Separated alt-tab window cycle from overview mode

ash/wm/window_cycle_list.cc

Index: ash/wm/window_cycle_list.cc
diff --git a/ash/wm/window_cycle_list.cc b/ash/wm/window_cycle_list.cc
new file mode 100644
index 0000000000000000000000000000000000000000..19f0dcc41a08355dfe6370c5e869722e1ff419bf
--- /dev/null
+++ b/ash/wm/window_cycle_list.cc
@@ -0,0 +1,186 @@
+// 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_list.h"
+
+#include "ash/shell.h"
+#include "ash/wm/mru_window_tracker.h"
+#include "ash/wm/window_animations.h"
+#include "ash/wm/window_state.h"
+#include "ash/wm/window_util.h"
+#include "ui/aura/window.h"
+
+namespace ash {
+
+// Returns the window immediately below |window| in the current container.
+aura::Window* GetWindowBelow(aura::Window* window) {
+  aura::Window* parent = window->parent();
+  if (!parent)
+    return NULL;
+  aura::Window* below = NULL;
+  for (aura::Window::Windows::const_iterator iter = parent->children().begin();
+       iter != parent->children().end(); ++iter) {
+    if (*iter == window)
+      return below;
+    below = *iter;
+  }
+  NOTREACHED();
+  return NULL;
+}
+
+// This class restores and moves a window to the front of the stacking order for
+// the duration of the class's scope.
+class ScopedShowWindow : public aura::WindowObserver {
+ public:
+  ScopedShowWindow();
+  virtual ~ScopedShowWindow();
+
+  // Show |window| at the top of the stacking order.
+  void Show(aura::Window* window);
+
+  // Cancel restoring the window on going out of scope.
+  void CancelRestore();
+
+  aura::Window* window() { return window_; }
+
+  // aura::WindowObserver:
+  virtual void OnWillRemoveWindow(aura::Window* window) OVERRIDE;
+
+ private:
+  // The window being shown.
+  aura::Window* window_;
+
+  // The window immediately below where window_ belongs.
+  aura::Window* stack_window_above_;
+
+  // If true, minimize window_ on going out of scope.
+  bool minimized_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedShowWindow);
+};
+
+ScopedShowWindow::ScopedShowWindow()
+    : window_(NULL),
+      stack_window_above_(NULL),
+      minimized_(false) {
+}
+
+void ScopedShowWindow::Show(aura::Window* window) {
+  DCHECK(!window_);
+  window_ = window;
+  stack_window_above_ = GetWindowBelow(window);
+  minimized_ = wm::GetWindowState(window)->IsMinimized();
+  window_->parent()->AddObserver(this);
+  window_->Show();
+  wm::GetWindowState(window_)->Activate();
+}
+
+ScopedShowWindow::~ScopedShowWindow() {
+  if (window_) {
+    window_->parent()->RemoveObserver(this);
+
+    // Restore window's stacking position.
+    if (stack_window_above_)
+      window_->parent()->StackChildAbove(window_, stack_window_above_);
+    else
+      window_->parent()->StackChildAtBottom(window_);
+
+    // Restore minimized state.
+    if (minimized_)
+      wm::GetWindowState(window_)->Minimize();
+  }
+}
+
+void ScopedShowWindow::CancelRestore() {
+  if (!window_)
+    return;
+  window_->parent()->RemoveObserver(this);
+  window_ = stack_window_above_ = NULL;
+}
+
+void ScopedShowWindow::OnWillRemoveWindow(aura::Window* window) {
+  if (window == window_) {
+    CancelRestore();
+  } else if (window == stack_window_above_) {
+    // If the window this window was above is removed, use the next window down
+    // as the restore marker.
+    stack_window_above_ = GetWindowBelow(stack_window_above_);
+  }
+}
+
+WindowCycleList::WindowCycleList(const WindowList& windows)
+    : windows_(windows),
+      current_index_(-1) {
+  ash::Shell::GetInstance()->mru_window_tracker()->SetIgnoreActivations(true);
+  // Locate the currently active window in the list to use as our start point.
+  aura::Window* active_window = wm::GetActiveWindow();
+
+  // The active window may not be in the cycle list, which is expected if there
+  // are additional modal windows on the screen.
+  current_index_ = GetWindowIndex(active_window);
+
+  for (WindowList::const_iterator i = windows_.begin(); i != windows_.end();
+       ++i) {
+    (*i)->AddObserver(this);
+  }
+}
+
+WindowCycleList::~WindowCycleList() {
+  ash::Shell::GetInstance()->mru_window_tracker()->SetIgnoreActivations(false);
+  for (WindowList::const_iterator i = windows_.begin(); i != windows_.end();
+       ++i) {
+    (*i)->RemoveObserver(this);
+  }
+  if (showing_window_)
+    showing_window_->CancelRestore();
+}
+
+void WindowCycleList::Step(Direction direction) {
+  if (windows_.empty())
+    return;
+
+  if (current_index_ == -1) {
+    // We weren't able to find our active window in the shell delegate's

