Fix UIKitBackend onOpenURL, fix WindowGroupNode windowSizeIsFinal logic

UIKitBackend's onOpenURL stuff didn't handle URLs from launch because
the delegate method gets fired before any view graphs get a chance to
register their respective onOpenURL methods. It also didn't handle
post-launch URLs (universal links received when already open in the
background) cause the required delegate methods weren't implemented.

Author: stackotter

Sources/AppKitBackend/AppKitBackend.swift

@@ -73,7 +73,7 @@ public final class AppKitBackend: AppBackend {
         )
     }
 
-    public func isFixedSizeWindow(_ window: Window) -> Bool {
+    public func isWindowProgrammaticallyResizable(_ window: Window) -> Bool {
         !window.styleMask.contains(.fullScreen)
     }
 
@@ -183,24 +183,35 @@ public final class AppKitBackend: AppBackend {
         let appMenu = NSMenu(title: appName)
         appMenu.addItem(
             withTitle: "About \(appName)",
-            action: #selector(NSApp.orderFrontStandardAboutPanel(_:)), keyEquivalent: "")
+            action: #selector(NSApp.orderFrontStandardAboutPanel(_:)),
+            keyEquivalent: ""
+        )
         appMenu.addItem(NSMenuItem.separator())
 
         let hideMenu = appMenu.addItem(
-            withTitle: "Hide \(appName)", action: #selector(NSApp.hide(_:)), keyEquivalent: "h")
+            withTitle: "Hide \(appName)",
+            action: #selector(NSApp.hide(_:)),
+            keyEquivalent: "h"
+        )
         hideMenu.keyEquivalentModifierMask = .command
 
         let hideOthers = appMenu.addItem(
-            withTitle: "Hide Others", action: #selector(NSApp.hideOtherApplications(_:)),
-            keyEquivalent: "h")
+            withTitle: "Hide Others",
+            action: #selector(NSApp.hideOtherApplications(_:)),
+            keyEquivalent: "h"
+        )
         hideOthers.keyEquivalentModifierMask = [.option, .command]
 
         appMenu.addItem(
-            withTitle: "Show All", action: #selector(NSApp.unhideAllApplications(_:)),
-            keyEquivalent: "")
+            withTitle: "Show All",
+            action: #selector(NSApp.unhideAllApplications(_:)),
+            keyEquivalent: ""
+        )
 
         let quitMenu = appMenu.addItem(
-            withTitle: "Quit \(appName)", action: #selector(NSApp.terminate(_:)), keyEquivalent: "q"
+            withTitle: "Quit \(appName)",
+            action: #selector(NSApp.terminate(_:)),
+            keyEquivalent: "q"
         )
         quitMenu.keyEquivalentModifierMask = .command
 

Sources/GtkBackend/GtkBackend.swift

@@ -119,9 +119,9 @@ public final class GtkBackend: AppBackend {
         return SIMD2(size.width, size.height)
     }
 
-    public func isFixedSizeWindow(_ window: Window) -> Bool {
+    public func isWindowProgrammaticallyResizable(_ window: Window) -> Bool {
         // TODO: Detect whether window is fullscreen
-        return false
+        return true
     }
 
     public func setSize(ofWindow window: Window, to newSize: SIMD2<Int>) {

Sources/SwiftCrossUI/Backend/AppBackend.swift

@@ -11,7 +11,8 @@ import Foundation
 /// ``AppBackend/setTitle(ofWindow:to:)``, ``AppBackend/setResizability(ofWindow:to:)``,
 /// ``AppBackend/setChild(ofWindow:to:)``, ``AppBackend/show(window:)``,
 /// ``AppBackend/runMainLoop()``, ``AppBackend/runInMainThread(action:)``,
-/// ``AppBackend/isFixedSizeWindow(_:)``, ``AppBackend/show(widget:)``.
+/// ``AppBackend/isWindowProgrammaticallyResizable(_:)``,
+/// ``AppBackend/show(widget:)``.
 /// Many of these can simply be given dummy implementations until you're ready
 /// to implement them properly.
 ///
@@ -119,7 +120,7 @@ public protocol AppBackend {
     func size(ofWindow window: Window) -> SIMD2<Int>
     /// Check whether a window is programmatically resizable. This value does not necessarily
     /// reflect whether the window is resizable by the user.
-    func isFixedSizeWindow(_ window: Window) -> Bool
+    func isWindowProgrammaticallyResizable(_ window: Window) -> Bool
     /// Sets the size of the given window in pixels.
     func setSize(ofWindow window: Window, to newSize: SIMD2<Int>)
     /// Sets the minimum width and height of the window. Prevents the user from making the

Sources/SwiftCrossUI/Scenes/WindowGroupNode.swift

@@ -52,7 +52,9 @@ public final class WindowGroupNode<Content: View>: SceneGraphNode {
                 self.scene,
                 proposedWindowSize: newSize,
                 backend: backend,
-                environment: parentEnvironment
+                environment: parentEnvironment,
+                windowSizeIsFinal:
+                    !backend.isWindowProgrammaticallyResizable(window)
             )
         }
     }
@@ -66,16 +68,17 @@ public final class WindowGroupNode<Content: View>: SceneGraphNode {
             fatalError("Scene updated with a backend incompatible with the window it was given")
         }
 
