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

Author: goderbauer

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;
     }