Aura: Switch window mode when screen resolution changes

ash/shell.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/shell.h"
 
 #include <algorithm>
 
 #include "ash/accelerators/accelerator_controller.h"
 #include "ash/accelerators/accelerator_filter.h"
@@ skipping 40 matching lines @@
 #include "ui/gfx/compositor/layer_animator.h"
 #include "ui/gfx/screen.h"
 #include "ui/gfx/size.h"
 #include "ui/views/widget/native_widget_aura.h"
 #include "ui/views/widget/widget.h"
 
 namespace ash {
 
 namespace {
 
+using aura::Window;
 using views::Widget;
 
 // Screen width at or below which we automatically start in compact window mode,
 // in pixels. Should be at least 1366 pixels, the resolution of ChromeOS ZGB
 // device displays, as we traditionally used a single window on those devices.
 const int kCompactWindowModeWidthThreshold = 1366;
 
+// Returns suggested window mode for a given monitor size.
+Shell::WindowMode SuggestedWindowMode(const gfx::Size& monitor_size) {
+  // Developers often run the Aura shell in small windows on their desktop.
+  // Prefer overlapping mode for them.
+  if (!aura::RootWindow::use_fullscreen_host_window())
+    return Shell::MODE_OVERLAPPING;
+
+  // If the screen is narrow we prefer a single compact window display.
+  // We explicitly don't care about height, since users don't generally stack
+  // browser windows vertically.
+  if (monitor_size.width() <= kCompactWindowModeWidthThreshold)
+    return Shell::MODE_COMPACT;
+
+  return Shell::MODE_OVERLAPPING;
+}
+
 // Creates each of the special window containers that holds windows of various
 // types in the shell UI. They are added to |containers| from back to front in
 // the z-index.
 void CreateSpecialContainers(aura::Window::Windows* containers) {
   aura::Window* unparented_control_container = new aura::Window(NULL);
   unparented_control_container->set_id(
       internal::kShellWindowId_UnparentedControlContainer);
   containers->push_back(unparented_control_container);
 
   aura::Window* background_container = new aura::Window(NULL);
@@ skipping 265 matching lines @@
     std::string mode =
         command_line->GetSwitchValueASCII(switches::kAuraWindowMode);
     if (mode == switches::kAuraWindowModeCompact)
       return MODE_COMPACT;
     if (mode == switches::kAuraWindowModeManaged)
       return MODE_MANAGED;
     if (mode == switches::kAuraWindowModeOverlapping)
       return MODE_OVERLAPPING;
   }
 
-  // Developers often run the Aura shell in small windows on their desktop.
-  // Prefer overlapping mode for them.
-  if (!aura::RootWindow::use_fullscreen_host_window())
-    return MODE_OVERLAPPING;
-
-  // If the screen is narrow we prefer a single compact window display.
-  // We explicitly don't care about height, since users don't generally stack
-  // browser windows vertically.
-  if (monitor_size.width() <= kCompactWindowModeWidthThreshold)
-    return MODE_COMPACT;
-
-  return MODE_OVERLAPPING;
+  // Without an explicit command line flag, guess based on the monitor size.
+  return SuggestedWindowMode(monitor_size);
 }
 
 aura::Window* Shell::GetContainer(int container_id) {
   return const_cast<aura::Window*>(
       const_cast<const Shell*>(this)->GetContainer(container_id));
 }
 
 const aura::Window* Shell::GetContainer(int container_id) const {
   return aura::RootWindow::GetInstance()->GetChildById(container_id);
 }
@@ skipping 27 matching lines @@
 
 void Shell::ChangeWindowMode(WindowMode mode) {
   if (mode == window_mode_)
     return;
   // Window mode must be set before we resize/layout the windows.
   window_mode_ = mode;
   if (window_mode_ == MODE_COMPACT)
     SetupCompactWindowMode();
   else
     SetupNonCompactWindowMode();
-  // Force a layout.
-  aura::RootWindow::GetInstance()->layout_manager()->OnWindowResized();
+}
+
+void Shell::SetWindowModeForMonitorSize(const gfx::Size& monitor_size) {
+  // Don't allow changes if we're locked in compact mode.
+  CommandLine* command_line = CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(switches::kAuraForceCompactWindowMode))
+    return;
+
+  // If we're running on a device, a resolution change means the user plugged in
+  // or unplugged an external monitor. Change window mode to be appropriate for
+  // the new screen resolution.
+  WindowMode new_mode = SuggestedWindowMode(monitor_size);
+  ChangeWindowMode(new_mode);
 }
 
 bool Shell::IsScreenLocked() const {
   const aura::Window* lock_screen_container = GetContainer(
       internal::kShellWindowId_LockScreenContainer);
   return lock_screen_container->StopsEventPropagation();
 }
 
 bool Shell::IsModalWindowOpen() const {
   aura::Window* modal_container =
@@ skipping 97 matching lines @@
 
   // Create the desktop background image.
   root_window_layout_->SetBackgroundWidget(internal::CreateDesktopBackground());
 }
 
 void Shell::ResetLayoutManager(int container_id) {
   GetContainer(container_id)->SetLayoutManager(NULL);
 }
 
 }  // namespace ash