Remove unnecessary null checks in flutter/painting (#118925)

packages/flutter/lib/src/painting/_network_image_io.dart

@@ -19,9 +19,7 @@ class NetworkImage extends image_provider.ImageProvider<image_provider.NetworkIm
   /// Creates an object that fetches the image at the given URL.
   ///
   /// The arguments [url] and [scale] must not be null.
-  const NetworkImage(this.url, { this.scale = 1.0, this.headers })
-    : assert(url != null),
-      assert(scale != null);
+  const NetworkImage(this.url, { this.scale = 1.0, this.headers });
 
   @override
   final String url;

packages/flutter/lib/src/painting/_network_image_web.dart

@@ -39,9 +39,7 @@ class NetworkImage
   /// Creates an object that fetches the image at the given URL.
   ///
   /// The arguments [url] and [scale] must not be null.
-  const NetworkImage(this.url, {this.scale = 1.0, this.headers})
-      : assert(url != null),
-        assert(scale != null);
+  const NetworkImage(this.url, {this.scale = 1.0, this.headers});
 
   @override
   final String url;

packages/flutter/lib/src/painting/alignment.dart

@@ -87,7 +87,6 @@ abstract class AlignmentGeometry {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static AlignmentGeometry? lerp(AlignmentGeometry? a, AlignmentGeometry? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }
@@ -188,9 +187,7 @@ class Alignment extends AlignmentGeometry {
   /// Creates an alignment.
   ///
   /// The [x] and [y] arguments must not be null.
-  const Alignment(this.x, this.y)
-    : assert(x != null),
-      assert(y != null);
+  const Alignment(this.x, this.y);
 
   /// The distance fraction in the horizontal direction.
   ///
@@ -340,7 +337,6 @@ class Alignment extends AlignmentGeometry {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static Alignment? lerp(Alignment? a, Alignment? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }
@@ -407,9 +403,7 @@ class AlignmentDirectional extends AlignmentGeometry {
   /// Creates a directional alignment.
   ///
   /// The [start] and [y] arguments must not be null.
-  const AlignmentDirectional(this.start, this.y)
-    : assert(start != null),
-      assert(y != null);
+  const AlignmentDirectional(this.start, this.y);
 
   /// The distance fraction in the horizontal direction.
   ///
@@ -534,7 +528,6 @@ class AlignmentDirectional extends AlignmentGeometry {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static AlignmentDirectional? lerp(AlignmentDirectional? a, AlignmentDirectional? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }
@@ -682,8 +675,7 @@ class TextAlignVertical {
   /// Creates a TextAlignVertical from any y value between -1.0 and 1.0.
   const TextAlignVertical({
     required this.y,
-  }) : assert(y != null),
-       assert(y >= -1.0 && y <= 1.0);
+  }) : assert(y >= -1.0 && y <= 1.0);
 
   /// A value ranging from -1.0 to 1.0 that defines the topmost and bottommost
   /// locations of the top and bottom of the input box.

packages/flutter/lib/src/painting/basic_types.dart

@@ -136,7 +136,6 @@ enum Axis {
 ///
 ///  * [flipAxisDirection], which does the same thing for [AxisDirection] values.
 Axis flipAxis(Axis direction) {
-  assert(direction != null);
   switch (direction) {
     case Axis.horizontal:
       return Axis.vertical;
@@ -204,7 +203,6 @@ enum AxisDirection {
 /// [AxisDirection.down] and returns [Axis.horizontal] for [AxisDirection.left]
 /// and [AxisDirection.right].
 Axis axisDirectionToAxis(AxisDirection axisDirection) {
-  assert(axisDirection != null);
   switch (axisDirection) {
     case AxisDirection.up:
     case AxisDirection.down:
@@ -220,7 +218,6 @@ Axis axisDirectionToAxis(AxisDirection axisDirection) {
 /// Specifically, returns [AxisDirection.left] for [TextDirection.rtl] and
 /// [AxisDirection.right] for [TextDirection.ltr].
 AxisDirection textDirectionToAxisDirection(TextDirection textDirection) {
-  assert(textDirection != null);
   switch (textDirection) {
     case TextDirection.rtl:
       return AxisDirection.left;
@@ -239,7 +236,6 @@ AxisDirection textDirectionToAxisDirection(TextDirection textDirection) {
 ///
 ///  * [flipAxis], which does the same thing for [Axis] values.
 AxisDirection flipAxisDirection(AxisDirection axisDirection) {
-  assert(axisDirection != null);
   switch (axisDirection) {
     case AxisDirection.up:
       return AxisDirection.down;
@@ -258,7 +254,6 @@ AxisDirection flipAxisDirection(AxisDirection axisDirection) {
 /// Specifically, returns true for [AxisDirection.up] and [AxisDirection.left]
 /// and false for [AxisDirection.down] and [AxisDirection.right].
 bool axisDirectionIsReversed(AxisDirection axisDirection) {
-  assert(axisDirection != null);
   switch (axisDirection) {
     case AxisDirection.up:
     case AxisDirection.left:

packages/flutter/lib/src/painting/beveled_rectangle_border.dart

@@ -25,8 +25,7 @@ class BeveledRectangleBorder extends OutlinedBorder {
   const BeveledRectangleBorder({
     super.side,
     this.borderRadius = BorderRadius.zero,
-  }) : assert(side != null),
-       assert(borderRadius != null);
+  });
 
   /// The radii for each corner.
   ///
@@ -49,7 +48,6 @@ class BeveledRectangleBorder extends OutlinedBorder {
 
   @override
   ShapeBorder? lerpFrom(ShapeBorder? a, double t) {
-    assert(t != null);
     if (a is BeveledRectangleBorder) {
       return BeveledRectangleBorder(
         side: BorderSide.lerp(a.side, side, t),
@@ -61,7 +59,6 @@ class BeveledRectangleBorder extends OutlinedBorder {
 
   @override
   ShapeBorder? lerpTo(ShapeBorder? b, double t) {
-    assert(t != null);
     if (b is BeveledRectangleBorder) {
       return BeveledRectangleBorder(
         side: BorderSide.lerp(side, b.side, t),

packages/flutter/lib/src/painting/binding.dart

@@ -111,7 +111,6 @@ mixin PaintingBinding on BindingBase, ServicesBinding {
   }) {
     assert(cacheWidth == null || cacheWidth > 0);
     assert(cacheHeight == null || cacheHeight > 0);
-    assert(allowUpscaling != null);
     return ui.instantiateImageCodec(
       bytes,
       targetWidth: cacheWidth,
@@ -149,7 +148,6 @@ mixin PaintingBinding on BindingBase, ServicesBinding {
   }) {
     assert(cacheWidth == null || cacheWidth > 0);
     assert(cacheHeight == null || cacheHeight > 0);
-    assert(allowUpscaling != null);
     return ui.instantiateImageCodecFromBuffer(
       buffer,
       targetWidth: cacheWidth,

packages/flutter/lib/src/painting/border_radius.dart

@@ -129,7 +129,6 @@ abstract class BorderRadiusGeometry {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static BorderRadiusGeometry? lerp(BorderRadiusGeometry? a, BorderRadiusGeometry? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }
@@ -507,7 +506,6 @@ class BorderRadius extends BorderRadiusGeometry {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static BorderRadius? lerp(BorderRadius? a, BorderRadius? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }
@@ -729,7 +727,6 @@ class BorderRadiusDirectional extends BorderRadiusGeometry {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static BorderRadiusDirectional? lerp(BorderRadiusDirectional? a, BorderRadiusDirectional? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }

packages/flutter/lib/src/painting/borders.dart

@@ -66,11 +66,7 @@ class BorderSide with Diagnosticable {
     this.width = 1.0,
     this.style = BorderStyle.solid,
     this.strokeAlign = strokeAlignInside,
-  }) : assert(color != null),
-       assert(width != null),
-       assert(width >= 0.0),
-       assert(style != null),
-       assert(strokeAlign != null);
+  }) : assert(width >= 0.0);
 
