Support longpress drag selection

ui/touch_selection/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 "base/logging.h"
 #include "base/memory/scoped_ptr.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() {}
   virtual void SetEnabled(bool enabled) = 0;
   virtual void SetOrientation(TouchHandleOrientation orientation) = 0;
   virtual void SetAlpha(float alpha) = 0;
   virtual void SetFocus(const gfx::PointF& position) = 0;
   virtual gfx::RectF GetVisibleBounds() const = 0;
 };
 
 // Interface through which |TouchHandle| communicates handle manipulation and
 // requests concrete drawable instances.
-class UI_TOUCH_SELECTION_EXPORT TouchHandleClient {
+class UI_TOUCH_SELECTION_EXPORT TouchHandleClient
+    : public TouchSelectionDraggableClient {
  public:
-  virtual ~TouchHandleClient() {}
-  virtual void OnHandleDragBegin(const TouchHandle& handle) = 0;
-  virtual void OnHandleDragUpdate(const TouchHandle& handle,
-                                  const gfx::PointF& new_position) = 0;
-  virtual void OnHandleDragEnd(const TouchHandle& handle) = 0;
+  ~TouchHandleClient() override {}
   virtual void OnHandleTapped(const TouchHandle& handle) = 0;
   virtual void SetNeedsAnimate() = 0;
   virtual scoped_ptr<TouchHandleDrawable> CreateDrawable() = 0;
   virtual base::TimeDelta GetTapTimeout() const = 0;
-  virtual float GetTapSlop() const = 0;
 };
 
 // Responsible for displaying a selection or insertion handle for text
 // interaction.
-class UI_TOUCH_SELECTION_EXPORT TouchHandle {
+class UI_TOUCH_SELECTION_EXPORT TouchHandle : public TouchSelectionDraggable {
  public:
   // The drawable will be enabled but invisible until otherwise specified.
   TouchHandle(TouchHandleClient* client, TouchHandleOrientation orientation);
-  ~TouchHandle();
+  ~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 handle placement to |position|.
   // 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 SetPosition(const gfx::PointF& position);
 
   // 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);
 
-  // Allows touch-dragging of the handle. Returns true if the event was
-  // consumed, in which case the caller should cease further handling.
-  bool WillHandleTouchEvent(const MotionEvent& event);
-
   // 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;
 
-  bool is_dragging() const { return is_dragging_; }
   const gfx::PointF& position() const { return position_; }
   TouchHandleOrientation orientation() const { return orientation_; }
 
  private:
   void BeginDrag();
   void EndDrag();
   void BeginFade();
   void EndFade();
   void SetAlpha(float alpha);
 
   scoped_ptr<TouchHandleDrawable> drawable_;
 
   TouchHandleClient* const client_;
 
   gfx::PointF position_;
   TouchHandleOrientation orientation_;
   TouchHandleOrientation deferred_orientation_;
 
   gfx::PointF touch_down_position_;
-  gfx::Vector2dF touch_to_focus_offset_;
+  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 visibilty 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_;
 
   DISALLOW_COPY_AND_ASSIGN(TouchHandle);
 };
 
 }  // namespace ui
 
 #endif  // UI_TOUCH_SELECTION_TOUCH_HANDLE_H_