Create drag windows on all displays

ash/wm/drag_window_controller.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/wm/drag_window_controller.h"
 
+#include <algorithm>
+
+#include "ash/display/window_tree_host_manager.h"
+#include "ash/screen_util.h"
+#include "ash/shell.h"
 #include "ash/shell_window_ids.h"
 #include "ash/wm/window_util.h"
+#include "ui/aura/client/aura_constants.h"
 #include "ui/aura/client/screen_position_client.h"
 #include "ui/aura/window.h"
+#include "ui/aura/window_delegate.h"
 #include "ui/aura/window_event_dispatcher.h"
+#include "ui/base/hit_test.h"
 #include "ui/compositor/layer.h"
 #include "ui/compositor/layer_tree_owner.h"
 #include "ui/compositor/scoped_layer_animation_settings.h"
 #include "ui/views/view.h"
 #include "ui/views/widget/widget.h"
 #include "ui/wm/core/shadow_types.h"
 #include "ui/wm/core/window_util.h"
 
 namespace ash {
 
+// This keeps tack of the drag window's state. It creates/destory/updates bounds
+// and opacity based on the current bounds.
+class DragWindowController::DragWindowDetails : public aura::WindowDelegate {
+ public:
+  DragWindowDetails(const gfx::Display& display, aura::Window* original_window)
+      : root_window_(Shell::GetInstance()
+                         ->window_tree_host_manager()
+                         ->GetRootWindowForDisplayId(display.id())) {}
+
+  ~DragWindowDetails() override {
+    if (drag_window_) {
+      delete drag_window_;

[stevenjb, 2016/03/29 18:56:13]

nit: I had to remind myself that this was safe, maybe add a comment like
"Deleting the window will remove itself from its parent, see
aura::Window::~Window."

+      drag_window_ = nullptr;

[stevenjb, 2016/03/29 18:56:13]

This should be handled in  OnWindowDestroying, right?

[oshima, 2016/03/30 21:21:02]

Yep, changed to DCHECK.

+    }
+  }
+
+  void Update(aura::Window* original_window,
+              const gfx::Rect& bounds_in_screen,
+              const gfx::Point& drag_location_in_screen) {
+    gfx::Rect root_bounds_in_screen = root_window_->GetBoundsInScreen();
+    if (!root_bounds_in_screen.Intersects(bounds_in_screen)) {
+      delete drag_window_;
+      drag_window_ = nullptr;

[stevenjb, 2016/03/29 18:56:13]

Same here? This pattern implies ownership. Perhaps something like this would be
more clear:

delete drag_window_;  // Unparented in destructor, nulled in OnWindowDestroying

Or just "Nulled in OnWindowDestroying" since that implies that ownership is
addressed in the destructor.

[oshima, 2016/03/30 21:21:02]