-        let isFixedSize = backend.isFixedSizeWindow(window)
+        let isProgramaticallyResizable =
+            backend.isWindowProgrammaticallyResizable(window)
 
         _ = update(
             newScene,
-            proposedWindowSize: isFirstUpdate && !isFixedSize
+            proposedWindowSize: isFirstUpdate && isProgramaticallyResizable
                 ? (newScene ?? scene).defaultSize
                 : backend.size(ofWindow: window),
             backend: backend,
             environment: environment,
-            windowSizeIsFinal: isFixedSize
+            windowSizeIsFinal: !isProgramaticallyResizable
         )
     }
 
@@ -119,16 +122,18 @@ public final class WindowGroupNode<Content: View>: SceneGraphNode {
             }
             .with(\.window, window)
 
-        // Perform a dry-run update of the root view to check if the window needs to
-        // change size.
-        let contentResult = viewGraph.update(
-            with: newScene?.body,
-            proposedSize: proposedWindowSize,
-            environment: environment,
-            dryRun: !windowSizeIsFinal
-        )
-
+        let dryRunResult: ViewUpdateResult?
         if !windowSizeIsFinal {
+            // Perform a dry-run update of the root view to check if the window
+            // needs to change size.
+            let contentResult = viewGraph.update(
+                with: newScene?.body,
+                proposedSize: proposedWindowSize,
+                environment: environment,
+                dryRun: true
+            )
+            dryRunResult = contentResult
+
             let newWindowSize = computeNewWindowSize(
                 currentProposedSize: proposedWindowSize,
                 backend: backend,
@@ -148,6 +153,8 @@ public final class WindowGroupNode<Content: View>: SceneGraphNode {
                     windowSizeIsFinal: false
                 )
             }
+        } else {
+            dryRunResult = nil
         }
 
         let finalContentResult = viewGraph.update(
@@ -178,14 +185,14 @@ public final class WindowGroupNode<Content: View>: SceneGraphNode {
         // Anyway, Gtk3Backend isn't really intended to be a recommended
         // backend so I think this is a fine solution for now (people should
         // only use Gtk3Backend if they can't use GtkBackend).
-        if finalContentResult.size != contentResult.size {
+        if let dryRunResult, finalContentResult.size != dryRunResult.size {
             print(
                 """
                 warning: Final window content size didn't match dry-run size. This is a sign that
                          either view size caching is broken or that backend.naturalSize(of:) is 
                          broken (or both).
-                      -> contentSize:      \(contentResult.size)
-                      -> finalContentSize: \(finalContentResult.size)
+                      -> dryRunResult.size:       \(dryRunResult.size)
+                      -> finalContentResult.size: \(finalContentResult.size)
                 """
             )
 
@@ -203,17 +210,20 @@ public final class WindowGroupNode<Content: View>: SceneGraphNode {
                     scene,
                     proposedWindowSize: newWindowSize,
                     backend: backend,
-                    environment: environment
+                    environment: environment,
+                    windowSizeIsFinal: true
                 )
             }
         }
 
+        // Set this even if the window isn't programmatically resizable
+        // because the window may still be user resizable.
         if scene.resizability.isResizable {
             backend.setMinimumSize(
                 ofWindow: window,
                 to: SIMD2(
-                    contentResult.size.minimumWidth,
-                    contentResult.size.minimumHeight
+                    finalContentResult.size.minimumWidth,
+                    finalContentResult.size.minimumHeight
                 )
             )
         }
@@ -222,8 +232,8 @@ public final class WindowGroupNode<Content: View>: SceneGraphNode {
             ofChildAt: 0,
             in: containerWidget.into(),
             to: SIMD2(
-                (proposedWindowSize.x - contentResult.size.size.x) / 2,
-                (proposedWindowSize.y - contentResult.size.size.y) / 2
+                (proposedWindowSize.x - finalContentResult.size.size.x) / 2,
+                (proposedWindowSize.y - finalContentResult.size.size.y) / 2
             )
         )
 

Sources/SwiftCrossUI/ViewGraph/ViewGraph.swift

@@ -26,20 +26,22 @@ public class ViewGraph<Root: View> {
     /// The environment most recently provided by this node's parent scene.
     private var parentEnvironment: EnvironmentValues
 
+    private var isFirstUpdate = true
+    private var setIncomingURLHandler: (@escaping (URL) -> Void) -> Void
+
     /// Creates a view graph for a root view with a specific backend.
     public init<Backend: AppBackend>(
-        for view: Root, backend: Backend, environment: EnvironmentValues
+        for view: Root,
+        backend: Backend,
+        environment: EnvironmentValues
     ) {
         rootNode = AnyViewGraphNode(for: view, backend: backend, environment: environment)
 
         self.view = view
         windowSize = .zero
         parentEnvironment = environment
         currentRootViewResult = ViewUpdateResult.leafView(size: .empty)
-
-        backend.setIncomingURLHandler { url in
-            self.currentRootViewResult.preferences.onOpenURL?(url)
-        }
+        setIncomingURLHandler = backend.setIncomingURLHandler(to:)
     }
 
