Fixes #22417

Summary

This PR addresses layout constraint issues for CarouselView on Mac Catalyst where the control could exceed its layout constraints, causing layout problems when items are added dynamically.

Changes

1. CarouselViewHandler.iOS.cs - Layout Constraint Fix

Modified the GetDesiredSize method to properly clamp the returned size to the provided constraints:

public override Size GetDesiredSize(double widthConstraint, double heightConstraint)
{
    var size = this.GetDesiredSizeFromHandler(widthConstraint, heightConstraint);

    // Clamp size to constraints to prevent exceeding them on Mac Catalyst
    if (!double.IsInfinity(widthConstraint) && size.Width > widthConstraint)
    {
        size.Width = widthConstraint;
    }

    if (!double.IsInfinity(heightConstraint) && size.Height > heightConstraint)
    {
        size.Height = heightConstraint;
    }

    return size;
}

Before: The method directly returned the result from GetDesiredSizeFromHandler(), which could exceed layout constraints.

After: The method now ensures that if width or height constraints are not infinite and the calculated size exceeds them, the size is clamped to the constraints.

2. Issue22417.cs - Test Update

Removed && TEST_FAILS_ON_CATALYST from the test preprocessor directive:

// Before
#if TEST_FAILS_ON_WINDOWS && TEST_FAILS_ON_CATALYST

// After  
#if TEST_FAILS_ON_WINDOWS

This allows the test to run on Mac Catalyst since the layout constraint fix should resolve the issue described in the test case.

Testing

The test case Issue22417 demonstrates the issue where adding items to a CarouselView with HeightRequest="250" and HorizontalOptions="Center" would not display properly due to layout constraint violations. With this fix, the CarouselView respects its layout constraints and displays newly added items correctly.

Impact

• ✅ Fixes layout constraint issues on Mac Catalyst
• ✅ Potentially improves layout behavior on iOS as well
• ✅ No breaking changes to public API
• ✅ Minimal, surgical changes focused on the specific issue

This pull request was created as a result of the following prompt from Copilot chat.

Full diff for PR #30622:

---

1. src/Controls/src/Core/Handlers/Items/CarouselViewHandler.iOS.cs

• Fixes how GetDesiredSize returns its value to ensure size never exceeds constraints on Mac Catalyst (and possibly iOS).
• Now, if width or height constraints are not infinite and the calculated size exceeds them, the size is clamped to the constraints. This addresses layout issues described in the related test case.

2. src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue22417.cs

• Removes && TEST_FAILS_ON_CATALYST from the test preprocessor directive, reflecting that the test should now pass on Catalyst with the fix.

3. Add Public API Unshipped files

• Adds the contents of src/Controls/src/Core/PublicAPI/net/PublicAPI.Unshipped.txt and src/Controls/src/Core/PublicAPI/netstandard/PublicAPI.Unshipped.txt as shown above. These document API surface changes for the .NET and .NET Standard targets.

No other files are changed.

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This PR addresses layout constraint issues for CarouselView on Mac Catalyst as described in Issue #22417 and updates the test definition for that issue. It also includes the required unshipped API files for .NET and .NET Standard.

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