per offline chat, I changed to DCHECK and added comment

+      layer_owner_.reset();
+      return;
+    }
+    if (!drag_window_)
+      CreateDragWindow(original_window, bounds_in_screen);
+
+    gfx::Rect bounds_in_root = ScreenUtil::ConvertRectFromScreen(
+        drag_window_->parent(), bounds_in_screen);
+    drag_window_->SetBounds(bounds_in_root);
+    if (root_bounds_in_screen.Contains(drag_location_in_screen)) {
+      SetOpacity(original_window, 1.f);
+    } else {
+      drag_window_->SetBounds(bounds_in_root);
+      gfx::Rect visible_bounds = root_bounds_in_screen;
+      visible_bounds.Intersect(bounds_in_screen);
+      SetOpacity(original_window,
+                 GetDragWindowOpacity(bounds_in_screen, visible_bounds));
+    }
+  }
+
+ private:
+  friend class DragWindowController;
+
+  void CreateDragWindow(aura::Window* original_window,
+                        const gfx::Rect& bounds_in_screen) {
+    DCHECK(!drag_window_);
+    drag_window_ = new aura::Window(this);
+    int parent_id = original_window->parent()->id();
+    aura::Window* container = root_window_->GetChildById(parent_id);
+
+    drag_window_->SetType(ui::wm::WINDOW_TYPE_POPUP);
+    drag_window_->SetTransparent(true);
+    drag_window_->Init(ui::LAYER_TEXTURED);
+    drag_window_->SetName("DragWindow");
+    drag_window_->set_id(kShellWindowId_PhantomWindow);
+    drag_window_->SetProperty(aura::client::kAnimationsDisabledKey, true);
+    container->AddChild(drag_window_);
+    drag_window_->SetBounds(bounds_in_screen);
+    SetShadowType(drag_window_, ::wm::SHADOW_TYPE_RECTANGULAR);
+
+    RecreateWindowLayers(original_window);
+    layer_owner_->root()->SetVisible(true);
+    drag_window_->layer()->Add(layer_owner_->root());
+    drag_window_->layer()->StackAtTop(layer_owner_->root());
+
+    // Show the widget after all the setups.
+    drag_window_->Show();
+
+    // Fade the window in.
+    ui::Layer* drag_layer = drag_window_->layer();
+    drag_layer->SetOpacity(0);
+    ui::ScopedLayerAnimationSettings scoped_setter(drag_layer->GetAnimator());
+    drag_layer->SetOpacity(1);
+  }
+
+  void RecreateWindowLayers(aura::Window* original_window) {
+    DCHECK(!layer_owner_.get());
+    layer_owner_ = ::wm::RecreateLayers(original_window);
+    // TODO(oshima): Recreated child layers may not have been painted
+    // yet, and may not be able to paint to because it does not have
+    // its original delegate.
+    layer_owner_->root()->set_delegate(original_window->layer()->delegate());
+    // Place the layer at (0, 0) of the DragWindowController's window.
+    gfx::Rect layer_bounds = layer_owner_->root()->bounds();
+    layer_bounds.set_origin(gfx::Point(0, 0));
+    layer_owner_->root()->SetBounds(layer_bounds);
+    layer_owner_->root()->SetVisible(false);
+    // Detach it from the current container.
+    layer_owner_->root()->parent()->Remove(layer_owner_->root());
+  }
+
+  void SetOpacity(const aura::Window* original_window, float opacity) {
+    ui::Layer* layer = drag_window_->layer();
+    ui::ScopedLayerAnimationSettings scoped_setter(layer->GetAnimator());
+    layer->SetOpacity(opacity);
+    layer_owner_->root()->SetOpacity(1.0f);
+  }
+
+  // aura::WindowDelegate:
+  gfx::Size GetMinimumSize() const override { return gfx::Size(); }
+  gfx::Size GetMaximumSize() const override { return gfx::Size(); }
+  void OnBoundsChanged(const gfx::Rect& old_bounds,
+                       const gfx::Rect& new_bounds) override {}
+  gfx::NativeCursor GetCursor(const gfx::Point& point) override {
+    return gfx::kNullCursor;
+  }
+  int GetNonClientComponent(const gfx::Point& point) const override {
+    return HTNOWHERE;
+  }
+  bool ShouldDescendIntoChildForEventHandling(
+      aura::Window* child,
+      const gfx::Point& location) override {
+    return false;
+  }
+  bool CanFocus() override { return false; }
+  void OnCaptureLost() override {}
+  void OnPaint(const ui::PaintContext& context) override {}
+  void OnDeviceScaleFactorChanged(float device_scale_factor) override {}
+  void OnWindowDestroyed(aura::Window* window) override {}
+  void OnWindowTargetVisibilityChanged(bool visible) override {}
+  bool HasHitTestMask() const override { return false; }
+  void GetHitTestMask(gfx::Path* mask) const override {}
+  void OnWindowDestroying(aura::Window* window) override {
+    DCHECK_EQ(drag_window_, window);
+    drag_window_ = nullptr;
+  }
+
+  aura::Window* root_window_;
+
+  aura::Window* drag_window_ = nullptr;  // Owned by the container.
+
+  // The copy of window_->layer() and its descendants.
+  scoped_ptr<ui::LayerTreeOwner> layer_owner_;
+
+  DISALLOW_COPY_AND_ASSIGN(DragWindowDetails);
+};
+
+// static
+float DragWindowController::GetDragWindowOpacity(
+    const gfx::Rect& window_bounds,
+    const gfx::Rect& visible_bounds) {
+  // The maximum opacity of the drag phantom window.
+  static const float kMaxOpacity = 0.8f;
+
+  return kMaxOpacity * visible_bounds.size().GetArea() /
+         window_bounds.size().GetArea();
+}
+
