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Merged
jfversluis merged 7 commits into from
Mar 20, 2026
Merged

[net11.0] Trimmable StyleSheets #33160

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62431eb
Introduce IsCssEnabled feature switch and infer its default value bas…
simonrozsival Dec 15, 2025
fd2c514
Skip loading CSS style sheets when CSS support is trimmed
simonrozsival Dec 15, 2025
122b1b7
Throw in CSS-related APIs when CSS is disabled
simonrozsival Dec 15, 2025
1a9e611
Enable CSS in TestCases.HostApp and add unit tests
simonrozsival Jan 16, 2026
c0bb0f8
Improve CSS disabled error messages and add documentation
simonrozsival Jan 16, 2026
eb59e75
Use public ILineHeightElement instead of obsolete Internals version
simonrozsival Mar 11, 2026
fa6afda
Use nameof pattern for IsCssEnabled + clarify docs
simonrozsival Mar 11, 2026
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16 changes: 16 additions & 0 deletions docs/design/FeatureSwitches.md
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Expand Up @@ -7,6 +7,7 @@ The following switches are toggled for applications running on Mono for `TrimMod
| MSBuild Property Name | AppContext Setting | Description |
|-|-|-|
| MauiXamlInflator | N/A | Controls how XAML files are processed. See [XAML Inflator](#mauixamlinflator) section below. |
| MauiCssEnabled | Microsoft.Maui.RuntimeFeature.IsCssEnabled | When disabled, CSS stylesheets cannot be used. Defaults to `false` when no `MauiCss` items are present in the project, and `true` otherwise. |
| MauiEnableIVisualAssemblyScanning | Microsoft.Maui.RuntimeFeature.IsIVisualAssemblyScanningEnabled | When enabled, MAUI will scan assemblies for types implementing `IVisual` and for `[assembly: Visual(...)]` attributes and register these types. |
| MauiShellSearchResultsRendererDisplayMemberNameSupported | Microsoft.Maui.RuntimeFeature.IsShellSearchResultsRendererDisplayMemberNameSupported | When disabled, it is necessary to always set `ItemTemplate` of any `SearchHandler`. Displaying search results through `DisplayMemberName` will not work. |
| MauiQueryPropertyAttributeSupport | Microsoft.Maui.RuntimeFeature.IsQueryPropertyAttributeSupported | When disabled, the `[QueryProperty(...)]` attributes won't be used to set values to properties when navigating. |
Expand Down Expand Up @@ -54,6 +55,21 @@ You can override the inflator for individual XAML files using item metadata:
**Changes in .NET 12:**
- The `[XamlCompilation]` attribute will be obsolete with `error: true` and becomes a no-op. Use MSBuild properties or item metadata instead.

## MauiCssEnabled

When this feature is disabled, CSS stylesheets cannot be parsed or applied to UI elements. Any attempt to use CSS will throw a `NotSupportedException`.

**Default behavior**: In optimized builds (`PublishAot=true` or `TrimMode=full`), this feature is automatically disabled when your project has no `MauiCss` items (CSS files), and automatically enabled when CSS files are present. In development builds, CSS is always enabled regardless of whether `MauiCss` items are present.

**When to enable manually**: If your app loads CSS stylesheets dynamically at runtime (e.g., from a network source or embedded resources) rather than including them as `MauiCss` build items, you need to explicitly enable this feature in your optimized builds:

```xml
<PropertyGroup>
<MauiCssEnabled>true</MauiCssEnabled>
</PropertyGroup>
```

**Trimming benefits**: When disabled, the .NET trimmer can eliminate CSS-related code paths, reducing the final application size.
## MauiEnableIVisualAssemblyScanning

When this feature is not enabled, custom and third party `IVisual` types will not be automatically discovered and registered.
Expand Down
7 changes: 6 additions & 1 deletion ...rols/src/Build.Tasks/nuget/buildTransitive/netstandard2.0/Microsoft.Maui.Controls.targets
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Expand Up @@ -323,6 +323,7 @@
<MauiImplicitCastOperatorsUsageViaReflectionSupport Condition="'$(MauiImplicitCastOperatorsUsageViaReflectionSupport)' == ''">false</MauiImplicitCastOperatorsUsageViaReflectionSupport>
<MauiEnableXamlCBindingWithSourceCompilation Condition="'$(MauiEnableXamlCBindingWithSourceCompilation)' == ''">true</MauiEnableXamlCBindingWithSourceCompilation>
<MauiHybridWebViewSupported Condition="'$(MauiHybridWebViewSupported)' == ''">false</MauiHybridWebViewSupported>
<MauiCssEnabled Condition="'$(MauiCssEnabled)' == '' and '@(MauiCss->Count())' == '0'">false</MauiCssEnabled>
<!-- FIXME: https://github.com/xamarin/xamarin-macios/issues/22065 -->
<MobileAggressiveAttributeTrimming Condition="'$(PublishAot)' == 'true' and '$(MobileAggressiveAttributeTrimming)' == ''">false</MobileAggressiveAttributeTrimming>

