Listen to XI_HierarchyChanged events and call setxkbmap when needed.

chrome/browser/chromeos/xinput_hierarchy_changed_event_listener.cc

Index: chrome/browser/chromeos/xinput_hierarchy_changed_event_listener.cc
diff --git a/chrome/browser/chromeos/xinput_hierarchy_changed_event_listener.cc b/chrome/browser/chromeos/xinput_hierarchy_changed_event_listener.cc
new file mode 100644
index 0000000000000000000000000000000000000000..ddd0367bbc3bc737b3087949881bda1177b2c177
--- /dev/null
+++ b/chrome/browser/chromeos/xinput_hierarchy_changed_event_listener.cc
@@ -0,0 +1,132 @@
+// 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.
+
+// TODO(yusukes): Remove the #if once the ARM bot (crbug.com/84694) is fixed.
+#if defined(HAVE_XINPUT2)
+
+#include "chrome/browser/chromeos/xinput_hierarchy_changed_event_listener.h"
+
+#include <gdk/gdkx.h>
+#include <X11/Xlib.h>
+#include <X11/extensions/XInput2.h>
+
+#include "chrome/browser/chromeos/input_method/xkeyboard.h"
+
+namespace {
+
+// Gets the major opcode for XInput2. Returns -1 on error.
+int GetXInputOpCode() {
+  static const char kExtensionName[] = "XInputExtension";
+  int xi_opcode = -1;
+  int event;
+  int error;
+
+  Display* display = MessageLoopForUI::current()->GetDisplay();
+  if (!XQueryExtension(display, kExtensionName, &xi_opcode, &event, &error)) {
+    VLOG(1) << "X Input extension not available: error=" << error;
+    return -1;
+  }
+  return xi_opcode;
+}
+
+// Starts listening to the XI_HierarchyChanged events.
+void SelectXInputEvents() {
+  XIEventMask evmask;
+  unsigned char mask[XIMaskLen(XI_LASTEVENT)] = {0};
+  XISetMask(mask, XI_HierarchyChanged);
+
+  evmask.deviceid = XIAllDevices;
+  evmask.mask_len = sizeof(mask);
+  evmask.mask = mask;
+
+  Display* display = MessageLoopForUI::current()->GetDisplay();
+  XISelectEvents(display, DefaultRootWindow(display), &evmask, 1);
+}
+
+// Checks the |event| and asynchronously sets the XKB layout when necessary.
+void HandleHierarchyChangedEvent(XIHierarchyEvent* event) {
+  for (int i = 0; i < event->num_info; ++i) {
+    XIHierarchyInfo* info = &event->info[i];
+    if ((event->flags & XISlaveAdded) &&
+        (info->use == XIFloatingSlave) &&
+        (info->flags & XISlaveAdded)) {
+      chromeos::input_method::ReapplyCurrentKeyboardLayout();
+      break;
+    }
+  }
+}
+
+}  // namespace
+
+namespace chromeos {
+
+// static
+XInputHierarchyChangedEventListener*
+XInputHierarchyChangedEventListener::GetInstance() {
+  return Singleton<XInputHierarchyChangedEventListener>::get();
+}
+
+XInputHierarchyChangedEventListener::XInputHierarchyChangedEventListener()
+    : stopped_(false),
+      xiopcode_(GetXInputOpCode()) {
+  SelectXInputEvents();
+
+#if defined(TOUCH_UI)
+  MessageLoopForUI::current()->AddObserver(this);
+#else
+  gdk_window_add_filter(NULL, GdkEventFilter, this);
+#endif
+}
+
+XInputHierarchyChangedEventListener::~XInputHierarchyChangedEventListener() {
+  Stop();
+}
+
+void XInputHierarchyChangedEventListener::Stop() {
+  if (stopped_)
+    return;
+
+#if defined(TOUCH_UI)
+  MessageLoopForUI::current()->RemoveObserver(this);
+#else
+  gdk_window_remove_filter(NULL, GdkEventFilter, this);
+#endif
+  stopped_ = true;
+  xiopcode_ = -1;
+}
+
+// static
+GdkFilterReturn XInputHierarchyChangedEventListener::GdkEventFilter(
+    GdkXEvent* gxevent, GdkEvent* gevent, gpointer data) {
+  XInputHierarchyChangedEventListener* listener =
+      static_cast<XInputHierarchyChangedEventListener*>(data);
+  XEvent* xevent = static_cast<XEvent*>(gxevent);
+
+  return listener->WillProcessXEvent(xevent) ? GDK_FILTER_REMOVE
+                                             : GDK_FILTER_CONTINUE;
+}
+
+bool XInputHierarchyChangedEventListener::WillProcessXEvent(XEvent* xevent) {
+  if ((xevent->xcookie.type != GenericEvent) ||
+      (xevent->xcookie.extension != xiopcode_)) {
+    return false;
+  }
+  if (!XGetEventData(xevent->xgeneric.display, &xevent->xcookie)) {
+    VLOG(1) << "XGetEventData failed";
+    return false;
+  }
+
+  XGenericEventCookie* cookie = &(xevent->xcookie);
+  const bool should_consume = (cookie->evtype == XI_HierarchyChanged);
+  if (should_consume) {
+    HandleHierarchyChangedEvent(static_cast<XIHierarchyEvent*>(cookie->data));
+  }
+  XFreeEventData(xevent->xgeneric.display, cookie);
+
+  return should_consume;
+}
+
+}  // namespace chromeos
+
+#endif