[iOS] [Mac] Fix for Gradient background size is incorrect when invalidating parent

[Tamilarasan-Paranthaman]

Root Cause of the issue

• During the initial and dynamic rendering of the view, the Gradient Layer frame is not applied correctly. Additionally, the Gradient Layer frame updates unnecessarily for all UIViews, causing the Gradient Layer to appear incorrectly sized.

Description of Change

• The issue was resolved by retrieving the superlayer (parent) of the Gradient Layer and updating its bounds to match the Gradient Layer's frame.

Issues Fixed

Fixes #26057
Fixes #20218

Tested the behaviour in the following platforms

• Android
• Windows
• iOS
• Mac

Screenshot

iOS

Before Issue Fix	After Issue Fix
iOSGradientIssue.mov	iOSGradientFix.mov

Mac

Before Issue Fix	After Issue Fix
MacGradientIssue.mov	MacGradientFix.mov

[dotnet-policy-service]

Hey there @Tamilarasan-Paranthaman! Thank you so much for your PR! Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

[jsuarezruiz]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[jsuarezruiz]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[kubaflo]

Hi, @albyrock87 I remember you were making some changes to this viewExtension.cs when you were working on the border fix. Does this PR look good to you?

[albyrock87]

@kubaflo my PR #24848 should already fix this, at least that's my guess.
Also note that my PR basically gets rid of UpdateBackgroundLayers.

[kubaflo]

@albyrock87 I see! Your PR is great! Maybe you should also include a UI test for this issue in your PR as well #24848

Copilot reviewed 6 out of 7 changed files in this pull request and generated no suggestions.

Files not reviewed (1)

• src/Controls/tests/TestCases.HostApp/Issues/Issue26057.xaml: Language not supported

Comments skipped due to low confidence (1)

src/Controls/tests/TestCases.HostApp/Issues/Issue26057.xaml.cs:16

• Ensure that 'stack' is properly defined and used within this context. The current snippet does not provide enough information about 'stack'.

(stack as IView).InvalidateMeasure();

[albyrock87]

I will add this UI test on my PR to confirm it fixes this issue too.

[albyrock87]

@Tamilarasan-Paranthaman I've added you as co-author on #24848 where I've just included your UI test and verified it works fine