Revert "Improve CupertinoPopupSurface appearance" (flutter#154893)

Reverts flutter#151430 to fix
flutter#154887 until I can investigate
further.

Co-authored-by: Tong Mu <dkwingsmt@users.noreply.github.com>

Author: davidhicks980

packages/flutter/lib/src/cupertino/dialog.dart

@@ -79,6 +79,7 @@ const TextStyle _kActionSheetContentStyle = TextStyle(
 );
 
 // Generic constants shared between Dialog and ActionSheet.
+const double _kBlurAmount = 20.0;
 const double _kCornerRadius = 14.0;
 const double _kDividerThickness = 0.3;
 
@@ -491,34 +492,20 @@ class _CupertinoAlertDialogState extends State<CupertinoAlertDialog> {
   }
 }
 
-/// An iOS-style component for creating modal overlays like dialogs and action
-/// sheets.
+/// Rounded rectangle surface that looks like an iOS popup surface, e.g., alert dialog
+/// and action sheet.
 ///
-/// By default, [CupertinoPopupSurface] generates a rounded rectangle surface
-/// that applies two effects to the background content:
-///
-///   1. Background filter: Saturates and then blurs content behind the surface.
-///   2. Overlay color: Covers the filtered background with a transparent
-///      surface color. The color adapts to the CupertinoTheme's brightness:
-///      light gray when the ambient [CupertinoTheme] brightness is
-///      [Brightness.light], and dark gray when [Brightness.dark].
-///
-/// The blur strength can be changed by setting [blurSigma] to a positive value,
-/// or removed by setting the [blurSigma] to 0.
-///
-/// The saturation effect can be removed for debugging by setting
-/// [debugIsVibrancePainted] to false. The saturation effect is not supported on
-/// web with the skwasm renderer and will not be applied regardless of the value
-/// of [debugIsVibrancePainted].
-///
-/// The surface color can be disabled by setting [isSurfacePainted] to false,
-/// which is useful for more complicated layouts, such as rendering divider gaps
-/// in [CupertinoAlertDialog] or rendering custom surface colors.
+/// A [CupertinoPopupSurface] can be configured to paint or not paint a white
+/// color on top of its blurred area. Typical usage should paint white on top
+/// of the blur. However, the white paint can be disabled for the purpose of
+/// rendering divider gaps for a more complicated layout, e.g., [CupertinoAlertDialog].
+/// Additionally, the white paint can be disabled to render a blurred rounded
+/// rectangle without any color (similar to iOS's volume control popup).
 ///
 /// {@tool dartpad}
 /// This sample shows how to use a [CupertinoPopupSurface]. The [CupertinoPopupSurface]
-/// shows a modal popup from the bottom of the screen.
-/// Toggle the switch to configure its surface color.
+/// shows a model popup from the bottom of the screen.
+/// Toggling the switch to configure its surface color.
 ///
 /// ** See code in examples/api/lib/cupertino/dialog/cupertino_popup_surface.0.dart **
 /// {@end-tool}
@@ -532,29 +519,9 @@ class CupertinoPopupSurface extends StatelessWidget {
   /// Creates an iOS-style rounded rectangle popup surface.
   const CupertinoPopupSurface({
     super.key,
-    this.blurSigma = defaultBlurSigma,
     this.isSurfacePainted = true,
-    this.debugIsVibrancePainted = true,
-    required this.child,
-  }) : assert(blurSigma >= 0, 'CupertinoPopupSurface requires a non-negative blur sigma.');
-
-  /// The strength of the gaussian blur applied to the area beneath this
-  /// surface.
-  ///
-  /// Defaults to [defaultBlurSigma]. Setting [blurSigma] to 0 will remove the
-  /// blur filter.
-  final double blurSigma;
-
-  /// Whether or not the area beneath this surface should be saturated with a
-  /// [ColorFilter].
-  ///
-  /// The appearance of the [ColorFilter] is determined by the [Brightness]
-  /// value obtained from the ambient [CupertinoTheme].
-  ///
-  /// The vibrance is always painted if asserts are disabled.
-  ///
-  /// Defaults to true.
-  final bool debugIsVibrancePainted;
+    this.child,
+  });
 
   /// Whether or not to paint a translucent white on top of this surface's
   /// blurred background. [isSurfacePainted] should be true for a typical popup
@@ -564,148 +531,26 @@ class CupertinoPopupSurface extends StatelessWidget {
   /// Some popups, like iOS's volume control popup, choose to render a blurred
   /// area without any white paint covering it. To achieve this effect,
   /// [isSurfacePainted] should be set to false.
-  ///
-  /// Defaults to true.
   final bool isSurfacePainted;
 
