Bug 1043853 - Share the code for structured cloning of ImageData objects across main-thread and workers implementations; r=jst

dom/base/nsJSEnvironment.cpp

@@ -54,10 +54,11 @@
 #include "nsScriptNameSpaceManager.h"
 #include "StructuredCloneTags.h"
 #include "mozilla/AutoRestore.h"
-#include "mozilla/dom/ErrorEvent.h"
-#include "mozilla/dom/ImageData.h"
 #include "mozilla/dom/CryptoKey.h"
+#include "mozilla/dom/ErrorEvent.h"
 #include "mozilla/dom/ImageDataBinding.h"
+#include "mozilla/dom/ImageData.h"
+#include "mozilla/dom/StructuredClone.h"
 #include "mozilla/dom/SubtleCryptoBinding.h"
 #include "nsAXPCNativeCallContext.h"
 #include "mozilla/CycleCollectedJSRuntime.h"
@@ -2811,25 +2812,7 @@ NS_DOMReadStructuredClone(JSContext* cx,
                           void* closure)
 {
   if (tag == SCTAG_DOM_IMAGEDATA) {
-    // Read the information out of the stream.
-    uint32_t width, height;
-    JS::Rooted<JS::Value> dataArray(cx);
-    if (!JS_ReadUint32Pair(reader, &width, &height) ||
-        !JS_ReadTypedArray(reader, &dataArray)) {
-      return nullptr;
-    }
-    MOZ_ASSERT(dataArray.isObject());
-
-    // Protect the result from a moving GC in ~nsRefPtr.
-    JS::Rooted<JSObject*> result(cx);
-    {
-      // Construct the ImageData.
-      nsRefPtr<ImageData> imageData = new ImageData(width, height,
-                                                    dataArray.toObject());
-      // Wrap it in a JS::Value.
-      result = imageData->WrapObject(cx);
-    }
-    return result;
+    return ReadStructuredCloneImageData(cx, reader);
   } else if (tag == SCTAG_DOM_WEBCRYPTO_KEY) {
     nsIGlobalObject *global = xpc::GetNativeForGlobal(JS::CurrentGlobalOrNull(cx));
     if (!global) {
@@ -2863,17 +2846,7 @@ NS_DOMWriteStructuredClone(JSContext* cx,
   // Handle ImageData cloning
   ImageData* imageData;
   if (NS_SUCCEEDED(UNWRAP_OBJECT(ImageData, obj, imageData))) {
-    // Prepare the ImageData internals.
-    uint32_t width = imageData->Width();
-    uint32_t height = imageData->Height();
-    JS::Rooted<JSObject*> dataArray(cx, imageData->GetDataObject());
-
-    // Write the internals to the stream.
-    JSAutoCompartment ac(cx, dataArray);
-    JS::Rooted<JS::Value> arrayValue(cx, JS::ObjectValue(*dataArray));
-    return JS_WriteUint32Pair(writer, SCTAG_DOM_IMAGEDATA, 0) &&
-           JS_WriteUint32Pair(writer, width, height) &&
-           JS_WriteTypedArray(writer, arrayValue);
+    return WriteStructuredCloneImageData(cx, writer, imageData);
   }
 
   // Handle Key cloning

dom/bindings/StructuredClone.cpp

@@ -0,0 +1,56 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/StructuredClone.h"
+
+#include "js/StructuredClone.h"
+#include "mozilla/dom/ImageData.h"
+#include "mozilla/dom/StructuredCloneTags.h"
+
+namespace mozilla {
+namespace dom {
+
+JSObject*
+ReadStructuredCloneImageData(JSContext* aCx, JSStructuredCloneReader* aReader)
+{
+  // Read the information out of the stream.
+  uint32_t width, height;
+  JS::Rooted<JS::Value> dataArray(aCx);
+  if (!JS_ReadUint32Pair(aReader, &width, &height) ||
+      !JS_ReadTypedArray(aReader, &dataArray)) {
+    return nullptr;
+  }
+  MOZ_ASSERT(dataArray.isObject());
+
+  // Protect the result from a moving GC in ~nsRefPtr.
+  JS::Rooted<JSObject*> result(aCx);
+  {
+    // Construct the ImageData.
+    nsRefPtr<ImageData> imageData = new ImageData(width, height,
+                                                  dataArray.toObject());
+    // Wrap it in a JS::Value.
+    result = imageData->WrapObject(aCx);
+  }
+  return result;
+}
+
+bool
+WriteStructuredCloneImageData(JSContext* aCx, JSStructuredCloneWriter* aWriter,
+                              ImageData* aImageData)
+{
+  uint32_t width = aImageData->Width();
+  uint32_t height = aImageData->Height();
+  JS::Rooted<JSObject*> dataArray(aCx, aImageData->GetDataObject());
+
+  JSAutoCompartment ac(aCx, dataArray);
+  JS::Rooted<JS::Value> arrayValue(aCx, JS::ObjectValue(*dataArray));
+  return JS_WriteUint32Pair(aWriter, SCTAG_DOM_IMAGEDATA, 0) &&
+         JS_WriteUint32Pair(aWriter, width, height) &&
+         JS_WriteTypedArray(aWriter, arrayValue);
+}
+
+} // namespace dom
+} // namespace mozilla

