CrOS Tablet Window management - Split Screen part I

ash/wm/overview/window_selector.cc

Index: ash/wm/overview/window_selector.cc
diff --git a/ash/wm/overview/window_selector.cc b/ash/wm/overview/window_selector.cc
index 76bdee5d0a5df0d43b389118d44f1869d3de38f4..a599a521f46a40e9f8b9e7034364f8474b5a40e2 100644
--- a/ash/wm/overview/window_selector.cc
+++ b/ash/wm/overview/window_selector.cc
@@ -20,10 +20,12 @@
 #include "ash/shell.h"
 #include "ash/shell_port.h"
 #include "ash/wm/mru_window_tracker.h"
+#include "ash/wm/overview/overview_window_drag_controller.h"
 #include "ash/wm/overview/window_grid.h"
 #include "ash/wm/overview/window_selector_delegate.h"
 #include "ash/wm/overview/window_selector_item.h"
 #include "ash/wm/panels/panel_layout_manager.h"
+#include "ash/wm/splitview/split_view_controller.h"

[varkha, 2017/06/21 01:51:53]

nit: Not necessary since you have to bring it in this .cc file's header file?

[xdai1, 2017/06/22 21:46:34]

Removed. Thanks!

 #include "ash/wm/switchable_windows.h"
 #include "ash/wm/window_state.h"
 #include "ash/wm/window_util.h"
@@ -138,13 +140,33 @@ void UpdateShelfVisibility() {
     Shelf::ForWindow(root)->UpdateVisibilityState();
 }
 
+// Returns the bounds for the overview window grids according to the split view
+// state. If split view mode is active, the overview window should open on the
+// opposite side of the default snap window.
+gfx::Rect GetGridsBoundsInScreen(aura::Window* root_window) {

[varkha, 2017/06/21 01:51:53]

nit: I have a mild preference for simpler GetGridBoundsInScreen() since you are
only getting bounds for a single grid and cannot use "'" in the name.
nit: Caching Shell::Get()->split_view_controller() in a local variable could
simplify this a bit since you use it in every branch.

[varkha, 2017/06/21 01:51:53]

Could root_window be const* ? That would help remove the const_cast in line 588.

[xdai1, 2017/06/22 21:46:33]

Done.

[xdai1, 2017/06/22 21:46:33]

This const_cast is inevitable, either in line 588, or in
split_view_controller.cc when calculating GetDisplayWorkAreaBoundsInScreen() if
I modify this function to accept const*. 

[varkha, 2017/06/26 16:40:07]

I thought GetDisplayWorkAreaBoundsInScreen() could be made to accept const
Window*, maybe with some additional plumbing in ScreenUtil.

+  if (Shell::Get()->IsSplitViewModeActive()) {
+    SplitViewController::State state =
+        Shell::Get()->split_view_controller()->state();
+    SplitViewController::State oppsite_state =
+        (state == SplitViewController::LEFT_SNAPPED)
+            ? SplitViewController::RIGHT_SNAPPED
+            : SplitViewController::LEFT_SNAPPED;
+    return Shell::Get()
+        ->split_view_controller()
+        ->GetSnappedWindowBoundsInScreen(root_window, oppsite_state);
+  } else {
+    return Shell::Get()
+        ->split_view_controller()
+        ->GetDisplayWorkAreaBoundsInScreen(root_window);
+  }
+}
+
 gfx::Rect GetTextFilterPosition(aura::Window* root_window) {
-  gfx::Rect total_bounds = ScreenUtil::GetDisplayWorkAreaBoundsInParent(
-      root_window->GetChildById(kShellWindowId_DefaultContainer));
-  ::wm::ConvertRectToScreen(root_window, &total_bounds);
+  gfx::Rect total_bounds = GetGridsBoundsInScreen(root_window);

[varkha, 2017/06/21 01:51:53]

nit: const.

[xdai1, 2017/06/22 21:46:34]

Done.

   return gfx::Rect(
       0.5 * (total_bounds.width() -
-             std::min(kTextFilterWidth, total_bounds.width())),
+             std::min(kTextFilterWidth, total_bounds.width())) +
+          total_bounds.x(),

[varkha, 2017/06/21 01:51:53]

nit: x + offset rather than offset + x to make it consistent with how y is
spelled out.