   /// The widget below this widget in the tree.
-  // Because [CupertinoPopupSurface] is composed of proxy boxes, which mimic
-  // the size of their child, a [child] is required to ensure that this surface
-  // has a size.
-  final Widget child;
-
-  /// The default strength of the blur applied to widgets underlying a
-  /// [CupertinoPopupSurface].
-  ///
-  /// Eyeballed from the iOS 17 simulator.
-  static const double defaultBlurSigma = 30.0;
-
-  /// The default corner radius of a [CupertinoPopupSurface].
-  static const BorderRadius _clipper = BorderRadius.all(Radius.circular(14));
-
-  // The [ColorFilter] matrix used to saturate widgets underlying a
-  // [CupertinoPopupSurface] when the ambient [CupertinoThemeData.brightness] is
-  // [Brightness.light].
-  //
-  // To derive this matrix, the saturation matrix was taken from
-  // https://docs.rainmeter.net/tips/colormatrix-guide/ and was tweaked to
-  // resemble the iOS 17 simulator.
-  //
-  // The matrix can be derived from the following function:
-  // static List<double> get _lightSaturationMatrix {
-  //    const double lightLumR = 0.26;
-  //    const double lightLumG = 0.4;
-  //    const double lightLumB = 0.17;
-  //    const double saturation = 2.0;
-  //    const double sr = (1 - saturation) * lightLumR;
-  //    const double sg = (1 - saturation) * lightLumG;
-  //    const double sb = (1 - saturation) * lightLumB;
-  //    return <double>[
-  //      sr + saturation, sg, sb, 0.0, 0.0,
-  //      sr, sg + saturation, sb, 0.0, 0.0,
-  //      sr, sg, sb + saturation, 0.0, 0.0,
-  //      0.0, 0.0, 0.0, 1.0, 0.0,
-  //    ];
-  //  }
-  static const List<double> _lightSaturationMatrix = <double>[
-     1.74, -0.40, -0.17, 0.00, 0.00,
-    -0.26,  1.60, -0.17, 0.00, 0.00,
-    -0.26, -0.40,  1.83, 0.00, 0.00,
-     0.00,  0.00,  0.00, 1.00, 0.00
-  ];
-
-  // The [ColorFilter] matrix used to saturate widgets underlying a
-  // [CupertinoPopupSurface] when the ambient [CupertinoThemeData.brightness] is
-  // [Brightness.dark].
-  //
-  // To derive this matrix, the saturation matrix was taken from
-  // https://docs.rainmeter.net/tips/colormatrix-guide/ and was tweaked to
-  // resemble the iOS 17 simulator.
-  //
-  // The matrix can be derived from the following function:
-  // static List<double> get _darkSaturationMatrix {
-  //    const double additive = 0.3;
-  //    const double darkLumR = 0.45;
-  //    const double darkLumG = 0.8;
-  //    const double darkLumB = 0.16;
-  //    const double saturation = 1.7;
-  //    const double sr = (1 - saturation) * darkLumR;
-  //    const double sg = (1 - saturation) * darkLumG;
-  //    const double sb = (1 - saturation) * darkLumB;
-  //    return <double>[
-  //      sr + saturation, sg, sb, 0.0, additive,
-  //      sr, sg + saturation, sb, 0.0, additive,
-  //      sr, sg, sb + saturation, 0.0, additive,
-  //      0.0, 0.0, 0.0, 1.0, 0.0,
-  //    ];
-  //  }
-  static const List<double> _darkSaturationMatrix = <double>[
-     1.39, -0.56, -0.11, 0.00, 0.30,
-    -0.32,  1.14, -0.11, 0.00, 0.30,
-    -0.32, -0.56,  1.59, 0.00, 0.30,
-     0.00,  0.00,  0.00, 1.00, 0.00
-  ];
-
-  ImageFilter? _buildFilter(Brightness? brightness) {
-    bool isVibrancePainted = true;
-    assert(() {
-      isVibrancePainted = debugIsVibrancePainted;
-      return true;
-    }());
-    if ((kIsWeb && !isSkiaWeb) || !isVibrancePainted) {
-      if (blurSigma == 0) {
-        return null;
-      }
-      return ImageFilter.blur(
-        sigmaX: blurSigma,
-        sigmaY: blurSigma,
-      );
-    }
-
-    final ColorFilter colorFilter = switch (brightness) {
-      Brightness.dark          => const ColorFilter.matrix(_darkSaturationMatrix),
-      Brightness.light || null => const ColorFilter.matrix(_lightSaturationMatrix)
-    };
-
-    if (blurSigma == 0) {
-      return colorFilter;
-    }
-
-    return ImageFilter.compose(
-      inner: colorFilter,
-      outer: ImageFilter.blur(
-        sigmaX: blurSigma,
-        sigmaY: blurSigma,
-      ),
-    );
-  }
+  final Widget? child;
 
   @override
   Widget build(BuildContext context) {
-    final ImageFilter? filter = _buildFilter(CupertinoTheme.maybeBrightnessOf(context));
-    Widget contents = child;
-
+    Widget? contents = child;
     if (isSurfacePainted) {
       contents = ColoredBox(
         color: CupertinoDynamicColor.resolve(_kDialogColor, context),
         child: contents,
       );
     }
-
-    if (filter != null) {
-      return ClipRRect(
-        borderRadius: _clipper,
-        child: BackdropFilter(
-          blendMode: BlendMode.src,
-          filter: filter,
-          child: contents,
-        ),
-      );
-    }
-
     return ClipRRect(
-      borderRadius: _clipper,
-      child: contents,
+      borderRadius: const BorderRadius.all(Radius.circular(_kCornerRadius)),
+      child: BackdropFilter(
+        filter: ImageFilter.blur(sigmaX: _kBlurAmount, sigmaY: _kBlurAmount),
+        child: contents,
+      ),
     );
   }
 }
@@ -1280,10 +1125,7 @@ class _CupertinoActionSheetState extends State<CupertinoActionSheet> {
         child: ClipRRect(
           borderRadius: const BorderRadius.all(Radius.circular(12.0)),
           child: BackdropFilter(
-            filter: ImageFilter.blur(
-              sigmaX: CupertinoPopupSurface.defaultBlurSigma,
-              sigmaY: CupertinoPopupSurface.defaultBlurSigma,
-            ),
+            filter: ImageFilter.blur(sigmaX: _kBlurAmount, sigmaY: _kBlurAmount),
             child: _ActionSheetMainSheet(
               pressedIndex: _pressedIndex,
               onPressedUpdate: _onPressedUpdate,