migrate part of painting to nullsafety (#63495)

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

@@ -510,7 +510,7 @@ abstract class OutlinedBorder extends ShapeBorder {
 
   /// Returns a copy of this OutlinedBorder that draws its outline with the
   /// specified [side], if [side] is non-null.
-  OutlinedBorder copyWith({ BorderSide side });
+  OutlinedBorder copyWith({ BorderSide? side });
 }
 
 /// Represents the addition of two otherwise-incompatible borders.

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

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
 
 import 'dart:math' as math;
 
@@ -40,21 +39,21 @@ class CircleBorder extends OutlinedBorder {
   ShapeBorder scale(double t) => CircleBorder(side: side.scale(t));
 
   @override
-  ShapeBorder lerpFrom(ShapeBorder a, double t) {
+  ShapeBorder? lerpFrom(ShapeBorder? a, double t) {
     if (a is CircleBorder)
       return CircleBorder(side: BorderSide.lerp(a.side, side, t));
     return super.lerpFrom(a, t);
   }
 
   @override
-  ShapeBorder lerpTo(ShapeBorder b, double t) {
+  ShapeBorder? lerpTo(ShapeBorder? b, double t) {
     if (b is CircleBorder)
       return CircleBorder(side: BorderSide.lerp(side, b.side, t));
     return super.lerpTo(b, t);
   }
 
   @override
-  Path getInnerPath(Rect rect, { TextDirection textDirection }) {
+  Path getInnerPath(Rect rect, { TextDirection? textDirection }) {
     return Path()
       ..addOval(Rect.fromCircle(
         center: rect.center,
@@ -63,7 +62,7 @@ class CircleBorder extends OutlinedBorder {
   }
 
   @override
-  Path getOuterPath(Rect rect, { TextDirection textDirection }) {
+  Path getOuterPath(Rect rect, { TextDirection? textDirection }) {
     return Path()
       ..addOval(Rect.fromCircle(
         center: rect.center,
@@ -72,12 +71,12 @@ class CircleBorder extends OutlinedBorder {
   }
 
   @override
-  CircleBorder copyWith({ BorderSide side }) {
+  CircleBorder copyWith({ BorderSide? side }) {
     return CircleBorder(side: side ?? this.side);
   }
 
   @override
-  void paint(Canvas canvas, Rect rect, { TextDirection textDirection }) {
+  void paint(Canvas canvas, Rect rect, { TextDirection? textDirection }) {
     switch (side.style) {
       case BorderStyle.none:
         break;

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

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
 
 import 'dart:ui' show Canvas, Clip, Path, Paint, Rect, RRect;
 

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

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
 
 import 'dart:math' as math;
 
@@ -61,24 +60,24 @@ class ContinuousRectangleBorder extends OutlinedBorder {
   }
 
   @override
-  ShapeBorder lerpFrom(ShapeBorder a, double t) {
+  ShapeBorder? lerpFrom(ShapeBorder? a, double t) {
     assert(t != null);
     if (a is ContinuousRectangleBorder) {
       return ContinuousRectangleBorder(
         side: BorderSide.lerp(a.side, side, t),
-        borderRadius: BorderRadiusGeometry.lerp(a.borderRadius, borderRadius, t),
+        borderRadius: BorderRadiusGeometry.lerp(a.borderRadius, borderRadius, t)!,
       );
     }
     return super.lerpFrom(a, t);
   }
 
   @override
-  ShapeBorder lerpTo(ShapeBorder b, double t) {
+  ShapeBorder? lerpTo(ShapeBorder? b, double t) {
     assert(t != null);
     if (b is ContinuousRectangleBorder) {
       return ContinuousRectangleBorder(
         side: BorderSide.lerp(side, b.side, t),
-        borderRadius: BorderRadiusGeometry.lerp(borderRadius, b.borderRadius, t),
+        borderRadius: BorderRadiusGeometry.lerp(borderRadius, b.borderRadius, t)!,
       );
     }
     return super.lerpTo(b, t);
@@ -125,17 +124,17 @@ class ContinuousRectangleBorder extends OutlinedBorder {
   }
 
   @override
-  Path getInnerPath(Rect rect, { TextDirection textDirection }) {
+  Path getInnerPath(Rect rect, { TextDirection? textDirection }) {
     return _getPath(borderRadius.resolve(textDirection).toRRect(rect).deflate(side.width));
   }
 
   @override
-  Path getOuterPath(Rect rect, { TextDirection textDirection }) {
+  Path getOuterPath(Rect rect, { TextDirection? textDirection }) {
     return _getPath(borderRadius.resolve(textDirection).toRRect(rect));
   }
 
   @override
-  ContinuousRectangleBorder copyWith({ BorderSide side, BorderRadius borderRadius }) {
+  ContinuousRectangleBorder copyWith({ BorderSide? side, BorderRadius? borderRadius }) {
     return ContinuousRectangleBorder(
       side: side ?? this.side,
       borderRadius: borderRadius ?? this.borderRadius,
@@ -143,7 +142,7 @@ class ContinuousRectangleBorder extends OutlinedBorder {
   }
 
   @override
-  void paint(Canvas canvas, Rect rect, { TextDirection textDirection }) {
+  void paint(Canvas canvas, Rect rect, { TextDirection? textDirection }) {
     if (rect.isEmpty)
       return;
     switch (side.style) {

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

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
 
 import 'package:flutter/foundation.dart';
 
@@ -58,7 +57,7 @@ abstract class Decoration with Diagnosticable {
   /// [EdgeInsetsGeometry.resolve] to obtain an absolute [EdgeInsets]. (For
   /// example, [BorderDirectional] will return an [EdgeInsetsDirectional] for
   /// its [padding].)
-  EdgeInsetsGeometry get padding => EdgeInsets.zero;
+  EdgeInsetsGeometry? get padding => EdgeInsets.zero;
 
   /// Whether this decoration is complex enough to benefit from caching its painting.
   bool get isComplex => false;
@@ -89,7 +88,7 @@ abstract class Decoration with Diagnosticable {
   ///
   /// Instead of calling this directly, use [Decoration.lerp].
   @protected
-  Decoration lerpFrom(Decoration a, double t) => null;
+  Decoration? lerpFrom(Decoration? a, double t) => null;
 
