Canvas.concat takes a 16-element Float32List instead of an array.

sky/engine/core/painting/Matrix4.cpp

Index: sky/engine/core/painting/Matrix4.cpp
diff --git a/sky/engine/core/painting/Rect.cpp b/sky/engine/core/painting/Matrix4.cpp
similarity index 51%
copy from sky/engine/core/painting/Rect.cpp
copy to sky/engine/core/painting/Matrix4.cpp
index ee0bb3cd26634b7f61298540aaafdca93e0079ce..220ac6d927006675958413f38760689ec45dee10 100644
--- a/sky/engine/core/painting/Rect.cpp
+++ b/sky/engine/core/painting/Matrix4.cpp
@@ -3,7 +3,7 @@
 // found in the LICENSE file.
 
 #include "sky/engine/config.h"
-#include "sky/engine/core/painting/Rect.h"
+#include "sky/engine/core/painting/Matrix4.h"
 
 #include "sky/engine/core/script/dom_dart_state.h"
 #include "sky/engine/tonic/dart_error.h"
@@ -12,18 +12,19 @@
 
 namespace blink {
 
-// Convert dart_rect._value[0...3] ==> SkRect.
-Rect DartConverter<Rect>::FromArgumentsWithNullCheck(Dart_NativeArguments args,
-                                                     int index,
-                                                     Dart_Handle& exception) {
-  Rect result;
+// Convert dart_matrix._value[0...16] ==> SkMatrix.
+Matrix4 DartConverter<Matrix4>::FromArgumentsWithNullCheck(
+    Dart_NativeArguments args,
+    int index,
+    Dart_Handle& exception) {
+  Matrix4 result;
   result.is_null = true;
 
-  Dart_Handle dart_rect = Dart_GetNativeArgument(args, index);
-  DCHECK(!LogIfError(dart_rect));
+  Dart_Handle dart_matrix = Dart_GetNativeArgument(args, index);
+  DCHECK(!LogIfError(dart_matrix));
 
   Dart_Handle value =
-      Dart_GetField(dart_rect, DOMDartState::Current()->value_handle());
+      Dart_GetField(dart_matrix, DOMDartState::Current()->value_handle());
   if (Dart_IsNull(value))
     return result;
 
@@ -33,16 +34,16 @@ Rect DartConverter<Rect>::FromArgumentsWithNullCheck(Dart_NativeArguments args,
   Dart_TypedDataAcquireData(
       value, &type, reinterpret_cast<void**>(&data), &num_elements);
   DCHECK(!LogIfError(value));
-  ASSERT(type == Dart_TypedData_kFloat32 && num_elements == 4);
+  ASSERT(type == Dart_TypedData_kFloat32 && num_elements == 16);
 
-  SkScalar* dest[] = {
-    &result.sk_rect.fLeft,
-    &result.sk_rect.fTop,
-    &result.sk_rect.fRight,
-    &result.sk_rect.fBottom
+  // Mappings from SkMatrix-index to input-index.
+  static const int kMappings[] = {
+    0, 4, 12,
+    1, 5, 13,
+    3, 7, 15,
   };
-  for (intptr_t i = 0; i < 4; ++i)
-    *dest[i] = data[i];
+  for (intptr_t i = 0; i < 9; ++i)
+    result.sk_matrix[i] = data[kMappings[i]];
 
   Dart_TypedDataReleaseData(value);