Split Screen mode implementation

athena/wm/split_view_controller.cc

 // Copyright 2014 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 "athena/wm/split_view_controller.h"
 
+#include <cmath>
+
+#include "athena/wm/public/window_list_provider.h"
+#include "athena/wm/public/window_manager.h"
+#include "base/bind.h"
 #include "ui/aura/window.h"
+#include "ui/compositor/layer_animation_observer.h"
+#include "ui/compositor/scoped_layer_animation_settings.h"
 #include "ui/events/event_handler.h"
+#include "ui/gfx/display.h"
+#include "ui/gfx/screen.h"
 
 namespace athena {
-
-SplitViewController::SplitViewController() {
+namespace {
+
+// An animation observer that runs a callback at the end of the animation, and
+// destroys itself.
+class CallbackAnimationObserver : public ui::ImplicitAnimationObserver {
+ public:
+  explicit CallbackAnimationObserver(const base::Closure& closure)
+      : closure_(closure) {}
+
+  virtual ~CallbackAnimationObserver() {}
+
+ private:
+  // Overridden from ui::ImplicitAnimationObserver:
+  virtual void OnImplicitAnimationsCompleted() OVERRIDE {
+    if (!closure_.is_null())
+      closure_.Run();
+    delete this;
+  }
+
+  const base::Closure closure_;
+
+  DISALLOW_COPY_AND_ASSIGN(CallbackAnimationObserver);
+};
+
+}  // namespace
+
+SplitViewController::SplitViewController(
+    aura::Window* container,
+    WindowListProvider* window_list_provider,
+    WindowManager* window_manager)
+    : state_(INACTIVE),
+      container_(container),
+      window_manager_(window_manager),
+      window_list_provider_(window_list_provider),
+      current_activity_window_(NULL),
+      left_window_(NULL),
+      right_window_(NULL),
+      separator_position_(0),
+      weak_factory_(this) {
+  window_manager->AddObserver(this);
 }
 
