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| 1 | +import AppKit |
| 2 | +import SwiftCrossUI |
| 3 | + |
| 4 | +public struct NSViewRepresentableContext<Coordinator> { |
| 5 | + public let coordinator: Coordinator |
| 6 | + public internal(set) var environment: EnvironmentValues |
| 7 | +} |
| 8 | + |
| 9 | +public protocol NSViewRepresentable: View where Content == Never { |
| 10 | + associatedtype NSViewType: NSView |
| 11 | + associatedtype Coordinator = Void |
| 12 | + |
| 13 | + /// Create the initial NSView instance. |
| 14 | + @MainActor |
| 15 | + func makeNSView(context: NSViewRepresentableContext<Coordinator>) -> NSViewType |
| 16 | + |
| 17 | + /// Update the view with new values. |
| 18 | + /// - Parameters: |
| 19 | + /// - nsView: The view to update. |
| 20 | + /// - context: The context, including the coordinator and potentially new environment |
| 21 | + /// values. |
| 22 | + /// - Note: This may be called even when `context` has not changed. |
| 23 | + @MainActor |
| 24 | + func updateNSView(_ nsView: NSViewType, context: NSViewRepresentableContext<Coordinator>) |
| 25 | + |
| 26 | + /// Make the coordinator for this view. |
| 27 | + /// |
| 28 | + /// The coordinator is used when the view needs to communicate changes to the rest of |
| 29 | + /// the view hierarchy (i.e. through bindings), and is often the view's delegate. |
| 30 | + @MainActor |
| 31 | + func makeCoordinator() -> Coordinator |
| 32 | + |
| 33 | + /// Compute the view's size. |
| 34 | + /// - Parameters: |
| 35 | + /// - proposal: The proposed frame for the view to render in. |
| 36 | + /// - nsVIew: The view being queried for its preferred size. |
| 37 | + /// - context: The context, including the coordinator and environment values. |
| 38 | + /// - Returns: Information about the view's size. The ``SwiftCrossUI/ViewSize/size`` |
| 39 | + /// property is what frame the view will actually be rendered with if the current layout |
| 40 | + /// pass is not a dry run, while the other properties are used to inform the layout engine |
| 41 | + /// how big or small the view can be. The ``SwiftCrossUI/ViewSize/idealSize`` property |
| 42 | + /// should not vary with the `proposal`, and should only depend on the view's contents. |
| 43 | + /// Pass `nil` for the maximum width/height if the view has no maximum size (and therefore |
| 44 | + /// may occupy the entire screen). |
| 45 | + /// |
| 46 | + /// The default implementation uses `nsView.intrinsicContentSize` and `nsView.sizeThatFits(_:)` |
| 47 | + /// to determine the return value. |
| 48 | + func determineViewSize( |
| 49 | + for proposal: SIMD2<Int>, nsView: NSViewType, |
| 50 | + context: NSViewRepresentableContext<Coordinator> |
| 51 | + ) -> ViewSize |
| 52 | + |
| 53 | + /// Called to clean up the view when it's removed. |
| 54 | + /// - Parameters: |
| 55 | + /// - nsVIew: The view being dismantled. |
| 56 | + /// - coordinator: The coordinator. |
| 57 | + /// |
| 58 | + /// This method is called after all AppKit lifecycle methods, such as |
| 59 | + /// `nsView.didMoveToSuperview()`. |
| 60 | + /// |
| 61 | + /// The default implementation does nothing. |
| 62 | + static func dismantleNSView(_ nsView: NSViewType, coordinator: Coordinator) |
| 63 | +} |
| 64 | + |
| 65 | +extension NSViewRepresentable { |
| 66 | + public static func dismantleNSView(_: NSViewType, coordinator _: Coordinator) { |
| 67 | + // no-op |
| 68 | + } |
| 69 | + |
| 70 | + public func determineViewSize( |
| 71 | + for proposal: SIMD2<Int>, nsView: NSViewType, |
| 72 | + context _: NSViewRepresentableContext<Coordinator> |
| 73 | + ) -> ViewSize { |
| 74 | + let intrinsicSize = nsView.intrinsicContentSize |
| 75 | + let sizeThatFits = nsView.fittingSize |
| 76 | + |
| 77 | + let roundedSizeThatFits = SIMD2( |
| 78 | + Int(sizeThatFits.width.rounded(.up)), |
| 79 | + Int(sizeThatFits.height.rounded(.up))) |
| 80 | + let roundedIntrinsicSize = SIMD2( |
| 81 | + Int(intrinsicSize.width.rounded(.awayFromZero)), |
| 82 | + Int(intrinsicSize.height.rounded(.awayFromZero))) |
| 83 | + |
| 84 | + return ViewSize( |
| 85 | + size: SIMD2( |
| 86 | + intrinsicSize.width < 0.0 ? proposal.x : roundedSizeThatFits.x, |
| 87 | + intrinsicSize.height < 0.0 ? proposal.y : roundedSizeThatFits.y |
| 88 | + ), |
| 89 | + // The 10 here is a somewhat arbitrary constant value so that it's always the same. |
| 90 | + // See also `Color` and `Picker`, which use the same constant. |
| 91 | + idealSize: SIMD2( |
| 92 | + intrinsicSize.width < 0.0 ? 10 : roundedIntrinsicSize.x, |
| 93 | + intrinsicSize.height < 0.0 ? 10 : roundedIntrinsicSize.y |
| 94 | + ), |