   /// Linearly interpolates from `this` to another [Decoration] (which may be of
   /// a different class).
@@ -118,7 +117,7 @@ abstract class Decoration with Diagnosticable {
   ///
   /// Instead of calling this directly, use [Decoration.lerp].
   @protected
-  Decoration lerpTo(Decoration b, double t) => null;
+  Decoration? lerpTo(Decoration? b, double t) => null;
 
   /// Linearly interpolates between two [Decoration]s.
   ///
@@ -127,12 +126,12 @@ abstract class Decoration with Diagnosticable {
   /// interpolated, then the interpolation is done via null (at `t == 0.5`).
   ///
   /// {@macro dart.ui.shadow.lerp}
-  static Decoration lerp(Decoration a, Decoration b, double t) {
+  static Decoration? lerp(Decoration? a, Decoration? b, double t) {
     assert(t != null);
     if (a == null && b == null)
       return null;
     if (a == null)
-      return b.lerpFrom(null, t) ?? b;
+      return b!.lerpFrom(null, t) ?? b;
     if (b == null)
       return a.lerpTo(null, t) ?? a;
     if (t == 0.0)
@@ -159,7 +158,7 @@ abstract class Decoration with Diagnosticable {
   /// is what [Container] uses), the `textDirection` parameter will be populated
   /// based on the ambient [Directionality] (by way of the [RenderDecoratedBox]
   /// renderer).
-  bool hitTest(Size size, Offset position, { TextDirection textDirection }) => true;
+  bool hitTest(Size size, Offset position, { TextDirection? textDirection }) => true;
 
   /// Returns a [BoxPainter] that will paint this decoration.
   ///
@@ -170,7 +169,7 @@ abstract class Decoration with Diagnosticable {
   BoxPainter createBoxPainter([ VoidCallback onChanged ]);
 
   /// Returns a closed [Path] that describes the outer edge of this decoration.
-  Path getClipPath(Rect rect, TextDirection textDirection) => null;
+  Path? getClipPath(Rect rect, TextDirection textDirection) => null;
 }
 
 /// A stateful class that can paint a particular [Decoration].
@@ -220,7 +219,7 @@ abstract class BoxPainter {
   ///
   /// Resources might not start to load until after [paint] has been called,
   /// because they might depend on the configuration.
-  final VoidCallback onChanged;
+  final VoidCallback? onChanged;
 
   /// Discard any resources being held by the object.
   ///

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

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
 
 import 'dart:developer' as developer;
 import 'dart:ui' as ui show Image;
@@ -44,7 +43,7 @@ class DecorationImage {
   /// The [image], [alignment], [repeat], and [matchTextDirection] arguments
   /// must not be null.
   const DecorationImage({
-    @required this.image,
+    required this.image,
     this.onError,
     this.colorFilter,
     this.fit,
@@ -66,10 +65,10 @@ class DecorationImage {
   final ImageProvider image;
 
   /// An optional error callback for errors emitted when loading [image].
-  final ImageErrorListener onError;
+  final ImageErrorListener? onError;
 
   /// A color filter to apply to the image before painting it.
-  final ColorFilter colorFilter;
+  final ColorFilter? colorFilter;
 
   /// How the image should be inscribed into the box.
   ///
@@ -77,7 +76,7 @@ class DecorationImage {
   /// [BoxFit.fill] if [centerSlice] is not null.
   ///
   /// See the discussion at [paintImage] for more details.
-  final BoxFit fit;
+  final BoxFit? fit;
 
   /// How to align the image within its bounds.
   ///
@@ -121,7 +120,7 @@ class DecorationImage {
   /// destination image size will result in [centerSlice] having no effect
   /// (since the nine regions of the image will be rendered with the same
   /// scaling, as if it wasn't specified).
-  final Rect centerSlice;
+  final Rect? centerSlice;
 
   /// How to paint any portions of the box that would not otherwise be covered
   /// by the image.
@@ -212,8 +211,8 @@ class DecorationImagePainter {
   final DecorationImage _details;
   final VoidCallback _onChanged;
 
-  ImageStream _imageStream;
-  ImageInfo _image;
+  ImageStream? _imageStream;
+  ImageInfo? _image;
 
