Wire RadioButton stroke color (and document corner-radius/thickness limits)

docs/maui-coverage.md

@@ -1,6 +1,6 @@
 # .NET MAUI ⇄ Microsoft.AndroidX.Compose.Maui backend coverage
 
-Generated by `scripts/maui-coverage.cs` on 2026-06-12 22:58 UTC.
+Generated by `scripts/maui-coverage.cs` on 2026-06-15 22:59 UTC.
 
 Pinned MAUI version: **10.0.20** (from `Directory.Build.targets`).
 
@@ -15,15 +15,15 @@ collected transitively across base mappers (`ViewHandler.ViewMapper`,
 
 - **Stock MAUI handlers in scope**: 43
 - **Handlers we override**: 24 (**55.8%**)
-- **Property-mapper keys covered**: 883 / 1224 (**72.1%**)
+- **Property-mapper keys covered**: 884 / 1224 (**72.2%**)
 
 ### Per-category coverage
 
 | Category | Handlers | Keys |
 | --- | --- | --- |
 | **Pages / Navigation** | 1/4 (25%) | 33/130 (25%) |
 | **Containers** | 5/5 (100%) | 166/174 (95%) |
-| **Leaves** | 18/18 (100%) | 684/695 (98%) |
+| **Leaves** | 18/18 (100%) | 685/695 (99%) |
 | **Menus / Toolbar** | 0/7 (0%) | 0/1 (0%) |
 | **Shapes** | 0/1 (0%) | 0/41 (0%) |
 | **App / Window** | 0/2 (0%) | 0/8 (0%) |
@@ -56,7 +56,7 @@ Sorted by category. ✅ = fully covered (100%), 🟡 = partial, ❌ = not implem
 | 🟡 | `LabelHandler` | Leaves | `Label` | `LabelHandler` | 39 / 40 (98%) |
 | 🟡 | `PickerHandler` | Leaves | `Picker` | `PickerHandler` | 40 / 41 (98%) |
 | ✅ | `ProgressBarHandler` | Leaves | `ProgressBar` | `ProgressBarHandler` | 33 / 33 (100%) |
-| 🟡 | `RadioButtonHandler` | Leaves | `RadioButton` | `RadioButtonHandler` | 36 / 39 (92%) |
+| 🟡 | `RadioButtonHandler` | Leaves | `RadioButton` | `RadioButtonHandler` | 37 / 39 (95%) |
 | 🟡 | `SearchBarHandler` | Leaves | `SearchBar` | `SearchBarHandler` | 46 / 47 (98%) |
 | 🟡 | `SliderHandler` | Leaves | `Slider` | `SliderHandler` | 37 / 38 (97%) |
 | ✅ | `StepperHandler` | Leaves | `Stepper` | `StepperHandler` | 35 / 35 (100%) |
@@ -113,8 +113,8 @@ Most often this is a non-trivial property we haven't wired up yet
 dashed stroke patterns on `Border`).
 
 - **`BorderHandler`** (88%) — missing: `StrokeDashOffset`, `StrokeDashPattern`, `StrokeLineCap`, `StrokeLineJoin`, `StrokeMiterLimit`
-- **`RadioButtonHandler`** (92%) — missing: `CornerRadius`, `StrokeColor`, `StrokeThickness`
 - **`ScrollViewHandler`** (94%) — missing: `HorizontalScrollBarVisibility`, `VerticalScrollBarVisibility`
+- **`RadioButtonHandler`** (95%) — missing: `CornerRadius`, `StrokeThickness`
 - **`ImageHandler`** (97%) — missing: `IsAnimationPlaying`
 - **`RefreshViewHandler`** (97%) — missing: `RefreshColor`
 - **`ImageButtonHandler`** (97%) — missing: `IsAnimationPlaying`
@@ -1175,12 +1175,11 @@ Backed by `ProgressBarHandler`. **33 / 33 keys (100%)**.
 
 ### 🟡 `RadioButtonHandler` — `RadioButton`
 
-Backed by `RadioButtonHandler`. **36 / 39 keys (92%)**.
+Backed by `RadioButtonHandler`. **37 / 39 keys (95%)**.
 
