Bug 947241. Make Gamepad used cached sequences for its buttons and axes. r=ted,peterv

dom/gamepad/Gamepad.cpp

@@ -19,7 +19,7 @@ NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(Gamepad)
   NS_INTERFACE_MAP_ENTRY(nsISupports)
 NS_INTERFACE_MAP_END
 
-NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE_2(Gamepad, mParent, mButtonsVariant)
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE_2(Gamepad, mParent, mButtons)
 
 Gamepad::Gamepad(nsISupports* aParent,
                  const nsAString& aID, uint32_t aIndex,
@@ -64,75 +64,10 @@ void
 Gamepad::SetAxis(uint32_t aAxis, double aValue)
 {
   MOZ_ASSERT(aAxis < mAxes.Length());
-  mAxes[aAxis] = aValue;
-}
-
-nsresult
-Gamepad::GetButtons(nsIVariant** aButtons)
-{
-  if (mButtonsVariant) {
-    NS_ADDREF(*aButtons = mButtonsVariant);
-    return NS_OK;
+  if (mAxes[aAxis] != aValue) {
+    mAxes[aAxis] = aValue;
+    GamepadBinding::ClearCachedAxesValue(this);
   }
-
-  nsRefPtr<nsVariant> out = new nsVariant();
-  NS_ENSURE_STATE(out);
-
-  if (mButtons.Length() == 0) {
-    nsresult rv = out->SetAsEmptyArray();
-    NS_ENSURE_SUCCESS(rv, rv);
-  } else {
-    // Note: The resulting nsIVariant dupes both the array and its elements.
-    GamepadButton** array = reinterpret_cast<GamepadButton**>
-                      (NS_Alloc(mButtons.Length() * sizeof(GamepadButton*)));
-    NS_ENSURE_TRUE(array, NS_ERROR_OUT_OF_MEMORY);
-
-    for (uint32_t i = 0; i < mButtons.Length(); ++i) {
-      array[i] = mButtons[i].get();
-    }
-
-    nsresult rv = out->SetAsArray(nsIDataType::VTYPE_INTERFACE,
-                                  nullptr,
-                                  mButtons.Length(),
-                                  reinterpret_cast<void*>(array));
-    NS_Free(array);
-    NS_ENSURE_SUCCESS(rv, rv);
-  }
-
-  mButtonsVariant = out;
-  *aButtons = out.forget().get();
-  return NS_OK;
-}
-
-nsresult
-Gamepad::GetAxes(nsIVariant** aAxes)
-{
-  nsRefPtr<nsVariant> out = new nsVariant();
-  NS_ENSURE_STATE(out);
-
-  if (mAxes.Length() == 0) {
-    nsresult rv = out->SetAsEmptyArray();
-    NS_ENSURE_SUCCESS(rv, rv);
-  } else {
-    // Note: The resulting nsIVariant dupes both the array and its elements.
-    double* array = reinterpret_cast<double*>
-                              (NS_Alloc(mAxes.Length() * sizeof(double)));
-    NS_ENSURE_TRUE(array, NS_ERROR_OUT_OF_MEMORY);
-
-    for (uint32_t i = 0; i < mAxes.Length(); ++i) {
-      array[i] = mAxes[i];
-    }
-
-    nsresult rv = out->SetAsArray(nsIDataType::VTYPE_DOUBLE,
-                                  nullptr,
-                                  mAxes.Length(),
-                                  reinterpret_cast<void*>(array));
-    NS_Free(array);
-    NS_ENSURE_SUCCESS(rv, rv);
-  }
-
-  *aAxes = out.forget().get();
-  return NS_OK;
 }
 
 void
@@ -148,9 +83,14 @@ Gamepad::SyncState(Gamepad* aOther)
     mButtons[i]->SetPressed(aOther->mButtons[i]->Pressed());
     mButtons[i]->SetValue(aOther->mButtons[i]->Value());
   }
+  bool changed = false;
   for (uint32_t i = 0; i < mAxes.Length(); ++i) {
+    changed = changed || (mAxes[i] != aOther->mAxes[i]);
     mAxes[i] = aOther->mAxes[i];
   }
+  if (changed) {
+    GamepadBinding::ClearCachedAxesValue(this);
+  }
 }
 
 already_AddRefed<Gamepad>

dom/gamepad/Gamepad.h

@@ -9,7 +9,6 @@
 #include "mozilla/dom/GamepadButton.h"
 #include <stdint.h>
 #include "nsCOMPtr.h"
-#include "nsIVariant.h"
 #include "nsString.h"
 #include "nsTArray.h"
 #include "nsWrapperCache.h"
@@ -78,26 +77,19 @@ public:
     return mIndex;
   }
 
-  already_AddRefed<nsIVariant> GetButtons(mozilla::ErrorResult& aRv)
+  void GetButtons(nsTArray<nsRefPtr<GamepadButton>>& aButtons) const
   {
-    nsCOMPtr<nsIVariant> buttons;
-    aRv = GetButtons(getter_AddRefs(buttons));
-    return buttons.forget();
+    aButtons = mButtons;
   }
 
-  already_AddRefed<nsIVariant> GetAxes(mozilla::ErrorResult& aRv)
+  void GetAxes(nsTArray<double>& aAxes) const
   {
-    nsCOMPtr<nsIVariant> axes;
-    aRv = GetAxes(getter_AddRefs(axes));
-    return axes.forget();
+    aAxes = mAxes;
   }
 
 private:
   virtual ~Gamepad() {}
 
-  nsresult GetButtons(nsIVariant** aButtons);
-  nsresult GetAxes(nsIVariant** aAxes);
-
 protected:
   nsCOMPtr<nsISupports> mParent;
   nsString mID;
@@ -112,9 +104,6 @@ protected:
   // Current state of buttons, axes.
   nsTArray<nsRefPtr<GamepadButton>> mButtons;
   nsTArray<double> mAxes;
-
-  // Cached variant array.
-  nsCOMPtr<nsIVariant> mButtonsVariant;
 };
 
 } // namespace dom

dom/webidl/Gamepad.webidl

@@ -3,8 +3,6 @@
  * 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/. */
 
-interface nsIVariant;
-
 [Pref="dom.gamepad.enabled"]
 interface GamepadButton {
   readonly    attribute boolean pressed;
@@ -39,13 +37,13 @@ interface Gamepad {
    * The current state of all buttons on the device, an
    * array of GamepadButton.
    */
-  [Throws]
-  readonly attribute nsIVariant buttons;
+  [Pure, Cached]
+  readonly attribute sequence<GamepadButton> buttons;
 
   /**
    * The current position of all axes on the device, an
    * array of doubles.
    */
-  [Throws]
-  readonly attribute nsIVariant axes;
+  [Pure, Cached]
+  readonly attribute sequence<double> axes;
 };