Expand Down Expand Up @@ -359,10 +360,14 @@
Condition="'$(MauiHybridWebViewSupported)' != ''"
Value="$(MauiHybridWebViewSupported)"
Trim="true" />
<RuntimeHostConfigurationOption Include="Microsoft.Maui.RuntimeFeature.IsCssEnabled"
Condition="'$(MauiCssEnabled)' != ''"
Value="$(MauiCssEnabled)"
Trim="true" />
<RuntimeHostConfigurationOption Include="Microsoft.Maui.RuntimeFeature.AreNamescopesSupported"
Condition="'$(MauiNamescopesSupported)' != ''"
Value="$(MauiNamescopesSupported)"
Trim="true" />
Trim="true" />
<RuntimeHostConfigurationOption Include="Microsoft.Maui.RuntimeFeature.EnableDiagnostics"
Condition="'$(EnableDiagnostics)' != ''"
Value="$(EnableDiagnostics)"
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99 changes: 0 additions & 99 deletions src/Controls/src/Core/Properties/AssemblyInfo.cs
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@@ -1,8 +1,6 @@
using System.Runtime.CompilerServices;
using Microsoft.Maui.Controls;
using Microsoft.Maui.Controls.Internals;
using Microsoft.Maui.Controls.StyleSheets;
using Compatibility = Microsoft.Maui.Controls.Compatibility;

[assembly: InternalsVisibleTo("Core.Benchmarks")]
[assembly: InternalsVisibleTo("Microsoft.AspNetCore.Components.WebView.Maui")]
Expand Down Expand Up @@ -85,100 +83,3 @@
[assembly: XmlnsPrefix("http://schemas.microsoft.com/dotnet/2021/maui", "maui")]
[assembly: XmlnsPrefix("http://schemas.microsoft.com/dotnet/2021/maui/design", "d")]
[assembly: XmlnsPrefix("http://schemas.microsoft.com/winfx/2009/xaml", "x")]

