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 0cf23ccd1da399f56cd8452c3f8d2d16bc9c96ef..7f5c3885785aeee747925d880a4d658435699790 100644
--- a/ash/wm/overview/window_selector_item.cc
+++ b/ash/wm/overview/window_selector_item.cc
@@ -99,6 +99,10 @@ 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.
@@ -111,8 +115,9 @@ 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 the drag events are only handled in

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

nit: "Note:" or "Note that"

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

Done.

+// maximized mode.
 class ShieldButton : public views::CustomButton {
  public:
   ShieldButton(views::ButtonListener* listener, const base::string16& name)
@@ -128,6 +133,65 @@ class ShieldButton : public views::CustomButton {
   // after the WindowSelectorItem has been destroyed.
   void ResetListener() { listener_ = nullptr; }
 
+  // views::CustomButton overrides:

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

nit: "// views::CustomButton:" for consistency.

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

Done.

+  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_);

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

Since this is a local class, I think it would look better if we simply store a
pointer to WindowSlsectorItem instead of ButtonListener and rename the variable
to selector_item_. This way you would not need the cast and using it as a
ButtonListener should still work.

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

|listener_| is a class member variable from the base class Button. So we still
need the cast here.

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

Acknowledged.

+  }
+
  protected:
   // views::View:
   const char* GetClassName() const override { return "ShieldButton"; }
@@ -398,7 +462,7 @@ WindowSelectorItem::WindowSelectorItem(aura::Window* window,
                                        WindowSelector* window_selector)
     : dimmed_(false),
       root_window_(window->GetRootWindow()),
-      transform_window_(window),
+      transform_window_(this, window),
       in_bounds_update_(false),
       selected_(false),
       caption_container_view_(nullptr),
@@ -534,7 +598,11 @@ 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()) {

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

nit: no {}

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

Done.

+    window_selector_->SelectWindow(this);
+  }
 }
 
 void WindowSelectorItem::OnWindowDestroying(aura::Window* window) {
@@ -557,6 +625,22 @@ float WindowSelectorItem::GetItemScale(const gfx::Size& size) {
       close_button_->GetPreferredSize().height());
 }
 
+void WindowSelectorItem::HandlePressEvent(
+    const gfx::Point& location_in_screen) {
+  PrepareDrag();
+  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();
 }
@@ -747,4 +831,29 @@ aura::Window* WindowSelectorItem::GetOverviewWindowForMinimizedStateForTest() {
   return transform_window_.GetOverviewWindowForMinimizedState();
 }
 
+void WindowSelectorItem::PrepareDrag() {
+  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);

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

Don't you need to revert this somewhere?

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

I don't think it's necessary since if the window was snapped, the selector item
will be deleted, and if the window was moved back to the overview grid, we
called WindowSelector::PositionWindows() in
OverviewWindowDragController::CompleteDrag() to recalculate all window selector
items' bounds.

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

Acknowledged.

+
+  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() {
+  aura::Window* widget_window = item_widget_->GetNativeWindow();
+  if (widget_window && widget_window->parent() == GetWindow()->parent()) {
+    widget_window->parent()->StackChildAtBottom(widget_window);

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

I don't think we should be changing the order relative to what it was at the
beginning of the drag. This seems to be changing that order so entering
overview, dragging an item and releasing could be changing state. Not sure if
the window would also get activated as a result of a drag but this will probably
change the stacking of windows while they are animated back to their original
positions.

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

I changed the animation time and confirmed that the windows stack does change. I
modified the function so that the windows stack remains the same after dragging.

+    widget_window->parent()->StackChildBelow(GetWindow(), widget_window);
+  }
+}
+
 }  // namespace ash