View .onHover { Bool in } modifier #212

MiaKoring · 2025-09-07T22:56:07Z

This PR introduces a new .onHover modifier to Views.
Related Issue: #211
Added in this PR:

Extension View
- onHover { Bool in }
protocol AppBackend
- createHoverTarget
- updateHoverTarget
- Default implementation for Backends without implementation
Backend Support
- AppKitBackend
- UIKitBackend
- GtkBackend
- WinUIBackend
Other changes:
- left & right NSClickGestureRecognizer now get set to nil in NSCustomTapGestureTarget when corresponding function gets set to nil
- UISlider now Supports macCatalyst (added through compilerflag)
- Added HoverExample
- (format_and_lint.sh and generate.sh automatic changes)

HoverExample erfolgreich getestet auf:
macOS 26 (AppKitBackend, GtkBackend, UIKitBackend (macCatalyst))
iPadOS 26 (UIKitBackend)
Windows 11 (WinUI Backend)
Fedora 44 (GtkBackend)

Notes:
Gtk versions below 4.20.0 may encounter compiling problems. I don’t know why or what caused it, I only used the generate script, but on 4.18.6 on Fedora 42 I got this Error:

/home/mia/Documents/swift-cross-ui/Sources/Gtk/Generated/PadActionType.swift:28:6: error: cannot find 'GTK_PAD_ACTION_DIAL' in scope
26 | case GTK_PAD_ACTION_STRIP:
27 |     self = .strip
28 | case GTK_PAD_ACTION_DIAL:
   |      `- error: cannot find 'GTK_PAD_ACTION_DIAL' in scope
29 |     self = .dial
30 |             default:

I checked and it should’ve been available since 4.0 https://docs.gtk.org/gtk4/enum.PadActionType.html
Maybe someone knows how to fix it and maybe it was just a local issue.

I made the weird Array-in-foreach-decision, since closed ranges didn't seem to be supported yet.

test.sh output

   Test Suite 'All tests' started at 2025-09-08 00:03:46.577.
Test Suite 'swift-cross-uiPackageTests.xctest' started at 2025-09-08 00:03:46.584.
Test Suite 'SwiftCrossUITests' started at 2025-09-08 00:03:46.584.
Test Case '-[SwiftCrossUITests.SwiftCrossUITests testBasicLayout]' started.
/Users/miakoring/Documents/Fork/swift-cross-ui/Tests/SwiftCrossUITests/SwiftCrossUITests.swift:203: error: -[SwiftCrossUITests.SwiftCrossUITests testBasicLayout] : XCTAssertEqual failed: ("ViewSize(size: SIMD2<Int>(102, 104), idealSize: SIMD2<Int>(102, 104), idealWidthForProposedHeight: 102, idealHeightForProposedWidth: 104, minimumWidth: 102, minimumHeight: 104, maximumWidth: 102.0, maximumHeight: 104.0, participateInStackLayoutsWhenEmpty: true)") is not equal to ("ViewSize(size: SIMD2<Int>(92, 96), idealSize: SIMD2<Int>(92, 96), idealWidthForProposedHeight: 92, idealHeightForProposedWidth: 96, minimumWidth: 92, minimumHeight: 96, maximumWidth: 92.0, maximumHeight: 96.0, participateInStackLayoutsWhenEmpty: true)") - View update result mismatch
Test Case '-[SwiftCrossUITests.SwiftCrossUITests testBasicLayout]' failed (0.204 seconds).
Test Case '-[SwiftCrossUITests.SwiftCrossUITests testCodableNavigationPath]' started.
Test Case '-[SwiftCrossUITests.SwiftCrossUITests testCodableNavigationPath]' passed (0.001 seconds).
Test Case '-[SwiftCrossUITests.SwiftCrossUITests testStateObservation]' started.
Test Case '-[SwiftCrossUITests.SwiftCrossUITests testStateObservation]' passed (0.000 seconds).
Test Case '-[SwiftCrossUITests.SwiftCrossUITests testThrottledStateObservation]' started.
Test Case '-[SwiftCrossUITests.SwiftCrossUITests testThrottledStateObservation]' passed (0.225 seconds).
Test Suite 'SwiftCrossUITests' failed at 2025-09-08 00:03:47.014.
	 Executed 4 tests, with 1 failure (0 unexpected) in 0.430 (0.431) seconds
Test Suite 'swift-cross-uiPackageTests.xctest' failed at 2025-09-08 00:03:47.014.
	 Executed 4 tests, with 1 failure (0 unexpected) in 0.430 (0.431) seconds
Test Suite 'All tests' failed at 2025-09-08 00:03:47.014.
	 Executed 4 tests, with 1 failure (0 unexpected) in 0.430 (0.437) seconds
􀟈  Test run started.
􀄵  Testing Library Version: 1084
􀄵  Target Platform: arm64e-apple-macos14.0
􁁛  Test run with 0 tests in 0 suites passed after 0.001 seconds.