   /// Creates a [BorderSide] that represents the addition of the two given
   /// [BorderSide]s.
@@ -84,8 +80,6 @@ class BorderSide with Diagnosticable {
   ///
   /// The arguments must not be null.
   static BorderSide merge(BorderSide a, BorderSide b) {
-    assert(a != null);
-    assert(b != null);
     assert(canMerge(a, b));
     final bool aIsNone = a.style == BorderStyle.none && a.width == 0.0;
     final bool bIsNone = b.style == BorderStyle.none && b.width == 0.0;
@@ -202,7 +196,6 @@ class BorderSide with Diagnosticable {
   /// Values for `t` are usually obtained from an [Animation<double>], such as
   /// an [AnimationController].
   BorderSide scale(double t) {
-    assert(t != null);
     return BorderSide(
       color: color,
       width: math.max(0.0, width * t),
@@ -239,8 +232,6 @@ class BorderSide with Diagnosticable {
   ///
   /// The arguments must not be null.
   static bool canMerge(BorderSide a, BorderSide b) {
-    assert(a != null);
-    assert(b != null);
     if ((a.style == BorderStyle.none && a.width == 0.0) ||
         (b.style == BorderStyle.none && b.width == 0.0)) {
       return true;
@@ -255,9 +246,6 @@ class BorderSide with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static BorderSide lerp(BorderSide a, BorderSide b, double t) {
-    assert(a != null);
-    assert(b != null);
-    assert(t != null);
     if (t == 0.0) {
       return a;
     }
@@ -517,7 +505,6 @@ abstract class ShapeBorder {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static ShapeBorder? lerp(ShapeBorder? a, ShapeBorder? b, double t) {
-    assert(t != null);
     ShapeBorder? result;
     if (b != null) {
       result = b.lerpFrom(a, t);
@@ -664,7 +651,7 @@ abstract class OutlinedBorder extends ShapeBorder {
   /// const constructors so that they can be used in const expressions.
   ///
   /// The value of [side] must not be null.
-  const OutlinedBorder({ this.side = BorderSide.none }) : assert(side != null);
+  const OutlinedBorder({ this.side = BorderSide.none });
 
   @override
   EdgeInsetsGeometry get dimensions => EdgeInsets.all(math.max(side.strokeInset, 0));
@@ -707,7 +694,6 @@ abstract class OutlinedBorder extends ShapeBorder {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static OutlinedBorder? lerp(OutlinedBorder? a, OutlinedBorder? b, double t) {
-    assert(t != null);
     ShapeBorder? result;
     if (b != null) {
       result = b.lerpFrom(a, t);
@@ -724,8 +710,7 @@ abstract class OutlinedBorder extends ShapeBorder {
 /// The borders are listed from the outside to the inside.
 class _CompoundBorder extends ShapeBorder {
   _CompoundBorder(this.borders)
-    : assert(borders != null),
-      assert(borders.length >= 2),
+    : assert(borders.length >= 2),
       assert(!borders.any((ShapeBorder border) => border is _CompoundBorder));
 
   final List<ShapeBorder> borders;
@@ -788,7 +773,6 @@ class _CompoundBorder extends ShapeBorder {
   }
 
   static _CompoundBorder lerp(ShapeBorder? a, ShapeBorder? b, double t) {
-    assert(t != null);
     assert(a is _CompoundBorder || b is _CompoundBorder); // Not really necessary, but all call sites currently intend this.
     final List<ShapeBorder?> aList = a is _CompoundBorder ? a.borders : <ShapeBorder?>[a];
     final List<ShapeBorder?> bList = b is _CompoundBorder ? b.borders : <ShapeBorder?>[b];
@@ -897,12 +881,6 @@ void paintBorder(
   BorderSide bottom = BorderSide.none,
   BorderSide left = BorderSide.none,
 }) {
-  assert(canvas != null);
-  assert(rect != null);
-  assert(top != null);
-  assert(right != null);
-  assert(bottom != null);
-  assert(left != null);
 
   // We draw the borders as filled shapes, unless the borders are hairline
   // borders, in which case we use PaintingStyle.stroke, with the stroke width

packages/flutter/lib/src/painting/box_border.dart

@@ -103,7 +103,6 @@ abstract class BoxBorder extends ShapeBorder {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static BoxBorder? lerp(BoxBorder? a, BoxBorder? b, double t) {
-    assert(t != null);
     if ((a is Border?) && (b is Border?)) {
       return Border.lerp(a, b, t);
     }
@@ -322,17 +321,13 @@ class Border extends BoxBorder {
     this.right = BorderSide.none,
     this.bottom = BorderSide.none,
     this.left = BorderSide.none,
-  }) : assert(top != null),
-       assert(right != null),
-       assert(bottom != null),
-       assert(left != null);
+  });
 
   /// Creates a border whose sides are all the same.
   ///
   /// The `side` argument must not be null.
   const Border.fromBorderSide(BorderSide side)
-      : assert(side != null),
-        top = side,
+      : top = side,
         right = side,
         bottom = side,
         left = side;
@@ -346,9 +341,7 @@ class Border extends BoxBorder {
   const Border.symmetric({
     BorderSide vertical = BorderSide.none,
     BorderSide horizontal = BorderSide.none,
-  }) : assert(vertical != null),
-       assert(horizontal != null),
-       left = vertical,
+  }) : left = vertical,
        top = horizontal,
        right = vertical,
        bottom = horizontal;
@@ -374,8 +367,6 @@ class Border extends BoxBorder {
   ///
   /// The arguments must not be null.
   static Border merge(Border a, Border b) {
-    assert(a != null);
-    assert(b != null);
     assert(BorderSide.canMerge(a.top, b.top));
     assert(BorderSide.canMerge(a.right, b.right));
     assert(BorderSide.canMerge(a.bottom, b.bottom));
@@ -478,7 +469,6 @@ class Border extends BoxBorder {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static Border? lerp(Border? a, Border? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }
@@ -650,10 +640,7 @@ class BorderDirectional extends BoxBorder {
     this.start = BorderSide.none,
     this.end = BorderSide.none,
     this.bottom = BorderSide.none,
-  }) : assert(top != null),
-       assert(start != null),
-       assert(end != null),
-       assert(bottom != null);
+  });
 
   /// Creates a [BorderDirectional] that represents the addition of the two
   /// given [BorderDirectional]s.
@@ -663,8 +650,6 @@ class BorderDirectional extends BoxBorder {
   ///
   /// The arguments must not be null.
   static BorderDirectional merge(BorderDirectional a, BorderDirectional b) {
-    assert(a != null);
-    assert(b != null);
     assert(BorderSide.canMerge(a.top, b.top));
     assert(BorderSide.canMerge(a.start, b.start));
     assert(BorderSide.canMerge(a.end, b.end));
@@ -826,7 +811,6 @@ class BorderDirectional extends BoxBorder {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static BorderDirectional? lerp(BorderDirectional? a, BorderDirectional? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }

packages/flutter/lib/src/painting/box_decoration.dart

@@ -93,8 +93,7 @@ class BoxDecoration extends Decoration {
     this.gradient,
     this.backgroundBlendMode,
     this.shape = BoxShape.rectangle,
-  }) : assert(shape != null),
-       assert(
+  }) : assert(
          backgroundBlendMode == null || color != null || gradient != null,
          "backgroundBlendMode applies to BoxDecoration's background color or "
          'gradient, but no color or gradient was provided.',
@@ -289,7 +288,6 @@ class BoxDecoration extends Decoration {
   ///    and which use [BoxDecoration.lerp] when interpolating two
   ///    [BoxDecoration]s or a [BoxDecoration] to or from null.
   static BoxDecoration? lerp(BoxDecoration? a, BoxDecoration? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }
@@ -365,7 +363,6 @@ class BoxDecoration extends Decoration {
 
