CrOS Tablet Window management - Split Screen part I

ash/wm/overview/window_selector_item.cc

Index: ash/wm/overview/window_selector_item.cc
diff --git a/ash/wm/overview/window_selector_item.cc b/ash/wm/overview/window_selector_item.cc
index 723e54bbaeb3811fa62c5cb4153177db84fc7efc..144fae5e06b333e446478dddbcb8a5290b16d56f 100644
--- a/ash/wm/overview/window_selector_item.cc
+++ b/ash/wm/overview/window_selector_item.cc
@@ -18,6 +18,7 @@
 #include "ash/wm/overview/overview_animation_type.h"
 #include "ash/wm/overview/scoped_overview_animation_settings.h"
 #include "ash/wm/overview/scoped_transform_overview_window.h"
+#include "ash/wm/overview/window_grid.h"
 #include "ash/wm/overview/window_selector.h"
 #include "ash/wm/overview/window_selector_controller.h"
 #include "ash/wm/window_state.h"
@@ -101,6 +102,10 @@ static const int kExitFadeInMilliseconds = 30;
 // this fraction of size.
 static const float kPreCloseScale = 0.02f;
 
+// Before dragging an overview window, the window will scale up |kPreDragScale|
+// to indicate its selection.
+static const float kDragWindowScale = 0.04f;
+
 // Convenience method to fade in a Window with predefined animation settings.
 // Note: The fade in animation will occur after a delay where the delay is how
 // long the lay out animations take.
@@ -113,8 +118,9 @@ void SetupFadeInAfterLayout(views::Widget* widget) {
   window->layer()->SetOpacity(1.0f);
 }
 
-// A Button that has a listener and listens to mouse clicks on the visible part
-// of an overview window.
+// A Button that has a listener and listens to mouse / gesture events on the
+// visible part of an overview window. Note that the drag events are only
+// handled in maximized mode.
 class ShieldButton : public views::CustomButton {
  public:
   ShieldButton(views::ButtonListener* listener, const base::string16& name)
@@ -130,6 +136,65 @@ class ShieldButton : public views::CustomButton {
   // after the WindowSelectorItem has been destroyed.
   void ResetListener() { listener_ = nullptr; }
 
+  // views::CustomButton:
+  bool OnMousePressed(const ui::MouseEvent& event) override {
+    if (listener() && SplitViewController::ShouldAllowSplitView()) {
+      gfx::Point location(event.location());
+      views::View::ConvertPointToScreen(this, &location);
+      listener()->HandlePressEvent(location);
+      return true;
+    }
+    return views::CustomButton::OnMousePressed(event);
+  }
+
+  void OnMouseReleased(const ui::MouseEvent& event) override {
+    if (listener() && SplitViewController::ShouldAllowSplitView()) {
+      gfx::Point location(event.location());
+      views::View::ConvertPointToScreen(this, &location);
+      listener()->HandleReleaseEvent(location);
+      return;
+    }
+    views::CustomButton::OnMouseReleased(event);
+  }
+
+  bool OnMouseDragged(const ui::MouseEvent& event) override {
+    if (listener() && SplitViewController::ShouldAllowSplitView()) {
+      gfx::Point location(event.location());
+      views::View::ConvertPointToScreen(this, &location);
+      listener()->HandleDragEvent(location);
+      return true;
+    }
+    return views::CustomButton::OnMouseDragged(event);
+  }
+
+  void OnGestureEvent(ui::GestureEvent* event) override {
+    if (listener() && SplitViewController::ShouldAllowSplitView()) {
+      gfx::Point location(event->location());
+      views::View::ConvertPointToScreen(this, &location);
+      switch (event->type()) {
+        case ui::ET_GESTURE_SCROLL_BEGIN:
+        case ui::ET_GESTURE_TAP_DOWN:
+          listener()->HandlePressEvent(location);
+          break;
+        case ui::ET_GESTURE_SCROLL_UPDATE:
+          listener()->HandleDragEvent(location);
+          break;
+        case ui::ET_GESTURE_END:
+          listener()->HandleReleaseEvent(location);
+          break;
+        default:
+          break;
+      }
+      event->SetHandled();
+      return;
+    }
+    views::CustomButton::OnGestureEvent(event);
+  }
+
+  WindowSelectorItem* listener() {
+    return static_cast<WindowSelectorItem*>(listener_);
+  }
+
  protected:
   // views::View:
   const char* GetClassName() const override { return "ShieldButton"; }
@@ -397,17 +462,19 @@ class WindowSelectorItem::CaptionContainerView : public views::View {
 };
 
 WindowSelectorItem::WindowSelectorItem(aura::Window* window,
-                                       WindowSelector* window_selector)
+                                       WindowSelector* window_selector,
+                                       WindowGrid* window_grid)
     : dimmed_(false),
       root_window_(window->GetRootWindow()),
-      transform_window_(window),
+      transform_window_(this, window),
       in_bounds_update_(false),
       selected_(false),
       caption_container_view_(nullptr),
       label_view_(nullptr),
       close_button_(new OverviewCloseButton(this)),
       window_selector_(window_selector),
-      background_view_(nullptr) {
+      background_view_(nullptr),
+      window_grid_(window_grid) {
   CreateWindowLabel(window->GetTitle());
   GetWindow()->AddObserver(this);
 }
@@ -542,7 +609,10 @@ void WindowSelectorItem::ButtonPressed(views::Button* sender,
     return;
   }
   CHECK(sender == caption_container_view_->listener_button());
-  window_selector_->SelectWindow(this);
+
+  // For other cases, the event is handled in OverviewWindowDragController.
+  if (!SplitViewController::ShouldAllowSplitView())
+    window_selector_->SelectWindow(this);
 }
 
 void WindowSelectorItem::OnWindowDestroying(aura::Window* window) {
@@ -565,6 +635,22 @@ float WindowSelectorItem::GetItemScale(const gfx::Size& size) {
       close_button_->GetPreferredSize().height());
 }
 