 Missing keys:
 
 - [ ] `CornerRadius`
-- [ ] `StrokeColor`
 - [ ] `StrokeThickness`
 
 <details><summary>All stock keys</summary>
@@ -1215,7 +1214,7 @@ Missing keys:
 - [x] `ScaleY`
 - [x] `Semantics`
 - [x] `Shadow`
-- [ ] `StrokeColor`
+- [x] `StrokeColor`
 - [ ] `StrokeThickness`
 - [x] `TextColor`
 - [x] `ToolTip`

src/Microsoft.AndroidX.Compose.Maui.Sample/Pages/TogglesPage.xaml

@@ -10,7 +10,7 @@
             * SwitchHandler      -> IsOn, OnColor (-> SwitchColors checkedTrack),
                                     ThumbColor (-> SwitchColors checkedThumb)
             * RadioButtonHandler -> IsChecked, Content (-> Compose Text inside a Row),
-                                    TextColor, FontSize.
+                                    TextColor, FontSize, StrokeColor.
 
         Each section has an echo Label updated from the control's
         CheckedChanged / Toggled event so manual taps verify the
@@ -72,7 +72,7 @@
                 x:Name="SwitchEcho"
                 Text="Default: True · Tinted: False" />
 
-            <Label Text="RadioButton — three options in a group."
+            <Label Text="RadioButton — three options in a group, plus stroke color."
                    FontAttributes="Bold" />
 
             <RadioButton
@@ -94,6 +94,12 @@
                 FontSize="18"
                 FontAttributes="Bold"
                 CheckedChanged="OnFruitChanged" />
+            <RadioButton
+                Content="Dragonfruit (red ring)"
+                Value="dragonfruit"
+                GroupName="fruit"
+                BorderColor="#D32F2F"
+                CheckedChanged="OnFruitChanged" />
 
             <Label
                 x:Name="FruitEcho"

src/Microsoft.AndroidX.Compose.Maui/Handlers/RadioButtonHandler.cs

@@ -1,4 +1,5 @@
 using AndroidX.Compose;
+using AndroidX.Compose.Material3;
 using AndroidX.Compose.Runtime;
 using Microsoft.AndroidX.Compose.Maui.Platform;
 using Microsoft.Maui.Handlers;
@@ -56,18 +57,28 @@ public partial class RadioButtonHandler : ComposeElementHandler<IRadioButton>
     public static IPropertyMapper<IRadioButton, RadioButtonHandler> Mapper =
         new PropertyMapper<IRadioButton, RadioButtonHandler>(ViewHandler.ViewMapper)
         {
-            [nameof(IRadioButton.IsChecked)]      = MapIsChecked,
-            [nameof(MauiRadioButton.Content)]     = MapContent,
-            [nameof(ITextStyle.TextColor)]        = MapTextColor,
-            [nameof(ITextStyle.Font)]             = MapFont,
-            [nameof(ITextStyle.CharacterSpacing)] = MapCharacterSpacing,
-            // TODO: IButtonStroke.{StrokeColor, StrokeThickness,
-            // CornerRadius} — Material 3's RadioButton renders a fixed
-            // 20dp circle with no public hook for an outer border or
-            // corner radius (the chrome is wholly owned by the
-            // composable's internal Canvas drawing). Wiring would
-            // require a hand-rolled custom radio composable rather than
-            // a public-facade extension. Out of scope for this PR.
+            [nameof(IRadioButton.IsChecked)]       = MapIsChecked,
+            [nameof(MauiRadioButton.Content)]      = MapContent,
+            [nameof(ITextStyle.TextColor)]         = MapTextColor,
+            [nameof(ITextStyle.Font)]              = MapFont,
+            [nameof(ITextStyle.CharacterSpacing)]  = MapCharacterSpacing,
+            [nameof(IButtonStroke.StrokeColor)]    = MapStrokeColor,
+            // TODO: IButtonStroke.{StrokeThickness, CornerRadius} —
+            // Material 3's RadioButton draws a fixed 20.dp circle whose
+            // ring thickness and shape are baked into the composable's
+            // internal Canvas (`drawCircle` with a hard-coded
+            // `RadioStrokeWidth = 2.dp`); the public surface
+            // (`RadioButtonColors`) only exposes the ring colour, not
+            // its geometry. Honouring these would require replacing
+            // the call to `RadioButtonKt.RadioButton` with a hand-rolled
+            // `Canvas { drawCircle / drawArc }` composable, which loses
+            // Material 3's ripple, state-layer, focus indicator, and
+            // accessibility chrome. A `CornerRadius` override is also
+            // semantically off — XAML callers reaching for it on a
+            // `RadioButton` are typically trying to make a control that
+            // is no longer recognisable as a radio button. Held back
+            // deliberately; revisit if a public M3 API surfaces these
+            // knobs.
         };
 
