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// 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 <gtk/gtk.h>
#include <glib.h>
#include "base/message_pump.h"
#include "base/observer_list.h"
#include "base/time.h"
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 Time& 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, gpointer 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.
Time 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_;
GPollFD wakeup_gpollfd_;
// List of observers.
ObserverList<Observer> observers_;
DISALLOW_COPY_AND_ASSIGN(MessagePumpForUI);
};
} // namespace base
#endif // BASE_MESSAGE_PUMP_GLIB_H_
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