Reduce CPU usage for input method switching.

chrome/browser/chromeos/status/input_method_menu_button.cc

 // Copyright (c) 2010 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.
 
 #include "chrome/browser/chromeos/status/input_method_menu_button.h"
 
 #include <string>
 
 #include "app/resource_bundle.h"
+#include "base/utf_string_conversions.h"
 #include "chrome/browser/chromeos/cros/cros_library.h"
 #include "chrome/browser/chromeos/cros/keyboard_library.h"
 #include "chrome/browser/chromeos/input_method/input_method_util.h"
 #include "chrome/browser/chromeos/status/status_area_host.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profile.h"
 
 namespace {
 
 // Returns PrefService object associated with |host|. Returns NULL if we are NOT
@@ skipping 27 matching lines @@
       host_(host) {
   set_border(NULL);
   set_use_menu_button_paint(true);
   SetFont(ResourceBundle::GetSharedInstance().GetFont(
       ResourceBundle::BaseFont).DeriveFont(kFontSizeDelta));
   SetEnabledColor(0xB3FFFFFF);  // White with 70% Alpha
   SetDisabledColor(0x00FFFFFF);  // White with 00% Alpha (invisible)
   SetShowMultipleIconStates(false);
   set_alignment(TextButton::ALIGN_CENTER);
 
+  chromeos::KeyboardLibrary* keyboard_library =
+      chromeos::CrosLibrary::Get()->GetKeyboardLibrary();
+  const std::string hardware_keyboard_id =  // e.g. "xkb:us::eng"
+      keyboard_library->GetHardwareKeyboardLayoutName();
+
   // Draw the default indicator "US". The default indicator "US" is used when
   // |pref_service| is not available (for example, unit tests) or |pref_service|
   // is available, but Chrome preferences are not available (for example,
   // initial OS boot).
-  InputMethodMenuButton::UpdateUI(L"US", L"");
+  InputMethodMenuButton::UpdateUI(hardware_keyboard_id, L"US", L"", 1);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // views::View implementation:
 
 gfx::Size InputMethodMenuButton::GetPreferredSize() {
   // If not enabled, then hide this button.
   if (!IsEnabled()) {
     return gfx::Size(0, 0);
   }
   return StatusAreaButton::GetPreferredSize();
 }
 
 void InputMethodMenuButton::OnLocaleChanged() {
   input_method::OnLocaleChanged();
+
+  chromeos::InputMethodLibrary* input_method_library =
+      chromeos::CrosLibrary::Get()->GetInputMethodLibrary();
   const InputMethodDescriptor& input_method =
-      CrosLibrary::Get()->GetInputMethodLibrary()->current_input_method();
-  UpdateUIFromInputMethod(input_method);
+      input_method_library->current_input_method();
+
+  // In general, we should not call an ibus-daemon API in the input method

[satorux1, 2010/12/01 06:40:18]

ibus-daemon -> input method ?

[Yusuke Sato, 2010/12/01 07:36:41]

Done.

+  // button classes (status/input_menu_button*.cc) for performance reasons (see
+  // http://crosbug.com/8284). However, since OnLocaleChanged is called only in
+  // OOBE/Login screen which does not have two or more Chrome windows, it's okay
+  // to call GetNumActiveInputMethods here.
+  const size_t num_active_input_methods =
+      input_method_library->GetNumActiveInputMethods();
+
+  UpdateUIFromInputMethod(input_method, num_active_input_methods);
   Layout();
   SchedulePaint();
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // InputMethodMenu::InputMethodMenuHost implementation:
 
-void InputMethodMenuButton::UpdateUI(
-    const std::wstring& name, const std::wstring& tooltip) {
+void InputMethodMenuButton::UpdateUI(const std::string& id,
+                                     const std::wstring& name,
+                                     const std::wstring& tooltip,
+                                     size_t num_active_input_methods) {
   // Hide the button only if there is only one input method, and the input
   // method is a XKB keyboard layout. We don't hide the button for other
   // types of input methods as these might have intra input method modes,
   // like Hiragana and Katakana modes in Japanese input methods.
-  scoped_ptr<InputMethodDescriptors> active_input_methods(
-      CrosLibrary::Get()->GetInputMethodLibrary()->GetActiveInputMethods());
-  if (active_input_methods->size() == 1 &&
-      input_method::IsKeyboardLayout(active_input_methods->at(0).id) &&
+  if (num_active_input_methods == 1 &&
+      input_method::IsKeyboardLayout(id) &&
       host_->IsBrowserMode()) {
     // As the disabled color is set to invisible, disabling makes the
     // button disappear.
     SetEnabled(false);
     SetTooltipText(L"");  // remove tooltip
   } else {
     SetEnabled(true);
     SetTooltipText(tooltip);
   }
   SetText(name);
   SchedulePaint();
 }
 
 void InputMethodMenuButton::OpenConfigUI() {
   host_->OpenButtonOptions(this);  // ask browser to open the DOMUI page.
 }
 
 bool InputMethodMenuButton::ShouldSupportConfigUI() {
   return host_->ShouldOpenButtonOptions(this);
 }
 
 }  // namespace chromeos