+void WindowSelectorItem::HandlePressEvent(
+    const gfx::Point& location_in_screen) {
+  StartDrag();
+  window_selector_->InitiateDrag(this, location_in_screen);
+}
+
+void WindowSelectorItem::HandleReleaseEvent(
+    const gfx::Point& location_in_screen) {
+  EndDrag();
+  window_selector_->CompleteDrag(this);
+}
+
+void WindowSelectorItem::HandleDragEvent(const gfx::Point& location_in_screen) {
+  window_selector_->Drag(this, location_in_screen);
+}
+
 gfx::Rect WindowSelectorItem::GetTargetBoundsInScreen() const {
   return transform_window_.GetTargetBoundsInScreen();
 }
@@ -755,4 +841,62 @@ aura::Window* WindowSelectorItem::GetOverviewWindowForMinimizedStateForTest() {
   return transform_window_.GetOverviewWindowForMinimizedState();
 }
 
+void WindowSelectorItem::StartDrag() {
+  gfx::Rect scaled_bounds(target_bounds_);
+  scaled_bounds.Inset(-target_bounds_.width() * kDragWindowScale,
+                      -target_bounds_.height() * kDragWindowScale);
+  OverviewAnimationType animation_type =
+      OverviewAnimationType::OVERVIEW_ANIMATION_CLOSING_SELECTOR_ITEM;
+  SetBounds(scaled_bounds, animation_type);
+
+  aura::Window* widget_window = item_widget_->GetNativeWindow();
+  if (widget_window && widget_window->parent() == GetWindow()->parent()) {
+    // TODO(xdai): This might not work if there is an always on top window.
+    // See crbug.com/733760.
+    widget_window->parent()->StackChildAtTop(widget_window);
+    widget_window->parent()->StackChildBelow(GetWindow(), widget_window);
+  }
+}
+
+void WindowSelectorItem::EndDrag() {
+  // First stack this item's window below the snapped window if split view mode
+  // is active.
+  aura::Window* dragged_window = GetWindow();
+  aura::Window* dragged_widget_window = item_widget_->GetNativeWindow();
+  if (Shell::Get()->IsSplitViewModeActive()) {
+    aura::Window* snapped_window =
+        Shell::Get()->split_view_controller()->GetDefaultSnappedWindow();

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

nit: you could cache the parent here (e.g. dragged_widget_window->parent()) to
simplify.

[xdai1, 2017/06/26 21:44:00]

Done.

+    if (snapped_window->parent() == dragged_widget_window->parent() &&
+        snapped_window->parent() == dragged_window->parent()) {
+      dragged_widget_window->parent()->StackChildBelow(dragged_widget_window,
+                                                       snapped_window);
+      dragged_widget_window->parent()->StackChildBelow(dragged_window,
+                                                       dragged_widget_window);
+    }
+  }
+
+  // Then find the window which is stacked right above this selector item's

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

nit: is -> was

[xdai1, 2017/06/26 21:44:00]

Done.

+  // window before dragging and stack this selector item's window below it.
+  const std::vector<std::unique_ptr<WindowSelectorItem>>& selector_items =
+      window_grid_->window_list();
+  size_t position_in_grid = 0;
+  for (size_t index = 0; index < selector_items.size(); index++) {
+    if (selector_items[index].get() == this) {
+      position_in_grid = index;
+      break;
+    }
+  }

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

See the comment below, but just a concern here. Have you checked that this logic
works when you have transient children (e.g. open modal dialogs) where there
might be more than one window in the stacking order between the overview items?

[xdai1, 2017/06/26 21:44:00]

I checked the scenario you described here (ctrl-o to open the File browser in a
browser window) and there is no problem with the stack logic. The reason is
WindowStackingClient::AdjustStacking() will do the right thing for the transient
windows.

+  for (int i = position_in_grid - 1; i >= 0; i--) {

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

Since you are breaking out of the for loop first time you enter it, could you
replace it with a condition?

Not sure - is it something like this?

if (position_in_grid < 2)
  return;
aura::Window* stacking_target =
    selector_items[position_in_grid - 2].get()->GetWindow();
... stack ...
And you could use the cached parent here as well from above.

[xdai1, 2017/06/26 21:44:00]

Sorry, I intended to put "break;" in the if-clause. 

+    aura::Window* stacking_target = selector_items[i].get()->GetWindow();
+    if (stacking_target->parent() == dragged_widget_window->parent() &&
+        stacking_target->parent() == dragged_window->parent()) {
+      dragged_widget_window->parent()->StackChildBelow(dragged_widget_window,
+                                                       stacking_target);
+      dragged_widget_window->parent()->StackChildBelow(dragged_window,
+                                                       dragged_widget_window);
+    }
+    break;
+  }
+}
+
 }  // namespace ash