   @override
   bool hitTest(Size size, Offset position, { TextDirection? textDirection }) {
-    assert(shape != null);
     assert((Offset.zero & size).contains(position));
     switch (shape) {
       case BoxShape.rectangle:
@@ -391,15 +388,13 @@ class BoxDecoration extends Decoration {
 
 /// An object that paints a [BoxDecoration] into a canvas.
 class _BoxDecorationPainter extends BoxPainter {
-  _BoxDecorationPainter(this._decoration, super.onChanged)
-    : assert(_decoration != null);
+  _BoxDecorationPainter(this._decoration, super.onChanged);
 
   final BoxDecoration _decoration;
 
   Paint? _cachedBackgroundPaint;
   Rect? _rectForCachedBackgroundPaint;
   Paint _getBackgroundPaint(Rect rect, TextDirection? textDirection) {
-    assert(rect != null);
     assert(_decoration.gradient != null || _rectForCachedBackgroundPaint == null);
 
     if (_cachedBackgroundPaint == null ||
@@ -489,7 +484,6 @@ class _BoxDecorationPainter extends BoxPainter {
   /// Paint the box decoration into the given location on the given canvas.
   @override
   void paint(Canvas canvas, Offset offset, ImageConfiguration configuration) {
-    assert(configuration != null);
     assert(configuration.size != null);
     final Rect rect = offset & configuration.size!;
     final TextDirection? textDirection = configuration.textDirection;

packages/flutter/lib/src/painting/box_shadow.dart

@@ -86,7 +86,6 @@ class BoxShadow extends ui.Shadow {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static BoxShadow? lerp(BoxShadow? a, BoxShadow? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }
@@ -111,7 +110,6 @@ class BoxShadow extends ui.Shadow {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static List<BoxShadow>? lerpList(List<BoxShadow>? a, List<BoxShadow>? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }

packages/flutter/lib/src/painting/circle_border.dart

@@ -33,9 +33,7 @@ class CircleBorder extends OutlinedBorder {
   ///
   /// The [side] argument must not be null.
   const CircleBorder({ super.side, this.eccentricity = 0.0 })
-      : assert(side != null),
-        assert(eccentricity != null),
-        assert(eccentricity >= 0.0, 'The eccentricity argument $eccentricity is not greater than or equal to zero.'),
+      : assert(eccentricity >= 0.0, 'The eccentricity argument $eccentricity is not greater than or equal to zero.'),
         assert(eccentricity <= 1.0, 'The eccentricity argument $eccentricity is not less than or equal to one.');
 
   /// Defines the ratio (0.0-1.0) from which the border will deform

packages/flutter/lib/src/painting/clip.dart

@@ -10,7 +10,6 @@ abstract class ClipContext {
   Canvas get canvas;
 
   void _clipAndPaint(void Function(bool doAntiAlias) canvasClipCall, Clip clipBehavior, Rect bounds, VoidCallback painter) {
-    assert(canvasClipCall != null);
     canvas.save();
     switch (clipBehavior) {
       case Clip.none:

packages/flutter/lib/src/painting/colors.dart

@@ -89,11 +89,7 @@ class HSVColor {
   /// All the arguments must not be null and be in their respective ranges. See
   /// the fields for each parameter for a description of their ranges.
   const HSVColor.fromAHSV(this.alpha, this.hue, this.saturation, this.value)
-    : assert(alpha != null),
-      assert(hue != null),
-      assert(saturation != null),
-      assert(value != null),
-      assert(alpha >= 0.0),
+    : assert(alpha >= 0.0),
       assert(alpha <= 1.0),
       assert(hue >= 0.0),
       assert(hue <= 360.0),
@@ -198,7 +194,6 @@ class HSVColor {
   ///
   /// Values outside of the valid range for each channel will be clamped.
   static HSVColor? lerp(HSVColor? a, HSVColor? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }
@@ -262,11 +257,7 @@ class HSLColor {
   /// All the arguments must not be null and be in their respective ranges. See
   /// the fields for each parameter for a description of their ranges.
   const HSLColor.fromAHSL(this.alpha, this.hue, this.saturation, this.lightness)
-    : assert(alpha != null),
-      assert(hue != null),
-      assert(saturation != null),
-      assert(lightness != null),
-      assert(alpha >= 0.0),
+    : assert(alpha >= 0.0),
       assert(alpha <= 1.0),
       assert(hue >= 0.0),
       assert(hue <= 360.0),
@@ -386,7 +377,6 @@ class HSLColor {
   /// Values for `t` are usually obtained from an [Animation<double>], such as
   /// an [AnimationController].
   static HSLColor? lerp(HSLColor? a, HSLColor? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }
@@ -519,9 +509,7 @@ class ColorProperty extends DiagnosticsProperty<Color> {
     super.defaultValue,
     super.style,
     super.level,
-  }) : assert(showName != null),
-       assert(style != null),
-       assert(level != null);
+  });
 
   @override
   Map<String, Object?> toJsonMap(DiagnosticsSerializationDelegate delegate) {

packages/flutter/lib/src/painting/continuous_rectangle_border.dart

@@ -37,8 +37,7 @@ class ContinuousRectangleBorder extends OutlinedBorder {
   const ContinuousRectangleBorder({
     super.side,
     this.borderRadius = BorderRadius.zero,
-  }) : assert(side != null),
-       assert(borderRadius != null);
+  });
 
   /// The radius for each corner.
   ///
@@ -59,7 +58,6 @@ class ContinuousRectangleBorder extends OutlinedBorder {
 
   @override
   ShapeBorder? lerpFrom(ShapeBorder? a, double t) {
-    assert(t != null);
     if (a is ContinuousRectangleBorder) {
       return ContinuousRectangleBorder(
         side: BorderSide.lerp(a.side, side, t),
@@ -71,7 +69,6 @@ class ContinuousRectangleBorder extends OutlinedBorder {
 
   @override
   ShapeBorder? lerpTo(ShapeBorder? b, double t) {
-    assert(t != null);
     if (b is ContinuousRectangleBorder) {
       return ContinuousRectangleBorder(
         side: BorderSide.lerp(side, b.side, t),

packages/flutter/lib/src/painting/decoration.dart

@@ -129,7 +129,6 @@ abstract class Decoration with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static Decoration? lerp(Decoration? a, Decoration? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }

packages/flutter/lib/src/painting/decoration_image.dart

@@ -57,11 +57,7 @@ class DecorationImage {
     this.filterQuality = FilterQuality.low,
     this.invertColors = false,
     this.isAntiAlias = false,
-  }) : assert(image != null),
-       assert(alignment != null),
-       assert(repeat != null),
-       assert(matchTextDirection != null),
-       assert(scale != null);
+  });
 
   /// The image to be painted into the decoration.
   ///
@@ -181,7 +177,6 @@ class DecorationImage {
   /// image needs to be repainted, e.g. because it is loading incrementally or
   /// because it is animated.
   DecorationImagePainter createPainter(VoidCallback onChanged) {
-    assert(onChanged != null);
     return DecorationImagePainter._(this, onChanged);
   }
 