Added: - onHover(_ action: (Bool) -> Void) View Extension - OnHoverModifier TypeSafeView - createHoverTarget(wrapping: Widget) -> Widget to AppBackend Protocol - updateHoverTarget(_: Widget, environment: EnvironmentValues, action: (Bool) -> Void) to AppBackend Protocol - corresponding default implementations - AppKitBackend hover implementation - createHoverTarget implementation - updateHoverTarget implementation - NSCustomHoverTarget (NSView notifying about hovers) - HoverExample Fixed: - AppKitBackend - fixed reference removing for NSClickGestureRecognizer in NSCustomTapGestureTarget

…ming fixes in AppKitBackend - tapGestureRecognizer and longPressGestureRecognizer now get removed if their corresponding handler is set to nil. - Added Hoverable Widget - Added hovertarget creation & update functions - added macCalatalyst as compatible for UISlider since it supports it

stackotter

Thanks for the PR! This will be quite useful for making more interactive apps. I've just requested a few changes around some implementation details but overall your approach to implementing this modifier was great.

Examples/Sources/HoverExample/HoverApp.swift

stackotter · 2025-09-15T02:33:06Z

Sources/UIKitBackend/UIKitBackend+Control.swift

+                // should be impossible at the moment of implementation
+                // keeping it to be save in case of later changes


It's safe to remove these comments, I don't think anyone will question that this is sensible (because the current guarantee that hoverChangesHandlers won't get set to nil is external to the HoverableWidget type)

stackotter · 2025-09-15T02:39:41Z

Sources/WinUIBackend/WinUIBackend.swift

+        hoverTarget.width = hoverTarget.child!.width
+        hoverTarget.height = hoverTarget.child!.height


I realise that this was copied from the tap gesture modifier, but I've just noticed that it is probably redundant (in both cases) since both modifiers call backend.setSize just before calling the corresponding updateBlahTarget methods.

I'm happy to try that out on my end after merging though if a getting a Windows VM up is a bit annoying on your end.

stackotter · 2025-09-15T02:43:38Z

Sources/AppKitBackend/AppKitBackend.swift

+    }
+
+    override func mouseExited(with event: NSEvent) {
+        // Mouse exited the view's bounds


Remove this comment

stackotter · 2025-09-15T02:44:36Z

Sources/AppKitBackend/AppKitBackend.swift

+                // should be impossible at the moment of implementation
+                // keeping it to be save in case of later changes


Similar to UIKitBackend, remove this comment, the code is sensible

stackotter · 2025-09-15T02:47:22Z

Sources/AppKitBackend/AppKitBackend.swift

+            options: options,
+            owner: self,
+            userInfo: nil)
+        self.addTrackingArea(trackingArea!)


Avoid the force unwrap with an intermediate variable like you did in the didSet above.

Sources/AppKitBackend/AppKitBackend.swift

stackotter · 2025-09-15T02:55:04Z

I checked and it should’ve been available since 4.0 https://docs.gtk.org/gtk4/enum.PadActionType.html
Maybe someone knows how to fix it and maybe it was just a local issue.