 DragWindowController::DragWindowController(aura::Window* window)
-    : window_(window),
-      drag_widget_(NULL) {
-}
-
-DragWindowController::~DragWindowController() {
-  Hide();
-}
-
-void DragWindowController::SetDestinationDisplay(
-    const gfx::Display& dst_display) {
-  dst_display_ = dst_display;
-}
-
-void DragWindowController::Show() {
-  if (!drag_widget_)
-    CreateDragWidget(window_->GetBoundsInScreen());
-  drag_widget_->Show();
-}
-
-void DragWindowController::SetBounds(const gfx::Rect& bounds) {
-  DCHECK(drag_widget_);
-  bounds_ = bounds;
-  SetBoundsInternal(bounds);
-}
-
-void DragWindowController::Hide() {
-  if (drag_widget_) {
-    drag_widget_->Close();
-    drag_widget_ = NULL;
-  }
-  layer_owner_.reset();
-}
-
-void DragWindowController::SetOpacity(float opacity) {
-  DCHECK(drag_widget_);
-  ui::Layer* layer = drag_widget_->GetNativeWindow()->layer();
-  ui::ScopedLayerAnimationSettings scoped_setter(layer->GetAnimator());
-  layer->SetOpacity(opacity);
-}
-
-void DragWindowController::CreateDragWidget(const gfx::Rect& bounds) {
-  DCHECK(!drag_widget_);
-  drag_widget_ = new views::Widget;
-  views::Widget::InitParams params(views::Widget::InitParams::TYPE_POPUP);
-  params.opacity = views::Widget::InitParams::TRANSLUCENT_WINDOW;
-  params.parent = window_->parent();
-  params.keep_on_top = true;
-  drag_widget_->set_focus_on_creation(false);
-  drag_widget_->Init(params);
-  drag_widget_->SetVisibilityChangedAnimationsEnabled(false);
-  drag_widget_->GetNativeWindow()->SetName("DragWindow");
-  drag_widget_->GetNativeWindow()->set_id(kShellWindowId_PhantomWindow);
-  // Show shadow for the dragging window.
-  SetShadowType(drag_widget_->GetNativeWindow(),
-                ::wm::SHADOW_TYPE_RECTANGULAR);
-  SetBoundsInternal(bounds);
-  drag_widget_->StackAbove(window_);
-
-  RecreateWindowLayers();
-  aura::Window* window = drag_widget_->GetNativeWindow();
-  layer_owner_->root()->SetVisible(true);
-  window->layer()->Add(layer_owner_->root());
-  window->layer()->StackAtTop(layer_owner_->root());
-
-  // Show the widget after all the setups.
-  drag_widget_->Show();
-
-  // Fade the window in.
-  ui::Layer* widget_layer = drag_widget_->GetNativeWindow()->layer();
-  widget_layer->SetOpacity(0);
-  ui::ScopedLayerAnimationSettings scoped_setter(widget_layer->GetAnimator());
-  widget_layer->SetOpacity(1);
-}
-
-void DragWindowController::SetBoundsInternal(const gfx::Rect& bounds) {
-  aura::Window* window = drag_widget_->GetNativeWindow();
-  aura::client::ScreenPositionClient* screen_position_client =
-      aura::client::GetScreenPositionClient(window->GetRootWindow());
-  if (screen_position_client && dst_display_.is_valid())
-    screen_position_client->SetBounds(window, bounds, dst_display_);
-  else
-    drag_widget_->SetBounds(bounds);
-}
-
-void DragWindowController::RecreateWindowLayers() {
-  DCHECK(!layer_owner_.get());
-  layer_owner_ = ::wm::RecreateLayers(window_);
-  layer_owner_->root()->set_delegate(window_->layer()->delegate());
-  // Place the layer at (0, 0) of the DragWindowController's window.
-  gfx::Rect layer_bounds = layer_owner_->root()->bounds();
-  layer_bounds.set_origin(gfx::Point(0, 0));
-  layer_owner_->root()->SetBounds(layer_bounds);
-  layer_owner_->root()->SetVisible(false);
-  // Detach it from the current container.
-  layer_owner_->root()->parent()->Remove(layer_owner_->root());
+    : window_(window) {
+  DCHECK(drag_windows_.empty());
+  gfx::Screen* screen = gfx::Screen::GetScreen();
+  gfx::Display current = screen->GetDisplayNearestWindow(window_);
+
+  for (const gfx::Display& display : screen->GetAllDisplays()) {
+    if (current.id() == display.id())
+      continue;
+    drag_windows_.push_back(
+        make_scoped_ptr(new DragWindowDetails(display, window_)));
+  }
+}
+
+DragWindowController::~DragWindowController() {}
+
+void DragWindowController::Update(const gfx::Rect& bounds_in_screen,
+                                  const gfx::Point& drag_location_in_screen) {
+  for (scoped_ptr<DragWindowDetails>& details : drag_windows_)
+    details->Update(window_, bounds_in_screen, drag_location_in_screen);
+}
+
+int DragWindowController::GetDragWindowsCountForTest() const {
+  int count = 0;
+  for (const scoped_ptr<DragWindowDetails>& details : drag_windows_) {
+    if (details->drag_window_)
+      count++;
+  }
+  return count;
+}
+
+const aura::Window* DragWindowController::GetDragWindowForTest(
+    size_t index) const {
+  for (const scoped_ptr<DragWindowDetails>& details : drag_windows_) {
+    if (details->drag_window_) {
+      if (index == 0)
+        return details->drag_window_;
+      index--;
+    }
+  }
+  return nullptr;
+}
+
+const ui::LayerTreeOwner* DragWindowController::GetDragLayerOwnerForTest(
+    size_t index) const {
+  for (const scoped_ptr<DragWindowDetails>& details : drag_windows_) {
+    if (details->layer_owner_) {
+      if (index == 0)
+        return details->layer_owner_.get();
+      index--;
+    }
+  }
+  return nullptr;
 }
 
 }  // namespace ash