 SplitViewController::~SplitViewController() {
-}
-
+  window_manager_->RemoveObserver(this);
+}
+
+bool SplitViewController::IsSplitViewModeActive() const {
+  return state_ == ACTIVE;
+}
+
+void SplitViewController::UpdateLayout(bool animate) {
+  if  (!left_window_)
+    return;
+  CHECK(right_window_);
+  gfx::Transform left_transform;
+  gfx::Transform right_transform;
+  int container_width = container_->GetBoundsInScreen().width();
+  if (state_ == ACTIVE) {
+    // This method should only be called once in ACTIVE state when
+    // the left and rightwindows are still full screen and need to be resized.
+    CHECK_EQ(left_window_->bounds().width(), container_width);
+    CHECK_EQ(right_window_->bounds().width(), container_width);
+    // Windows should be resized via an animation when entering the ACTIVE
+    // state.
+    CHECK(animate);
+    // We scale the windows here, but when the animation finishes, we reset
+    // the scaling and update the window bounds to the proper size - see
+    // OnAnimationCompleted().
+    left_transform.Scale(.5, 1);
+    right_transform.Scale(.5, 1);
+    right_transform.Translate(container_width, 0);
+  } else {
+    left_transform.Translate(separator_position_ - container_width, 0);
+    right_transform.Translate(separator_position_, 0);
+  }
+  left_window_->Show();
+  right_window_->Show();
+  SetWindowTransform(left_window_, left_transform, animate);
+  SetWindowTransform(right_window_, right_transform, animate);
+}
+
+void SplitViewController::SetWindowTransform(aura::Window* window,
+                                             const gfx::Transform& transform,
+                                             bool animate) {
+  if (animate) {
+    scoped_refptr<ui::LayerAnimator> animator = window->layer()->GetAnimator();
+    ui::ScopedLayerAnimationSettings settings(animator);
+    settings.SetPreemptionStrategy(
+        ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
+    settings.AddObserver(new CallbackAnimationObserver(
+        base::Bind(&SplitViewController::OnAnimationCompleted,
+                   weak_factory_.GetWeakPtr(),
+                   window)));
+    window->SetTransform(transform);
+  } else {
+    window->SetTransform(transform);
+  }
+}
+
+void SplitViewController::OnAnimationCompleted(aura::Window* window) {
+  DCHECK(window == left_window_ || window == right_window_);
+  if (state_ == ACTIVE) {
+    gfx::Rect window_bounds = gfx::Rect(container_->bounds().size());
+    int container_width = window_bounds.width();
+    window_bounds.set_width(container_width / 2);
+    window->SetTransform(gfx::Transform());
+    if (window == left_window_) {
+      left_window_->SetBounds(window_bounds);
+    } else {
+      window_bounds.set_x(container_width / 2);
+      right_window_->SetBounds(window_bounds);
+    }
+  } else {
+    int container_width = container_->bounds().width();
+    window->SetTransform(gfx::Transform());
+    if (window == left_window_) {
+      if (separator_position_ == 0)
+        left_window_->Hide();
+      if (state_ == INACTIVE)
+        left_window_ = NULL;
+    } else {
+      if (separator_position_ == container_width)
+        right_window_->Hide();
+      if (state_ == INACTIVE)
+        right_window_ = NULL;
+    }
+  }
+}
+
+void SplitViewController::UpdateSeparatorPositionFromScrollDelta(float delta) {
+  gfx::Screen* screen = gfx::Screen::GetScreenFor(container_);
+  const gfx::Rect& display_bounds =
+      screen->GetDisplayNearestWindow(container_).bounds();
+  gfx::Rect container_bounds = container_->GetBoundsInScreen();
+  separator_position_ =
+      delta > 0 ? ((int)delta) + display_bounds.x() - container_bounds.x()
+                : display_bounds.right() - container_bounds.x() + delta;
+}
+
+aura::Window* SplitViewController::GetCurrentActivityWindow() {
+  if (!current_activity_window_) {
+    aura::Window::Windows windows = window_list_provider_->GetWindowList();
+    if (windows.empty())
+      return NULL;
+    current_activity_window_ = windows.back();
+  }
+  return current_activity_window_;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Begin BezelController::ScrollDelegate overrides.
 void SplitViewController::ScrollBegin(BezelController::Bezel bezel,
                                       float delta) {
-}
-
+  if (!CanScroll())
+    return;
+  state_ = SCROLLING;
+  aura::Window* current_window = GetCurrentActivityWindow();
+  CHECK(current_window);
+
+  aura::Window::Windows windows = window_list_provider_->GetWindowList();
+  CHECK(windows.size() >= 2);
+  aura::Window::Windows::const_iterator it =
+      std::find(windows.begin(), windows.end(), current_window);
+  CHECK(it != windows.end());
+
+  if (delta > 0) {
+    right_window_ = current_window;
+    // reverse iterator points to the position before normal iterator |it|
+    aura::Window::Windows::const_reverse_iterator rev_it(it);
+    // circle to end if needed.
+    left_window_ = rev_it == windows.rend() ? windows.back() : *(rev_it);
+  } else {
+    left_window_ = current_window;
+    ++it;
+    // circle to front if needed.
+    right_window_ = it == windows.end() ? windows.front() : *it;
+  }
+
+  CHECK(left_window_);
+  CHECK(right_window_);
+
+  // TODO(oshima|mfomitchev): crbug.com/388362
+  // Until we are properly hiding off-screen windows in window manager:
+  // Loop through all windows and hide them
+  for (it = windows.begin(); it != windows.end(); ++it) {
+    if (*it != left_window_ && *it != right_window_)
+      (*it)->Hide();
+  }
+
+  UpdateSeparatorPositionFromScrollDelta(delta);
+  UpdateLayout(false);
+}
+
+// Max distance from the scroll end position to the middle of the screen where
+// we would go into the split view mode.
+const int kMaxDistanceFromMiddle = 120;
 void SplitViewController::ScrollEnd() {
+  if (state_ != SCROLLING)
+    return;
+
+  int container_width = container_->GetBoundsInScreen().width();
+  if (std::abs(container_width / 2 - separator_position_) <=
+      kMaxDistanceFromMiddle) {
+    state_ = ACTIVE;
+    separator_position_ = container_width / 2;
+  } else if (separator_position_ < container_width / 2) {
+    separator_position_ = 0;
+    current_activity_window_ = right_window_;
+    state_ = INACTIVE;
+  } else {
+    separator_position_ = container_width;
+    current_activity_window_ = left_window_;
+    state_ = INACTIVE;
+  }
+  UpdateLayout(true);
 }
 
 void SplitViewController::ScrollUpdate(float delta) {
+  if (state_ != SCROLLING)
+    return;
+  UpdateSeparatorPositionFromScrollDelta(delta);
+  UpdateLayout(false);
 }
 
 bool SplitViewController::CanScroll() {
-  return false;
+  // TODO(mfomitchev): return false in vertical orientation, in full screen.
+  bool result = (!window_manager_->IsOverviewModeActive() &&
+                 !IsSplitViewModeActive() &&
+                 window_list_provider_->GetWindowList().size() >= 2);
+  return result;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// WindowManagerObserver overrides
+void SplitViewController::OnOverviewModeEnter() {
+  if (state_ == ACTIVE) {
+    CHECK(left_window_);
+    CHECK(right_window_);
+    window_list_provider_->MoveToFront(right_window_);
+    window_list_provider_->MoveToFront(left_window_);
+    // TODO(mfomitchev): This shouldn't be done here, but the overview mode's
+    // transition animation currently looks bad if the starting transform of
+    // any window is not gfx::Transform().
+    right_window_->SetTransform(gfx::Transform());
+  } else if (current_activity_window_) {
+    window_list_provider_->MoveToFront(current_activity_window_);
+  }
+  state_ = INACTIVE;
+  left_window_ = NULL;
+  right_window_ = NULL;
+  current_activity_window_ = NULL;
+}
+
+void SplitViewController::OnOverviewModeExit() {
 }
 
 }  // namespace athena