@@ -265,7 +260,7 @@ class DecorationImage {
 /// This object should be disposed using the [dispose] method when it is no
 /// longer needed.
 class DecorationImagePainter {
-  DecorationImagePainter._(this._details, this._onChanged) : assert(_details != null);
+  DecorationImagePainter._(this._details, this._onChanged);
 
   final DecorationImage _details;
   final VoidCallback _onChanged;
@@ -288,9 +283,6 @@ class DecorationImagePainter {
   /// then the `onChanged` callback passed to [DecorationImage.createPainter]
   /// will be called.
   void paint(Canvas canvas, Rect rect, Path? clipPath, ImageConfiguration configuration) {
-    assert(canvas != null);
-    assert(rect != null);
-    assert(configuration != null);
 
     bool flipHorizontally = false;
     if (_details.matchTextDirection) {
@@ -367,7 +359,6 @@ class DecorationImagePainter {
     }
     _image?.dispose();
     _image = value;
-    assert(_onChanged != null);
     if (!synchronousCall) {
       _onChanged();
     }
@@ -500,12 +491,6 @@ void paintImage({
   FilterQuality filterQuality = FilterQuality.low,
   bool isAntiAlias = false,
 }) {
-  assert(canvas != null);
-  assert(image != null);
-  assert(alignment != null);
-  assert(repeat != null);
-  assert(flipHorizontally != null);
-  assert(isAntiAlias != null);
   assert(
     image.debugGetOpenHandleStackTraces()?.isNotEmpty ?? true,
     'Cannot paint an image that is disposed.\n'

packages/flutter/lib/src/painting/edge_insets.dart

@@ -64,7 +64,6 @@ abstract class EdgeInsetsGeometry {
 
   /// The total offset in the given direction.
   double along(Axis axis) {
-    assert(axis != null);
     switch (axis) {
       case Axis.horizontal:
         return horizontal;
@@ -216,7 +215,6 @@ abstract class EdgeInsetsGeometry {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static EdgeInsetsGeometry? lerp(EdgeInsetsGeometry? a, EdgeInsetsGeometry? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }
@@ -604,7 +602,6 @@ class EdgeInsets extends EdgeInsetsGeometry {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static EdgeInsets? lerp(EdgeInsets? a, EdgeInsets? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }
@@ -871,7 +868,6 @@ class EdgeInsetsDirectional extends EdgeInsetsGeometry {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static EdgeInsetsDirectional? lerp(EdgeInsetsDirectional? a, EdgeInsetsDirectional? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }

packages/flutter/lib/src/painting/flutter_logo.dart

@@ -44,10 +44,7 @@ class FlutterLogoDecoration extends Decoration {
     this.textColor = const Color(0xFF757575),
     this.style = FlutterLogoStyle.markOnly,
     this.margin = EdgeInsets.zero,
-  }) : assert(textColor != null),
-       assert(style != null),
-       assert(margin != null),
-       _position = identical(style, FlutterLogoStyle.markOnly) ? 0.0 : identical(style, FlutterLogoStyle.horizontal) ? 1.0 : -1.0,
+  }) : _position = identical(style, FlutterLogoStyle.markOnly) ? 0.0 : identical(style, FlutterLogoStyle.horizontal) ? 1.0 : -1.0,
        _opacity = 1.0;
 
   const FlutterLogoDecoration._(this.textColor, this.style, this.margin, this._position, this._opacity);
@@ -78,12 +75,7 @@ class FlutterLogoDecoration extends Decoration {
   @override
   bool debugAssertIsValid() {
     assert(
-      textColor != null
-        && style != null
-        && margin != null
-        && _position != null
-        && _position.isFinite
-        && _opacity != null
+      _position.isFinite
         && _opacity >= 0.0
         && _opacity <= 1.0,
     );
@@ -107,7 +99,6 @@ class FlutterLogoDecoration extends Decoration {
   ///
   ///  * [Decoration.lerp], which interpolates between arbitrary decorations.
   static FlutterLogoDecoration? lerp(FlutterLogoDecoration? a, FlutterLogoDecoration? b, double t) {
-    assert(t != null);
     assert(a == null || a.debugAssertIsValid());
     assert(b == null || b.debugAssertIsValid());
     if (a == null && b == null) {
@@ -218,8 +209,7 @@ class FlutterLogoDecoration extends Decoration {
 /// An object that paints a [BoxDecoration] into a canvas.
 class _FlutterLogoPainter extends BoxPainter {
   _FlutterLogoPainter(this._config)
-      : assert(_config != null),
-        assert(_config.debugAssertIsValid()),
+      : assert(_config.debugAssertIsValid()),
         super(null) {
     _prepareText();
   }

packages/flutter/lib/src/painting/fractional_offset.dart

@@ -56,17 +56,13 @@ class FractionalOffset extends Alignment {
   ///
   /// The [dx] and [dy] arguments must not be null.
   const FractionalOffset(double dx, double dy)
-    : assert(dx != null),
-      assert(dy != null),
-      super(dx * 2.0 - 1.0, dy * 2.0 - 1.0);
+    : super(dx * 2.0 - 1.0, dy * 2.0 - 1.0);
 
   /// Creates a fractional offset from a specific offset and size.
   ///
   /// The returned [FractionalOffset] describes the position of the
   /// [Offset] in the [Size], as a fraction of the [Size].
   factory FractionalOffset.fromOffsetAndSize(Offset offset, Size size) {
-    assert(size != null);
-    assert(offset != null);
     return FractionalOffset(
       offset.dx / size.width,
       offset.dy / size.height,
@@ -180,7 +176,6 @@ class FractionalOffset extends Alignment {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static FractionalOffset? lerp(FractionalOffset? a, FractionalOffset? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }

packages/flutter/lib/src/painting/geometry.dart

@@ -45,12 +45,6 @@ Offset positionDependentBox({
   double verticalOffset = 0.0,
   double margin = 10.0,
 }) {
-  assert(size != null);
-  assert(childSize != null);
-  assert(target != null);
-  assert(verticalOffset != null);
-  assert(preferBelow != null);
-  assert(margin != null);
   // VERTICAL DIRECTION
   final bool fitsBelow = target.dy + verticalOffset + childSize.height <= size.height - margin;
   final bool fitsAbove = target.dy - verticalOffset - childSize.height >= margin;

packages/flutter/lib/src/painting/gradient.dart

@@ -20,11 +20,8 @@ class _ColorsAndStops {
 
 /// Calculate the color at position [t] of the gradient defined by [colors] and [stops].
 Color _sample(List<Color> colors, List<double> stops, double t) {
-  assert(colors != null);
   assert(colors.isNotEmpty);
-  assert(stops != null);
   assert(stops.isNotEmpty);
-  assert(t != null);
   if (t <= stops.first) {
     return colors.first;
   }
@@ -107,7 +104,6 @@ class GradientRotation extends GradientTransform {
 
   @override
   Matrix4 transform(Rect bounds, {TextDirection? textDirection}) {
-    assert(bounds != null);
     final double sinRadians = math.sin(radians);
     final double oneMinusCosRadians = 1 - math.cos(radians);
     final Offset center = bounds.center;
@@ -170,7 +166,7 @@ abstract class Gradient {
     required this.colors,
     this.stops,
     this.transform,
-  }) : assert(colors != null);
+  });
 
   /// The colors the gradient should obtain at each of the stops.
   ///
@@ -311,7 +307,6 @@ abstract class Gradient {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static Gradient? lerp(Gradient? a, Gradient? b, double t) {
-    assert(t != null);
     Gradient? result;
     if (b != null) {
       result = b.lerpFrom(a, t); // if a is null, this must return non-null
@@ -388,9 +383,7 @@ class LinearGradient extends Gradient {
     super.stops,
     this.tileMode = TileMode.clamp,
     super.transform,
-  }) : assert(begin != null),
-       assert(end != null),
-       assert(tileMode != null);
+  });
 