[xdai1, 2017/06/22 21:46:33]

Done.

       total_bounds.y() + total_bounds.height() * kTextFilterTopScreenProportion,
       std::min(kTextFilterWidth, total_bounds.width()), kTextFilterHeight);
 }
@@ -271,7 +293,8 @@ void WindowSelector::Init(const WindowList& windows) {
     // root windows that don't contain any panel windows.
     PanelLayoutManager::Get(root)->SetShowCalloutWidgets(false);
 
-    std::unique_ptr<WindowGrid> grid(new WindowGrid(root, windows, this));
+    std::unique_ptr<WindowGrid> grid(
+        new WindowGrid(root, windows, this, GetGridsBoundsInScreen(root)));
     if (grid->empty())
       continue;
     num_items_ += grid->size();
@@ -308,6 +331,7 @@ void WindowSelector::Init(const WindowList& windows) {
   UMA_HISTOGRAM_COUNTS_100("Ash.WindowSelector.Items", num_items_);
 
   Shell::Get()->activation_client()->AddObserver(this);
+  Shell::Get()->split_view_controller()->AddObserver(this);
 
   display::Screen::GetScreen()->AddObserver(this);
   ShellPort::Get()->RecordUserMetricsAction(UMA_WINDOW_OVERVIEW);
@@ -327,6 +351,11 @@ void WindowSelector::Shutdown() {
   // windows in response to work area changes from window activation.
   display::Screen::GetScreen()->RemoveObserver(this);
 
+  // Stop observing split view state changes before restoring window focus.
+  // Otherwise the activation of the window triggers OnSplitViewStateChanged()
+  // that will call into this function again.

[varkha, 2017/06/21 01:51:53]

Subtle! Thanks for commenting this!

+  Shell::Get()->split_view_controller()->RemoveObserver(this);
+
   size_t remaining_items = 0;
   for (std::unique_ptr<WindowGrid>& window_grid : grid_list_) {
     for (const auto& window_selector_item : window_grid->window_list())
@@ -446,6 +475,47 @@ void WindowSelector::WindowClosing(WindowSelectorItem* window) {
   grid_list_[selected_grid_index_]->WindowClosing(window);
 }
 
+void WindowSelector::SetBoundsForWindowGridsInScreen(const gfx::Rect bounds) {
+  for (std::unique_ptr<WindowGrid>& grid : grid_list_)
+    grid->SetTotalBoundsInScreen(bounds);
+}
+
+void WindowSelector::RemoveWindowSelectorItem(WindowSelectorItem* item) {
+  if (item->GetWindow()->HasObserver(this)) {
+    item->GetWindow()->RemoveObserver(this);
+    observed_windows_.erase(item->GetWindow());
+    if (item->GetWindow() == restore_focus_window_)
+      restore_focus_window_ = nullptr;
+  }
+
+  // Remove |item| from the corresponding grid.
+  for (std::unique_ptr<WindowGrid>& grid : grid_list_) {
+    if (grid->Contains(item->GetWindow())) {
+      grid->RemoveItem(item);
+      break;
+    }
+  }
+}
+
+void WindowSelector::InitiateDrag(WindowSelectorItem* item,
+                                  const gfx::Point& location_in_screen) {
+  window_drag_controller_.reset(new OverviewWindowDragController(this));
+  window_drag_controller_->InitiateDrag(item, location_in_screen);
+}
+
+void WindowSelector::Drag(WindowSelectorItem* item,
+                          const gfx::Point& location_in_screen) {
+  DCHECK(window_drag_controller_.get());
+  DCHECK_EQ(item, window_drag_controller_->item());
+  window_drag_controller_->Drag(location_in_screen);
+}
+
+void WindowSelector::CompleteDrag(WindowSelectorItem* item) {
+  DCHECK(window_drag_controller_.get());
+  DCHECK_EQ(item, window_drag_controller_->item());
+  window_drag_controller_->CompleteDrag();
+}
+
 bool WindowSelector::HandleKeyEvent(views::Textfield* sender,
                                     const ui::KeyEvent& key_event) {
   if (key_event.type() != ui::ET_KEY_PRESSED)
@@ -512,6 +582,11 @@ void WindowSelector::OnDisplayRemoved(const display::Display& display) {
 
 void WindowSelector::OnDisplayMetricsChanged(const display::Display& display,
                                              uint32_t metrics) {
+  // Re-calculate the bounds for the window grids and position all the windows.
+  for (std::unique_ptr<WindowGrid>& grid : grid_list_) {
+    SetBoundsForWindowGridsInScreen(
+        GetGridsBoundsInScreen(const_cast<aura::Window*>(grid->root_window())));
+  }
   PositionWindows(/* animate */ false);
   RepositionTextFilterOnDisplayMetricsChange();
 }
@@ -574,6 +649,11 @@ void WindowSelector::OnWindowActivated(ActivationReason reason,
     return;
   }
 
+  // Do not cancel the overview mode if the window activation was caused by
+  // snapping window to one side of the screen.

