chrome/browser/ui/views/tabs/glow_hover_controller.h

// Copyright 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.

#ifndef CHROME_BROWSER_UI_VIEWS_TABS_GLOW_HOVER_CONTROLLER_H_
#define CHROME_BROWSER_UI_VIEWS_TABS_GLOW_HOVER_CONTROLLER_H_

#include "base/macros.h"
#include "ui/gfx/animation/animation_delegate.h"
#include "ui/gfx/animation/slide_animation.h"

namespace gfx {
class Point;
}

namespace views {
class View;
}

// GlowHoverController is responsible for drawing a hover effect as is used by
// the tabstrip. Typical usage:
//   OnMouseEntered() -> invoke Show().
//   OnMouseMoved()   -> invoke SetLocation().
//   OnMouseExited()  -> invoke Hide().
//   OnPaint()        -> if ShouldDraw() returns true invoke Draw().
// Internally GlowHoverController uses an animation to animate the glow and
// invokes SchedulePaint() back on the View as necessary.
class GlowHoverController : public gfx::AnimationDelegate {
 public:
  enum class ShowStyle { kSubtle, kPronounced };

  enum class HideStyle {
    kGradual,    // The hover should fade out.
    kImmediate,  // The hover should cut off, with no fade out.
  };

  explicit GlowHoverController(views::View* view);
  ~GlowHoverController() override;

  // Sets the AnimationContainer used by the animation.
  void SetAnimationContainer(gfx::AnimationContainer* container);

  // Sets the location of the hover, relative to the View passed to the
  // constructor.
  void SetLocation(const gfx::Point& location);

  // Set opacity scale to use when Show is called with SUBTLE.
  void SetSubtleOpacityScale(double opacity_scale);

  const gfx::Point& location() const { return location_; }

  // Initiates showing the hover.
  void Show(ShowStyle style);

  // Hides the hover.
  void Hide(HideStyle);

  // Returns the value of the animation.
  double GetAnimationValue() const;

  SkAlpha GetAlpha() const;

  // Returns true if there is something to be drawn. Use this instead of
  // invoking Draw() if creating |mask_image| is expensive.
  bool ShouldDraw() const;

  // gfx::AnimationDelegate overrides:
  void AnimationEnded(const gfx::Animation* animation) override;
  void AnimationProgressed(const gfx::Animation* animation) override;

 private:
  // View we're drawing to.
  views::View* view_;

  // Opacity of the glow ramps up over time.
  gfx::SlideAnimation animation_;

  // Location of the glow, relative to view.
  gfx::Point location_;
  double opacity_scale_;
  double subtle_opacity_scale_;

  DISALLOW_COPY_AND_ASSIGN(GlowHoverController);
};

#endif  // CHROME_BROWSER_UI_VIEWS_TABS_GLOW_HOVER_CONTROLLER_H_