   /// The offset at which stop 0.0 of the gradient is placed.
   ///
@@ -493,7 +486,6 @@ class LinearGradient extends Gradient {
   /// Values for `t` are usually obtained from an [Animation<double>], such as
   /// an [AnimationController].
   static LinearGradient? lerp(LinearGradient? a, LinearGradient? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }
@@ -644,10 +636,7 @@ class RadialGradient extends Gradient {
     this.focal,
     this.focalRadius = 0.0,
     super.transform,
-  }) : assert(center != null),
-       assert(radius != null),
-       assert(tileMode != null),
-       assert(focalRadius != null);
+  });
 
   /// The center of the gradient, as an offset into the (-1.0, -1.0) x (1.0, 1.0)
   /// square describing the gradient which will be mapped onto the paint box.
@@ -776,7 +765,6 @@ class RadialGradient extends Gradient {
   /// Values for `t` are usually obtained from an [Animation<double>], such as
   /// an [AnimationController].
   static RadialGradient? lerp(RadialGradient? a, RadialGradient? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }
@@ -943,10 +931,7 @@ class SweepGradient extends Gradient {
     super.stops,
     this.tileMode = TileMode.clamp,
     super.transform,
-  }) : assert(center != null),
-       assert(startAngle != null),
-       assert(endAngle != null),
-       assert(tileMode != null);
+  });
 
   /// The center of the gradient, as an offset into the (-1.0, -1.0) x (1.0, 1.0)
   /// square describing the gradient which will be mapped onto the paint box.
@@ -1047,7 +1032,6 @@ class SweepGradient extends Gradient {
   /// Values for `t` are usually obtained from an [Animation<double>], such as
   /// an [AnimationController].
   static SweepGradient? lerp(SweepGradient? a, SweepGradient? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }

packages/flutter/lib/src/painting/image_cache.dart

@@ -99,7 +99,6 @@ class ImageCache {
   /// returning it to its original value will therefore immediately clear the
   /// cache.
   set maximumSize(int value) {
-    assert(value != null);
     assert(value >= 0);
     if (value == maximumSize) {
       return;
@@ -139,7 +138,6 @@ class ImageCache {
   /// returning it to its original value will therefore immediately clear the
   /// cache.
   set maximumSizeBytes(int value) {
-    assert(value != null);
     assert(value >= 0);
     if (value == _maximumSizeBytes) {
       return;
@@ -240,7 +238,6 @@ class ImageCache {
   ///
   ///  * [ImageProvider], for providing images to the [Image] widget.
   bool evict(Object key, { bool includeLive = true }) {
-    assert(includeLive != null);
     if (includeLive) {
       // Remove from live images - the cache will not be able to mark
       // it as complete, and it might be getting evicted because it
@@ -324,8 +321,6 @@ class ImageCache {
   /// no completers are cached and `null` is returned instead of a new
   /// completer.
   ImageStreamCompleter? putIfAbsent(Object key, ImageStreamCompleter Function() loader, { ImageErrorListener? onError }) {
-    assert(key != null);
-    assert(loader != null);
     TimelineTask? timelineTask;
     TimelineTask? listenerTask;
     if (!kReleaseMode) {
@@ -613,8 +608,7 @@ abstract class _CachedImageBase {
   _CachedImageBase(
     this.completer, {
     this.sizeBytes,
-  }) : assert(completer != null),
-       handle = completer.keepAlive();
+  }) : handle = completer.keepAlive();
 
   final ImageStreamCompleter completer;
   int? sizeBytes;

packages/flutter/lib/src/painting/image_provider.dart

@@ -348,7 +348,6 @@ abstract class ImageProvider<T extends Object> {
   /// See the Lifecycle documentation on [ImageProvider] for more information.
   @nonVirtual
   ImageStream resolve(ImageConfiguration configuration) {
-    assert(configuration != null);
     final ImageStream stream = createStream(configuration);
     // Load the key (potentially asynchronously), set up an error handling zone,
     // and call resolveStreamForKey.
@@ -407,7 +406,6 @@ abstract class ImageProvider<T extends Object> {
     required ImageConfiguration configuration,
     ImageErrorListener? handleError,
   }) {
-    assert(configuration != null);
     final Completer<ImageCacheStatus?> completer = Completer<ImageCacheStatus?>();
     _createErrorHandlerAndKey(
       configuration,
@@ -635,9 +633,7 @@ class AssetBundleImageKey {
     required this.bundle,
     required this.name,
     required this.scale,
-  }) : assert(bundle != null),
-       assert(name != null),
-       assert(scale != null);
+  });
 
   /// The bundle from which the image will be obtained.
   ///
@@ -733,10 +729,6 @@ abstract class AssetBundleImageProvider extends ImageProvider<AssetBundleImageKe
         PaintingBinding.instance.imageCache.evict(key);
         rethrow;
       }
-      if (buffer == null) {
-        PaintingBinding.instance.imageCache.evict(key);
-        throw StateError('Unable to read data');
-      }
       return decode(buffer);
     }
     ByteData data;
@@ -748,10 +740,6 @@ abstract class AssetBundleImageProvider extends ImageProvider<AssetBundleImageKe
       PaintingBinding.instance.imageCache.evict(key);
       rethrow;
     }
-    if (data == null) {
-      PaintingBinding.instance.imageCache.evict(key);
-      throw StateError('Unable to read data');
-    }
     return decodeDepreacted!(data.buffer.asUint8List());
   }
 }
@@ -803,8 +791,7 @@ class ResizeImage extends ImageProvider<ResizeImageKey> {
     this.width,
     this.height,
     this.allowUpscaling = false,
-  }) : assert(width != null || height != null),
-       assert(allowUpscaling != null);
+  }) : assert(width != null || height != null);
 
   /// The [ImageProvider] that this class wraps.
   final ImageProvider imageProvider;
@@ -950,9 +937,7 @@ class FileImage extends ImageProvider<FileImage> {
   /// Creates an object that decodes a [File] as an image.
   ///
   /// The arguments must not be null.
-  const FileImage(this.file, { this.scale = 1.0 })
-    : assert(file != null),
-      assert(scale != null);
+  const FileImage(this.file, { this.scale = 1.0 });
 
   /// The file to decode into an image.
   final File file;
@@ -1045,9 +1030,7 @@ class MemoryImage extends ImageProvider<MemoryImage> {
   /// Creates an object that decodes a [Uint8List] buffer as an image.
   ///
   /// The arguments must not be null.
-  const MemoryImage(this.bytes, { this.scale = 1.0 })
-    : assert(bytes != null),
-      assert(scale != null);
+  const MemoryImage(this.bytes, { this.scale = 1.0 });
 
   /// The bytes to decode into an image.
   ///
@@ -1204,8 +1187,7 @@ class ExactAssetImage extends AssetBundleImageProvider {
     this.scale = 1.0,
     this.bundle,
     this.package,
-  }) : assert(assetName != null),
-       assert(scale != null);
+  });
 
   /// The name of the asset.
   final String assetName;
@@ -1266,9 +1248,7 @@ class NetworkImageLoadException implements Exception {
   /// Creates a [NetworkImageLoadException] with the specified http [statusCode]
   /// and [uri].
   NetworkImageLoadException({required this.statusCode, required this.uri})
-      : assert(uri != null),
-        assert(statusCode != null),
-        _message = 'HTTP request failed, statusCode: $statusCode, $uri';
+      : _message = 'HTTP request failed, statusCode: $statusCode, $uri';
 