   /// Draw the image onto the given canvas.
   ///
@@ -229,7 +228,7 @@ class DecorationImagePainter {
   /// because it had not yet been loaded the first time this method was called,
   /// then the `onChanged` callback passed to [DecorationImage.createPainter]
   /// will be called.
-  void paint(Canvas canvas, Rect rect, Path clipPath, ImageConfiguration configuration) {
+  void paint(Canvas canvas, Rect rect, Path? clipPath, ImageConfiguration configuration) {
     assert(canvas != null);
     assert(rect != null);
     assert(configuration != null);
@@ -264,7 +263,7 @@ class DecorationImagePainter {
       );
       _imageStream?.removeListener(listener);
       _imageStream = newImageStream;
-      _imageStream.addListener(listener);
+      _imageStream!.addListener(listener);
     }
     if (_image == null)
       return;
@@ -277,9 +276,9 @@ class DecorationImagePainter {
     paintImage(
       canvas: canvas,
       rect: rect,
-      image: _image.image,
-      debugImageLabel: _image.debugLabel,
-      scale: _details.scale * _image.scale,
+      image: _image!.image,
+      debugImageLabel: _image!.debugLabel,
+      scale: _details.scale * _image!.scale,
       colorFilter: _details.colorFilter,
       fit: _details.fit,
       alignment: _details.alignment.resolve(configuration.textDirection),
@@ -409,15 +408,15 @@ void debugFlushLastFrameImageSizeInfo() {
 ///  * [DecorationImage], which holds a configuration for calling this function.
 ///  * [BoxDecoration], which uses this function to paint a [DecorationImage].
 void paintImage({
-  @required Canvas canvas,
-  @required Rect rect,
-  @required ui.Image image,
-  String debugImageLabel,
+  required Canvas canvas,
+  required Rect rect,
+  required ui.Image image,
+  String? debugImageLabel,
   double scale = 1.0,
-  ColorFilter colorFilter,
-  BoxFit fit,
+  ColorFilter? colorFilter,
+  BoxFit? fit,
   Alignment alignment = Alignment.center,
-  Rect centerSlice,
+  Rect? centerSlice,
   ImageRepeat repeat = ImageRepeat.noRepeat,
   bool flipHorizontally = false,
   bool invertColors = false,
@@ -434,7 +433,7 @@ void paintImage({
     return;
   Size outputSize = rect.size;
   Size inputSize = Size(image.width.toDouble(), image.height.toDouble());
-  Offset sliceBorder;
+  Offset? sliceBorder;
   if (centerSlice != null) {
     sliceBorder = Offset(
       centerSlice.left + inputSize.width - centerSlice.right,
@@ -449,7 +448,7 @@ void paintImage({
   final Size sourceSize = fittedSizes.source * scale;
   Size destinationSize = fittedSizes.destination;
   if (centerSlice != null) {
-    outputSize += sliceBorder;
+    outputSize += sliceBorder!;
     destinationSize += sliceBorder;
     // We don't have the ability to draw a subset of the image at the same time
     // as we apply a nine-patch stretch.
@@ -523,23 +522,23 @@ void paintImage({
     }());
     // Avoid emitting events that are the same as those emitted in the last frame.
     if (!_lastFrameImageSizeInfo.contains(sizeInfo)) {
-      final ImageSizeInfo existingSizeInfo = _pendingImageSizeInfo[sizeInfo.source];
+      final ImageSizeInfo? existingSizeInfo = _pendingImageSizeInfo[sizeInfo.source];
       if (existingSizeInfo == null || existingSizeInfo.displaySizeInBytes < sizeInfo.displaySizeInBytes) {
-        _pendingImageSizeInfo[sizeInfo.source] = sizeInfo;
+        _pendingImageSizeInfo[sizeInfo.source!] = sizeInfo;
       }
       if (debugOnPaintImage != null) {
-        debugOnPaintImage(sizeInfo);
+        debugOnPaintImage!(sizeInfo);
       }
-      SchedulerBinding.instance.addPostFrameCallback((Duration timeStamp) {
+      SchedulerBinding.instance!.addPostFrameCallback((Duration timeStamp) {
         _lastFrameImageSizeInfo = _pendingImageSizeInfo.values.toSet();
         if (_pendingImageSizeInfo.isEmpty) {
           return;
         }
         developer.postEvent(
           'Flutter.ImageSizesForFrame',
-          <Object, Object>{
+          <String, Object>{
             for (ImageSizeInfo imageSizeInfo in _pendingImageSizeInfo.values)
-              imageSizeInfo.source: imageSizeInfo.toJson()
+              imageSizeInfo.source!: imageSizeInfo.toJson()
           },
         );
         _pendingImageSizeInfo = <String, ImageSizeInfo>{};

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

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
 
 import 'dart:ui' as ui show lerpDouble;
 
@@ -139,16 +138,14 @@ class FractionalOffset extends Alignment {
   Alignment operator -(Alignment other) {
     if (other is! FractionalOffset)
       return super - other;
-    final FractionalOffset typedOther = other as FractionalOffset;
-    return FractionalOffset(dx - typedOther.dx, dy - typedOther.dy);
+    return FractionalOffset(dx - other.dx, dy - other.dy);
   }
 
   @override
   Alignment operator +(Alignment other) {
     if (other is! FractionalOffset)
       return super + other;
-    final FractionalOffset typedOther = other as FractionalOffset;
-    return FractionalOffset(dx + typedOther.dx, dy + typedOther.dy);
+    return FractionalOffset(dx + other.dx, dy + other.dy);
   }
 
   @override
@@ -181,15 +178,15 @@ class FractionalOffset extends Alignment {
   /// If either is null, this function interpolates from [FractionalOffset.center].
   ///
   /// {@macro dart.ui.shadow.lerp}
-  static FractionalOffset lerp(FractionalOffset a, FractionalOffset b, double t) {
+  static FractionalOffset? lerp(FractionalOffset? a, FractionalOffset? b, double t) {
     assert(t != null);
     if (a == null && b == null)
       return null;
     if (a == null)
-      return FractionalOffset(ui.lerpDouble(0.5, b.dx, t), ui.lerpDouble(0.5, b.dy, t));
+      return FractionalOffset(ui.lerpDouble(0.5, b!.dx, t)!, ui.lerpDouble(0.5, b.dy, t)!);
     if (b == null)
-      return FractionalOffset(ui.lerpDouble(a.dx, 0.5, t), ui.lerpDouble(a.dy, 0.5, t));
-    return FractionalOffset(ui.lerpDouble(a.dx, b.dx, t), ui.lerpDouble(a.dy, b.dy, t));
+      return FractionalOffset(ui.lerpDouble(a.dx, 0.5, t)!, ui.lerpDouble(a.dy, 0.5, t)!);
+    return FractionalOffset(ui.lerpDouble(a.dx, b.dx, t)!, ui.lerpDouble(a.dy, b.dy, t)!);
   }
 
   @override

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

@@ -2,12 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
 
 import 'dart:math' as math;
 
-import 'package:flutter/foundation.dart';
-
 import 'basic_types.dart';
 
 /// Position a child box within a container box, either above or below a target
@@ -41,10 +38,10 @@ import 'basic_types.dart';
 ///
 /// The arguments must not be null.
 Offset positionDependentBox({
-  @required Size size,
-  @required Size childSize,
-  @required Offset target,
-  @required bool preferBelow,
+  required Size size,
+  required Size childSize,
+  required Offset target,
+  required bool preferBelow,
   double verticalOffset = 0.0,
   double margin = 10.0,
 }) {

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

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
 
 import 'dart:async';
 import 'dart:typed_data';
@@ -23,7 +22,7 @@ import 'binding.dart';
 /// [PaintingBinding.instantiateImageCodec], and therefore can be mocked in
 /// tests.
 Future<ui.Image> decodeImageFromList(Uint8List bytes) async {
-  final ui.Codec codec = await PaintingBinding.instance.instantiateImageCodec(bytes);
+  final ui.Codec codec = await PaintingBinding.instance!.instantiateImageCodec(bytes);
   final ui.FrameInfo frameInfo = await codec.getNextFrame();
   return frameInfo.image;
 }

