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      1 // Copyright (c) 2012 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 #include "ui/base/x/active_window_watcher_x.h"
      6 
      7 #include <gdk/gdk.h>
      8 #include <gdk/gdkx.h>
      9 
     10 #include "base/memory/singleton.h"
     11 #include "ui/base/gtk/gdk_x_compat.h"
     12 #include "ui/base/gtk/gtk_compat.h"
     13 #include "ui/base/x/active_window_watcher_x_observer.h"
     14 #include "ui/base/x/root_window_property_watcher_x.h"
     15 #include "ui/base/x/x11_util.h"
     16 
     17 namespace ui {
     18 
     19 static const char* const kNetActiveWindow = "_NET_ACTIVE_WINDOW";
     20 
     21 // static
     22 ActiveWindowWatcherX* ActiveWindowWatcherX::GetInstance() {
     23   return Singleton<ActiveWindowWatcherX>::get();
     24 }
     25 
     26 // static
     27 void ActiveWindowWatcherX::AddObserver(ActiveWindowWatcherXObserver* observer) {
     28   // Ensure that RootWindowPropertyWatcherX exists.
     29   internal::RootWindowPropertyWatcherX::GetInstance();
     30   GetInstance()->observers_.AddObserver(observer);
     31 }
     32 
     33 // static
     34 void ActiveWindowWatcherX::RemoveObserver(
     35     ActiveWindowWatcherXObserver* observer) {
     36   GetInstance()->observers_.RemoveObserver(observer);
     37 }
     38 
     39 // static
     40 Atom ActiveWindowWatcherX::GetPropertyAtom() {
     41   return GetAtom(kNetActiveWindow);
     42 }
     43 
     44 // static
     45 void ActiveWindowWatcherX::Notify() {
     46   GetInstance()->NotifyActiveWindowChanged();
     47 }
     48 
     49 // static
     50 bool ActiveWindowWatcherX::WMSupportsActivation() {
     51   return gdk_x11_screen_supports_net_wm_hint(
     52       gdk_screen_get_default(),
     53       gdk_atom_intern_static_string(kNetActiveWindow));
     54 }
     55 
     56 ActiveWindowWatcherX::ActiveWindowWatcherX() {
     57 }
     58 
     59 ActiveWindowWatcherX::~ActiveWindowWatcherX() {
     60 }
     61 
     62 void ActiveWindowWatcherX::NotifyActiveWindowChanged() {
     63   // We don't use gdk_screen_get_active_window() because it caches
     64   // whether or not the window manager supports _NET_ACTIVE_WINDOW.
     65   // This causes problems at startup for chromiumos.
     66   Atom type = None;
     67   int format = 0;  // size in bits of each item in 'property'
     68   long unsigned int num_items = 0, remaining_bytes = 0;
     69   unsigned char* property = NULL;
     70 
     71   XGetWindowProperty(gdk_x11_get_default_xdisplay(),
     72                      GDK_WINDOW_XID(gdk_get_default_root_window()),
     73                      GetAtom(kNetActiveWindow),
     74                      0,      // offset into property data to read
     75                      1,      // length to get in 32-bit quantities
     76                      False,  // deleted
     77                      AnyPropertyType,
     78                      &type,
     79                      &format,
     80                      &num_items,
     81                      &remaining_bytes,
     82                      &property);
     83 
     84   // Check that the property was set and contained a single 32-bit item (we
     85   // don't check that remaining_bytes is 0, though, as XFCE's window manager
     86   // seems to actually store two values in the property for some unknown
     87   // reason.)
     88   if (format == 32 && num_items == 1) {
     89     int xid = *reinterpret_cast<int*>(property);
     90     GdkDisplay* display = gdk_display_get_default();
     91     GdkWindow* active_window = gdk_x11_window_lookup_for_display(display, xid);
     92     FOR_EACH_OBSERVER(ActiveWindowWatcherXObserver, observers_,
     93                       ActiveWindowChanged(active_window));
     94   }
     95   if (property)
     96     XFree(property);
     97 }
     98 
     99 }  // namespace ui
    100