Add always on top windows to the alt+tab list

ash/wm/window_cycle_controller.cc

 // Copyright (c) 2012 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 "ash/wm/window_cycle_controller.h"
 
 #include <algorithm>
 
 #include "ash/shell.h"
 #include "ash/shell_delegate.h"
 #include "ash/shell_window_ids.h"
+#include "ash/wm/activation_controller.h"
 #include "ash/wm/window_cycle_list.h"
 #include "ash/wm/window_util.h"
 #include "ui/aura/event.h"
 #include "ui/aura/event_filter.h"
 #include "ui/aura/root_window.h"
 
 namespace ash {
 
 namespace {
 
+// List of containers whose children we will cycle through.
+const int kContainerIds[] = {
+  internal::kShellWindowId_DefaultContainer,
+  internal::kShellWindowId_AlwaysOnTopContainer
+};
+
 // Filter to watch for the termination of a keyboard gesture to cycle through
 // multiple windows.
 class WindowCycleEventFilter : public aura::EventFilter {
  public:
   WindowCycleEventFilter();
   virtual ~WindowCycleEventFilter();
 
   // Overridden from aura::EventFilter:
   virtual bool PreHandleKeyEvent(aura::Window* target,
                                  aura::KeyEvent* event) OVERRIDE;
@@ skipping 44 matching lines @@
     aura::GestureEvent* event) {
   return ui::GESTURE_STATUS_UNKNOWN;  // Not handled.
 }
 
 }  // namespace
 
 //////////////////////////////////////////////////////////////////////////////
 // WindowCycleController, public:
 
 WindowCycleController::WindowCycleController() {
+  Shell::GetInstance()->activation_controller()->AddObserver(this);
 }
 
 WindowCycleController::~WindowCycleController() {
+  Shell::RootWindowList root_windows = Shell::GetAllRootWindows();
+  for (Shell::RootWindowList::const_iterator iter = root_windows.begin();
+       iter != root_windows.end(); ++iter) {
+    for (size_t i = 0; i < arraysize(kContainerIds); ++i) {
+      aura::Window* container = Shell::GetContainer(*iter, kContainerIds[i]);
+      if (container)
+        container->RemoveObserver(this);
+    }
+  }
+
+  Shell::GetInstance()->activation_controller()->RemoveObserver(this);
   StopCycling();
 }
 
 // static
 bool WindowCycleController::CanCycle() {
   // Don't allow window cycling if the screen is locked or a modal dialog is
   // open.
   return !Shell::GetInstance()->IsScreenLocked() &&
          !Shell::GetInstance()->IsModalWindowOpen();
 }
@@ skipping 20 matching lines @@
     Step(direction);
     StopCycling();
   }
 }
 
 void WindowCycleController::AltKeyReleased() {
   StopCycling();
 }
 
 // static
-std::vector<aura::Window*> WindowCycleController::BuildWindowList() {
+std::vector<aura::Window*> WindowCycleController::BuildWindowList(
+    const std::list<aura::Window*>* mru_windows) {
   WindowCycleList::WindowList windows;
   Shell::RootWindowList root_windows = Shell::GetAllRootWindows();
 
   for (Shell::RootWindowList::const_iterator iter = root_windows.begin();
        iter != root_windows.end(); ++iter) {
     if (*iter == Shell::GetActiveRootWindow())
       continue;
-    aura::Window* default_container = Shell::GetContainer(
-        *iter, internal::kShellWindowId_DefaultContainer);
-    WindowCycleList::WindowList children = default_container->children();
+    for (size_t i = 0; i < arraysize(kContainerIds); ++i) {
+      aura::Window* container = Shell::GetContainer(*iter, kContainerIds[i]);
+      WindowCycleList::WindowList children = container->children();
+      windows.insert(windows.end(), children.begin(), children.end());
+    }
+  }
+
+  for (size_t i = 0; i < arraysize(kContainerIds); ++i) {
+    aura::Window* container =
+        Shell::GetContainer(Shell::GetActiveRootWindow(), kContainerIds[i]);
+
+    WindowCycleList::WindowList children = container->children();
     windows.insert(windows.end(), children.begin(), children.end());
   }
-  // Add windows in the active root windows last so that the topmost window
-  // in the active root window becomes the front of the list.
-  aura::Window* default_container = Shell::GetContainer(
-      Shell::GetActiveRootWindow(),
-      internal::kShellWindowId_DefaultContainer);
-
-  WindowCycleList::WindowList children = default_container->children();
-  windows.insert(windows.end(), children.begin(), children.end());
 
