Support longpress drag selection

ui/touch_selection/touch_selection_controller.cc

Index: ui/touch_selection/touch_selection_controller.cc
diff --git a/ui/touch_selection/touch_selection_controller.cc b/ui/touch_selection/touch_selection_controller.cc
index ad010c3807275ac0aee8b74fe7b2dc227e8c4510..5bf999baedc28b09557c46cc326cff83ed67b3bc 100644
--- a/ui/touch_selection/touch_selection_controller.cc
+++ b/ui/touch_selection/touch_selection_controller.cc
@@ -47,7 +47,7 @@ TouchSelectionController::TouchSelectionController(
     bool show_on_tap_for_empty_editable)
     : client_(client),
       tap_timeout_(tap_timeout),
-      tap_slop_(tap_slop),
+      tap_slop_squared_(static_cast<double>(tap_slop) * tap_slop),
       force_next_update_(false),
       show_on_tap_for_empty_editable_(show_on_tap_for_empty_editable),
       response_pending_input_event_(INPUT_EVENT_TYPE_NONE),
@@ -59,6 +59,7 @@ TouchSelectionController::TouchSelectionController(
       selection_empty_(false),
       selection_editable_(false),
       temporarily_hidden_(false),
+      longpress_drag_selector_(this),
       selection_handle_dragged_(false) {
   DCHECK(client_);
 }
@@ -94,8 +95,8 @@ void TouchSelectionController::OnSelectionBoundsChanged(
       &response_pending_input_event_, causal_input_event);
 
   const bool is_selection_dragging = active_status_ == SELECTION_ACTIVE &&
-                                     (start_selection_handle_->is_dragging() ||
-                                      end_selection_handle_->is_dragging());
+                                     (start_selection_handle_->IsActive() ||
+                                      end_selection_handle_->IsActive());
 
   // It's possible that the bounds temporarily overlap while a selection handle
   // is being dragged, incorrectly reporting a CENTER orientation.
@@ -128,6 +129,9 @@ void TouchSelectionController::OnSelectionBoundsChanged(
 }
 
 bool TouchSelectionController::WillHandleTouchEvent(const MotionEvent& event) {
+  if (longpress_drag_selector_.WillHandleTouchEvent(event))
+    return true;
+
   if (active_status_ == INSERTION_ACTIVE) {
     DCHECK(insertion_handle_);
     return insertion_handle_->WillHandleTouchEvent(event);
@@ -136,10 +140,10 @@ bool TouchSelectionController::WillHandleTouchEvent(const MotionEvent& event) {
   if (active_status_ == SELECTION_ACTIVE) {
     DCHECK(start_selection_handle_);
     DCHECK(end_selection_handle_);
-    if (start_selection_handle_->is_dragging())
+    if (start_selection_handle_->IsActive())
       return start_selection_handle_->WillHandleTouchEvent(event);
 
-    if (end_selection_handle_->is_dragging())
+    if (end_selection_handle_->IsActive())
       return end_selection_handle_->WillHandleTouchEvent(event);
 
     const gfx::PointF event_pos(event.GetX(), event.GetY());
@@ -168,10 +172,12 @@ bool TouchSelectionController::WillHandleTapEvent(const gfx::PointF& location) {
 }
 
 bool TouchSelectionController::WillHandleLongPressEvent(
+    base::TimeTicks event_time,
     const gfx::PointF& location) {
   if (WillHandleTapOrLongPress(location))
     return true;
 
