Refactor GestureNavigation to eliminate code redundancy

content/browser/web_contents/aura/window_slider.h

-// Copyright (c) 2013 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.
-
-#ifndef CONTENT_BROWSER_WEB_CONTENTS_AURA_WINDOW_SLIDER_H_
-#define CONTENT_BROWSER_WEB_CONTENTS_AURA_WINDOW_SLIDER_H_
-
-#include "base/compiler_specific.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/memory/weak_ptr.h"
-#include "content/common/content_export.h"
-#include "ui/aura/window_observer.h"
-#include "ui/compositor/layer_animator.h"
-#include "ui/events/event_handler.h"
-
-namespace ui {
-class Layer;
-}
-
-namespace content {
-
-class ShadowLayerDelegate;
-
-// A class for sliding the layer in a Window on top of other layers.
-class CONTENT_EXPORT WindowSlider : public ui::EventHandler,
-                                    public aura::WindowObserver {
- public:
-  class CONTENT_EXPORT Delegate {
-   public:
-    virtual ~Delegate() {}
-
-    // Creates a layer to show behind the window-layer. Called when the
-    // window-layer starts sliding out to reveal the layer underneath.
-    // The WindowSlider takes ownership of the created layer.
-    virtual ui::Layer* CreateBackLayer() = 0;
-
-    // Creates a layer to show on top of the window-layer. Called when the new
-    // layer needs to start sliding in on top of the window-layer.
-    // The WindowSlider takes ownership of the created layer.
-    virtual ui::Layer* CreateFrontLayer() = 0;
-
-    // Called when the slide is aborted. Note that when the slide is aborted,
-    // the WindowSlider resets any transform it applied on the window-layer.
-    virtual void OnWindowSlideAborted() = 0;
-
-    // Called when the slide is about to be complete. The delegate can take
-    // action with the assumption that slide will complete soon (within the
-    // duration of the final transition animation effect).
-    // This callback is always preceeded by CreateBackLayer() or by
-    // CreateFrontLayer() callback, and is guaranteed to be followed by the
-    // OnWindowSlideCompleted() callback.
-    virtual void OnWindowSlideCompleting() = 0;
-
-    // Called when the window slide completes. Note that at the end the
-    // window-layer may have been transformed. The callback here should reset
-    // the transform if necessary. |layer| is the slider's layer (previously
-    // created via CreateBackLayer() or CreateFrontLayer()).
-    virtual void OnWindowSlideCompleted(scoped_ptr<ui::Layer> layer) = 0;
-
-    // Called when the slider is destroyed.
-    virtual void OnWindowSliderDestroyed() = 0;
-  };
-
-  // The WindowSlider slides the layers in the |owner| window. It starts
-  // intercepting scroll events on |event_window|, and uses those events to
-  // control the layer-slide. The lifetime of the slider is managed by the
-  // lifetime of |owner|, i.e. if |owner| is destroyed, then the slider also
-  // destroys itself.
-  WindowSlider(Delegate* delegate,
-               aura::Window* event_window,
-               aura::Window* owner);
-
-  ~WindowSlider() override;
-
-  // Changes the owner of the slider.
-  void ChangeOwner(aura::Window* new_owner);
-
-  bool IsSlideInProgress() const;
-
- private:
-  // Sets up the slider layer correctly (sets the correct bounds of the layer,
-  // parents it to the right layer, and sets up the correct stacking order).
-  void SetupSliderLayer();
-
-  void UpdateForScroll(float x_offset, float y_offset);
-
-  // Completes or resets the slide depending on whether the sliding layer
-  // passed the "complete slide threshold".
-  void CompleteOrResetSlide();
-
-  // Stops all slider-owned animations, progressing them to their end-points.
-  // Note that depending on the sate of the Delegate and the WindowSlider, this
-  // may destroy the WindowSlider through animation callbacks.
-  void CompleteActiveAnimations();
-
-  // Resets in-progress slide if any, and starts the animation of the slidden
-  // window to its original position.
-  void ResetSlide();
-
-  // The following callbacks are triggered after an animation.
-  void SlideAnimationCompleted(scoped_ptr<ui::Layer> layer,
-                               scoped_ptr<ShadowLayerDelegate> shadow);
-
-  void ResetSlideAnimationCompleted(scoped_ptr<ui::Layer> layer,
-                                    scoped_ptr<ShadowLayerDelegate> shadow);
-
-  // Overridden from ui::EventHandler:
-  void OnKeyEvent(ui::KeyEvent* event) override;
-  void OnMouseEvent(ui::MouseEvent* event) override;
-  void OnScrollEvent(ui::ScrollEvent* event) override;
-  void OnGestureEvent(ui::GestureEvent* event) override;
-
-  // Overridden from aura::WindowObserver:
-  void OnWindowRemovingFromRootWindow(aura::Window* window,
-                                      aura::Window* new_root) override;
-
-  Delegate* delegate_;
-
-  // The slider intercepts scroll events from this window. The slider does not
-  // own |event_window_|. If |event_window_| is destroyed, then the slider stops
-  // listening for events, but it doesn't destroy itself.
-  aura::Window* event_window_;
-
-  // The window the slider operates on. The lifetime of the slider is bound to
-  // this window (i.e. if |owner_| does, the slider destroys itself). The slider
-  // can also delete itself when a slide gesture is completed. This does not
-  // destroy |owner_|.
-  aura::Window* owner_;
-
-  // Set to the Animator of the currently active animation. If no animation is
-  // active, this is set to NULL.
-  ui::LayerAnimator* active_animator_;
-
-  // The accumulated amount of horizontal scroll.
-  float delta_x_;
-
-  // This keeps track of the layer created by the delegate.
-  scoped_ptr<ui::Layer> slider_;
-
-  // This manages the shadow for the layers.
-  scoped_ptr<ShadowLayerDelegate> shadow_;
-
-  float active_start_threshold_;
-
-  const float start_threshold_touchscreen_;
-  const float start_threshold_touchpad_;
-  const float complete_threshold_;
-
-  base::WeakPtrFactory<WindowSlider> weak_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(WindowSlider);
-};
-
-}  // namespace content
-
-#endif  // CONTENT_BROWSER_WEB_CONTENTS_AURA_WINDOW_SLIDER_H_