fix RangeSlider, with no overlayShape shifts to the left (#125483)

packages/flutter/lib/src/material/slider_theme.dart

@@ -1771,6 +1771,52 @@ class RoundedRectSliderTrackShape extends SliderTrackShape with BaseSliderTrackS
   }
 }
 
+
+/// Base range slider track shape that provides an implementation of [getPreferredRect] for
+/// default sizing.
+///
+/// The height is set from [SliderThemeData.trackHeight] and the width of the
+/// parent box less the larger of the widths of [SliderThemeData.rangeThumbShape] and
+/// [SliderThemeData.overlayShape].
+///
+/// See also:
+///
+///  * [RectangularRangeSliderTrackShape], which is a track shape with sharp
+///    rectangular edges
+mixin BaseRangeSliderTrackShape {
+  /// Returns a rect that represents the track bounds that fits within the
+  /// [Slider].
+  ///
+  /// The width is the width of the [RangeSlider], but padded by the max
+  /// of the overlay and thumb radius. The height is defined by the  [SliderThemeData.trackHeight].
+  ///
+  /// The [Rect] is centered both horizontally and vertically within the slider
+  /// bounds.
+  Rect getPreferredRect({
+    required RenderBox parentBox,
+    Offset offset = Offset.zero,
+    required SliderThemeData sliderTheme,
+    bool isEnabled = false,
+    bool isDiscrete = false,
+  }) {
+    assert(sliderTheme.rangeThumbShape != null);
+    assert(sliderTheme.overlayShape != null);
+    assert(sliderTheme.trackHeight != null);
+    final double thumbWidth = sliderTheme.rangeThumbShape!.getPreferredSize(isEnabled, isDiscrete).width;
+    final double overlayWidth = sliderTheme.overlayShape!.getPreferredSize(isEnabled, isDiscrete).width;
+    final double trackHeight = sliderTheme.trackHeight!;
+    assert(overlayWidth >= 0);
+    assert(trackHeight >= 0);
+
+    final double trackLeft = offset.dx + math.max(overlayWidth / 2, thumbWidth / 2);
+    final double trackTop = offset.dy + (parentBox.size.height - trackHeight) / 2;
+    final double trackRight = trackLeft + parentBox.size.width - math.max(thumbWidth, overlayWidth);
+    final double trackBottom = trackTop + trackHeight;
+    // If the parentBox'size less than slider's size the trackRight will be less than trackLeft, so switch them.
+    return Rect.fromLTRB(math.min(trackLeft, trackRight), trackTop, math.max(trackLeft, trackRight), trackBottom);
+  }
+}
+
 /// A [RangeSlider] track that's a simple rectangle.
 ///
 /// It paints a solid colored rectangle, vertically centered in the
@@ -1798,35 +1844,13 @@ class RoundedRectSliderTrackShape extends SliderTrackShape with BaseSliderTrackS
 ///    the [RangeSlider]'s track.
 ///  * [RoundedRectRangeSliderTrackShape], for a similar track with rounded
 ///    edges.
-class RectangularRangeSliderTrackShape extends RangeSliderTrackShape {
+class RectangularRangeSliderTrackShape extends RangeSliderTrackShape with BaseRangeSliderTrackShape {
   /// Create a slider track with rectangular outer edges.
   ///
   /// The middle track segment is the selected range and is active, and the two
   /// outer track segments are inactive.
   const RectangularRangeSliderTrackShape();
 