| 95 | + minimumWidth: max(0, roundedIntrinsicSize.x), |
| 96 | + minimumHeight: max(0, roundedIntrinsicSize.x), |
| 97 | + maximumWidth: nil, |
| 98 | + maximumHeight: nil |
| 99 | + ) |
| 100 | + } |
| 101 | +} |
| 102 | + |
| 103 | +extension View where Self: NSViewRepresentable { |
| 104 | + public var body: Never { |
| 105 | + preconditionFailure("This should never be called") |
| 106 | + } |
| 107 | + |
| 108 | + public func children<Backend: AppBackend>( |
| 109 | + backend _: Backend, |
| 110 | + snapshots _: [ViewGraphSnapshotter.NodeSnapshot]?, |
| 111 | + environment _: EnvironmentValues |
| 112 | + ) -> any ViewGraphNodeChildren { |
| 113 | + EmptyViewChildren() |
| 114 | + } |
| 115 | + |
| 116 | + public func layoutableChildren<Backend: AppBackend>( |
| 117 | + backend _: Backend, |
| 118 | + children _: any ViewGraphNodeChildren |
| 119 | + ) -> [LayoutSystem.LayoutableChild] { |
| 120 | + [] |
| 121 | + } |
| 122 | + |
| 123 | + public func asWidget<Backend: AppBackend>( |
| 124 | + _: any ViewGraphNodeChildren, |
| 125 | + backend _: Backend |
| 126 | + ) -> Backend.Widget { |
| 127 | + if let widget = RepresentingWidget(representable: self) as? Backend.Widget { |
| 128 | + return widget |
| 129 | + } else { |
| 130 | + fatalError("NSViewRepresentable requested by \(Backend.self)") |
| 131 | + } |
| 132 | + } |
| 133 | + |
| 134 | + public func update<Backend: AppBackend>( |
| 135 | + _ widget: Backend.Widget, |
| 136 | + children: any ViewGraphNodeChildren, |
| 137 | + proposedSize: SIMD2<Int>, |
| 138 | + environment: EnvironmentValues, |
| 139 | + backend: Backend, |
| 140 | + dryRun: Bool |
| 141 | + ) -> ViewUpdateResult { |
| 142 | + guard let backend = backend as? AppKitBackend else { |
| 143 | + fatalError("NSViewRepresentable updated by \(Backend.self)") |
| 144 | + } |
| 145 | + |
| 146 | + let representingWidget = widget as! RepresentingWidget<Self> |
| 147 | + representingWidget.update(with: environment) |
| 148 | + |
| 149 | + let size = |
| 150 | + representingWidget.representable.determineViewSize( |
| 151 | + for: proposedSize, |
| 152 | + nsView: representingWidget.subview, |
| 153 | + context: representingWidget.context! |
| 154 | + ) |
| 155 | + |
| 156 | + if !dryRun { |
| 157 | + backend.setSize(of: representingWidget, to: size.size) |
| 158 | + } |
| 159 | + |
| 160 | + return ViewUpdateResult.leafView(size: size) |
| 161 | + } |
| 162 | +} |
| 163 | + |
| 164 | +extension NSViewRepresentable where Coordinator == Void { |
| 165 | + public func makeCoordinator() { |
| 166 | + return () |
| 167 | + } |
| 168 | +} |
| 169 | + |
| 170 | +/// Exists to handle `deinit`, the rest of the stuff is just in here cause |
| 171 | +/// it's a convenient location. |
| 172 | +final class RepresentingWidget<Representable: NSViewRepresentable>: NSView { |
| 173 | + var representable: Representable |
| 174 | + var context: NSViewRepresentableContext<Representable.Coordinator>? |
| 175 | + |
| 176 | + init(representable: Representable) { |
| 177 | + self.representable = representable |
| 178 | + super.init(frame: .zero) |
| 179 | + |
| 180 | + self.translatesAutoresizingMaskIntoConstraints = false |
| 181 | + } |
| 182 | + |
| 183 | + @available(*, unavailable) |
| 184 | + required init?(coder: NSCoder) { |
| 185 | + fatalError("init(coder:) is not used for this view") |
| 186 | + } |
| 187 | + |
| 188 | + lazy var subview: Representable.NSViewType = { |
| 189 | + let view = representable.makeNSView(context: context!) |
| 190 | + |
| 191 | + self.addSubview(view) |
| 192 | + |
| 193 | + view.translatesAutoresizingMaskIntoConstraints = false |
| 194 | + NSLayoutConstraint.activate([ |
| 195 | + view.topAnchor.constraint(equalTo: self.topAnchor), |
| 196 | + view.leadingAnchor.constraint(equalTo: self.leadingAnchor), |
| 197 | + view.trailingAnchor.constraint(equalTo: self.trailingAnchor), |
| 198 | + view.bottomAnchor.constraint(equalTo: self.bottomAnchor), |
| 199 | + ]) |
| 200 | + |
| 201 | + return view |
| 202 | + }() |
| 203 | + |
| 204 | + func update(with environment: EnvironmentValues) { |
| 205 | + if context == nil { |
| 206 | + context = .init(coordinator: representable.makeCoordinator(), environment: environment) |
| 207 | + } else { |
| 208 | + context!.environment = environment |
| 209 | + representable.updateNSView(subview, context: context!) |
| 210 | + } |
| 211 | + } |
| 212 | + |
| 213 | + deinit { |
| 214 | + if let context { |
| 215 | + Representable.dismantleNSView(subview, coordinator: context.coordinator) |
| 216 | + } |
| 217 | + } |
| 218 | +} |
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