     /// <summary>Command mapper (inherits view-level commands; no extras).</summary>
@@ -80,6 +91,7 @@ public partial class RadioButtonHandler : ComposeElementHandler<IRadioButton>
     readonly MutableState<int?>   _fontSize = new((int?)null);
     readonly MutableState<bool>   _bold     = new(false);
     readonly MutableState<float?> _letterSpacing = new((float?)null);
+    readonly MutableState<long?>  _strokeColor   = new((long?)null);
 
     /// <summary>Construct a handler with the default mappers.</summary>
     public RadioButtonHandler() : base(Mapper, CommandMapper) { }
@@ -99,8 +111,13 @@ public override ComposableNode BuildNode(IComposer composer)
         var bold   = _bold.Value;
         var spacing = _letterSpacing.Value;
         var label  = _label.Value;
+        var stroke = _strokeColor.Value;
 
         var radio = new ComposeRadioButton(selected: _checked.Value, onClick: OnSelected);
+        if (stroke is not null)
+            radio.Colors = composer.RadioButtonColors(
+                selectedColor:   stroke,
+                unselectedColor: stroke);
         var gestureModifier = Modifier.Companion.ApplyGestures(virtualView, MauiContext).ApplySemantics(virtualView);
         if (string.IsNullOrEmpty(label))
         {
@@ -124,7 +141,12 @@ public override ComposableNode BuildNode(IComposer composer)
             radio,
             text,
         };
-        row.Modifier = gestureModifier;
+        // Fill the available width so the radio sits at the start of its
+        // layout slot — without it the Row hugs `radio + label` and the
+        // MAUI host centers each row independently, which makes a column
+        // of radios with different label lengths visibly stagger
+        // horizontally. Matches stock MAUI's left-anchored layout.
+        row.Modifier = Modifier.Companion.FillMaxWidth().Then(gestureModifier);
         return row;
     }
 
@@ -187,4 +209,16 @@ public static void MapFont(RadioButtonHandler handler, IRadioButton rb)
     /// </summary>
     public static void MapCharacterSpacing(RadioButtonHandler handler, IRadioButton rb) =>
         handler._letterSpacing.Value = rb.CharacterSpacing != 0 ? (float)rb.CharacterSpacing : null;
+
+    /// <summary>
+    /// Map <see cref="IButtonStroke.StrokeColor"/> to the Compose
+    /// <see cref="RadioButtonColors"/> ring slots — applied to both
+    /// <c>selectedColor</c> and <c>unselectedColor</c> so the user-
+    /// supplied colour is visible whether the radio is on or off
+    /// (matches stock MAUI's <c>UpdateStrokeColor</c>, which tints
+    /// the ring drawable in every check state). The disabled-state
+    /// ring colour stays on the M3 theme default.
+    /// </summary>
+    public static void MapStrokeColor(RadioButtonHandler handler, IRadioButton rb) =>
+        handler._strokeColor.Value = ColorMapping.ToPackedLong(rb.StrokeColor);
 }

