touch_handle.h

// 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.

#ifndef UI_TOUCH_SELECTION_TOUCH_HANDLE_H_
#define UI_TOUCH_SELECTION_TOUCH_HANDLE_H_

#include <memory>

#include "base/logging.h"
#include "base/macros.h"
#include "base/time/time.h"
#include "ui/events/gesture_detection/motion_event.h"
#include "ui/gfx/geometry/point_f.h"
#include "ui/gfx/geometry/rect_f.h"
#include "ui/gfx/geometry/vector2d_f.h"
#include "ui/touch_selection/touch_handle_orientation.h"
#include "ui/touch_selection/touch_selection_draggable.h"
#include "ui/touch_selection/ui_touch_selection_export.h"

namespace ui {

class TouchHandle;

// Interface through which |TouchHandle| delegates rendering-specific duties.
class UI_TOUCH_SELECTION_EXPORT TouchHandleDrawable {
 public:
  virtual ~TouchHandleDrawable() {}

  // Sets whether the handle is active, allowing resource cleanup if necessary.
  virtual void SetEnabled(bool enabled) = 0;

  // Update the handle visuals to |orientation|.
  // |mirror_vertical| and |mirror_horizontal| are used to invert the drawables
  // if required for adaptive handle orientation.
  virtual void SetOrientation(ui::TouchHandleOrientation orientation,
                              bool mirror_vertical,
                              bool mirror_horizontal) = 0;

  // Sets the origin position of the touch handle.
  // |origin| takes care of positioning the handle drawable based on
  // its visible bounds.
  virtual void SetOrigin(const gfx::PointF& origin) = 0;

  // Sets the transparency |alpha| for the handle drawable.
  virtual void SetAlpha(float alpha) = 0;

  // Returns the visible bounds of the handle drawable.
  // The bounds includes the transparent horizontal padding.
  virtual gfx::RectF GetVisibleBounds() const = 0;

  // Returns the transparent horizontal padding ratio of the handle drawable.
  virtual float GetDrawableHorizontalPaddingRatio() const = 0;
};

// Interface through which |TouchHandle| communicates handle manipulation and
// requests concrete drawable instances.
class UI_TOUCH_SELECTION_EXPORT TouchHandleClient
    : public TouchSelectionDraggableClient {
 public:
  ~TouchHandleClient() override {}
  virtual void OnHandleTapped(const TouchHandle& handle) = 0;
  virtual void SetNeedsAnimate() = 0;
  virtual std::unique_ptr<TouchHandleDrawable> CreateDrawable() = 0;
  virtual base::TimeDelta GetMaxTapDuration() const = 0;
  virtual bool IsAdaptiveHandleOrientationEnabled() const = 0;
};

// Responsible for displaying a selection or insertion handle for text
// interaction.
class UI_TOUCH_SELECTION_EXPORT TouchHandle : public TouchSelectionDraggable {
 public:
  // The drawable will be enabled but invisible until otherwise specified.
  TouchHandle(TouchHandleClient* client,
              TouchHandleOrientation orientation,
              const gfx::RectF& viewport_rect);
  ~TouchHandle() override;

  // TouchSelectionDraggable implementation.
  bool WillHandleTouchEvent(const MotionEvent& event) override;
  bool IsActive() const override;

  // Sets whether the handle is active, allowing resource cleanup if necessary.
  // If false, active animations or touch drag sequences will be cancelled.
  // While disabled, manipulation is *explicitly not supported*, and may lead to
  // undesirable and/or unstable side-effects. The handle can be safely
  // re-enabled to allow continued operation.
  void SetEnabled(bool enabled);

  enum AnimationStyle { ANIMATION_NONE, ANIMATION_SMOOTH };
  // Update the handle visibility, fading in/out according to |animation_style|.
  // If an animation is in-progress, it will be overriden appropriately.
  void SetVisible(bool visible, AnimationStyle animation_style);

  // Update the focus points for the handles. The handle will be positioned
  // either |top| or |bottom| based on the mirror parameters.
  // Note: If a fade out animation is active or the handle is invisible, the
  // handle position will not be updated until the handle regains visibility.
  void SetFocus(const gfx::PointF& top, const gfx::PointF& bottom);

  // Update the viewport rect, based on which the handle decide its inversion.
  void SetViewportRect(const gfx::RectF& viewport_rect);

  // Update the handle visuals to |orientation|.
  // Note: If the handle is being dragged, the orientation change will be
  // deferred until the drag has ceased.
  void SetOrientation(TouchHandleOrientation orientation);

  // Ticks an active animation, as requested to the client by |SetNeedsAnimate|.
  // Returns true if an animation is active and requires further ticking.
  bool Animate(base::TimeTicks frame_time);

  // Get the visible bounds of the handle, based on the current position and
  // the drawable's size/orientation. If the handle is invisible or disabled,
  // the bounds will be empty.
  gfx::RectF GetVisibleBounds() const;

  // Updates the handle layout if the is_handle_layout_update_required_ flag is
  // set. Will be called once per frame update, avoids multiple updates for
  // for the same frame update due to more than one parameter updates.
  void UpdateHandleLayout();

  const gfx::PointF& focus_bottom() const { return focus_bottom_; }
  TouchHandleOrientation orientation() const { return orientation_; }
  float alpha() const { return alpha_; }

 private:
  gfx::PointF ComputeHandleOrigin() const;
  void BeginDrag();
  void EndDrag();
  void BeginFade();
  void EndFade();
  void SetAlpha(float alpha);
  void SetUpdateLayoutRequired();

  std::unique_ptr<TouchHandleDrawable> drawable_;

  TouchHandleClient* const client_;

  gfx::PointF focus_bottom_;
  gfx::PointF focus_top_;
  gfx::RectF viewport_rect_;
  TouchHandleOrientation orientation_;
  TouchHandleOrientation deferred_orientation_;

  gfx::PointF touch_down_position_;
  gfx::Vector2dF touch_drag_offset_;
  base::TimeTicks touch_down_time_;

  // Note that when a fade animation is active, |is_visible_| and |position_|
  // may not reflect the actual visibility and position of the drawable. This
  // discrepancy is resolved either upon fade completion or cancellation.
  base::TimeTicks fade_end_time_;
  gfx::PointF fade_start_position_;
  float alpha_;
  bool animate_deferred_fade_;

  bool enabled_;
  bool is_visible_;
  bool is_dragging_;
  bool is_drag_within_tap_region_;
  bool is_handle_layout_update_required_;

  // Mirror variables determine if the handles should be inverted or not.
  bool mirror_vertical_;
  bool mirror_horizontal_;
  float handle_horizontal_padding_;

  DISALLOW_COPY_AND_ASSIGN(TouchHandle);
};

}  // namespace ui

#endif  // UI_TOUCH_SELECTION_TOUCH_HANDLE_H_