   /// The HTTP status code from the server.
   final int statusCode;

packages/flutter/lib/src/painting/image_resolution.dart

@@ -244,7 +244,7 @@ class AssetImage extends AssetBundleImageProvider {
     this.assetName, {
     this.bundle,
     this.package,
-  }) : assert(assetName != null);
+  });
 
   /// The name of the main asset from the set of images to choose from. See the
   /// documentation for the [AssetImage] class itself for details.

packages/flutter/lib/src/painting/image_stream.dart

@@ -23,9 +23,7 @@ class ImageInfo {
   /// Both the [image] and the [scale] must not be null.
   ///
   /// The [debugLabel] may be used to identify the source of this image.
-  const ImageInfo({ required this.image, this.scale = 1.0, this.debugLabel })
-    : assert(image != null),
-      assert(scale != null);
+  const ImageInfo({ required this.image, this.scale = 1.0, this.debugLabel });
 
   /// Creates an [ImageInfo] with a cloned [image].
   ///
@@ -167,7 +165,7 @@ class ImageStreamListener {
     this.onImage, {
     this.onChunk,
     this.onError,
-  }) : assert(onImage != null);
+  });
 
   /// Callback for getting notified that an image is available.
   ///
@@ -623,7 +621,6 @@ abstract class ImageStreamCompleter with Diagnosticable {
   ///
   /// This callback will never fire if [removeListener] is never called.
   void addOnLastListenerRemovedCallback(VoidCallback callback) {
-    assert(callback != null);
     _checkDisposed();
     _onLastListenerRemovedCallbacks.add(callback);
   }
@@ -631,7 +628,6 @@ abstract class ImageStreamCompleter with Diagnosticable {
   /// Removes a callback previously supplied to
   /// [addOnLastListenerRemovedCallback].
   void removeOnLastListenerRemovedCallback(VoidCallback callback) {
-    assert(callback != null);
     _checkDisposed();
     _onLastListenerRemovedCallbacks.remove(callback);
   }
@@ -789,8 +785,7 @@ class OneFrameImageStreamCompleter extends ImageStreamCompleter {
   /// argument on [FlutterErrorDetails] set to true, meaning that by default the
   /// message is only dumped to the console in debug mode (see [
   /// FlutterErrorDetails]).
-  OneFrameImageStreamCompleter(Future<ImageInfo> image, { InformationCollector? informationCollector })
-      : assert(image != null) {
+  OneFrameImageStreamCompleter(Future<ImageInfo> image, { InformationCollector? informationCollector }) {
     image.then<void>(setImage, onError: (Object error, StackTrace stack) {
       reportError(
         context: ErrorDescription('resolving a single-frame image stream'),
@@ -859,8 +854,7 @@ class MultiFrameImageStreamCompleter extends ImageStreamCompleter {
     String? debugLabel,
     Stream<ImageChunkEvent>? chunkEvents,
     InformationCollector? informationCollector,
-  }) : assert(codec != null),
-       _informationCollector = informationCollector,
+  }) : _informationCollector = informationCollector,
        _scale = scale {
     this.debugLabel = debugLabel;
     codec.then<void>(_handleCodecReady, onError: (Object error, StackTrace stack) {

packages/flutter/lib/src/painting/inline_span.dart

@@ -60,9 +60,7 @@ class InlineSpanSemanticsInformation {
     this.semanticsLabel,
     this.stringAttributes = const <ui.StringAttribute>[],
     this.recognizer,
-  }) : assert(text != null),
-       assert(isPlaceholder != null),
-       assert(isPlaceholder == false || (text == '\uFFFC' && semanticsLabel == null && recognizer == null)),
+  }) : assert(isPlaceholder == false || (text == '\uFFFC' && semanticsLabel == null && recognizer == null)),
        requiresOwnNode = isPlaceholder || recognizer != null;
 
   /// The text info for a [PlaceholderSpan].

packages/flutter/lib/src/painting/matrix_utils.dart

@@ -18,7 +18,6 @@ class MatrixUtils {
   ///
   /// Otherwise, returns null.
   static Offset? getAsTranslation(Matrix4 transform) {
-    assert(transform != null);
     final Float64List values = transform.storage;
     // Values are stored in column-major order.
     if (values[0] == 1.0 && // col 1
@@ -45,7 +44,6 @@ class MatrixUtils {
   ///
   /// Otherwise, returns null.
   static double? getAsScale(Matrix4 transform) {
-    assert(transform != null);
     final Float64List values = transform.storage;
     // Values are stored in column-major order.
     if (values[1] == 0.0 && // col 1 (value 0 is the scale)
@@ -81,7 +79,6 @@ class MatrixUtils {
     if (b == null) {
       return isIdentity(a);
     }
-    assert(a != null && b != null);
     return a.storage[0] == b.storage[0]
         && a.storage[1] == b.storage[1]
         && a.storage[2] == b.storage[2]
@@ -102,7 +99,6 @@ class MatrixUtils {
 
   /// Whether the given matrix is the identity matrix.
   static bool isIdentity(Matrix4 a) {
-    assert(a != null);
     return a.storage[0] == 1.0 // col 1
         && a.storage[1] == 0.0
         && a.storage[2] == 0.0
@@ -437,7 +433,6 @@ class MatrixUtils {
   /// The transformed rect is then projected back into the plane with z equals
   /// 0.0 before computing its bounding rect.
   static Rect inverseTransformRect(Matrix4 transform, Rect rect) {
-    assert(rect != null);
     // As exposed by `unrelated_type_equality_checks`, this assert was a no-op.
     // Fixing it introduces a bunch of runtime failures; for more context see:
     // https://github.com/flutter/flutter/pull/31568
@@ -487,10 +482,7 @@ class MatrixUtils {
     double perspective = 0.001,
     Axis orientation = Axis.vertical,
   }) {
-    assert(radius != null);
-    assert(angle != null);
     assert(perspective >= 0 && perspective <= 1.0);
-    assert(orientation != null);
 
     // Pre-multiplied matrix of a projection matrix and a view matrix.
     //
@@ -561,8 +553,7 @@ class TransformProperty extends DiagnosticsProperty<Matrix4> {
     super.showName,
     super.defaultValue,
     super.level,
-  }) : assert(showName != null),
-       assert(level != null);
+  });
 
   @override
   String valueToString({ TextTreeConfiguration? parentConfiguration }) {

packages/flutter/lib/src/painting/rounded_rectangle_border.dart

@@ -30,8 +30,7 @@ class RoundedRectangleBorder extends OutlinedBorder {
   const RoundedRectangleBorder({
     super.side,
     this.borderRadius = BorderRadius.zero,
-  }) : assert(side != null),
-       assert(borderRadius != null);
+  });
 
   /// The radii for each corner.
   final BorderRadiusGeometry borderRadius;
@@ -46,7 +45,6 @@ class RoundedRectangleBorder extends OutlinedBorder {
 
   @override
   ShapeBorder? lerpFrom(ShapeBorder? a, double t) {
-    assert(t != null);
     if (a is RoundedRectangleBorder) {
       return RoundedRectangleBorder(
         side: BorderSide.lerp(a.side, side, t),
@@ -66,7 +64,6 @@ class RoundedRectangleBorder extends OutlinedBorder {
 
