Support longpress drag selection

ui/touch_selection/touch_selection_controller.h

Index: ui/touch_selection/touch_selection_controller.h
diff --git a/ui/touch_selection/touch_selection_controller.h b/ui/touch_selection/touch_selection_controller.h
index 115dd0d637046b44aa49c42e832fc5e82489cc95..594b78238ac8bb28f21bfd110445faa8853f8f59 100644
--- a/ui/touch_selection/touch_selection_controller.h
+++ b/ui/touch_selection/touch_selection_controller.h
@@ -5,9 +5,12 @@
 #ifndef UI_TOUCH_SELECTION_TOUCH_SELECTION_CONTROLLER_H_
 #define UI_TOUCH_SELECTION_TOUCH_SELECTION_CONTROLLER_H_
 
+#include "base/time/time.h"
 #include "ui/base/touch/selection_bound.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/longpress_drag_selector.h"
 #include "ui/touch_selection/selection_event_type.h"
 #include "ui/touch_selection/touch_handle.h"
 #include "ui/touch_selection/touch_handle_orientation.h"
@@ -34,7 +37,8 @@ class UI_TOUCH_SELECTION_EXPORT TouchSelectionControllerClient {
 
 // Controller for manipulating text selection via touch input.
 class UI_TOUCH_SELECTION_EXPORT TouchSelectionController
-    : public TouchHandleClient {
+    : public TouchHandleClient,
+      public LongPressDragSelectorClient {
  public:
   TouchSelectionController(TouchSelectionControllerClient* client,
                            base::TimeDelta tap_timeout,
@@ -59,7 +63,8 @@ class UI_TOUCH_SELECTION_EXPORT TouchSelectionController
 
   // To be called before forwarding a longpress event. This allows automatically
   // showing the selection or insertion handles from subsequent bounds changes.
-  void OnLongPressEvent();
+  void OnLongPressEvent(base::TimeTicks event_time,
+                        const gfx::PointF& location);
 
   // Allow showing the selection handles from the most recent selection bounds
   // update (if valid), or a future valid bounds update.
@@ -101,15 +106,21 @@ class UI_TOUCH_SELECTION_EXPORT TouchSelectionController
   enum InputEventType { TAP, LONG_PRESS, INPUT_EVENT_TYPE_NONE };
 
   // TouchHandleClient implementation.
-  void OnHandleDragBegin(const TouchHandle& handle) override;
-  void OnHandleDragUpdate(const TouchHandle& handle,
-                          const gfx::PointF& new_position) override;
-  void OnHandleDragEnd(const TouchHandle& handle) override;
+  void OnDragBegin(const TouchSelectionDraggable& draggable,
+                   const gfx::PointF& drag_position) override;
+  void OnDragUpdate(const TouchSelectionDraggable& draggable,
+                    const gfx::PointF& drag_position) override;
+  void OnDragEnd(const TouchSelectionDraggable& draggable) override;
+  bool IsWithinTapSlop(const gfx::Vector2dF& delta) const override;
   void OnHandleTapped(const TouchHandle& handle) override;
   void SetNeedsAnimate() override;
   scoped_ptr<TouchHandleDrawable> CreateDrawable() override;
   base::TimeDelta GetTapTimeout() const override;
-  float GetTapSlop() const override;
+
+  // LongPressDragSelectorClient implementation.
+  void OnLongPressDragDetectionStateChanged() override;
+  gfx::PointF GetSelectionStart() const override;
+  gfx::PointF GetSelectionEnd() const override;
 
   void ShowInsertionHandleAutomatically();
   void ShowSelectionHandlesAutomatically();
@@ -123,6 +134,10 @@ class UI_TOUCH_SELECTION_EXPORT TouchSelectionController
   void DeactivateSelection();
   void ResetCachedValuesIfInactive();
 
+  bool WillHandleTouchEventForLongPressDrag(const MotionEvent& event);
+  void SetTemporarilyHiddenForLongPressDrag(bool hidden);
+  void RefreshHandleVisibility();
+
   gfx::Vector2dF GetStartLineOffset() const;
   gfx::Vector2dF GetEndLineOffset() const;
   bool GetStartVisible() const;
@@ -133,7 +148,7 @@ class UI_TOUCH_SELECTION_EXPORT TouchSelectionController
 
   TouchSelectionControllerClient* const client_;
   const base::TimeDelta tap_timeout_;
-  const float tap_slop_;
+  const double tap_slop_squared_;
 
   // Controls whether an insertion handle is shown on a tap for an empty
   // editable text.
@@ -160,6 +175,14 @@ class UI_TOUCH_SELECTION_EXPORT TouchSelectionController
 
   bool temporarily_hidden_;
 
+  // Offset from the start of a drag sequence to a reasonable position on the
+  // corresponding line of text. This helps ensure that the initial selection
+  // induced by the drag doesn't "jump" between lines.
+  gfx::Vector2dF drag_line_offset_;
+
+  // Longpress drag allows direct manipulation of longpress-initiated selection.
+  LongPressDragSelector longpress_drag_selector_;
+
   base::TimeTicks selection_start_time_;
   // Whether a selection handle was dragged during the current 'selection
   // session' - i.e. since the current selection has been activated.