/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ /* vim: set ts=8 sts=2 et sw=2 tw=80: */ // Copyright (c) 2008 The Chromium Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #ifndef BASE_MESSAGE_PUMP_GLIB_H_ #define BASE_MESSAGE_PUMP_GLIB_H_ #include "base/message_pump.h" #include "base/observer_list.h" #include "base/time.h" #include "mozilla/UniquePtr.h" #include "mozilla/Atomics.h" typedef union _GdkEvent GdkEvent; typedef struct _GMainContext GMainContext; typedef struct _GPollFD GPollFD; typedef struct _GSource GSource; namespace base { // This class implements a MessagePump needed for TYPE_UI MessageLoops on // OS_LINUX platforms using GLib. class MessagePumpForUI : public MessagePump { public: // Observer is notified prior to a GdkEvent event being dispatched. As // Observers are notified of every change, they have to be FAST! class Observer { public: virtual ~Observer() {} // This method is called before processing a message. virtual void WillProcessEvent(GdkEvent* event) = 0; // This method is called after processing a message. virtual void DidProcessEvent(GdkEvent* event) = 0; }; // Dispatcher is used during a nested invocation of Run to dispatch events. // If Run is invoked with a non-NULL Dispatcher, MessageLoop does not // dispatch events (or invoke gtk_main_do_event), rather every event is // passed to Dispatcher's Dispatch method for dispatch. It is up to the // Dispatcher to dispatch, or not, the event. // // The nested loop is exited by either posting a quit, or returning false // from Dispatch. class Dispatcher { public: virtual ~Dispatcher() {} // Dispatches the event. If true is returned processing continues as // normal. If false is returned, the nested loop exits immediately. virtual bool Dispatch(GdkEvent* event) = 0; }; MessagePumpForUI(); virtual ~MessagePumpForUI(); // Like MessagePump::Run, but GdkEvent objects are routed through dispatcher. virtual void RunWithDispatcher(Delegate* delegate, Dispatcher* dispatcher); virtual void Run(Delegate* delegate) { RunWithDispatcher(delegate, NULL); } virtual void Quit(); virtual void ScheduleWork(); virtual void ScheduleDelayedWork(const TimeTicks& delayed_work_time); // Internal methods used for processing the pump callbacks. They are // public for simplicity but should not be used directly. HandlePrepare // is called during the prepare step of glib, and returns a timeout that // will be passed to the poll. HandleCheck is called after the poll // has completed, and returns whether or not HandleDispatch should be called. // HandleDispatch is called if HandleCheck returned true. int HandlePrepare(); bool HandleCheck(); void HandleDispatch(); // Adds an Observer, which will start receiving notifications immediately. void AddObserver(Observer* observer); // Removes an Observer. It is safe to call this method while an Observer is // receiving a notification callback. void RemoveObserver(Observer* observer); private: // We may make recursive calls to Run, so we save state that needs to be // separate between them in this structure type. struct RunState { Delegate* delegate; Dispatcher* dispatcher; // Used to flag that the current Run() invocation should return ASAP. bool should_quit; // Used to count how many Run() invocations are on the stack. int run_depth; // This keeps the state of whether the pump got signaled that there was new // work to be done. Since we eat the message on the wake up pipe as soon as // we get it, we keep that state here to stay consistent. bool has_work; }; // Invoked from EventDispatcher. Notifies all observers we're about to // process an event. void WillProcessEvent(GdkEvent* event); // Invoked from EventDispatcher. Notifies all observers we processed an // event. void DidProcessEvent(GdkEvent* event); // Callback prior to gdk dispatching an event. static void EventDispatcher(GdkEvent* event, void* data); RunState* state_; // This is a GLib structure that we can add event sources to. We use the // default GLib context, which is the one to which all GTK events are // dispatched. GMainContext* context_; // This is the time when we need to do delayed work. TimeTicks delayed_work_time_; // The work source. It is shared by all calls to Run and destroyed when // the message pump is destroyed. GSource* work_source_; // We use a wakeup pipe to make sure we'll get out of the glib polling phase // when another thread has scheduled us to do some work. There is a glib // mechanism g_main_context_wakeup, but this won't guarantee that our event's // Dispatch() will be called. int wakeup_pipe_read_; int wakeup_pipe_write_; // Use an autoptr to avoid needing the definition of GPollFD in the header. mozilla::UniquePtr<GPollFD> wakeup_gpollfd_; mozilla::Atomic<bool> pipe_full_; // List of observers. ObserverList<Observer> observers_; DISALLOW_COPY_AND_ASSIGN(MessagePumpForUI); }; } // namespace base #endif // BASE_MESSAGE_PUMP_GLIB_H_