Separated alt-tab window cycle from overview mode

ash/wm/window_cycle_list.cc

+// Copyright 2014 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_(0) {
+  ash::Shell::GetInstance()->mru_window_tracker()->SetIgnoreActivations(true);
+
+  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(WindowCycleController::Direction direction) {
+  if (windows_.empty())
+    return;
+
+  // When there is only one window, we should give feedback to the user.
+  if (windows_.size() == 1) {
+    ::wm::AnimateWindow(windows_[0], ::wm::WINDOW_ANIMATION_TYPE_BOUNCE);
+    return;
+  }
+
+  DCHECK(static_cast<size_t>(current_index_) < windows_.size());
+
+  // We're in a valid cycle, so step forward or backward.
+  current_index_ += direction == WindowCycleController::FORWARD ? 1 : -1;
+
+  // 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_]);
+}
+
+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 ||
+      current_index_ == static_cast<int>(windows_.size()))
+    current_index_--;
+  // If the first window was destroyed, move the index to the new first window.

[flackr, 2014/05/05 13:58:56]

If the first window was destroyed, either current_index == removed_index in
which case is still 0, or current_index > removed_index in which case is at
least 0 now. The only way it would become -1 is if the windows list is now
empty, which we should probably have a way of handling.

[Nina, 2014/05/05 15:44:29]

Hmm this is true, and if there are no windows calling step has no effect. I
think I'll remove the if.

+  if (current_index_ == -1)
+    current_index_ = 0;
+}
+
+}  // namespace ash