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

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
 
 import 'dart:async';
 import 'dart:collection';
@@ -153,11 +152,11 @@ class AssetImage extends AssetBundleImageProvider {
   ///
   /// The image is obtained by calling [AssetBundle.load] on the given [bundle]
   /// using the key given by [keyName].
-  final AssetBundle bundle;
+  final AssetBundle? bundle;
 
   /// The name of the package from which the image is included. See the
   /// documentation for the [AssetImage] class itself for details.
-  final String package;
+  final String? package;
 
   // We assume the main asset is designed for a device pixel ratio of 1.0
   static const double _naturalResolution = 1.0;
@@ -171,16 +170,16 @@ class AssetImage extends AssetBundleImageProvider {
     // that we resolve each future in a new call frame, and thus not in this
     // build/layout/paint sequence.)
     final AssetBundle chosenBundle = bundle ?? configuration.bundle ?? rootBundle;
-    Completer<AssetBundleImageKey> completer;
-    Future<AssetBundleImageKey> result;
+    Completer<AssetBundleImageKey>? completer;
+    Future<AssetBundleImageKey>? result;
 
-    chosenBundle.loadStructuredData<Map<String, List<String>>>(_kAssetManifestFileName, _manifestParser).then<void>(
-      (Map<String, List<String>> manifest) {
+    chosenBundle.loadStructuredData<Map<String, List<String>>?>(_kAssetManifestFileName, _manifestParser).then<void>(
+      (Map<String, List<String>>? manifest) {
         final String chosenName = _chooseVariant(
           keyName,
           configuration,
           manifest == null ? null : manifest[keyName],
-        );
+        )!;
         final double chosenScale = _parseScale(chosenName);
         final AssetBundleImageKey key = AssetBundleImageKey(
           bundle: chosenBundle,
@@ -200,17 +199,17 @@ class AssetImage extends AssetBundleImageProvider {
           result = SynchronousFuture<AssetBundleImageKey>(key);
         }
       }
-    ).catchError((dynamic error, StackTrace stack) {
+    ).catchError((Object error, StackTrace stack) {
       // We had an error. (This guarantees we weren't called synchronously.)
       // Forward the error to the caller.
       assert(completer != null);
       assert(result == null);
-      completer.completeError(error, stack);
+      completer!.completeError(error, stack);
     });
     if (result != null) {
       // The code above ran synchronously, and came up with an answer.
       // Return the SynchronousFuture that we created above.
-      return result;
+      return result!;
     }
     // The code above hasn't yet run its "then" handler yet. Let's prepare a
     // completer for it to use when it does run.
@@ -218,9 +217,9 @@ class AssetImage extends AssetBundleImageProvider {
     return completer.future;
   }
 
-  static Future<Map<String, List<String>>> _manifestParser(String jsonData) {
+  static Future<Map<String, List<String>>?> _manifestParser(String? jsonData) {
     if (jsonData == null)
-      return SynchronousFuture<Map<String, List<String>>>(null);
+      return SynchronousFuture<Map<String, List<String>>?>(null);
     // TODO(ianh): JSON decoding really shouldn't be on the main thread.
     final Map<String, dynamic> parsedJson = json.decode(jsonData) as Map<String, dynamic>;
     final Iterable<String> keys = parsedJson.keys;
@@ -228,10 +227,10 @@ class AssetImage extends AssetBundleImageProvider {
         Map<String, List<String>>.fromIterables(keys,
           keys.map<List<String>>((String key) => List<String>.from(parsedJson[key] as List<dynamic>)));
     // TODO(ianh): convert that data structure to the right types.
-    return SynchronousFuture<Map<String, List<String>>>(parsedManifest);
+    return SynchronousFuture<Map<String, List<String>>?>(parsedManifest);
   }
 
-  String _chooseVariant(String main, ImageConfiguration config, List<String> candidates) {
+  String? _chooseVariant(String main, ImageConfiguration config, List<String>? candidates) {
     if (config.devicePixelRatio == null || candidates == null || candidates.isEmpty)
       return main;
     // TODO(ianh): Consider moving this parsing logic into _manifestParser.
@@ -241,15 +240,15 @@ class AssetImage extends AssetBundleImageProvider {
     // TODO(ianh): implement support for config.locale, config.textDirection,
     // config.size, config.platform (then document this over in the Image.asset
     // docs)
-    return _findNearest(mapping, config.devicePixelRatio);
+    return _findNearest(mapping, config.devicePixelRatio!);
   }
 
   // Return the value for the key in a [SplayTreeMap] nearest the provided key.
-  String _findNearest(SplayTreeMap<double, String> candidates, double value) {
+  String? _findNearest(SplayTreeMap<double, String> candidates, double value) {
     if (candidates.containsKey(value))
-      return candidates[value];
-    final double lower = candidates.lastKeyBefore(value);
-    final double upper = candidates.firstKeyAfter(value);
+      return candidates[value]!;
+    final double? lower = candidates.lastKeyBefore(value);
+    final double? upper = candidates.firstKeyAfter(value);
     if (lower == null)
       return candidates[upper];
     if (upper == null)
@@ -273,9 +272,9 @@ class AssetImage extends AssetBundleImageProvider {
       directoryPath = assetUri.pathSegments[assetUri.pathSegments.length - 2];
     }
 
-    final Match match = _extractRatioRegExp.firstMatch(directoryPath);
+    final Match? match = _extractRatioRegExp.firstMatch(directoryPath);
     if (match != null && match.groupCount > 0)
-      return double.parse(match.group(1));
+      return double.parse(match.group(1)!);
     return _naturalResolution; // i.e. default to 1.0x
   }
 

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

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
 
 import 'dart:typed_data';
 
