Refactor the glib message-pump, and use it as the base for a gtk message pump and an X message pump.

base/message_pump_x.h

+// Copyright (c) 2011 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_X_H
+#define BASE_MESSAGE_PUMP_X_H
+
+#include "base/message_pump.h"
+#include "base/message_pump_glib.h"
+
+#include <bitset>
+
+#include <glib.h>
+#include <gtk/gtk.h>
+
+typedef union _XEvent XEvent;
+
+namespace base {
+
+// The documentation for this class is in message_pump_glib.h
+class BASE_API MessagePumpObserver {
+ public:
+   enum EventStatus {
+     EVENT_CONTINUE,    // The event should be dispatched as normal.
+     EVENT_HANDLED      // The event should not be processed any farther.
+   };
+
+  // This method is called before processing an XEvent. If the method returns
+  // EVENT_HANDLED, it indicates the event has already been handled, so the
+  // event is not processed any farther. If the method returns EVENT_CONTINUE,
+  // the event dispatching proceeds as normal.
+  virtual EventStatus WillProcessXEvent(XEvent* xevent);
+
+ protected:
+  virtual ~MessagePumpObserver() {}
+};
+
+// The documentation for this class is in message_pump_glib.h
+//
+// The nested loop is exited by either posting a quit, or returning EVENT_QUIT
+// from Dispatch.
+class MessagePumpDispatcher {
+ public:
+  enum DispatchStatus {
+    EVENT_IGNORED,    // The event was not processed.
+    EVENT_PROCESSED,  // The event has been processed.
+    EVENT_QUIT        // The event was processed and the message-loop should
+                      // terminate.
+  };
+
+  // Dispatches the event. EVENT_IGNORED is returned if the event was ignored
+  // (i.e. not processed). EVENT_PROCESSED is returned if the event was
+  // processed. The nested loop exits immediately if EVENT_QUIT is returned.
+  virtual DispatchStatus Dispatch(XEvent* xevent) = 0;
+
+ protected:
+  virtual ~MessagePumpDispatcher() {}
+};
+
+// This class implements a message-pump for dispatching X events.
+class MessagePumpX : public MessagePumpGlib {
+ public:
+  MessagePumpX();
+  virtual ~MessagePumpX();
+
+  // Indicates whether a GDK event was injected by chrome (when |true|) or if it
+  // was captured and being processed by GDK (when |false|).
+  bool IsDispatchingEvent(void) { return dispatching_event_; }
+
+  // Overridden from MessagePumpGlib:
+  virtual bool RunOnce(GMainContext* context, bool block) OVERRIDE;
+
+ private:
+  // Some XEvent's can't be directly read from X event queue and will go
+  // through GDK's dispatching process and may get discarded. This function
+  // sets up a filter to intercept those XEvent's we are interested in
+  // and dispatches them so that they won't get lost.
+  static GdkFilterReturn GdkEventFilter(GdkXEvent* gxevent,
+                                        GdkEvent* gevent,
+                                        gpointer data);
+
+  static void EventDispatcherX(GdkEvent* event, gpointer data);
+
+  // Decides whether we are interested in processing this XEvent.
+  bool ShouldCaptureXEvent(XEvent* event);
+
+  // Dispatches the XEvent and returns true if we should exit the current loop
+  // of message processing.
+  bool ProcessXEvent(XEvent* event);
+
+  // Sends the event to the observers. If an observer returns true, then it does
+  // not send the event to any other observers and returns true. Returns false
+  // if no observer returns true.
+  bool WillProcessXEvent(XEvent* xevent);
+
+  // Update the lookup table and flag the events that should be captured and
+  // processed so that GDK doesn't get to them.
+  void InitializeEventsToCapture(void);
+
+#if defined(HAVE_XINPUT2)
+  // Initialize X2 input.
+  void InitializeXInput2(void);
+
+  // The opcode used for checking events.
+  int xiopcode_;
+#endif
+
+  // The event source for GDK events.
+  GSource* gdksource_;
+
+  // The default GDK event dispatcher. This is stored so that it can be restored
+  // when necessary during nested event dispatching.
+  gboolean (*gdkdispatcher_)(GSource*, GSourceFunc, void*);
+
+  // Indicates whether a GDK event was injected by chrome (when |true|) or if it
+  // was captured and being processed by GDK (when |false|).
+  bool dispatching_event_;
+
+#if ! GTK_CHECK_VERSION(2,18,0)
+// GDK_EVENT_LAST was introduced in GTK+ 2.18.0. For earlier versions, we pick a
+// large enough value (the value of GDK_EVENT_LAST in 2.18.0) so that it works
+// for all versions.
+#define GDK_EVENT_LAST 37
+#endif
+
+// Ideally we would #include X.h for LASTEvent, but it brings in a lot of stupid
+// stuff (like Time, CurrentTime etc.) that messes up a lot of things. So define
+// XLASTEvent here to a large enough value so that it works.
+#define XLASTEvent 40
+
+  // We do not want to process all the events ourselves. So we use a lookup
+  // table to quickly check if a particular event should be handled by us or if
+  // it should be passed on to the default GDK handler.
+  std::bitset<XLASTEvent> capture_x_events_;
+  std::bitset<GDK_EVENT_LAST> capture_gdk_events_;
+
+  DISALLOW_COPY_AND_ASSIGN(MessagePumpX);
+};
+
+typedef MessagePumpX MessagePumpForUI;
+
+}  // namespace base
+
+#endif  // BASE_MESSAGE_PUMP_X_H