     /// Recomputes the entire UI (e.g. due to the root view's state updating).
@@ -60,6 +62,12 @@ public class ViewGraph<Root: View> {
             dryRun: dryRun
         )
         self.currentRootViewResult = result
+        if isFirstUpdate, !dryRun {
+            setIncomingURLHandler { url in
+                self.currentRootViewResult.preferences.onOpenURL?(url)
+            }
+            isFirstUpdate = false
+        }
         return result
     }
 

Sources/UIKitBackend/BaseWidget.swift

@@ -6,39 +6,39 @@ public class BaseWidget: UIView {
     private var widthConstraint: NSLayoutConstraint?
     private var heightConstraint: NSLayoutConstraint?
 
-    internal var x = 0 {
+    var x = 0 {
         didSet {
             if x != oldValue {
                 updateLeftConstraint()
             }
         }
     }
 
-    internal var y = 0 {
+    var y = 0 {
         didSet {
             if y != oldValue {
                 updateTopConstraint()
             }
         }
     }
 
-    internal var width = 0 {
+    var width = 0 {
         didSet {
             if width != oldValue {
                 updateWidthConstraint()
             }
         }
     }
 
-    internal var height = 0 {
+    var height = 0 {
         didSet {
             if height != oldValue {
                 updateHeightConstraint()
             }
         }
     }
 
-    internal init() {
+    init() {
         super.init(frame: .zero)
 
         self.translatesAutoresizingMaskIntoConstraints = false
@@ -89,7 +89,7 @@ extension UIKitBackend {
     public typealias Widget = BaseWidget
 }
 
-internal class WrapperWidget<View: UIView>: BaseWidget {
+class WrapperWidget<View: UIView>: BaseWidget {
     init(child: View) {
         super.init()
 

Sources/UIKitBackend/Font+UIFont.swift

@@ -2,7 +2,7 @@ import SwiftCrossUI
 import UIKit
 
 extension Font {
-    internal var uiFont: UIFont {
+    var uiFont: UIFont {
         switch self {
             case .system(let size, let weight, let design):
                 let weight: UIFont.Weight =

Sources/UIKitBackend/UIColor+Color.swift

@@ -2,7 +2,7 @@ import SwiftCrossUI
 import UIKit
 
 extension UIColor {
-    internal convenience init(color: Color) {
+    convenience init(color: Color) {
         self.init(
             red: CGFloat(color.red),
             green: CGFloat(color.green),
@@ -13,7 +13,7 @@ extension UIColor {
 }
 
 extension Color {
-    internal init(_ uiColor: UIColor) {
+    init(_ uiColor: UIColor) {
         let ciColor = CIColor(color: uiColor)
 
         self.init(
@@ -24,7 +24,7 @@ extension Color {
         )
     }
 
-    internal var uiColor: UIColor {
+    var uiColor: UIColor {
         UIColor(color: self)
     }
 }

Sources/UIKitBackend/UIKitBackend+Alert.swift

@@ -3,10 +3,10 @@ import UIKit
 
 extension UIKitBackend {
     public final class Alert {
-        internal let controller: UIAlertController
-        internal var handler: ((Int) -> Void)?
+        let controller: UIAlertController
+        var handler: ((Int) -> Void)?
 
-        internal init() {
+        init() {
             self.controller = UIAlertController(title: nil, message: nil, preferredStyle: .alert)
         }
     }
@@ -25,9 +25,9 @@ extension UIKitBackend {
 
         for (i, actionLabel) in actionLabels.enumerated() {
             let action = UIAlertAction(title: actionLabel, style: .default) {
-                [unowned self, weak alert] _ in
+                [weak alert] _ in
                 guard let alert else { return }
-                alert.handler!(i)
+                alert.handler?(i)
             }
             alert.controller.addAction(action)
         }
@@ -38,7 +38,7 @@ extension UIKitBackend {
         window: Window?,
         responseHandler handleResponse: @escaping (Int) -> Void
     ) {
-        guard let window = window ?? mainWindow else {
+        guard let window = window ?? Self.mainWindow else {
             assertionFailure("Could not find window in which to display alert")
             return
         }
@@ -49,6 +49,5 @@ extension UIKitBackend {
 
     public func dismissAlert(_ alert: Alert, window: Window?) {
         alert.controller.dismiss(animated: false)
-
     }
 }

Sources/UIKitBackend/UIKitBackend+Container.swift

@@ -1,7 +1,7 @@
 import SwiftCrossUI
 import UIKit
 
-internal final class ScrollWidget: WrapperWidget<UIScrollView> {
+final class ScrollWidget: WrapperWidget<UIScrollView> {
     private var childWidthConstraint: NSLayoutConstraint?
     private var childHeightConstraint: NSLayoutConstraint?