   // Removes unfocusable windows.
   WindowCycleList::WindowList::iterator last =
       std::remove_if(
           windows.begin(),
           windows.end(),
           std::not1(std::ptr_fun(ash::wm::CanActivateWindow)));
   windows.erase(last, windows.end());
+
+  // Put the windows in the mru_windows list at the head, if it's available.
+  if (mru_windows) {
+    // Iterate through the list backwards, so that we can move each window to
+    // the front of the windows list as we find them.
+    for (std::list<aura::Window*>::const_reverse_iterator ix =
+         mru_windows->rbegin();
+         ix != mru_windows->rend(); ++ix) {
+      WindowCycleList::WindowList::iterator window =
+          std::find(windows.begin(), windows.end(), *ix);
+      if (window != windows.end()) {
+        windows.erase(window);
+        windows.push_back(*ix);
+      }
+    }
+  }
+
   // Window cycling expects the topmost window at the front of the list.
   std::reverse(windows.begin(), windows.end());
+
   return windows;
 }
 
+void WindowCycleController::OnRootWindowAdded(aura::RootWindow* root_window) {
+  for (size_t i = 0; i < arraysize(kContainerIds); ++i) {
+    aura::Window* container =
+        Shell::GetContainer(root_window, kContainerIds[i]);
+    container->AddObserver(this);
+  }
+}
+
 //////////////////////////////////////////////////////////////////////////////
 // WindowCycleController, private:
 
 void WindowCycleController::StartCycling() {
-  windows_.reset(new WindowCycleList(BuildWindowList()));
+  windows_.reset(new WindowCycleList(BuildWindowList(&mru_windows_)));
 }
 
 void WindowCycleController::Step(Direction direction) {
   DCHECK(windows_.get());
   windows_->Step(direction == FORWARD ? WindowCycleList::FORWARD :
                  WindowCycleList::BACKWARD);
 }
 
 void WindowCycleController::StopCycling() {
   windows_.reset();
   // Remove our key event filter.
   if (event_filter_.get()) {
     Shell::GetInstance()->RemoveEnvEventFilter(event_filter_.get());
     event_filter_.reset();
   }
+
+  // Add the currently focused window to the MRU list
+  aura::Window* active_window = wm::GetActiveWindow();
+  mru_windows_.remove(active_window);
+  mru_windows_.push_front(active_window);
+}
+
+// static
+bool WindowCycleController::IsTrackedWindow(aura::Window* window) {
+  if (!window)
+    return false;
+  for (size_t i = 0; i < arraysize(kContainerIds); ++i) {
+    if (window->id() == kContainerIds[i]) {
+      return true;
+    }
+  }
+  return false;
 }
 
 void WindowCycleController::InstallEventFilter() {
   event_filter_.reset(new WindowCycleEventFilter());
   Shell::GetInstance()->AddEnvEventFilter(event_filter_.get());
 }
 
+void WindowCycleController::OnWindowActivated(aura::Window* active,
+                                              aura::Window* old_active) {
+  if (active && !IsCycling() && IsTrackedWindow(active->parent())) {
+    mru_windows_.remove(active);
+    mru_windows_.push_front(active);
+  }
+}
+
+void WindowCycleController::OnWillRemoveWindow(aura::Window* window) {
+  mru_windows_.remove(window);
+}
+
+void WindowCycleController::OnWindowDestroying(aura::Window* window) {
+  window->RemoveObserver(this);
+}
+
 }  // namespace ash