CScrollMode_Disabled
+        scrollViewer.horizontalScrollBarVisibility =
+            hasHorizontalScrollBar
+            ? __x_ABI_CMicrosoft_CUI_CXaml_CControls_CScrollBarVisibility_Visible
+            : __x_ABI_CMicrosoft_CUI_CXaml_CControls_CScrollBarVisibility_Hidden
+
+        scrollViewer.isVerticalRailEnabled = hasVerticalScrollBar
+        scrollViewer.verticalScrollMode =
+            hasVerticalScrollBar
+            ? __x_ABI_CMicrosoft_CUI_CXaml_CControls_CScrollMode_Enabled
+            : __x_ABI_CMicrosoft_CUI_CXaml_CControls_CScrollMode_Disabled
+        scrollViewer.verticalScrollBarVisibility =
+            hasVerticalScrollBar
+            ? __x_ABI_CMicrosoft_CUI_CXaml_CControls_CScrollBarVisibility_Visible
+            : __x_ABI_CMicrosoft_CUI_CXaml_CControls_CScrollBarVisibility_Hidden
+    }
 
     public func createSlider() -> Widget {
         let slider = Slider()
@@ -847,12 +876,3 @@ final class CustomComboBox: ComboBox {
 final class CustomSplitView: SplitView {
     var sidebarResizeHandler: (() -> Void)?
 }
-
-extension WindowsFoundation.Size {
-    init(_ other: SIMD2<Int>) {
-        self.init(
-            width: Float(other.x),
-            height: Float(other.y)
-        )
-    }
-}