base/message_pump_x.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_MESSAGE_PUMP_X_H
   6 #define BASE_MESSAGE_PUMP_X_H
   7
   8 #include "base/message_pump.h"
   9 #include "base/message_pump_glib.h"
  10 #include "base/message_pump_observer.h"
  11
  12 #include <bitset>
  13
  14 #include <glib.h>
  15
  16 #if defined(TOOLKIT_USES_GTK)
  17 #include <gtk/gtk.h>
  18 #endif
  19
  20 typedef struct _XDisplay Display;
  21
  22 namespace base {
  23
  24 // The documentation for this class is in message_pump_glib.h
  25 //
  26 // The nested loop is exited by either posting a quit, or returning EVENT_QUIT
  27 // from Dispatch.
  28 class MessagePumpDispatcher {
  29  public:
  30   enum DispatchStatus {
  31     EVENT_IGNORED,    // The event was not processed.
  32     EVENT_PROCESSED,  // The event has been processed.
  33     EVENT_QUIT        // The event was processed and the message-loop should
  34                       // terminate.
  35   };
  36
  37   // Dispatches the event. EVENT_IGNORED is returned if the event was ignored
  38   // (i.e. not processed). EVENT_PROCESSED is returned if the event was
  39   // processed. The nested loop exits immediately if EVENT_QUIT is returned.
  40   virtual DispatchStatus Dispatch(XEvent* xevent) = 0;
  41
  42  protected:
  43   virtual ~MessagePumpDispatcher() {}
  44 };
  45
  46 // This class implements a message-pump for dispatching X events.
  47 class BASE_EXPORT MessagePumpX : public MessagePumpGlib {
  48  public:
  49   MessagePumpX();
  50   virtual ~MessagePumpX();
  51
  52   // Overridden from MessagePumpGlib:
  53   virtual bool RunOnce(GMainContext* context, bool block) OVERRIDE;
  54
  55   // Returns default X Display.
  56   static Display* GetDefaultXDisplay();
  57
  58   // Returns true if the system supports XINPUT2.
  59   static bool HasXInput2();
  60
  61  private:
  62   // Initializes the glib event source for X.
  63   void InitXSource();
  64
  65   // Decides whether we are interested in processing this XEvent.
  66   bool ShouldCaptureXEvent(XEvent* event);
  67
  68   // Dispatches the XEvent and returns true if we should exit the current loop
  69   // of message processing.
  70   bool ProcessXEvent(XEvent* event);
  71
  72   // Sends the event to the observers. If an observer returns true, then it does
  73   // not send the event to any other observers and returns true. Returns false
  74   // if no observer returns true.
  75   bool WillProcessXEvent(XEvent* xevent);
  76   void DidProcessXEvent(XEvent* xevent);
  77 #if defined(TOOLKIT_USES_GTK)
  78   // Some XEvent's can't be directly read from X event queue and will go
  79   // through GDK's dispatching process and may get discarded. This function
  80   // sets up a filter to intercept those XEvent's we are interested in
  81   // and dispatches them so that they won't get lost.
  82   static GdkFilterReturn GdkEventFilter(GdkXEvent* gxevent,
  83                                         GdkEvent* gevent,
  84                                         gpointer data);
  85
  86   static void EventDispatcherX(GdkEvent* event, gpointer data);
  87
  88   // Indicates whether a GDK event was injected by chrome (when |true|) or if it
  89   // was captured and being processed by GDK (when |false|).
  90   bool IsDispatchingEvent(void) { return dispatching_event_; }
  91
  92   // Update the lookup table and flag the events that should be captured and
  93   // processed so that GDK doesn't get to them.
  94   void InitializeEventsToCapture(void);
  95
  96   // The event source for GDK events.
  97   GSource* gdksource_;
  98
  99   // The default GDK event dispatcher. This is stored so that it can be restored
 100   // when necessary during nested event dispatching.
 101   gboolean (*gdkdispatcher_)(GSource*, GSourceFunc, void*);
 102
 103   // Indicates whether a GDK event was injected by chrome (when |true|) or if it
 104   // was captured and being processed by GDK (when |false|).
 105   bool dispatching_event_;
 106
 107 #if ! GTK_CHECK_VERSION(2,18,0)
 108 // GDK_EVENT_LAST was introduced in GTK+ 2.18.0. For earlier versions, we pick a
 109 // large enough value (the value of GDK_EVENT_LAST in 2.18.0) so that it works
 110 // for all versions.
 111 #define GDK_EVENT_LAST 37
 112 #endif
 113
 114 // Ideally we would #include X.h for LASTEvent, but it brings in a lot of stupid
 115 // stuff (like Time, CurrentTime etc.) that messes up a lot of things. So define
 116 // XLASTEvent here to a large enough value so that it works.
 117 #define XLASTEvent 40
 118
 119   // We do not want to process all the events ourselves. So we use a lookup
 120   // table to quickly check if a particular event should be handled by us or if
 121   // it should be passed on to the default GDK handler.
 122   std::bitset<XLASTEvent> capture_x_events_;
 123   std::bitset<GDK_EVENT_LAST> capture_gdk_events_;
 124 #endif  // defined(TOOLKIT_USES_GTK)
 125
 126   // The event source for X events (used only when GTK event processing is
 127   // disabled).
 128   GSource* x_source_;
 129
 130   DISALLOW_COPY_AND_ASSIGN(MessagePumpX);
 131 };
 132
 133 typedef MessagePumpX MessagePumpForUI;
 134
 135 }  // namespace base
 136
 137 #endif  // BASE_MESSAGE_PUMP_X_H