athena: Allow getting into split-view mode from overview-mode.

athena/wm/overview_toolbar.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/overview_toolbar.h"
+
+#include "athena/common/closure_animation_observer.h"
+#include "base/bind.h"
+#include "base/strings/utf_string_conversions.h"
+#include "base/time/time.h"
+#include "grit/athena_resources.h"
+#include "ui/aura/window.h"
+#include "ui/base/resource/resource_bundle.h"
+#include "ui/compositor/layer.h"
+#include "ui/compositor/layer_delegate.h"
+#include "ui/compositor/scoped_layer_animation_settings.h"
+#include "ui/events/event.h"
+#include "ui/gfx/canvas.h"
+#include "ui/gfx/transform.h"
+
+namespace {
+
+const int kActionButtonImageSize = 54;
+const int kActionButtonTextSize = 20;
+const int kActionButtonPaddingFromRight = 32;
+}
+
+namespace athena {
+
+class ActionButton : public ui::LayerDelegate {

[Jun Mukai, 2014/08/13 17:00:23]

got confused, why this is a layer delegate rather than a CustomButton?
it seems no one is handling the button, so this would look like a button but
doesn't behave as a button?

[sadrul, 2014/08/13 19:25:29]

Pretty much, yeah. I considered making this a views Button at first. But these
buttons live only during the gesture, and do not get a chance to interact with
any events. So the sole purpose of these is to show something to the user.
Creating a Widget with the views in them felt too heavy-handed for that, and I
chose to use only a Layer since that is sufficient for our purposes (paint
something on the screen, sometimes with transforms).