@@ -22,7 +21,7 @@ class MatrixUtils {
   /// nothing but a 2D translation.
   ///
   /// Otherwise, returns null.
-  static Offset getAsTranslation(Matrix4 transform) {
+  static Offset? getAsTranslation(Matrix4 transform) {
     assert(transform != null);
     final Float64List values = transform.storage;
     // Values are stored in column-major order.
@@ -49,7 +48,7 @@ class MatrixUtils {
   /// scale, if the matrix is nothing but a symmetric 2D scale transform.
   ///
   /// Otherwise, returns null.
-  static double getAsScale(Matrix4 transform) {
+  static double? getAsScale(Matrix4 transform) {
     assert(transform != null);
     final Float64List values = transform.storage;
     // Values are stored in column-major order.
@@ -75,12 +74,12 @@ class MatrixUtils {
 
   /// Returns true if the given matrices are exactly equal, and false
   /// otherwise. Null values are assumed to be the identity matrix.
-  static bool matrixEquals(Matrix4 a, Matrix4 b) {
+  static bool matrixEquals(Matrix4? a, Matrix4? b) {
     if (identical(a, b))
       return true;
     assert(a != null || b != null);
     if (a == null)
-      return isIdentity(b);
+      return isIdentity(b!);
     if (b == null)
       return isIdentity(a);
     assert(a != null && b != null);
@@ -165,8 +164,6 @@ class MatrixUtils {
         storage[7] == 0.0 &&
         storage[15] == 1.0;
 
-    _minMax ??= Float64List(4);
-
     _accumulate(storage, rect.left,  rect.top,    true,  isAffine);
     _accumulate(storage, rect.right, rect.top,    false, isAffine);
     _accumulate(storage, rect.left,  rect.bottom, false, isAffine);
@@ -175,7 +172,7 @@ class MatrixUtils {
     return Rect.fromLTRB(_minMax[0], _minMax[1], _minMax[2], _minMax[3]);
   }
 
-  static Float64List _minMax;
+  static late final Float64List _minMax = Float64List(4);
   static void _accumulate(Float64List m, double x, double y, bool first, bool isAffine) {
     final double w = isAffine ? 1.0 : 1.0 / (m[3] * x + m[7] * y + m[15]);
     final double tx = (m[0] * x + m[4] * y + m[12]) * w;
@@ -485,8 +482,8 @@ class MatrixUtils {
   /// almost always possible to end up seeing the inner side of the cylinder
   /// or the back side of the transformed plane before π / 2 when perspective > 0.
   static Matrix4 createCylindricalProjectionTransform({
-    @required double radius,
-    @required double angle,
+    required double radius,
+    required double angle,
     double perspective = 0.001,
     Axis orientation = Axis.vertical,
   }) {
@@ -541,7 +538,7 @@ class MatrixUtils {
 /// useful for [TransformProperty].
 ///
 /// If the argument is null, returns a list with the single string "null".
-List<String> debugDescribeTransform(Matrix4 transform) {
+List<String> debugDescribeTransform(Matrix4? transform) {
   if (transform == null)
     return const <String>['null'];
   return <String>[
@@ -559,9 +556,9 @@ class TransformProperty extends DiagnosticsProperty<Matrix4> {
   /// The [showName] and [level] arguments must not be null.
   TransformProperty(
     String name,
-    Matrix4 value, {
+    Matrix4? value, {
     bool showName = true,
-    Object defaultValue = kNoDefaultValue,
+    Object? defaultValue = kNoDefaultValue,
     DiagnosticLevel level = DiagnosticLevel.info,
   }) : assert(showName != null),
        assert(level != null),
@@ -574,15 +571,15 @@ class TransformProperty extends DiagnosticsProperty<Matrix4> {
        );
 
   @override
-  String valueToString({ TextTreeConfiguration parentConfiguration }) {
+  String valueToString({ TextTreeConfiguration? parentConfiguration }) {
     if (parentConfiguration != null && !parentConfiguration.lineBreakProperties) {
       // Format the value on a single line to be compatible with the parent's
       // style.
       final List<String> values = <String>[
-        '${debugFormatDouble(value.entry(0, 0))},${debugFormatDouble(value.entry(0, 1))},${debugFormatDouble(value.entry(0, 2))},${debugFormatDouble(value.entry(0, 3))}',
-        '${debugFormatDouble(value.entry(1, 0))},${debugFormatDouble(value.entry(1, 1))},${debugFormatDouble(value.entry(1, 2))},${debugFormatDouble(value.entry(1, 3))}',
-        '${debugFormatDouble(value.entry(2, 0))},${debugFormatDouble(value.entry(2, 1))},${debugFormatDouble(value.entry(2, 2))},${debugFormatDouble(value.entry(2, 3))}',
-        '${debugFormatDouble(value.entry(3, 0))},${debugFormatDouble(value.entry(3, 1))},${debugFormatDouble(value.entry(3, 2))},${debugFormatDouble(value.entry(3, 3))}',
+        '${debugFormatDouble(value!.entry(0, 0))},${debugFormatDouble(value!.entry(0, 1))},${debugFormatDouble(value!.entry(0, 2))},${debugFormatDouble(value!.entry(0, 3))}',
+        '${debugFormatDouble(value!.entry(1, 0))},${debugFormatDouble(value!.entry(1, 1))},${debugFormatDouble(value!.entry(1, 2))},${debugFormatDouble(value!.entry(1, 3))}',
+        '${debugFormatDouble(value!.entry(2, 0))},${debugFormatDouble(value!.entry(2, 1))},${debugFormatDouble(value!.entry(2, 2))},${debugFormatDouble(value!.entry(2, 3))}',
+        '${debugFormatDouble(value!.entry(3, 0))},${debugFormatDouble(value!.entry(3, 1))},${debugFormatDouble(value!.entry(3, 2))},${debugFormatDouble(value!.entry(3, 3))}',
       ];
       return '[${values.join('; ')}]';
     }

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

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
 
 import 'dart:ui' as ui show lerpDouble;
 