   @override
   ShapeBorder? lerpTo(ShapeBorder? b, double t) {
-    assert(t != null);
     if (b is RoundedRectangleBorder) {
       return RoundedRectangleBorder(
         side: BorderSide.lerp(side, b.side, t),
@@ -165,9 +162,7 @@ class _RoundedRectangleToCircleBorder extends OutlinedBorder {
     this.borderRadius = BorderRadius.zero,
     required this.circularity,
     required this.eccentricity,
-  }) : assert(side != null),
-       assert(borderRadius != null),
-       assert(circularity != null);
+  });
 
   final BorderRadiusGeometry borderRadius;
   final double circularity;
@@ -185,7 +180,6 @@ class _RoundedRectangleToCircleBorder extends OutlinedBorder {
 
   @override
   ShapeBorder? lerpFrom(ShapeBorder? a, double t) {
-    assert(t != null);
     if (a is RoundedRectangleBorder) {
       return _RoundedRectangleToCircleBorder(
         side: BorderSide.lerp(a.side, side, t),

packages/flutter/lib/src/painting/shape_decoration.dart

@@ -76,8 +76,7 @@ class ShapeDecoration extends Decoration {
     this.gradient,
     this.shadows,
     required this.shape,
-  }) : assert(!(color != null && gradient != null)),
-       assert(shape != null);
+  }) : assert(!(color != null && gradient != null));
 
   /// Creates a shape decoration configured to match a [BoxDecoration].
   ///
@@ -91,7 +90,6 @@ class ShapeDecoration extends Decoration {
   /// transition from a [BoxShape.circle] to [BoxShape.rectangle]).
   factory ShapeDecoration.fromBoxDecoration(BoxDecoration source) {
     final ShapeBorder shape;
-    assert(source.shape != null);
     switch (source.shape) {
       case BoxShape.circle:
         if (source.border != null) {
@@ -227,7 +225,6 @@ class ShapeDecoration extends Decoration {
   ///    and which use [ShapeDecoration.lerp] when interpolating two
   ///    [ShapeDecoration]s or a [ShapeDecoration] to or from null.
   static ShapeDecoration? lerp(ShapeDecoration? a, ShapeDecoration? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }
@@ -299,8 +296,7 @@ class ShapeDecoration extends Decoration {
 /// An object that paints a [ShapeDecoration] into a canvas.
 class _ShapeDecorationPainter extends BoxPainter {
   _ShapeDecorationPainter(this._decoration, VoidCallback onChanged)
-    : assert(_decoration != null),
-      super(onChanged);
+    : super(onChanged);
 
   final ShapeDecoration _decoration;
 
@@ -318,7 +314,6 @@ class _ShapeDecorationPainter extends BoxPainter {
   VoidCallback get onChanged => super.onChanged!;
 
   void _precache(Rect rect, TextDirection? textDirection) {
-    assert(rect != null);
     if (rect == _lastRect && textDirection == _lastTextDirection) {
       return;
     }
@@ -409,7 +404,6 @@ class _ShapeDecorationPainter extends BoxPainter {
 
   @override
   void paint(Canvas canvas, Offset offset, ImageConfiguration configuration) {
-    assert(configuration != null);
     assert(configuration.size != null);
     final Rect rect = offset & configuration.size!;
     final TextDirection? textDirection = configuration.textDirection;

packages/flutter/lib/src/painting/stadium_border.dart

@@ -27,14 +27,13 @@ class StadiumBorder extends OutlinedBorder {
   /// Create a stadium border.
   ///
   /// The [side] argument must not be null.
-  const StadiumBorder({ super.side }) : assert(side != null);
+  const StadiumBorder({ super.side });
 
   @override
   ShapeBorder scale(double t) => StadiumBorder(side: side.scale(t));
 
   @override
   ShapeBorder? lerpFrom(ShapeBorder? a, double t) {
-    assert(t != null);
     if (a is StadiumBorder) {
       return StadiumBorder(side: BorderSide.lerp(a.side, side, t));
     }
@@ -57,7 +56,6 @@ class StadiumBorder extends OutlinedBorder {
 
   @override
   ShapeBorder? lerpTo(ShapeBorder? b, double t) {
-    assert(t != null);
     if (b is StadiumBorder) {
       return StadiumBorder(side: BorderSide.lerp(side, b.side, t));
     }
@@ -144,8 +142,7 @@ class _StadiumToCircleBorder extends OutlinedBorder {
     super.side,
     this.circularity = 0.0,
     required this.eccentricity,
-  }) : assert(side != null),
-       assert(circularity != null);
+  });
 
   final double circularity;
   final double eccentricity;
@@ -161,7 +158,6 @@ class _StadiumToCircleBorder extends OutlinedBorder {
 
   @override
   ShapeBorder? lerpFrom(ShapeBorder? a, double t) {
-    assert(t != null);
     if (a is StadiumBorder) {
       return _StadiumToCircleBorder(
         side: BorderSide.lerp(a.side, side, t),
@@ -188,7 +184,6 @@ class _StadiumToCircleBorder extends OutlinedBorder {
 
   @override
   ShapeBorder? lerpTo(ShapeBorder? b, double t) {
-    assert(t != null);
     if (b is StadiumBorder) {
       return _StadiumToCircleBorder(
         side: BorderSide.lerp(side, b.side, t),
@@ -326,9 +321,7 @@ class _StadiumToRoundedRectangleBorder extends OutlinedBorder {
     super.side,
     this.borderRadius = BorderRadius.zero,
     this.rectilinearity = 0.0,
-  }) : assert(side != null),
-       assert(borderRadius != null),
-       assert(rectilinearity != null);
+  });
 
   final BorderRadiusGeometry borderRadius;
 
@@ -345,7 +338,6 @@ class _StadiumToRoundedRectangleBorder extends OutlinedBorder {
 
   @override
   ShapeBorder? lerpFrom(ShapeBorder? a, double t) {
-    assert(t != null);
     if (a is StadiumBorder) {
       return _StadiumToRoundedRectangleBorder(
         side: BorderSide.lerp(a.side, side, t),
@@ -372,7 +364,6 @@ class _StadiumToRoundedRectangleBorder extends OutlinedBorder {
 
   @override
   ShapeBorder? lerpTo(ShapeBorder? b, double t) {
-    assert(t != null);
     if (b is StadiumBorder) {
       return _StadiumToRoundedRectangleBorder(
         side: BorderSide.lerp(side, b.side, t),

packages/flutter/lib/src/painting/star_border.dart

@@ -468,8 +468,8 @@ class _StarGenerator {
     required this.rotation,
     required this.squash,
   })  : assert(points > 1),
-        assert(innerRadiusRatio == null || innerRadiusRatio <= 1),
-        assert(innerRadiusRatio == null || innerRadiusRatio >= 0),
+        assert(innerRadiusRatio <= 1),
+        assert(innerRadiusRatio >= 0),
         assert(squash >= 0),
         assert(squash <= 1),
         assert(pointRounding >= 0),
@@ -484,7 +484,6 @@ class _StarGenerator {
   final double valleyRounding;
   final double rotation;
   final double squash;
-  bool get isStar => innerRadiusRatio != null;
 
   Path generate(Rect rect) {
     final double radius = rect.shortestSide / 2;

packages/flutter/lib/src/painting/strut_style.dart

@@ -347,8 +347,7 @@ class StrutStyle with Diagnosticable {
     this.forceStrutHeight,
     String? debugLabel,
     String? package,
-  }) : assert(textStyle != null),
-       assert(fontSize == null || fontSize > 0),
+  }) : assert(fontSize == null || fontSize > 0),
        assert(leading == null || leading >= 0),
        assert(package == null || fontFamily != null || fontFamilyFallback != null),
        fontFamily = fontFamily != null ? (package == null ? fontFamily : 'packages/$package/$fontFamily') : textStyle.fontFamily,

packages/flutter/lib/src/painting/text_painter.dart

@@ -74,8 +74,7 @@ class PlaceholderDimensions {
     required this.alignment,
     this.baseline,
     this.baselineOffset,
-  }) : assert(size != null),
-       assert(alignment != null);
+  });
 