[assembly: StyleProperty("background-color", typeof(VisualElement), nameof(VisualElement.BackgroundColorProperty))]
[assembly: StyleProperty("background", typeof(VisualElement), nameof(VisualElement.BackgroundProperty))]
[assembly: StyleProperty("background-image", typeof(Page), nameof(Page.BackgroundImageSourceProperty))]
[assembly: StyleProperty("border-color", typeof(IBorderElement), nameof(BorderElement.BorderColorProperty))]
[assembly: StyleProperty("border-color", typeof(IBorderView), nameof(Border.StrokeProperty))]
[assembly: StyleProperty("border-radius", typeof(ICornerElement), nameof(CornerElement.CornerRadiusProperty))]
[assembly: StyleProperty("border-radius", typeof(Button), nameof(Button.CornerRadiusProperty))]
#pragma warning disable CS0618 // Type or member is obsolete
[assembly: StyleProperty("border-radius", typeof(Frame), nameof(Frame.CornerRadiusProperty))]
#pragma warning restore CS0618 // Type or member is obsolete
[assembly: StyleProperty("border-radius", typeof(IBorderView), nameof(Border.StrokeShapeProperty))]
[assembly: StyleProperty("border-radius", typeof(ImageButton), nameof(BorderElement.CornerRadiusProperty))]
[assembly: StyleProperty("border-width", typeof(IBorderElement), nameof(BorderElement.BorderWidthProperty))]
[assembly: StyleProperty("border-width", typeof(IBorderView), nameof(Border.StrokeThicknessProperty))]
[assembly: StyleProperty("color", typeof(IColorElement), nameof(ColorElement.ColorProperty), Inherited = true)]
[assembly: StyleProperty("color", typeof(ITextElement), nameof(TextElement.TextColorProperty), Inherited = true)]
[assembly: StyleProperty("text-transform", typeof(ITextElement), nameof(TextElement.TextTransformProperty), Inherited = true)]
[assembly: StyleProperty("color", typeof(ProgressBar), nameof(ProgressBar.ProgressColorProperty))]
[assembly: StyleProperty("color", typeof(Switch), nameof(Switch.OnColorProperty))]
[assembly: StyleProperty("column-gap", typeof(Grid), nameof(Grid.ColumnSpacingProperty))]
[assembly: StyleProperty("direction", typeof(VisualElement), nameof(VisualElement.FlowDirectionProperty), Inherited = true)]
[assembly: StyleProperty("font-family", typeof(IFontElement), nameof(FontElement.FontFamilyProperty), Inherited = true)]
[assembly: StyleProperty("font-size", typeof(IFontElement), nameof(FontElement.FontSizeProperty), Inherited = true)]
[assembly: StyleProperty("font-style", typeof(IFontElement), nameof(FontElement.FontAttributesProperty), Inherited = true)]
[assembly: StyleProperty("height", typeof(VisualElement), nameof(VisualElement.HeightRequestProperty))]
[assembly: StyleProperty("margin", typeof(View), nameof(View.MarginProperty))]
[assembly: StyleProperty("margin-left", typeof(View), nameof(View.MarginLeftProperty))]
[assembly: StyleProperty("margin-top", typeof(View), nameof(View.MarginTopProperty))]
[assembly: StyleProperty("margin-right", typeof(View), nameof(View.MarginRightProperty))]
[assembly: StyleProperty("margin-bottom", typeof(View), nameof(View.MarginBottomProperty))]
[assembly: StyleProperty("max-lines", typeof(Label), nameof(Label.MaxLinesProperty))]
[assembly: StyleProperty("min-height", typeof(VisualElement), nameof(VisualElement.MinimumHeightRequestProperty))]
[assembly: StyleProperty("min-width", typeof(VisualElement), nameof(VisualElement.MinimumWidthRequestProperty))]
[assembly: StyleProperty("opacity", typeof(VisualElement), nameof(VisualElement.OpacityProperty))]
[assembly: StyleProperty("padding", typeof(IPaddingElement), nameof(PaddingElement.PaddingProperty))]
[assembly: StyleProperty("padding-left", typeof(IPaddingElement), nameof(PaddingElement.PaddingLeftProperty), PropertyOwnerType = typeof(PaddingElement))]
[assembly: StyleProperty("padding-top", typeof(IPaddingElement), nameof(PaddingElement.PaddingTopProperty), PropertyOwnerType = typeof(PaddingElement))]
[assembly: StyleProperty("padding-right", typeof(IPaddingElement), nameof(PaddingElement.PaddingRightProperty), PropertyOwnerType = typeof(PaddingElement))]
[assembly: StyleProperty("padding-bottom", typeof(IPaddingElement), nameof(PaddingElement.PaddingBottomProperty), PropertyOwnerType = typeof(PaddingElement))]
[assembly: StyleProperty("row-gap", typeof(Grid), nameof(Grid.RowSpacingProperty))]
[assembly: StyleProperty("text-align", typeof(ITextAlignmentElement), nameof(TextAlignmentElement.HorizontalTextAlignmentProperty), Inherited = true)]
[assembly: StyleProperty("text-decoration", typeof(IDecorableTextElement), nameof(DecorableTextElement.TextDecorationsProperty))]
[assembly: StyleProperty("transform", typeof(VisualElement), nameof(VisualElement.TransformProperty))]
[assembly: StyleProperty("transform-origin", typeof(VisualElement), nameof(VisualElement.TransformOriginProperty))]
[assembly: StyleProperty("vertical-align", typeof(ITextAlignmentElement), nameof(TextAlignmentElement.VerticalTextAlignmentProperty))]
[assembly: StyleProperty("visibility", typeof(VisualElement), nameof(VisualElement.IsVisibleProperty), Inherited = true)]
[assembly: StyleProperty("width", typeof(VisualElement), nameof(VisualElement.WidthRequestProperty))]
[assembly: StyleProperty("letter-spacing", typeof(ITextElement), nameof(TextElement.CharacterSpacingProperty), Inherited = true)]
[assembly: StyleProperty("line-height", typeof(Microsoft.Maui.Controls.ILineHeightElement), nameof(LineHeightElement.LineHeightProperty), Inherited = true)]

//flex
[assembly: StyleProperty("align-content", typeof(FlexLayout), nameof(FlexLayout.AlignContentProperty))]
[assembly: StyleProperty("align-items", typeof(FlexLayout), nameof(FlexLayout.AlignItemsProperty))]
[assembly: StyleProperty("align-self", typeof(VisualElement), nameof(FlexLayout.AlignSelfProperty), PropertyOwnerType = typeof(FlexLayout))]
[assembly: StyleProperty("flex-direction", typeof(FlexLayout), nameof(FlexLayout.DirectionProperty))]
[assembly: StyleProperty("flex-basis", typeof(VisualElement), nameof(FlexLayout.BasisProperty), PropertyOwnerType = typeof(FlexLayout))]
[assembly: StyleProperty("flex-grow", typeof(VisualElement), nameof(FlexLayout.GrowProperty), PropertyOwnerType = typeof(FlexLayout))]
[assembly: StyleProperty("flex-shrink", typeof(VisualElement), nameof(FlexLayout.ShrinkProperty), PropertyOwnerType = typeof(FlexLayout))]
[assembly: StyleProperty("flex-wrap", typeof(VisualElement), nameof(FlexLayout.WrapProperty), PropertyOwnerType = typeof(FlexLayout))]
[assembly: StyleProperty("justify-content", typeof(FlexLayout), nameof(FlexLayout.JustifyContentProperty))]
[assembly: StyleProperty("order", typeof(VisualElement), nameof(FlexLayout.OrderProperty), PropertyOwnerType = typeof(FlexLayout))]
[assembly: StyleProperty("position", typeof(FlexLayout), nameof(FlexLayout.PositionProperty))]

