ash/home_screen/home_screen_delegate.h

// Copyright 2019 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 ASH_HOME_SCREEN_HOME_SCREEN_DELEGATE_H_
#define ASH_HOME_SCREEN_HOME_SCREEN_DELEGATE_H_

#include "base/callback.h"
#include "base/optional.h"
#include "ui/compositor/scoped_layer_animation_settings.h"

namespace aura {
class Window;
}  // namespace aura

namespace ash {

// Delegate for implementation-specific home screen behavior.
class HomeScreenDelegate {
 public:
  // Callback which fills out the passed settings object, allowing the caller to
  // animate with the given settings.
  using UpdateAnimationSettingsCallback =
      base::RepeatingCallback<void(ui::ScopedLayerAnimationSettings* settings)>;

  enum class AnimationTrigger {
    // Launcher animation is triggered by drag release.
    kDragRelease,

    // Launcher animation is triggered by pressing the AppList button.
    kLauncherButton,

    // Launcher animation is triggered by window activation.
    kHideForWindow,

    // Launcher animation is triggered by entering/exiting overview mode.
    kOverviewMode
  };

  virtual ~HomeScreenDelegate() = default;

  // Shows the home screen view.
  virtual void ShowHomeScreenView() = 0;

  // Gets the home screen window, if available, or null if the home screen
  // window is being hidden for effects (e.g. when dragging windows or
  // previewing the wallpaper).
  virtual aura::Window* GetHomeScreenWindow() = 0;

  // Updates the y position and opacity of the home launcher view. If |callback|
  // is non-null, it should be called with animation settings.
  virtual void UpdateYPositionAndOpacityForHomeLauncher(
      int y_position_in_screen,
      float opacity,
      UpdateAnimationSettingsCallback callback) = 0;

  // Updates the home launcher view after its show animation has completed.
  virtual void UpdateAfterHomeLauncherShown() = 0;

  // Returns an optional animation duration which is going to be used to set
  // the transition animation if provided.
  virtual base::Optional<base::TimeDelta> GetOptionalAnimationDuration() = 0;

  // Triggered when dragging launcher in tablet mode starts/proceeds/ends. They
  // cover both dragging launcher to show and hide.
  virtual void OnHomeLauncherDragStart() {}
  virtual void OnHomeLauncherDragInProgress() {}
  virtual void OnHomeLauncherDragEnd() {}

  // Propagates the home launcher animation transition. |trigger| is what
  // triggers the home launcher animation; |launcher_will_show| indicates
  // whether the launcher will show by the end of animation.
  virtual void NotifyHomeLauncherAnimationTransition(AnimationTrigger trigger,
                                                     bool launcher_will_show) {}
};

}  // namespace ash

#endif  // ASH_HOME_SCREEN_HOME_SCREEN_DELEGATE_H_