src/Microsoft.AndroidX.Compose.SourceGenerators/ComposeReferenceTypes.cs

@@ -43,6 +43,7 @@ internal static class ComposeReferenceTypes
         "AndroidX.Compose.Material3.ButtonColors",
         "AndroidX.Compose.Material3.SliderColors",
         "AndroidX.Compose.Material3.CheckboxColors",
+        "AndroidX.Compose.Material3.RadioButtonColors",
         "AndroidX.Compose.Material3.SwitchColors",
         "AndroidX.Compose.UI.Text.TextStyle",
         "AndroidX.Compose.UI.Text.Input.IVisualTransformation",

src/Microsoft.AndroidX.Compose/ComposeBridges.cs

@@ -3725,20 +3725,21 @@ public static partial void Switch(bool @checked, IFunction1 onCheckedChange, IMo
 
     [ComposeFacade(Defaults = typeof(RadioButtonDefault))]
     public static partial void RadioButton(
-        bool        selected,
-        IFunction0  onClick,
-        IModifier?  modifier,
-        bool        enabled  = true,
-        int         defaults = 0,
-        IComposer   composer = null!);
-
-    public static partial void RadioButton(bool selected, IFunction0 onClick, IModifier? modifier, bool enabled, int defaults, IComposer composer)
+        bool                                       selected,
+        IFunction0                                 onClick,
+        IModifier?                                 modifier,
+        bool                                       enabled  = true,
+        AndroidX.Compose.Material3.RadioButtonColors? colors = null,
+        int                                        defaults = 0,
+        IComposer                                  composer = null!);
+
+    public static partial void RadioButton(bool selected, IFunction0 onClick, IModifier? modifier, bool enabled, AndroidX.Compose.Material3.RadioButtonColors? colors, int defaults, IComposer composer)
         => RadioButtonKt.RadioButton(
             selected:          selected,
             onClick:           onClick,
             modifier:          modifier,
             enabled:           enabled,
-            colors:            null,
+            colors:            colors,
             interactionSource: null,
             _composer:         composer,
             p7:                0,

src/Microsoft.AndroidX.Compose/ComposeExtensions.RadioButtonDefaults.cs

@@ -0,0 +1,63 @@
+using System.Runtime.CompilerServices;
+using AndroidX.Compose.Material3;
+using AndroidX.Compose.Runtime;
+
+namespace AndroidX.Compose;
+
+/// <summary>
+/// Static factories mirroring Kotlin's
+/// <c>androidx.compose.material3.RadioButtonDefaults</c> singleton —
+/// returns a <see cref="RadioButtonColors"/> configured for a particular
+/// override pattern. Surfaced as <see cref="IComposer"/> extensions so
+/// call sites read <c>composer.RadioButtonColors(selectedColor: ...)</c>.
+/// </summary>
+public static partial class ComposeExtensions
+{
+    /// <summary>
+    /// Mirrors Kotlin's
+    /// <c>RadioButtonDefaults.colors(selectedColor = …, unselectedColor = …,
+    /// disabledSelectedColor = …, disabledUnselectedColor = …)</c>.
+    ///
+    /// <para>The Kotlin <c>colors(...)</c> factory takes a
+    /// <c>$default</c> bitmask, but the C# binder strips it because
+    /// every parameter is the <c>@JvmInline value class Color</c>. We
+    /// therefore call the parameterless <c>colors(composer, _changed)</c>
+    /// to obtain the theme defaults and build the result via the bound
+    /// <c>RadioButtonColors.copy(...)</c> overload — the only
+    /// four-<c>long</c> entry point that survives the binder strip.</para>
+    ///
+    /// <para>Each non-<c>null</c> argument substitutes for the
+    /// corresponding default; <c>null</c> falls back to the value from
+    /// the current <c>MaterialTheme</c>.</para>
+    /// </summary>
+    public static RadioButtonColors RadioButtonColors(
+        this IComposer composer,
+        long? selectedColor = null,
+        long? unselectedColor = null,
+        long? disabledSelectedColor = null,
+        long? disabledUnselectedColor = null,
+        [CallerLineNumber] int line = 0,
+        [CallerFilePath] string file = "")
+    {
+        ArgumentNullException.ThrowIfNull(composer);
+
+        composer.StartReplaceableGroup(SourceLocationKey.Compute(line, file));
+        try
+        {
+            var d = AndroidX.Compose.Material3.RadioButtonDefaults.Instance.Colors(composer, 0);
+            if (selectedColor is null && unselectedColor is null
+                && disabledSelectedColor is null && disabledUnselectedColor is null)
+                return d;
+
+            return d.Copy(
+                selectedColor:           selectedColor           ?? d.SelectedColor,
+                unselectedColor:         unselectedColor         ?? d.UnselectedColor,
+                disabledSelectedColor:   disabledSelectedColor   ?? d.DisabledSelectedColor,
+                disabledUnselectedColor: disabledUnselectedColor ?? d.DisabledUnselectedColor);
+        }
+        finally
+        {
+            composer.EndReplaceableGroup();
+        }
+    }
+}