@@ -54,12 +53,12 @@ class RoundedRectangleBorder extends OutlinedBorder {
   }
 
   @override
-  ShapeBorder lerpFrom(ShapeBorder a, double t) {
+  ShapeBorder? lerpFrom(ShapeBorder? a, double t) {
     assert(t != null);
     if (a is RoundedRectangleBorder) {
       return RoundedRectangleBorder(
         side: BorderSide.lerp(a.side, side, t),
-        borderRadius: BorderRadiusGeometry.lerp(a.borderRadius, borderRadius, t),
+        borderRadius: BorderRadiusGeometry.lerp(a.borderRadius, borderRadius, t)!,
       );
     }
     if (a is CircleBorder) {
@@ -73,12 +72,12 @@ class RoundedRectangleBorder extends OutlinedBorder {
   }
 
   @override
-  ShapeBorder lerpTo(ShapeBorder b, double t) {
+  ShapeBorder? lerpTo(ShapeBorder? b, double t) {
     assert(t != null);
     if (b is RoundedRectangleBorder) {
       return RoundedRectangleBorder(
         side: BorderSide.lerp(side, b.side, t),
-        borderRadius: BorderRadiusGeometry.lerp(borderRadius, b.borderRadius, t),
+        borderRadius: BorderRadiusGeometry.lerp(borderRadius, b.borderRadius, t)!,
       );
     }
     if (b is CircleBorder) {
@@ -94,7 +93,7 @@ class RoundedRectangleBorder extends OutlinedBorder {
   /// Returns a copy of this RoundedRectangleBorder with the given fields
   /// replaced with the new values.
   @override
-  RoundedRectangleBorder copyWith({ BorderSide side, BorderRadius borderRadius }) {
+  RoundedRectangleBorder copyWith({ BorderSide? side, BorderRadius? borderRadius }) {
     return RoundedRectangleBorder(
       side: side ?? this.side,
       borderRadius: borderRadius ?? this.borderRadius,
@@ -102,19 +101,19 @@ class RoundedRectangleBorder extends OutlinedBorder {
   }
 
   @override
-  Path getInnerPath(Rect rect, { TextDirection textDirection }) {
+  Path getInnerPath(Rect rect, { TextDirection? textDirection }) {
     return Path()
       ..addRRect(borderRadius.resolve(textDirection).toRRect(rect).deflate(side.width));
   }
 
   @override
-  Path getOuterPath(Rect rect, { TextDirection textDirection }) {
+  Path getOuterPath(Rect rect, { TextDirection? textDirection }) {
     return Path()
       ..addRRect(borderRadius.resolve(textDirection).toRRect(rect));
   }
 
   @override
-  void paint(Canvas canvas, Rect rect, { TextDirection textDirection }) {
+  void paint(Canvas canvas, Rect rect, { TextDirection? textDirection }) {
     switch (side.style) {
       case BorderStyle.none:
         break;
@@ -154,7 +153,7 @@ class _RoundedRectangleToCircleBorder extends OutlinedBorder {
   const _RoundedRectangleToCircleBorder({
     BorderSide side = BorderSide.none,
     this.borderRadius = BorderRadius.zero,
-    @required this.circleness,
+    required this.circleness,
   }) : assert(side != null),
        assert(borderRadius != null),
        assert(circleness != null),
@@ -179,12 +178,12 @@ class _RoundedRectangleToCircleBorder extends OutlinedBorder {
   }
 
   @override
-  ShapeBorder lerpFrom(ShapeBorder a, double t) {
+  ShapeBorder? lerpFrom(ShapeBorder? a, double t) {
     assert(t != null);
     if (a is RoundedRectangleBorder) {
       return _RoundedRectangleToCircleBorder(
         side: BorderSide.lerp(a.side, side, t),
-        borderRadius: BorderRadiusGeometry.lerp(a.borderRadius, borderRadius, t),
+        borderRadius: BorderRadiusGeometry.lerp(a.borderRadius, borderRadius, t)!,
         circleness: circleness * t,
       );
     }
@@ -198,19 +197,19 @@ class _RoundedRectangleToCircleBorder extends OutlinedBorder {
     if (a is _RoundedRectangleToCircleBorder) {
       return _RoundedRectangleToCircleBorder(
         side: BorderSide.lerp(a.side, side, t),
-        borderRadius: BorderRadiusGeometry.lerp(a.borderRadius, borderRadius, t),
-        circleness: ui.lerpDouble(a.circleness, circleness, t),
+        borderRadius: BorderRadiusGeometry.lerp(a.borderRadius, borderRadius, t)!,
+        circleness: ui.lerpDouble(a.circleness, circleness, t)!,
       );
     }
     return super.lerpFrom(a, t);
   }
 
   @override
-  ShapeBorder lerpTo(ShapeBorder b, double t) {
+  ShapeBorder? lerpTo(ShapeBorder? b, double t) {
     if (b is RoundedRectangleBorder) {
       return _RoundedRectangleToCircleBorder(
         side: BorderSide.lerp(side, b.side, t),
-        borderRadius: BorderRadiusGeometry.lerp(borderRadius, b.borderRadius, t),
+        borderRadius: BorderRadiusGeometry.lerp(borderRadius, b.borderRadius, t)!,
         circleness: circleness * (1.0 - t),
       );
     }
@@ -224,8 +223,8 @@ class _RoundedRectangleToCircleBorder extends OutlinedBorder {
     if (b is _RoundedRectangleToCircleBorder) {
       return _RoundedRectangleToCircleBorder(
         side: BorderSide.lerp(side, b.side, t),
-        borderRadius: BorderRadiusGeometry.lerp(borderRadius, b.borderRadius, t),
-        circleness: ui.lerpDouble(circleness, b.circleness, t),
+        borderRadius: BorderRadiusGeometry.lerp(borderRadius, b.borderRadius, t)!,
+        circleness: ui.lerpDouble(circleness, b.circleness, t)!,
       );
     }
     return super.lerpTo(b, t);
@@ -253,7 +252,7 @@ class _RoundedRectangleToCircleBorder extends OutlinedBorder {
     }
   }
 
-  BorderRadius _adjustBorderRadius(Rect rect, TextDirection textDirection) {
+  BorderRadius? _adjustBorderRadius(Rect rect, TextDirection? textDirection) {
     final BorderRadius resolvedRadius = borderRadius.resolve(textDirection);
     if (circleness == 0.0)
       return resolvedRadius;
@@ -261,19 +260,19 @@ class _RoundedRectangleToCircleBorder extends OutlinedBorder {
   }
 
