widget/android/WindowEvent.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_widget_WindowEvent_h
   8 #define mozilla_widget_WindowEvent_h
   9
  10 #include "nsThreadUtils.h"
  11 #include "mozilla/jni/Natives.h"
  12
  13 namespace mozilla {
  14 namespace widget {
  15
  16 // An Event subclass that guards against stale events.
  17 // (See the implmentation of mozilla::jni::detail::ProxyNativeCall for info
  18 //  about the default template parameters for this class)
  19 template <typename Lambda, bool IsStatic = Lambda::isStatic,
  20           typename InstanceType = typename Lambda::ThisArgType,
  21           class Impl = typename Lambda::TargetClass>
  22 class WindowEvent : public Runnable {
  23   bool IsStaleCall() {
  24     if (IsStatic) {
  25       // Static calls are never stale.
  26       return false;
  27     }
  28
  29     return jni::NativePtrTraits<Impl>::IsStale(mInstance);
  30   }
  31
  32   Lambda mLambda;
  33   const InstanceType mInstance;
  34
  35  public:
  36   WindowEvent(Lambda&& aLambda, InstanceType&& aInstance)
  37       : Runnable("mozilla::widget::WindowEvent"),
  38         mLambda(std::move(aLambda)),
  39         mInstance(std::forward<InstanceType>(aInstance)) {}
  40
  41   explicit WindowEvent(Lambda&& aLambda)
  42       : Runnable("mozilla::widget::WindowEvent"),
  43         mLambda(std::move(aLambda)),
  44         mInstance(mLambda.GetThisArg()) {}
  45
  46   NS_IMETHOD Run() override {
  47     if (!IsStaleCall()) {
  48       mLambda();
  49     }
  50     return NS_OK;
  51   }
  52 };
  53
  54 }  // namespace widget
  55 }  // namespace mozilla
  56
  57 #endif  // mozilla_widget_WindowEvent_h