Check the matrix in pushTransform (#8758)

Fixes flutter/flutter#31650

flow/layers/transform_layer.cc

@@ -15,8 +15,8 @@ TransformLayer::~TransformLayer() = default;
 void TransformLayer::Preroll(PrerollContext* context, const SkMatrix& matrix) {
   // Checks (in some degree) that SkMatrix transform_ is valid and initialized.
   //
-  // We need this even if is_set_ is true since one can call set_transform with
-  // an uninitialized SkMatrix.
+  // We need this even if transform_ is initialized to identity since one can
+  // call set_transform with an uninitialized SkMatrix.
   //
   // If transform_ is uninitialized, this assert may look flaky as it doesn't
   // fail all the time, and some rerun may make it pass. But don't ignore it and

lib/ui/compositing.dart

@@ -57,10 +57,7 @@ class SceneBuilder extends NativeFieldWrapperClass2 {
   ///
   /// See [pop] for details about the operation stack.
   EngineLayer pushTransform(Float64List matrix4) {
-    if (matrix4 == null)
-      throw new ArgumentError('"matrix4" argument cannot be null');
-    if (matrix4.length != 16)
-      throw new ArgumentError('"matrix4" must have 16 entries.');
+    assert(_matrix4IsValid(matrix4));
     return _pushTransform(matrix4);
   }
   EngineLayer _pushTransform(Float64List matrix4) native 'SceneBuilder_pushTransform';

lib/ui/painting.dart

@@ -42,6 +42,7 @@ bool _offsetIsValid(Offset offset) {
 bool _matrix4IsValid(Float64List matrix4) {
   assert(matrix4 != null, 'Matrix4 argument was null.');
   assert(matrix4.length == 16, 'Matrix4 must have 16 entries.');
+  assert(matrix4.every((double value) => value.isFinite), 'Matrix4 entries must be finite.');
   return true;
 }
 

testing/dart/compositing_test.dart

+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:typed_data' show Float64List;
+import 'dart:ui';
+
+import 'package:test/test.dart';
+
+void main() {
+  test('pushTransform validates the matrix', () {
+    final SceneBuilder builder = SceneBuilder();
+    final Float64List matrix4 = Float64List.fromList(<double>[
+      1, 0, 0, 0,
+      0, 1, 0, 0,
+      0, 0, 1, 0,
+      0, 0, 0, 1,
+    ]);
+    expect(builder.pushTransform(matrix4), isNotNull);
+
+    final Float64List matrix4WrongLength = Float64List.fromList(<double>[
+      1, 0, 0, 0,
+      0, 1, 0,
+      0, 0, 1, 0,
+      0, 0, 0,
+    ]);
+    expect(
+      () => builder.pushTransform(matrix4WrongLength),
+      throwsA(const TypeMatcher<AssertionError>()),
+    );
+
+    final Float64List matrix4NaN = Float64List.fromList(<double>[
+      1, 0, 0, 0,
+      0, 1, 0, 0,
+      0, 0, 1, 0,
+      0, 0, 0, double.nan,
+    ]);
+    expect(
+      () => builder.pushTransform(matrix4NaN),
+      throwsA(const TypeMatcher<AssertionError>()),
+    );
+
+    final Float64List matrix4Infinity = Float64List.fromList(<double>[
+      1, 0, 0, 0,
+      0, 1, 0, 0,
+      0, 0, 1, 0,
+      0, 0, 0, double.infinity,
+    ]);
+    expect(
+      () => builder.pushTransform(matrix4NaN),
+      throwsA(const TypeMatcher<AssertionError>()),
+    );
+  });
+}