-  @override
-  Rect getPreferredRect({
-    required RenderBox parentBox,
-    Offset offset = Offset.zero,
-    required SliderThemeData sliderTheme,
-    bool isEnabled = false,
-    bool isDiscrete = false,
-  }) {
-    assert(sliderTheme.overlayShape != null);
-    final double overlayWidth = sliderTheme.overlayShape!.getPreferredSize(isEnabled, isDiscrete).width;
-    final double trackHeight = sliderTheme.trackHeight!;
-    assert(overlayWidth >= 0);
-    assert(trackHeight >= 0);
-
-    final double trackLeft = offset.dx + overlayWidth / 2;
-    final double trackTop = offset.dy + (parentBox.size.height - trackHeight) / 2;
-    final double trackRight = trackLeft + parentBox.size.width - overlayWidth;
-    final double trackBottom = trackTop + trackHeight;
-    // If the parentBox'size less than slider's size the trackRight will be less than trackLeft, so switch them.
-    return Rect.fromLTRB(math.min(trackLeft, trackRight), trackTop, math.max(trackLeft, trackRight), trackBottom);
-  }
-
   @override
   void paint(
     PaintingContext context,
@@ -1913,36 +1937,13 @@ class RectangularRangeSliderTrackShape extends RangeSliderTrackShape {
 ///  * [RangeSliderTrackShape], which can be used to create custom shapes for
 ///    the [RangeSlider]'s track.
 ///  * [RectangularRangeSliderTrackShape], for a similar track with sharp edges.
-class RoundedRectRangeSliderTrackShape extends RangeSliderTrackShape {
+class RoundedRectRangeSliderTrackShape extends RangeSliderTrackShape with BaseRangeSliderTrackShape {
   /// Create a slider track with rounded outer edges.
   ///
   /// The middle track segment is the selected range and is active, and the two
   /// outer track segments are inactive.
   const RoundedRectRangeSliderTrackShape();
 
-  @override
-  Rect getPreferredRect({
-    required RenderBox parentBox,
-    Offset offset = Offset.zero,
-    required SliderThemeData sliderTheme,
-    bool isEnabled = false,
-    bool isDiscrete = false,
-  }) {
-    assert(sliderTheme.overlayShape != null);
-    assert(sliderTheme.trackHeight != null);
-    final double overlayWidth = sliderTheme.overlayShape!.getPreferredSize(isEnabled, isDiscrete).width;
-    final double trackHeight = sliderTheme.trackHeight!;
-    assert(overlayWidth >= 0);
-    assert(trackHeight >= 0);
-
-    final double trackLeft = offset.dx + overlayWidth / 2;
-    final double trackTop = offset.dy + (parentBox.size.height - trackHeight) / 2;
-    final double trackRight = trackLeft + parentBox.size.width - overlayWidth;
-    final double trackBottom = trackTop + trackHeight;
-    // If the parentBox'size less than slider's size the trackRight will be less than trackLeft, so switch them.
-    return Rect.fromLTRB(math.min(trackLeft, trackRight), trackTop, math.max(trackLeft, trackRight), trackBottom);
-  }
-
   @override
   void paint(
     PaintingContext context,

packages/flutter/test/material/slider_theme_test.dart

@@ -1430,6 +1430,51 @@ void main() {
     );
   });
 
+  // Regression test for https://github.com/flutter/flutter/issues/125467
+  testWidgets('The RangeSlider track layout correctly when the overlay size is smaller than the thumb size', (WidgetTester tester) async {
+    final SliderThemeData sliderTheme = ThemeData().sliderTheme.copyWith(
+      overlayShape: SliderComponentShape.noOverlay,
+    );
+
+    await tester.pumpWidget(_buildRangeApp(sliderTheme, values: const RangeValues(0.0, 1.0)));
+
+    final MaterialInkController material = Material.of(
+      tester.element(find.byType(RangeSlider)),
+    );
+
+    // The track rectangle begins at 10 pixels from the left of the screen and ends 10 pixels from the right
+    // (790 pixels from the left). The main check here it that the track itself should be centered on
+    // the 800 pixel-wide screen.
+    expect(
+      material,
+      paints
+        // active track RRect. Starts 10 pixels from left of screen.
+        ..rrect(rrect: RRect.fromLTRBAndCorners(
+          10.0,
+          298.0,
+          10.0,
+          302.0,
+          topLeft: const Radius.circular(2.0),
+          bottomLeft: const Radius.circular(2.0),
+        ))
+      // active track RRect Start 10 pixels from left screen.
+        ..rect(rect:const Rect.fromLTRB(10.0, 297.0, 790.0, 303.0),)
+        // inactive track RRect. Ends 10 pixels from right of screen.
+        ..rrect(rrect: RRect.fromLTRBAndCorners(
+          790.0,
+          298.0,
+          790.0,
+          302.0,
+          topRight: const Radius.circular(2.0),
+          bottomRight: const Radius.circular(2.0),
+        ))
+        // The thumb Left.
+        ..circle(x: 10.0, y: 300.0, radius: 10.0)
+        // The thumb Right.
+        ..circle(x: 790.0, y: 300.0, radius: 10.0),
+    );
+  });
+
   // Only the thumb, overlay, and tick mark have special shortcuts to provide
   // no-op or empty shapes.
   //