   @override
-  Path getInnerPath(Rect rect, { TextDirection textDirection }) {
+  Path getInnerPath(Rect rect, { TextDirection? textDirection }) {
     return Path()
-      ..addRRect(_adjustBorderRadius(rect, textDirection).toRRect(_adjustRect(rect)).deflate(side.width));
+      ..addRRect(_adjustBorderRadius(rect, textDirection)!.toRRect(_adjustRect(rect)).deflate(side.width));
   }
 
   @override
-  Path getOuterPath(Rect rect, { TextDirection textDirection }) {
+  Path getOuterPath(Rect rect, { TextDirection? textDirection }) {
     return Path()
-      ..addRRect(_adjustBorderRadius(rect, textDirection).toRRect(_adjustRect(rect)));
+      ..addRRect(_adjustBorderRadius(rect, textDirection)!.toRRect(_adjustRect(rect)));
   }
 
   @override
-  _RoundedRectangleToCircleBorder copyWith({ BorderSide side, BorderRadius borderRadius, double circleness }) {
+  _RoundedRectangleToCircleBorder copyWith({ BorderSide? side, BorderRadius? borderRadius, double? circleness }) {
     return _RoundedRectangleToCircleBorder(
       side: side ?? this.side,
       borderRadius: borderRadius ?? this.borderRadius,
@@ -282,16 +281,16 @@ class _RoundedRectangleToCircleBorder extends OutlinedBorder {
   }
 
   @override
-  void paint(Canvas canvas, Rect rect, { TextDirection textDirection }) {
+  void paint(Canvas canvas, Rect rect, { TextDirection? textDirection }) {
     switch (side.style) {
       case BorderStyle.none:
         break;
       case BorderStyle.solid:
         final double width = side.width;
         if (width == 0.0) {
-          canvas.drawRRect(_adjustBorderRadius(rect, textDirection).toRRect(_adjustRect(rect)), side.toPaint());
+          canvas.drawRRect(_adjustBorderRadius(rect, textDirection)!.toRRect(_adjustRect(rect)), side.toPaint());
         } else {
-          final RRect outer = _adjustBorderRadius(rect, textDirection).toRRect(_adjustRect(rect));
+          final RRect outer = _adjustBorderRadius(rect, textDirection)!.toRRect(_adjustRect(rect));
           final RRect inner = outer.deflate(width);
           final Paint paint = Paint()
             ..color = side.color;

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

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
 
 import 'package:flutter/foundation.dart';
 
@@ -77,7 +76,7 @@ class ShapeDecoration extends Decoration {
     this.image,
     this.gradient,
     this.shadows,
-    @required this.shape,
+    required this.shape,
   }) : assert(!(color != null && gradient != null)),
        assert(shape != null);
 
@@ -97,18 +96,18 @@ class ShapeDecoration extends Decoration {
     switch (source.shape) {
       case BoxShape.circle:
         if (source.border != null) {
-          assert(source.border.isUniform);
-          shape = CircleBorder(side: source.border.top);
+          assert(source.border!.isUniform);
+          shape = CircleBorder(side: source.border!.top);
         } else {
           shape = const CircleBorder();
         }
         break;
       case BoxShape.rectangle:
         if (source.borderRadius != null) {
-          assert(source.border == null || source.border.isUniform);
+          assert(source.border == null || source.border!.isUniform);
           shape = RoundedRectangleBorder(
             side: source.border?.top ?? BorderSide.none,
-            borderRadius: source.borderRadius,
+            borderRadius: source.borderRadius!,
           );
         } else {
           shape = source.border ?? const Border();
@@ -134,19 +133,19 @@ class ShapeDecoration extends Decoration {
   /// The color is under the [image].
   ///
   /// If a [gradient] is specified, [color] must be null.
-  final Color color;
+  final Color? color;
 
   /// A gradient to use when filling the shape.
   ///
   /// The gradient is under the [image].
   ///
   /// If a [color] is specified, [gradient] must be null.
-  final Gradient gradient;
+  final Gradient? gradient;
 
   /// An image to paint inside the shape (clipped to its outline).
   ///
   /// The image is drawn over the [color] or [gradient].
-  final DecorationImage image;
+  final DecorationImage? image;
 
   /// A list of shadows cast by the [shape].
   ///
@@ -155,7 +154,7 @@ class ShapeDecoration extends Decoration {
   ///  * [kElevationToShadow], for some predefined shadows used in Material
   ///    Design.
   ///  * [PhysicalModel], a widget for showing shadows.
-  final List<BoxShadow> shadows;
+  final List<BoxShadow>? shadows;
 
   /// The shape to fill the [color], [gradient], and [image] into and to cast as
   /// the [shadows].
@@ -191,23 +190,23 @@ class ShapeDecoration extends Decoration {
   bool get isComplex => shadows != null;
 
   @override
-  ShapeDecoration lerpFrom(Decoration a, double t) {
+  ShapeDecoration? lerpFrom(Decoration? a, double t) {
     if (a is BoxDecoration) {
       return ShapeDecoration.lerp(ShapeDecoration.fromBoxDecoration(a), this, t);
     } else if (a == null || a is ShapeDecoration) {
       return ShapeDecoration.lerp(a as ShapeDecoration, this, t);
     }
-    return super.lerpFrom(a, t) as ShapeDecoration;
+    return super.lerpFrom(a, t) as ShapeDecoration?;
   }
 
   @override
-  ShapeDecoration lerpTo(Decoration b, double t) {
+  ShapeDecoration? lerpTo(Decoration? b, double t) {
     if (b is BoxDecoration) {
       return ShapeDecoration.lerp(this, ShapeDecoration.fromBoxDecoration(b), t);
     } else if (b == null || b is ShapeDecoration) {
       return ShapeDecoration.lerp(this, b as ShapeDecoration, t);
     }
-    return super.lerpTo(b, t) as ShapeDecoration;
+    return super.lerpTo(b, t) as ShapeDecoration?;
   }
 
