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