//xf specific
[assembly: StyleProperty("-maui-placeholder", typeof(IPlaceholderElement), nameof(PlaceholderElement.PlaceholderProperty))]
[assembly: StyleProperty("-maui-placeholder-color", typeof(IPlaceholderElement), nameof(PlaceholderElement.PlaceholderColorProperty))]
[assembly: StyleProperty("-maui-max-length", typeof(InputView), nameof(InputView.MaxLengthProperty))]
[assembly: StyleProperty("-maui-bar-background-color", typeof(IBarElement), nameof(BarElement.BarBackgroundColorProperty))]
[assembly: StyleProperty("-maui-bar-text-color", typeof(IBarElement), nameof(BarElement.BarTextColorProperty))]
[assembly: StyleProperty("-maui-orientation", typeof(ScrollView), nameof(ScrollView.OrientationProperty))]
[assembly: StyleProperty("-maui-horizontal-scroll-bar-visibility", typeof(ScrollView), nameof(ScrollView.HorizontalScrollBarVisibilityProperty))]
[assembly: StyleProperty("-maui-vertical-scroll-bar-visibility", typeof(ScrollView), nameof(ScrollView.VerticalScrollBarVisibilityProperty))]
[assembly: StyleProperty("-maui-min-track-color", typeof(Slider), nameof(Slider.MinimumTrackColorProperty))]
[assembly: StyleProperty("-maui-max-track-color", typeof(Slider), nameof(Slider.MaximumTrackColorProperty))]
[assembly: StyleProperty("-maui-thumb-color", typeof(Slider), nameof(Slider.ThumbColorProperty))]
[assembly: StyleProperty("-maui-spacing", typeof(StackBase), nameof(StackBase.SpacingProperty))]
[assembly: StyleProperty("-maui-orientation", typeof(StackLayout), nameof(StackLayout.OrientationProperty))]

[assembly: StyleProperty("-maui-visual", typeof(VisualElement), nameof(VisualElement.VisualProperty))]
[assembly: StyleProperty("-maui-vertical-text-alignment", typeof(Label), nameof(TextAlignmentElement.VerticalTextAlignmentProperty))]
[assembly: StyleProperty("-maui-thumb-color", typeof(Switch), nameof(Switch.ThumbColorProperty))]

[assembly: StyleProperty("-maui-shadow", typeof(VisualElement), nameof(VisualElement.ShadowProperty))]

//shell
[assembly: StyleProperty("-maui-flyout-background", typeof(Shell), nameof(Shell.FlyoutBackgroundColorProperty))]
[assembly: StyleProperty("-maui-shell-background", typeof(Element), nameof(Shell.BackgroundColorProperty), PropertyOwnerType = typeof(Shell))]
[assembly: StyleProperty("-maui-shell-disabled", typeof(Element), nameof(Shell.DisabledColorProperty), PropertyOwnerType = typeof(Shell))]
[assembly: StyleProperty("-maui-shell-foreground", typeof(Element), nameof(Shell.ForegroundColorProperty), PropertyOwnerType = typeof(Shell))]
[assembly: StyleProperty("-maui-shell-tabbar-background", typeof(Element), nameof(Shell.TabBarBackgroundColorProperty), PropertyOwnerType = typeof(Shell))]
[assembly: StyleProperty("-maui-shell-tabbar-disabled", typeof(Element), nameof(Shell.TabBarDisabledColorProperty), PropertyOwnerType = typeof(Shell))]
[assembly: StyleProperty("-maui-shell-tabbar-foreground", typeof(Element), nameof(Shell.TabBarForegroundColorProperty), PropertyOwnerType = typeof(Shell))]
[assembly: StyleProperty("-maui-shell-tabbar-title", typeof(Element), nameof(Shell.TabBarTitleColorProperty), PropertyOwnerType = typeof(Shell))]
[assembly: StyleProperty("-maui-shell-tabbar-unselected", typeof(Element), nameof(Shell.TabBarUnselectedColorProperty), PropertyOwnerType = typeof(Shell))]
[assembly: StyleProperty("-maui-shell-title", typeof(Element), nameof(Shell.TitleColorProperty), PropertyOwnerType = typeof(Shell))]
[assembly: StyleProperty("-maui-shell-unselected", typeof(Element), nameof(Shell.UnselectedColorProperty), PropertyOwnerType = typeof(Shell))]
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