Add HSplitView and VSplitView

Co-authored-by: desbeers nick@desbeers.nl

Sources/Core/View/SplitView.swift

@@ -0,0 +1,131 @@
+//
+//  SplitView.swift
+//  Adwaita
+//
+//  Created by david-swift on 19.09.2025.
+//
+
+import CAdw
+import Foundation
+
+/// A split view.
+struct SplitView: AdwaitaWidget {
+
+    /// The start widget.
+    @ViewProperty(
+        set: { widget, view in gtk_paned_set_start_child(.init(widget), view.cast()) },
+        pointer: OpaquePointer.self,
+        subview: OpaquePointer.self,
+        context: AdwaitaMainView.self
+    )
+    var start
+    /// The end widget.
+    @ViewProperty(
+        set: { widget, view in gtk_paned_set_end_child(.init(widget), view.cast()) },
+        pointer: OpaquePointer.self,
+        subview: OpaquePointer.self,
+        context: AdwaitaMainView.self
+    )
+    var end
+    /// Position of the splitter
+    @BindingProperty(
+        observe: { _, binding, storage in
+            storage.notify(name: "position") {
+                binding.wrappedValue = Int(gtk_paned_get_position(storage.opaquePointer))
+            }
+        },
+        set: { widget, value, _ in gtk_paned_set_position(widget, Int32(value)) },
+        pointer: OpaquePointer.self
+    )
+    var splitter: Binding<Int> = .constant(0)
+    /// Whether the split view is vertical.
+    var vertical: Bool
+
+    /// Initialize a split view.
+    /// - Parameters:
+    ///     - splitter: The position of the splitter.
+    ///     - vertical: Whether to make the splitter vertical.
+    ///     - start: The start widget.
+    ///     - end: The end widget.
+    init(
+        splitter: Binding<Int>,
+        vertical: Bool,
+        start: Body,
+        end: Body
+    ) {
+        self.vertical = vertical
+        self.splitter = splitter
+        self.start = start
+        self.end = end
+    }
+
+    /// Initialize the widget.
+    func initializeWidget() -> Any {
+        gtk_paned_new(vertical ? GTK_ORIENTATION_VERTICAL : GTK_ORIENTATION_HORIZONTAL).opaque() as Any
+    }
+
+}
+
+/// A horizontal split view.
+public struct HSplitView: SimpleView {
+
+    /// The splitter.
+    @Binding var splitter: Int
+    /// The start widget.
+    var start: Body
+    /// The end widget.
+    var end: Body
+
+    /// The view.
+    public var view: Body {
+        SplitView(splitter: $splitter, vertical: false, start: start, end: end)
+    }
+
+    /// Initialize a horizontal split view.
+    /// - Parameters:
+    ///     - splitter: The position of the splitter.
+    ///     - start: The start widget.
+    ///     - end: The end widget.
+    public init(
+        splitter: Binding<Int>,
+        @ViewBuilder start: () -> Body,
+        @ViewBuilder end: () -> Body
+    ) {
+        self._splitter = splitter
+        self.start = start()
+        self.end = end()
+    }
+
+}
+
+/// A vertical split view.
+public struct VSplitView: SimpleView {
+
+    /// The splitter.
+    @Binding var splitter: Int
+    /// The start widget.
+    var start: Body
+    /// The end widget.
+    var end: Body
+
+    /// The view.
+    public var view: Body {
+        SplitView(splitter: $splitter, vertical: true, start: start, end: end)
+    }
+
+    /// Initialize a vertical split view.
+    /// - Parameters:
+    ///     - splitter: The position of the splitter.
+    ///     - start: The start widget.
+    ///     - end: The end widget.
+    public init(
+        splitter: Binding<Int>,
+        @ViewBuilder start: () -> Body,
+        @ViewBuilder end: () -> Body
+    ) {
+        self._splitter = splitter
+        self.start = start()
+        self.end = end()
+    }
+
+}

Sources/Demo/Page.swift

@@ -33,6 +33,7 @@ enum Page: String, Identifiable, CaseIterable, Codable, CustomStringConvertible
     case idle
     case fixed
     case textEditor
+    case splitView
 
     var id: Self {
         self
@@ -52,6 +53,8 @@ enum Page: String, Identifiable, CaseIterable, Codable, CustomStringConvertible
             return "Password Checker"
         case .textEditor:
             return "Text Editor"
+        case .splitView:
+            return "Split View"
         default:
             return rawValue.capitalized
         }
@@ -110,6 +113,8 @@ enum Page: String, Identifiable, CaseIterable, Codable, CustomStringConvertible
             return "Place widgets in a coordinate system"
         case .textEditor:
             return "A simple text editor"
+        case .splitView:
+            return "A split view whose panes are ajustable in size"
         }
     }
 
@@ -159,6 +164,8 @@ enum Page: String, Identifiable, CaseIterable, Codable, CustomStringConvertible
             FixedDemo()
         case .textEditor:
             TextEditorDemo()
+        case .splitView:
+            SplitViewDemo()
         }
     }
     // swiftlint:enable cyclomatic_complexity

Sources/Demo/SplitViewDemo.swift

@@ -0,0 +1,29 @@
+//
+//  SplitViewDemo.swift
+//  Adwaita
+//
+//  Created by david-swift on 16.09.25.
+//
+
+// swiftlint:disable missing_docs
+
+import Adwaita
+
+struct SplitViewDemo: View {
+
+    @State private var splitter = 200
+
+    var view: Body {
+        HSplitView(splitter: $splitter) {
+            Text("\(splitter) Pixels")
+        } end: {
+            Text("View 2")
+        }
+        .frame(minHeight: 200)
+        .card()
+        .padding()
+    }
+
+}
+
+// swiftlint:enable missing_docs