+ public:
+  ActionButton(int resource_id, const std::string& label)
+      : resource_id_(resource_id), label_(base::UTF8ToUTF16(label)) {
+    layer_.reset(new ui::Layer(ui::LAYER_TEXTURED));
+    layer_->set_delegate(this);
+    layer_->SetFillsBoundsOpaquely(false);
+    layer_->SetVisible(true);
+    layer_->SetOpacity(0);
+  }
+
+  virtual ~ActionButton() {}
+
+  static void DestroyAfterFadeout(scoped_ptr<ActionButton> button) {
+    ui::Layer* layer = button->layer();
+    ui::ScopedLayerAnimationSettings settings(layer->GetAnimator());
+    settings.AddObserver(new ClosureAnimationObserver(
+        base::Bind(&ActionButton::DestroyImmediately, base::Passed(&button))));
+    layer->SetOpacity(0);
+  }
+
+  void SetPosition(const gfx::Point& position) {
+    layer_->SetBounds(
+        gfx::Rect(position,
+                  gfx::Size(kActionButtonImageSize,
+                            kActionButtonImageSize + kActionButtonTextSize)));
+  }
+
+  ui::Layer* layer() { return layer_.get(); }
+
+ private:
+  static void DestroyImmediately(scoped_ptr<ActionButton> button) {
+    button.reset();
+  }
+
+  // ui::LayerDelegate:
+  virtual void OnPaintLayer(gfx::Canvas* canvas) OVERRIDE {
+    ui::ResourceBundle& bundle = ui::ResourceBundle::GetSharedInstance();
+    canvas->DrawImageInt(*bundle.GetImageSkiaNamed(resource_id_), 0, 0);
+    gfx::ShadowValues shadow;
+    shadow.push_back(gfx::ShadowValue(gfx::Point(0, 1), 2, SK_ColorBLACK));
+    shadow.push_back(gfx::ShadowValue(gfx::Point(0, -1), 2, SK_ColorBLACK));
+    canvas->DrawStringRectWithShadows(label_,
+                                      gfx::FontList(),
+                                      SK_ColorWHITE,
+                                      gfx::Rect(0,
+                                                kActionButtonImageSize,
+                                                kActionButtonImageSize,
+                                                kActionButtonTextSize),
+                                      0,
+                                      gfx::Canvas::TEXT_ALIGN_CENTER,
+                                      shadow);
+  }
+
+  virtual void OnDeviceScaleFactorChanged(float device_scale_factor) OVERRIDE {}
+  virtual base::Closure PrepareForLayerBoundsChange() OVERRIDE {
+    return base::Closure();
+  }
+
+  int resource_id_;
+  base::string16 label_;
+  scoped_ptr<ui::Layer> layer_;
+
+  DISALLOW_COPY_AND_ASSIGN(ActionButton);
+};
+
+OverviewToolbar::OverviewToolbar(aura::Window* container)
+    : shown_(false),
+      close_(new ActionButton(IDR_ATHENA_OVERVIEW_TRASH, "Close")),
+      split_(new ActionButton(IDR_ATHENA_OVERVIEW_SPLIT, "Split")),
+      current_action_(ACTION_TYPE_NONE),
+      container_bounds_(container->bounds()) {
+  const int kPaddingFromBottom = 200;
+  const int kPaddingBetweenButtons = 200;
+
+  int x = container_bounds_.right() -
+          (kActionButtonPaddingFromRight + kActionButtonImageSize);
+  int y = container_bounds_.bottom() -
+          (kPaddingFromBottom + kActionButtonImageSize);
+  split_->SetPosition(gfx::Point(x, y));
+  y -= kPaddingBetweenButtons;
+  close_->SetPosition(gfx::Point(x, y));
+
+  container->layer()->Add(split_->layer());
+  container->layer()->Add(close_->layer());
+}
+
+OverviewToolbar::~OverviewToolbar() {
+  // If the buttons are visible, then fade them out, instead of destroying them
+  // immediately.
+  if (shown_) {
+    ActionButton::DestroyAfterFadeout(split_.Pass());
+    ActionButton::DestroyAfterFadeout(close_.Pass());
+  }
+}
+
+OverviewToolbar::ActionType OverviewToolbar::GetHighlightAction(
+    const ui::GestureEvent& event) const {
+  if (IsEventOverButton(split_.get(), event))
+    return ACTION_TYPE_SPLIT;
+  if (IsEventOverButton(close_.get(), event))
+    return ACTION_TYPE_CLOSE;
+  return ACTION_TYPE_NONE;
+}
+
+void OverviewToolbar::SetHighlightAction(ActionType action) {
+  if (current_action_ == action)
+    return;
+  current_action_ = action;
+  if (!shown_) {
+    ShowActionButtons();
+  } else {
+    TransformButton(close_.get());
+    TransformButton(split_.get());
+  }
+}
+
+void OverviewToolbar::ShowActionButtons() {
+  if (!shown_)
+    ToggleActionButtonsVisibility();
+}
+
+void OverviewToolbar::HideActionButtons() {
+  if (shown_)
+    ToggleActionButtonsVisibility();
+}
+
+void OverviewToolbar::ToggleActionButtonsVisibility() {
+  shown_ = !shown_;
+  TransformButton(close_.get());
+  TransformButton(split_.get());
+}
+
+bool OverviewToolbar::IsEventOverButton(ActionButton* button,
+                                        const ui::GestureEvent& event) const {
+  const int kBoundsInsetForTarget = 30;
+  gfx::RectF bounds = button->layer()->bounds();
+  bounds.Inset(-kBoundsInsetForTarget, -kBoundsInsetForTarget);
+  return bounds.Contains(event.location());
+}
+
+gfx::Transform OverviewToolbar::ComputeTransformFor(
+    ActionButton* button) const {
+  if (!shown_)
+    return gfx::Transform();
+
+  const float kHighlightScale = 1.5;
+  bool button_is_highlighted =
+      (current_action_ == ACTION_TYPE_CLOSE && button == close_.get()) ||
+      (current_action_ == ACTION_TYPE_SPLIT && button == split_.get());
+  gfx::Transform transform;
+  if (button_is_highlighted) {
+    transform.Translate(-kActionButtonImageSize * (kHighlightScale - 1) / 2, 0);
+    transform.Scale(kHighlightScale, kHighlightScale);
+  }
+  return transform;
+}
+
+void OverviewToolbar::TransformButton(ActionButton* button) {
+  ui::ScopedLayerAnimationSettings split_settings(
+      button->layer()->GetAnimator());
+  split_settings.SetTweenType(gfx::Tween::SMOOTH_IN_OUT);
+  button->layer()->SetTransform(ComputeTransformFor(button));
+  button->layer()->SetOpacity(shown_ ? 1 : 0);
+}
+
+}  // namespace athena