dom/bindings/StructuredClone.h

@@ -0,0 +1,25 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+class JSObject;
+struct JSContext;
+struct JSStructuredCloneReader;
+struct JSStructuredCloneWriter;
+
+namespace mozilla {
+namespace dom {
+
+class ImageData;
+
+JSObject*
+ReadStructuredCloneImageData(JSContext* aCx, JSStructuredCloneReader* aReader);
+
+bool
+WriteStructuredCloneImageData(JSContext* aCx, JSStructuredCloneWriter* aWriter,
+                              ImageData* aImageData);
+
+} // namespace dom
+} // namespace mozilla

dom/bindings/moz.build

@@ -30,6 +30,7 @@ EXPORTS.mozilla.dom += [
     'OwningNonNull.h',
     'PrimitiveConversions.h',
     'RootedDictionary.h',
+    'StructuredClone.h',
     'ToJSValue.h',
     'TypedArray.h',
     'UnionMember.h',
@@ -81,6 +82,10 @@ UNIFIED_SOURCES += [
     'ToJSValue.cpp',
 ]
 
+SOURCES += [
+    'StructuredClone.cpp',
+]
+
 include('/ipc/chromium/chromium-config.mozbuild')
 
 if CONFIG['MOZ_AUDIO_CHANNEL_MANAGER']:

dom/workers/WorkerPrivate.cpp

@@ -48,6 +48,7 @@
 #include "mozilla/dom/MessageEventBinding.h"
 #include "mozilla/dom/MessagePortList.h"
 #include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/dom/StructuredClone.h"
 #include "mozilla/dom/WorkerBinding.h"
 #include "mozilla/Preferences.h"
 #include "nsAlgorithm.h"
@@ -352,25 +353,7 @@ struct WorkerStructuredCloneCallbacks
     // See if the object is an ImageData.
     else if (aTag == SCTAG_DOM_IMAGEDATA) {
       MOZ_ASSERT(!aData);
-
-      // Read the information out of the stream.
-      uint32_t width, height;
-      JS::Rooted<JS::Value> dataArray(aCx);
-      if (!JS_ReadUint32Pair(aReader, &width, &height) ||
-          !JS_ReadTypedArray(aReader, &dataArray))
-      {
-        return nullptr;
-      }
-      MOZ_ASSERT(dataArray.isObject());
-
-      {
-        // Construct the ImageData.
-        nsRefPtr<ImageData> imageData = new ImageData(width, height,
-                                                      dataArray.toObject());
-        // Wrap it in a JS::Value, protected from a moving GC during ~nsRefPtr.
-        result = imageData->WrapObject(aCx);
-      }
-      return result;
+      return ReadStructuredCloneImageData(aCx, aReader);
     }
 
     Error(aCx, 0);
@@ -418,17 +401,7 @@ struct WorkerStructuredCloneCallbacks
     {
       ImageData* imageData = nullptr;
       if (NS_SUCCEEDED(UNWRAP_OBJECT(ImageData, aObj, imageData))) {
-        // Prepare the ImageData internals.
-        uint32_t width = imageData->Width();
-        uint32_t height = imageData->Height();
-        JS::Rooted<JSObject*> dataArray(aCx, imageData->GetDataObject());
-
-        // Write the internals to the stream.
-        JSAutoCompartment ac(aCx, dataArray);
-        JS::Rooted<JS::Value> arrayValue(aCx, JS::ObjectValue(*dataArray));
-        return JS_WriteUint32Pair(aWriter, SCTAG_DOM_IMAGEDATA, 0) &&
-               JS_WriteUint32Pair(aWriter, width, height) &&
-               JS_WriteTypedArray(aWriter, arrayValue);
+        return WriteStructuredCloneImageData(aCx, aWriter, imageData);
       }
     }