Gtk can be pretty weird about availability information. I think the best we can do is add a hardcoded check to filter out the enum case in GtkCodeGen.generateEnum. Make sure to leave a comment explaining that the check exists due to incorrect Gtk availability info for that particular enum case.

stackotter · 2025-09-15T02:56:02Z

That's interesting that testBasicLayout fails on your machine. It should be unrelated to your PR, so ignore that for now. I'll have to look into why it's happening at some point.

# Conflicts: # Sources/GtkCodeGen/GtkCodeGen.swift

MiaKoring · 2025-09-15T14:49:53Z

I can’t test wether the linux compile bug is fixed because I don’t have a vm with older gtk atm. But I don’t see it in the generated code anymore. hopefully the build will now succeed

on WinUIBackend the explicit frame adjustments were indeed not necessary

stackotter · 2025-09-15T14:55:30Z

The PR froze safari for a few seconds when I tried to view the new changes because there are 266 changed files 😅 I think running ./format_and_lint.sh should fix that

MiaKoring · 2025-09-15T14:58:33Z

didn’t help did it?

stackotter

Just two small changes to make, other than that everything looks ready to merge

stackotter · 2025-09-17T10:04:56Z

Sources/GtkCodeGen/GtkCodeGen.swift

+            //can cause problems with gtk versions older than 4.20.0
+            guard
+                member.cIdentifier != "GTK_PAD_ACTION_DIAL",
+                member.name != "GTK_PAD_ACTION_DIAL"


For this check I meant that you should check that the enumeration name is "PadActionDial" when checking the member cIdentifier. I realise that the member names are prefixed so there won't be clashes, but it's probably nice for future refactorers to have the enumeration name check there so they know which enum the rule is meant to apply to.

guard enumeration.name != "PadActionDial" || member.cIdentifier != "GTK_PAD_ACTION_DIAL" else { return false }

(the enum name may be GtkPadActionDial instead of PadActionDial, not sure)

stackotter · 2025-09-17T10:05:34Z

Sources/GtkCodeGen/GtkCodeGen.swift

@@ -224,6 +226,14 @@ struct GtkCodeGen {
                return false
            }

+            //can cause problems with gtk versions older than 4.20.0


Put a space after the // and capitalise Can at the start of the sentence (to match the style of other comments)

added both "GtkPadActionDial" and "PadActionDial" because I couldn't find a definitive answer what its called

added both "GtkPadActionDial" and "PadActionDial" because I couldn't find a definitive answer what its called # Conflicts: # Sources/GtkCodeGen/GtkCodeGen.swift

MiaKoring · 2025-09-17T13:07:05Z

(I somehow accidentally deleted the member.doc check, just readded it in the Amend)

MiaKoring added 8 commits September 6, 2025 04:20

Fixed Default Hover implementation

0556998

added gtk4 support

77794a0

added winUI backend support

b8b3912

post format_and_lint

badbdfb

slight quality improvement in HoverExample

e086878

MiaKoring mentioned this pull request Sep 14, 2025

ForEach(ClosedRange<Int>) #213

Open

stackotter requested changes Sep 15, 2025

View reviewed changes

implemented requested changes

14b8123

MiaKoring requested a review from stackotter September 15, 2025 14:40

implemented requested changes

3436755

# Conflicts: # Sources/GtkCodeGen/GtkCodeGen.swift

format_and_lint

469e042

stackotter requested changes Sep 17, 2025

View reviewed changes

MiaKoring added 2 commits September 17, 2025 15:04

Comment Style, Pad Action exclusion Name changed

fbc4e5d

added both "GtkPadActionDial" and "PadActionDial" because I couldn't find a definitive answer what its called

Comment Style, Pad Action exclusion Name changed

a4721aa

added both "GtkPadActionDial" and "PadActionDial" because I couldn't find a definitive answer what its called # Conflicts: # Sources/GtkCodeGen/GtkCodeGen.swift

		// should be impossible at the moment of implementation
		// keeping it to be save in case of later changes

		hoverTarget.width = hoverTarget.child!.width
		hoverTarget.height = hoverTarget.child!.height

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View .onHover { Bool in } modifier #212

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View .onHover { Bool in } modifier #212

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MiaKoring commented Sep 7, 2025 •

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