Support for Adaptive Handle Orientation

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() {}
+
+  // Sets whether the handle is active, allowing resource cleanup if necessary.
   virtual void SetEnabled(bool enabled) = 0;
-  virtual void SetOrientation(TouchHandleOrientation orientation) = 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;
-  virtual void SetFocus(const gfx::PointF& position) = 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 scoped_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);
+  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 handle placement to |position|.
+  // 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 SetPosition(const gfx::PointF& position);
+  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;
 
-  const gfx::PointF& position() const { return position_; }
+  // 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_; }
 
  private:
+  gfx::PointF ComputeHandleOrigin() const;
   void BeginDrag();
   void EndDrag();
   void BeginFade();
   void EndFade();
   void SetAlpha(float alpha);
+  void SetUpdateLayoutRequired();
 
   scoped_ptr<TouchHandleDrawable> drawable_;
 
   TouchHandleClient* const client_;
 
-  gfx::PointF position_;
+  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_