+  longpress_drag_selector_.OnLongPressEvent(event_time, location);
   response_pending_input_event_ = LONG_PRESS;
   ShowSelectionHandlesAutomatically();
   ShowInsertionHandleAutomatically();
@@ -205,14 +211,7 @@ void TouchSelectionController::SetTemporarilyHidden(bool hidden) {
   if (temporarily_hidden_ == hidden)
     return;
   temporarily_hidden_ = hidden;
-
-  TouchHandle::AnimationStyle animation_style = GetAnimationStyle(true);
-  if (active_status_ == SELECTION_ACTIVE) {
-    start_selection_handle_->SetVisible(GetStartVisible(), animation_style);
-    end_selection_handle_->SetVisible(GetEndVisible(), animation_style);
-  } else if (active_status_ == INSERTION_ACTIVE) {
-    insertion_handle_->SetVisible(GetStartVisible(), animation_style);
-  }
+  RefreshHandleVisibility();
 }
 
 void TouchSelectionController::OnSelectionEditable(bool editable) {
@@ -283,20 +282,39 @@ const gfx::PointF& TouchSelectionController::GetEndPosition() const {
   return end_.edge_bottom();
 }
 
-void TouchSelectionController::OnHandleDragBegin(const TouchHandle& handle) {
-  if (&handle == insertion_handle_.get()) {
+void TouchSelectionController::OnDragBegin(
+    const TouchSelectionDraggable& draggable,
+    const gfx::PointF& drag_position) {
+  if (&draggable == insertion_handle_.get()) {
+    DCHECK_EQ(active_status_, INSERTION_ACTIVE);
     client_->OnSelectionEvent(INSERTION_DRAG_STARTED);
+    drag_line_offset_ = GetStartLineOffset();
     return;
   }
 
-  gfx::PointF base, extent;
-  if (&handle == start_selection_handle_.get()) {
-    base = end_selection_handle_->position() + GetEndLineOffset();
-    extent = start_selection_handle_->position() + GetStartLineOffset();
+  DCHECK_EQ(active_status_, SELECTION_ACTIVE);
+
+  bool extend_selection_start = false;
+  if (&draggable == start_selection_handle_.get()) {
+    extend_selection_start = true;
+  } else if (&draggable == end_selection_handle_.get()) {
+    extend_selection_start = false;
+  } else {
+    DCHECK_EQ(&draggable, &longpress_drag_selector_);
+    extend_selection_start =
+        (drag_position - GetStartPosition()).LengthSquared() <
+        (drag_position - GetEndPosition()).LengthSquared();
+  }
+
+  gfx::PointF base = GetStartPosition() + GetStartLineOffset();
+  gfx::PointF extent = GetEndPosition() + GetEndLineOffset();
+  if (extend_selection_start) {
+    std::swap(base, extent);
+    drag_line_offset_ = GetStartLineOffset();
   } else {
-    base = start_selection_handle_->position() + GetStartLineOffset();
-    extent = end_selection_handle_->position() + GetEndLineOffset();
+    drag_line_offset_ = GetEndLineOffset();
   }
+
   selection_handle_dragged_ = true;
 
   // When moving the handle we want to move only the extent point. Before doing
@@ -305,27 +323,31 @@ void TouchSelectionController::OnHandleDragBegin(const TouchHandle& handle) {
   client_->OnSelectionEvent(SELECTION_DRAG_STARTED);
 }
 
-void TouchSelectionController::OnHandleDragUpdate(const TouchHandle& handle,
-                                                  const gfx::PointF& position) {
+void TouchSelectionController::OnDragUpdate(
+    const TouchSelectionDraggable& draggable,
+    const gfx::PointF& drag_position) {
   // As the position corresponds to the bottom left point of the selection
   // bound, offset it by half the corresponding line height.
-  gfx::Vector2dF line_offset = &handle == start_selection_handle_.get()
-                                   ? GetStartLineOffset()
-                                   : GetEndLineOffset();
-  gfx::PointF line_position = position + line_offset;
-  if (&handle == insertion_handle_.get())
+  gfx::PointF line_position = drag_position + drag_line_offset_;
+  if (&draggable == insertion_handle_.get())
     client_->MoveCaret(line_position);
   else
     client_->MoveRangeSelectionExtent(line_position);
 }
 