[varkha, 2017/06/21 01:51:53]

<random_thought> This just made me think of scenario where you start dragging
with touch and then use the mouse while in gesture drag or vice versa. So just
make sure that this scenario doesn't cause some unexpected activation or other
side effects. </random_thought> 

[xdai1, 2017/06/22 21:46:33]

Plugged a mouse and check the scenarios you described. If there is no snapped
window yet when dragging a window around with touch, the mouse event on another
window item will cancel the overview mode and activate the window. If there is
one snapped window, when dragging another window around with touch, the mouse
event on a third window will cancel the overview mode and snap the third window
to the other side of the screen. and vice versa.

[varkha, 2017/06/26 16:40:07]

OK, thanks for checking this. I don't think those behaviors are truly very
important, as long as they do not cause some unexpected behaviour.

+  if (Shell::Get()->IsSplitViewModeActive())
+    return;
+
   // Don't restore focus on exit if a window was just activated.
   ResetFocusRestoreWindow(false);
   CancelSelection();
@@ -624,8 +704,39 @@ void WindowSelector::ContentsChanged(views::Textfield* sender,
   Move(WindowSelector::RIGHT, false);
 }
 
-aura::Window* WindowSelector::GetTextFilterWidgetWindow() {
-  return text_filter_widget_->GetNativeWindow();
+void WindowSelector::OnSplitViewStateChanged(
+    SplitViewController::State previous_state,
+    SplitViewController::State state) {
+  if (state != SplitViewController::NOSNAP) {
+    // Do not restore focus if a window was just snapped and activated.
+    ResetFocusRestoreWindow(false);
+  }
+
+  if (state == SplitViewController::LEFT_SNAPPED) {
+    aura::Window* snapped_window =
+        Shell::Get()->split_view_controller()->left_window();
+    const gfx::Rect bounds_in_screen =
+        Shell::Get()->split_view_controller()->GetSnappedWindowBoundsInScreen(
+            snapped_window, SplitViewController::RIGHT_SNAPPED);
+    SetBoundsForWindowGridsInScreen(bounds_in_screen);
+  } else if (state == SplitViewController::RIGHT_SNAPPED) {
+    aura::Window* snapped_window =
+        Shell::Get()->split_view_controller()->right_window();
+    const gfx::Rect bounds_in_screen =
+        Shell::Get()->split_view_controller()->GetSnappedWindowBoundsInScreen(
+            snapped_window, SplitViewController::LEFT_SNAPPED);
+    SetBoundsForWindowGridsInScreen(bounds_in_screen);
+  } else if (state == SplitViewController::BOTH_SNAPPED) {
+    CancelSelection();
+  } else {
+    DCHECK(state == SplitViewController::BOTH_SNAPPED ||
+           state == SplitViewController::NOSNAP);
+    // If two windows were snapped to both sides of the screen, end overview
+    // mode. If split view mode was ended (e.g., one of the snapped window was
+    // closed or minimized / fullscreened / maximized), also end overview mode
+    // if overview mode is active.
+    CancelSelection();
+  }
 }
 
 void WindowSelector::PositionWindows(bool animate) {
@@ -633,6 +744,10 @@ void WindowSelector::PositionWindows(bool animate) {
     grid->PositionWindows(animate);
 }
 
+aura::Window* WindowSelector::GetTextFilterWidgetWindow() {
+  return text_filter_widget_->GetNativeWindow();
+}
+
 void WindowSelector::RepositionTextFilterOnDisplayMetricsChange() {
   const gfx::Rect rect = GetTextFilterPosition(Shell::GetPrimaryRootWindow());
   text_filter_bottom_ = rect.bottom() + kTextFieldBottomMargin;