src/Microsoft.AndroidX.Compose/PublicAPI.Unshipped.txt

@@ -977,6 +977,8 @@ AndroidX.Compose.PullToRefreshState.DistanceFraction.get -> float
 AndroidX.Compose.PullToRefreshState.IsAnimating.get -> bool
 AndroidX.Compose.PullToRefreshState.PullToRefreshState() -> void
 AndroidX.Compose.RadioButton
+AndroidX.Compose.RadioButton.Colors.get -> AndroidX.Compose.Material3.RadioButtonColors?
+AndroidX.Compose.RadioButton.Colors.set -> void
 AndroidX.Compose.RadioButton.RadioButton(bool selected, System.Action! onClick, bool enabled = true) -> void
 AndroidX.Compose.RangeSlider
 AndroidX.Compose.RangeSlider.RangeSlider((float Start, float End) value, System.Action<(float Start, float End)>! onValueChange) -> void
@@ -1629,6 +1631,7 @@ static AndroidX.Compose.ComposeExtensions.ProduceState<T>(this AndroidX.Compose.
 static AndroidX.Compose.ComposeExtensions.ProduceState<T>(this AndroidX.Compose.Runtime.IComposer! composer, T initialValue, object? key1, System.Func<AndroidX.Compose.MutableState<T>!, System.Threading.CancellationToken, System.Threading.Tasks.Task!>! producer, int line = 0, string! file = "") -> AndroidX.Compose.MutableState<T>!
 static AndroidX.Compose.ComposeExtensions.ProduceState<T>(this AndroidX.Compose.Runtime.IComposer! composer, T initialValue, System.Func<AndroidX.Compose.MutableState<T>!, System.Threading.CancellationToken, System.Threading.Tasks.Task!>! producer, int line = 0, string! file = "") -> AndroidX.Compose.MutableState<T>!
 static AndroidX.Compose.ComposeExtensions.ProduceStateKeyed<T>(this AndroidX.Compose.Runtime.IComposer! composer, T initialValue, object?[]! keys, System.Func<AndroidX.Compose.MutableState<T>!, System.Threading.CancellationToken, System.Threading.Tasks.Task!>! producer, int line = 0, string! file = "") -> AndroidX.Compose.MutableState<T>!
+static AndroidX.Compose.ComposeExtensions.RadioButtonColors(this AndroidX.Compose.Runtime.IComposer! composer, long? selectedColor = null, long? unselectedColor = null, long? disabledSelectedColor = null, long? disabledUnselectedColor = null, int line = 0, string! file = "") -> AndroidX.Compose.Material3.RadioButtonColors!
 static AndroidX.Compose.ComposeExtensions.Remember<T>(this AndroidX.Compose.Runtime.IComposer! composer, System.Func<T>! factory, int line = 0, string! file = "") -> T
 static AndroidX.Compose.ComposeExtensions.Remember<T>(this AndroidX.Compose.Runtime.IComposer! composer, System.Func<T>! factory, object? key1, int line = 0, string! file = "") -> T
 static AndroidX.Compose.ComposeExtensions.Remember<T>(this AndroidX.Compose.Runtime.IComposer! composer, System.Func<T>! factory, object? key1, object? key2, int line = 0, string! file = "") -> T