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Fix Shell.TitleView not being centered #36458

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Merged
jfversluis merged 3 commits into from
Jul 9, 2026
Merged

Fix Shell.TitleView not being centered #36458

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972f637
Update ShellHandler.cs
SuthiYuvaraj Jul 8, 2026
6eb2db0
Update ShellTests.Windows.cs
SuthiYuvaraj Jul 9, 2026
5521552
Updated changes
SuthiYuvaraj Jul 9, 2026
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16 changes: 8 additions & 8 deletions src/Controls/src/Core/Handlers/Shell/ShellHandler.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,14 @@ public partial class ShellHandler
public static PropertyMapper<Shell, ShellHandler> Mapper =
new PropertyMapper<Shell, ShellHandler>(ElementMapper)
{
#if WINDOWS || TIZEN

@PureWeen PureWeen Jul 8, 2026

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⚠️ Cross-Platform Behavioral Consistency — this reorder also changes Tizen's initial mapper order, and Tizen was not tested.
Flagged by: 2/3 reviewers (low risk)

On Windows the move is safe because MapItems/MapFlyoutItems both end with handler.UpdateValue(nameof(Shell.CurrentItem)), so MapCurrentItem re-runs after them and SwitchShellItem is idempotent. On Tizen, however, MapItems/MapFlyoutItems call only UpdateItems() with no CurrentItem re-trigger — so this genuinely flips execution from UpdateCurrentItem()-before-UpdateItems() (current base) to UpdateItems()-first (this PR). That order existed in neither the original nor the current base. The two paths touch independent views so the risk is low, but please either smoke-test Shell startup on Tizen or confirm the Tizen ordering change is intentional (alternatively, scope the reorder to #if WINDOWS since the bug and verification are Windows-only).

💡 Because this ordering is load-bearing (it's now the second TitleView-centering regression caused by mapper order — #34758), consider a short comment right here explaining why the Toolbar/Items block must precede CurrentItem, so the next refactor doesn't silently undo it. (1/3 reviewers — optional.)

[nameof(IToolbarElement.Toolbar)] = (handler, view) => ViewHandler.MapToolbar(handler, view),
[nameof(IFlyoutView.Flyout)] = MapFlyout,
[nameof(Shell.Items)] = MapItems,
[nameof(Shell.FlyoutItems)] = MapFlyoutItems,
[nameof(Shell.FlyoutIcon)] = MapFlyoutIcon,
#endif
Comment on lines 17 to 20

[nameof(Shell.CurrentItem)] = MapCurrentItem,
[nameof(Shell.FlyoutBackground)] = MapFlyoutBackground,
[nameof(Shell.FlyoutBackgroundColor)] = MapFlyoutBackground,
Expand All @@ -33,14 +41,6 @@ public partial class ShellHandler
[nameof(Shell.FlyoutBackgroundImageAspect)] = MapFlyoutBackgroundImage,
[nameof(Shell.FlyoutVerticalScrollMode)] = MapFlyoutVerticalScrollMode,

#if WINDOWS || TIZEN
[nameof(IToolbarElement.Toolbar)] = (handler, view) => ViewHandler.MapToolbar(handler, view),
[nameof(IFlyoutView.Flyout)] = MapFlyout,
[nameof(Shell.Items)] = MapItems,
[nameof(Shell.FlyoutItems)] = MapFlyoutItems,
[nameof(Shell.FlyoutIcon)] = MapFlyoutIcon,
#endif

#if ANDROID
[nameof(Shell.FlyoutHeight)] = MapFlyoutHeight,
#endif
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43 changes: 43 additions & 0 deletions src/Controls/tests/DeviceTests/Elements/Shell/ShellTests.Windows.cs
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Expand Up @@ -64,6 +64,49 @@ await CreateHandlerAndAddToWindow<WindowHandlerStub>(new Controls.Window(shell),
});
}

[Fact(DisplayName = "Shell TitleView Is Centered On Initial Load")]
public async Task ShellTitleViewIsCenteredOnInitialLoad()
{
SetupBuilder();

var page = new ContentPage
{
Title = "Page 1",
Content = new Label { Text = "Body" }
};

var titleView = new Label
{
Text = "TitleView",
HorizontalOptions = LayoutOptions.Center
};

var shell = await CreateShellAsync(s =>
{
s.CurrentItem = page;
Shell.SetTitleView(s, titleView);
});

await CreateHandlerAndAddToWindow<ShellHandler>(shell, async (handler) =>
{
await OnFrameSetToNotEmpty(titleView);
await AssertEventually(() =>
{
var toolbar = GetPlatformToolbar(handler);
var platformTitleView = GetTitleView(handler);

return toolbar?.ActualWidth > 0 && platformTitleView?.ActualWidth > 0;
});

var toolbar = GetPlatformToolbar(handler);
var platformTitleView = GetTitleView(handler);
var titleViewCenterX = platformTitleView.GetLocationRelativeTo(toolbar).Value.X + (platformTitleView.ActualWidth / 2);
var toolbarCenterX = toolbar.ActualWidth / 2;

Assert.InRange(Math.Abs(titleViewCenterX - toolbarCenterX), 0, 2);
});
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}

static bool IsViewLaidOut(object platformView)
{
var frameworkElement = platformView as WFrameworkElement;
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