[tdanderson, 2014/05/01 18:51:39]

This worries me a little bit. I feel that a precondition of Step() should be
that current_index_ != 1. AFAICT, the only reason you have this here is for the
case when wm::GetActiveWindow() doesn't return a window in the MRU list. Are
there any other times when current_index_ == -1 here?

I suggest adding a DCHECK to verify that current_index_ is a valid index for the
window list, and move this logic into the constructor: If wm::GetActiveWindow()
returns a window not in the MRU list, then just set current_index_ = 0. Would
that work? Or better yet, simply initialize current_index_ to 0 in the
constructor initialization list.

[Nina, 2014/05/01 20:41:16]

Done.

+    // provided window list.  Just switch to the first (or last) one.
+    current_index_ = (direction == FORWARD ? 0 : windows_.size() - 1);

[tdanderson, 2014/05/01 18:51:39]

No () needed

[Nina, 2014/05/01 20:41:16]

Done.

+  } else {
+    // When there is only one window, we should give a feedback to user.

[tdanderson, 2014/05/01 18:51:39]

Double-check with the logs (or Rob if you can't find anything) to see if the
bounce animation was removed for a reason.

[Nina, 2014/05/01 20:41:16]

Could not find anything on the logs, I asked Rob and he said it was OK to bring
the animation back. Do you want to file a bug for it and see if someone raises
their hand?

[tdanderson, 2014/05/01 21:58:33]

I don't think that is necessary. If Rob is OK with adding it back in here then
let's just keep it in.

+    if (windows_.size() == 1) {
+      ::wm::AnimateWindow(windows_[0],
+                    ::wm::WINDOW_ANIMATION_TYPE_BOUNCE);

[tdanderson, 2014/05/01 18:51:39]

Spacing

[Nina, 2014/05/01 20:41:16]

Done.

+      return;
+    }
+    // We're in a valid cycle, so step forward or backward.
+    current_index_ += (direction == FORWARD ? 1 : -1);

[tdanderson, 2014/05/01 18:51:39]

No ()

[Nina, 2014/05/01 20:41:16]

Done.

+  }
+  // Wrap to window list size.
+  current_index_ = (current_index_ + windows_.size()) % windows_.size();
+  DCHECK(windows_[current_index_]);
+  // Make sure the next window is visible.
+  showing_window_.reset(new ScopedShowWindow);
+  showing_window_->Show(windows_[current_index_]);
+}
+
+int WindowCycleList::GetWindowIndex(aura::Window* window) {
+  WindowList::const_iterator it =
+      std::find(windows_.begin(), windows_.end(), window);
+  if (it == windows_.end())
+    return -1;  // Not found.
+  return it - windows_.begin();
+}
+
+void WindowCycleList::OnWindowDestroyed(aura::Window* window) {
+  window->RemoveObserver(this);
+
+  WindowList::iterator i = std::find(windows_.begin(), windows_.end(), window);
+  DCHECK(i != windows_.end());
+  int removed_index = static_cast<int>(i - windows_.begin());
+  windows_.erase(i);
+  if (current_index_ > removed_index)

[tdanderson, 2014/05/01 18:51:39]

combine lines 180-183 into a single check

[Nina, 2014/05/01 20:41:16]

Done.

+    current_index_--;
+  else if (current_index_ == static_cast<int>(windows_.size()))
+    current_index_--;
+}
+
+}  // namespace ash