   /// Linearly interpolate between two shapes.
@@ -228,7 +227,7 @@ class ShapeDecoration extends Decoration {
   ///  * [lerpFrom] and [lerpTo], which are used to implement [Decoration.lerp]
   ///    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) {
+  static ShapeDecoration? lerp(ShapeDecoration? a, ShapeDecoration? b, double t) {
     assert(t != null);
     if (a == null && b == null)
       return null;
@@ -241,9 +240,9 @@ class ShapeDecoration extends Decoration {
     return ShapeDecoration(
       color: Color.lerp(a?.color, b?.color, t),
       gradient: Gradient.lerp(a?.gradient, b?.gradient, t),
-      image: t < 0.5 ? a.image : b.image, // TODO(ianh): cross-fade the image
+      image: t < 0.5 ? a!.image : b!.image, // TODO(ianh): cross-fade the image
       shadows: BoxShadow.lerpList(a?.shadows, b?.shadows, t),
-      shape: ShapeBorder.lerp(a?.shape, b?.shape, t),
+      shape: ShapeBorder.lerp(a?.shape, b?.shape, t)!,
     );
   }
 
@@ -284,14 +283,14 @@ class ShapeDecoration extends Decoration {
   }
 
   @override
-  bool hitTest(Size size, Offset position, { TextDirection textDirection }) {
+  bool hitTest(Size size, Offset position, { TextDirection? textDirection }) {
     return shape.getOuterPath(Offset.zero & size, textDirection: textDirection).contains(position);
   }
 
   @override
-  _ShapeDecorationPainter createBoxPainter([ VoidCallback onChanged ]) {
+  _ShapeDecorationPainter createBoxPainter([ VoidCallback? onChanged ]) {
     assert(onChanged != null || image == null);
-    return _ShapeDecorationPainter(this, onChanged);
+    return _ShapeDecorationPainter(this, onChanged!);
   }
 }
 
@@ -303,16 +302,19 @@ class _ShapeDecorationPainter extends BoxPainter {
 
   final ShapeDecoration _decoration;
 
-  Rect _lastRect;
-  TextDirection _lastTextDirection;
-  Path _outerPath;
-  Path _innerPath;
-  Paint _interiorPaint;
-  int _shadowCount;
-  List<Path> _shadowPaths;
-  List<Paint> _shadowPaints;
+  Rect? _lastRect;
+  TextDirection? _lastTextDirection;
+  late Path _outerPath;
+  Path? _innerPath;
+  Paint? _interiorPaint;
+  int? _shadowCount;
+  late List<Path> _shadowPaths;
+  late List<Paint> _shadowPaints;
 
-  void _precache(Rect rect, TextDirection textDirection) {
+  @override
+  VoidCallback get onChanged => super.onChanged!;
+
+  void _precache(Rect rect, TextDirection? textDirection) {
     assert(rect != null);
     if (rect == _lastRect && textDirection == _lastTextDirection)
       return;
@@ -324,22 +326,22 @@ class _ShapeDecorationPainter extends BoxPainter {
     if (_interiorPaint == null && (_decoration.color != null || _decoration.gradient != null)) {
       _interiorPaint = Paint();
       if (_decoration.color != null)
-        _interiorPaint.color = _decoration.color;
+        _interiorPaint!.color = _decoration.color!;
     }
     if (_decoration.gradient != null)
-      _interiorPaint.shader = _decoration.gradient.createShader(rect);
+      _interiorPaint!.shader = _decoration.gradient!.createShader(rect);
     if (_decoration.shadows != null) {
       if (_shadowCount == null) {
-        _shadowCount = _decoration.shadows.length;
-        _shadowPaths = List<Path>(_shadowCount);
-        _shadowPaints = List<Paint>(_shadowCount);
-        for (int index = 0; index < _shadowCount; index += 1)
-          _shadowPaints[index] = _decoration.shadows[index].toPaint();
-      }
-      for (int index = 0; index < _shadowCount; index += 1) {
-        final BoxShadow shadow = _decoration.shadows[index];
-        _shadowPaths[index] = _decoration.shape.getOuterPath(rect.shift(shadow.offset).inflate(shadow.spreadRadius), textDirection: textDirection);
+        _shadowCount = _decoration.shadows!.length;
+        _shadowPaints = <Paint>[
+          ..._decoration.shadows!.map((BoxShadow shadow) => shadow.toPaint()),
+        ];
       }
+      _shadowPaths = <Path>[
+        ..._decoration.shadows!.map((BoxShadow shadow) {
+          return _decoration.shape.getOuterPath(rect.shift(shadow.offset).inflate(shadow.spreadRadius), textDirection: textDirection);
+        }),
+      ];
     }
     if (_interiorPaint != null || _shadowCount != null)
       _outerPath = _decoration.shape.getOuterPath(rect, textDirection: textDirection);
@@ -352,22 +354,22 @@ class _ShapeDecorationPainter extends BoxPainter {
 
   void _paintShadows(Canvas canvas) {
     if (_shadowCount != null) {
-      for (int index = 0; index < _shadowCount; index += 1)
+      for (int index = 0; index < _shadowCount!; index += 1)
         canvas.drawPath(_shadowPaths[index], _shadowPaints[index]);
     }
   }
 
   void _paintInterior(Canvas canvas) {
     if (_interiorPaint != null)
-      canvas.drawPath(_outerPath, _interiorPaint);
+      canvas.drawPath(_outerPath, _interiorPaint!);
   }
 
-  DecorationImagePainter _imagePainter;
+  DecorationImagePainter? _imagePainter;
   void _paintImage(Canvas canvas, ImageConfiguration configuration) {
     if (_decoration.image == null)
       return;
-    _imagePainter ??= _decoration.image.createPainter(onChanged);
-    _imagePainter.paint(canvas, _lastRect, _innerPath, configuration);
+    _imagePainter ??= _decoration.image!.createPainter(onChanged);
+    _imagePainter!.paint(canvas, _lastRect!, _innerPath, configuration);
   }
 
   @override
@@ -380,8 +382,8 @@ class _ShapeDecorationPainter extends BoxPainter {
   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;
+    final Rect rect = offset & configuration.size!;
+    final TextDirection? textDirection = configuration.textDirection;
     _precache(rect, textDirection);
     _paintShadows(canvas);
     _paintInterior(canvas);