-void TouchSelectionController::OnHandleDragEnd(const TouchHandle& handle) {
-  if (&handle == insertion_handle_.get())
+void TouchSelectionController::OnDragEnd(
+    const TouchSelectionDraggable& draggable) {
+  if (&draggable == insertion_handle_.get())
     client_->OnSelectionEvent(INSERTION_DRAG_STOPPED);
   else
     client_->OnSelectionEvent(SELECTION_DRAG_STOPPED);
 }
 
+bool TouchSelectionController::IsWithinTapSlop(
+    const gfx::Vector2dF& delta) const {
+  return delta.LengthSquared() < tap_slop_squared_;
+}
+
 void TouchSelectionController::OnHandleTapped(const TouchHandle& handle) {
   if (insertion_handle_ && &handle == insertion_handle_.get())
     client_->OnSelectionEvent(INSERTION_TAPPED);
@@ -343,8 +365,18 @@ base::TimeDelta TouchSelectionController::GetTapTimeout() const {
   return tap_timeout_;
 }
 
-float TouchSelectionController::GetTapSlop() const {
-  return tap_slop_;
+void TouchSelectionController::OnLongPressDragActiveStateChanged() {
+  // The handles should remain hidden for the duration of a longpress drag,
+  // including the time between a longpress and the start of drag motion.
+  RefreshHandleVisibility();
+}
+
+gfx::PointF TouchSelectionController::GetSelectionStart() const {
+  return GetStartPosition();
+}
+
+gfx::PointF TouchSelectionController::GetSelectionEnd() const {
+  return GetEndPosition();
 }
 
 void TouchSelectionController::ShowInsertionHandleAutomatically() {
@@ -474,6 +506,7 @@ void TouchSelectionController::ActivateSelection() {
     selection_handle_dragged_ = false;
     selection_start_time_ = base::TimeTicks::Now();
     response_pending_input_event_ = INPUT_EVENT_TYPE_NONE;
+    longpress_drag_selector_.OnSelectionActivated();
     client_->OnSelectionEvent(SELECTION_SHOWN);
   }
 }
@@ -484,6 +517,7 @@ void TouchSelectionController::DeactivateSelection() {
   DCHECK(start_selection_handle_);
   DCHECK(end_selection_handle_);
   LogSelectionEnd();
+  longpress_drag_selector_.OnSelectionDeactivated();
   start_selection_handle_->SetEnabled(false);
   end_selection_handle_->SetEnabled(false);
   active_status_ = INACTIVE;
@@ -495,6 +529,16 @@ void TouchSelectionController::ForceNextUpdateIfInactive() {
     force_next_update_ = true;
 }
 
+void TouchSelectionController::RefreshHandleVisibility() {
+  TouchHandle::AnimationStyle animation_style = GetAnimationStyle(true);
+  if (active_status_ == SELECTION_ACTIVE) {
+    start_selection_handle_->SetVisible(GetStartVisible(), animation_style);
+    end_selection_handle_->SetVisible(GetEndVisible(), animation_style);
+  }
+  if (active_status_ == INSERTION_ACTIVE)
+    insertion_handle_->SetVisible(GetStartVisible(), animation_style);
+}
+
 gfx::Vector2dF TouchSelectionController::GetStartLineOffset() const {
   return ComputeLineOffsetFromBottom(start_);
 }
@@ -504,11 +548,17 @@ gfx::Vector2dF TouchSelectionController::GetEndLineOffset() const {
 }
 
 bool TouchSelectionController::GetStartVisible() const {
-  return start_.visible() && !temporarily_hidden_;
+  if (!start_.visible())
+    return false;
+
+  return !temporarily_hidden_ && !longpress_drag_selector_.IsActive();
 }
 
 bool TouchSelectionController::GetEndVisible() const {
-  return end_.visible() && !temporarily_hidden_;
+  if (!end_.visible())
+    return false;
+
+  return !temporarily_hidden_ && !longpress_drag_selector_.IsActive();
 }
 
 TouchHandle::AnimationStyle TouchSelectionController::GetAnimationStyle(