   /// A constant representing an empty placeholder.
   static const PlaceholderDimensions empty = PlaceholderDimensions(size: Size.zero, alignment: ui.PlaceholderAlignment.bottom);
@@ -329,10 +328,7 @@ class TextPainter {
     TextWidthBasis textWidthBasis = TextWidthBasis.parent,
     ui.TextHeightBehavior? textHeightBehavior,
   }) : assert(text == null || text.debugAssertIsValid()),
-       assert(textAlign != null),
-       assert(textScaleFactor != null),
        assert(maxLines == null || maxLines > 0),
-       assert(textWidthBasis != null),
        _text = text,
        _textAlign = textAlign,
        _textDirection = textDirection,
@@ -527,7 +523,6 @@ class TextPainter {
   TextAlign get textAlign => _textAlign;
   TextAlign _textAlign;
   set textAlign(TextAlign value) {
-    assert(value != null);
     if (_textAlign == value) {
       return;
     }
@@ -571,7 +566,6 @@ class TextPainter {
   double get textScaleFactor => _textScaleFactor;
   double _textScaleFactor;
   set textScaleFactor(double value) {
-    assert(value != null);
     if (_textScaleFactor == value) {
       return;
     }
@@ -666,7 +660,6 @@ class TextPainter {
   TextWidthBasis get textWidthBasis => _textWidthBasis;
   TextWidthBasis _textWidthBasis;
   set textWidthBasis(TextWidthBasis value) {
-    assert(value != null);
     if (_textWidthBasis == value) {
       return;
     }
@@ -734,7 +727,6 @@ class TextPainter {
   ui.ParagraphStyle _createParagraphStyle([ TextDirection? defaultTextDirection ]) {
     // The defaultTextDirection argument is used for preferredLineHeight in case
     // textDirection hasn't yet been set.
-    assert(textAlign != null);
     assert(textDirection != null || defaultTextDirection != null, 'TextPainter.textDirection must be set to a non-null value before using the TextPainter.');
     return _text!.style?.getParagraphStyle(
       textAlign: textAlign,
@@ -847,7 +839,6 @@ class TextPainter {
   /// Valid only after [layout] has been called.
   double computeDistanceToActualBaseline(TextBaseline baseline) {
     assert(_debugAssertTextLayoutIsValid);
-    assert(baseline != null);
     switch (baseline) {
       case TextBaseline.alphabetic:
         return _paragraph!.alphabeticBaseline;
@@ -1134,7 +1125,6 @@ class TextPainter {
 
   Offset get _emptyOffset {
     assert(_debugAssertTextLayoutIsValid); // implies textDirection is non-null
-    assert(textAlign != null);
     switch (textAlign) {
       case TextAlign.left:
         return Offset.zero;
@@ -1199,7 +1189,6 @@ class TextPainter {
       return;
     }
     final int offset = position.offset;
-    assert(position.affinity != null);
     Rect? rect;
     switch (position.affinity) {
       case TextAffinity.upstream: {
@@ -1244,8 +1233,6 @@ class TextPainter {
     ui.BoxWidthStyle boxWidthStyle = ui.BoxWidthStyle.tight,
   }) {
     assert(_debugAssertTextLayoutIsValid);
-    assert(boxHeightStyle != null);
-    assert(boxWidthStyle != null);
     return _paragraph!.getBoxesForRange(
       selection.start,
       selection.end,

packages/flutter/lib/src/painting/text_span.dart

@@ -291,7 +291,6 @@ class TextSpan extends InlineSpan implements HitTestTarget, MouseTrackerAnnotati
     }
     if (children != null) {
       for (final InlineSpan child in children!) {
-        assert(child != null);
         child.build(
           builder,
           textScaleFactor: textScaleFactor,
@@ -452,18 +451,6 @@ class TextSpan extends InlineSpan implements HitTestTarget, MouseTrackerAnnotati
     assert(() {
       if (children != null) {
         for (final InlineSpan child in children!) {
-          if (child == null) {
-            throw FlutterError.fromParts(<DiagnosticsNode>[
-              ErrorSummary('TextSpan contains a null child.'),
-              ErrorDescription(
-                'A TextSpan object with a non-null child list should not have any nulls in its child list.',
-              ),
-              toDiagnosticsNode(
-                name: 'The full text in question was',
-                style: DiagnosticsTreeStyle.errorProperty,
-              ),
-            ]);
-          }
           assert(child.debugAssertIsValid());
         }
       }
@@ -590,14 +577,7 @@ class TextSpan extends InlineSpan implements HitTestTarget, MouseTrackerAnnotati
       return const <DiagnosticsNode>[];
     }
     return children!.map<DiagnosticsNode>((InlineSpan child) {
-      // `child` has a non-nullable return type, but might be null when running
-      // with weak checking, so we need to null check it anyway (and ignore the
-      // warning that the null-handling logic is dead code).
-      if (child != null) {
-        return child.toDiagnosticsNode();
-      } else {
-        return DiagnosticsNode.message('<null child>');
-      }
+      return child.toDiagnosticsNode();
     }).toList();
   }
 }

packages/flutter/lib/src/painting/text_style.dart

@@ -504,7 +504,6 @@ class TextStyle with Diagnosticable {
   }) : fontFamily = package == null ? fontFamily : 'packages/$package/$fontFamily',
        _fontFamilyFallback = fontFamilyFallback,
        _package = package,
-       assert(inherit != null),
        assert(color == null || foreground == null, _kColorForegroundWarning),
        assert(backgroundColor == null || background == null, _kColorBackgroundWarning);
 
@@ -961,21 +960,10 @@ class TextStyle with Diagnosticable {
     String? package,
     TextOverflow? overflow,
   }) {
-    assert(fontSizeFactor != null);
-    assert(fontSizeDelta != null);
     assert(fontSize != null || (fontSizeFactor == 1.0 && fontSizeDelta == 0.0));
-    assert(fontWeightDelta != null);
     assert(fontWeight != null || fontWeightDelta == 0.0);
-    assert(letterSpacingFactor != null);
-    assert(letterSpacingDelta != null);
     assert(letterSpacing != null || (letterSpacingFactor == 1.0 && letterSpacingDelta == 0.0));
-    assert(wordSpacingFactor != null);
-    assert(wordSpacingDelta != null);
     assert(wordSpacing != null || (wordSpacingFactor == 1.0 && wordSpacingDelta == 0.0));
-    assert(heightFactor != null);
-    assert(heightDelta != null);
-    assert(decorationThicknessFactor != null);
-    assert(decorationThicknessDelta != null);
     assert(decorationThickness != null || (decorationThicknessFactor == 1.0 && decorationThicknessDelta == 0.0));
 
     String? modifiedDebugLabel;
@@ -1106,7 +1094,6 @@ class TextStyle with Diagnosticable {
   /// as if they have a [background] paint (creating a new [Paint] if necessary
   /// based on the [backgroundColor] property).
   static TextStyle? lerp(TextStyle? a, TextStyle? b, double t) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }
@@ -1332,7 +1319,6 @@ class TextStyle with Diagnosticable {
     double? height,
     StrutStyle? strutStyle,
   }) {
-    assert(textScaleFactor != null);
     assert(maxLines == null || maxLines > 0);
     final ui.TextLeadingDistribution? leadingDistribution = this.leadingDistribution;
     final ui.TextHeightBehavior? effectiveTextHeightBehavior = textHeightBehavior