Support longpress drag selection

ui/touch_selection/touch_selection_controller.cc

 // 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.
 
 #include "ui/touch_selection/touch_selection_controller.h"
 
 #include "base/auto_reset.h"
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
 
@@ skipping 29 matching lines @@
 
 }  // namespace
 
 TouchSelectionController::TouchSelectionController(
     TouchSelectionControllerClient* client,
     base::TimeDelta tap_timeout,
     float tap_slop,
     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),
       show_on_tap_for_empty_editable_(show_on_tap_for_empty_editable),
       response_pending_input_event_(INPUT_EVENT_TYPE_NONE),
       start_orientation_(TouchHandleOrientation::UNDEFINED),
       end_orientation_(TouchHandleOrientation::UNDEFINED),
       is_insertion_active_(false),
       activate_insertion_automatically_(false),
       is_selection_active_(false),
       activate_selection_automatically_(false),
       selection_empty_(false),
       selection_editable_(false),
       temporarily_hidden_(false),
+      longpress_drag_selector_(this),
       selection_handle_dragged_(false) {
   DCHECK(client_);
 }
 
 TouchSelectionController::~TouchSelectionController() {
 }
 
 void TouchSelectionController::OnSelectionBoundsChanged(
     const SelectionBound& start,
     const SelectionBound& end) {
@@ skipping 13 matching lines @@
 
   // Ensure that |response_pending_input_event_| is cleared after the method
   // completes, while also making its current value available for the duration
   // of the call.
   InputEventType causal_input_event = response_pending_input_event_;
   response_pending_input_event_ = INPUT_EVENT_TYPE_NONE;
   base::AutoReset<InputEventType> auto_reset_response_pending_input_event(
       &response_pending_input_event_, causal_input_event);
 
   const bool is_selection_dragging =
-      is_selection_active_ && (start_selection_handle_->is_dragging() ||
-                               end_selection_handle_->is_dragging());
+      is_selection_active_ && (start_selection_handle_->IsDragging() ||
+                               end_selection_handle_->IsDragging());
 
   // It's possible that the bounds temporarily overlap while a selection handle
   // is being dragged, incorrectly reporting a CENTER orientation.
   // TODO(jdduke): This safeguard is racy, as it's possible the delayed response
   // from handle positioning occurs *after* the handle dragging has ceased.
   // Instead, prevent selection -> insertion transitions without an intervening
   // action or selection clearing of some sort, crbug.com/392696.
   if (is_selection_dragging) {
     if (start_orientation_ == TouchHandleOrientation::CENTER)
       start_orientation_ = start_selection_handle_->orientation();
@@ skipping 12 matching lines @@
   if (start_orientation_ == TouchHandleOrientation::CENTER &&
       selection_editable_) {
     OnInsertionChanged();
     return;
   }
 
   HideAndDisallowShowingAutomatically();
 }
 
 bool TouchSelectionController::WillHandleTouchEvent(const MotionEvent& event) {
+  if (longpress_drag_selector_.WillHandleTouchEvent(event))
+    return true;
+
   if (is_insertion_active_) {
     DCHECK(insertion_handle_);
     return insertion_handle_->WillHandleTouchEvent(event);
   }
 
   if (is_selection_active_) {
     DCHECK(start_selection_handle_);
     DCHECK(end_selection_handle_);
-    if (start_selection_handle_->is_dragging())
+    if (start_selection_handle_->IsDragging())
       return start_selection_handle_->WillHandleTouchEvent(event);
 
-    if (end_selection_handle_->is_dragging())
+    if (end_selection_handle_->IsDragging())
       return end_selection_handle_->WillHandleTouchEvent(event);
 
     const gfx::PointF event_pos(event.GetX(), event.GetY());
     if ((event_pos - GetStartPosition()).LengthSquared() <=
         (event_pos - GetEndPosition()).LengthSquared())
       return start_selection_handle_->WillHandleTouchEvent(event);
     else
       return end_selection_handle_->WillHandleTouchEvent(event);
   }
 
   return false;
 }
 
-void TouchSelectionController::OnLongPressEvent() {
+void TouchSelectionController::OnLongPressEvent(base::TimeTicks event_time,
+                                                const gfx::PointF& position) {
+  longpress_drag_selector_.OnLongPressEvent(event_time, position);
   response_pending_input_event_ = LONG_PRESS;
   ShowSelectionHandlesAutomatically();
   ShowInsertionHandleAutomatically();
   ResetCachedValuesIfInactive();
 }
 
 void TouchSelectionController::AllowShowingFromCurrentSelection() {
   if (is_selection_active_ || is_insertion_active_)
     return;
 
@@ skipping 19 matching lines @@
   DeactivateInsertion();
   DeactivateSelection();
   activate_insertion_automatically_ = false;
   activate_selection_automatically_ = false;
 }
 
 void TouchSelectionController::SetTemporarilyHidden(bool hidden) {
   if (temporarily_hidden_ == hidden)
     return;
   temporarily_hidden_ = hidden;
-
-  TouchHandle::AnimationStyle animation_style = GetAnimationStyle(true);
-  if (is_selection_active_) {
-    start_selection_handle_->SetVisible(GetStartVisible(), animation_style);
-    end_selection_handle_->SetVisible(GetEndVisible(), animation_style);
-  }
-  if (is_insertion_active_)
-    insertion_handle_->SetVisible(GetStartVisible(), animation_style);
+  RefreshHandleVisibility();
 }
 
 void TouchSelectionController::OnSelectionEditable(bool editable) {
   if (selection_editable_ == editable)
     return;
   selection_editable_ = editable;
   ResetCachedValuesIfInactive();
   if (!selection_editable_)
     DeactivateInsertion();
 }
@@ skipping 50 matching lines @@
 }
 
 const gfx::PointF& TouchSelectionController::GetStartPosition() const {
   return start_.edge_bottom();
 }
 
 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()) {
     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(is_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 {
-    base = start_selection_handle_->position() + GetStartLineOffset();
-    extent = end_selection_handle_->position() + GetEndLineOffset();
+    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 {
+    drag_line_offset_ = GetEndLineOffset();
+  }
+
   selection_handle_dragged_ = true;
 
   // When moving the handle we want to move only the extent point. Before doing
   // so we must make sure that the base point is set correctly.
   client_->SelectBetweenCoordinates(base, extent);
   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);
 }
 
 void TouchSelectionController::SetNeedsAnimate() {
   client_->SetNeedsAnimate();
 }
 
 scoped_ptr<TouchHandleDrawable> TouchSelectionController::CreateDrawable() {
   return client_->CreateDrawable();
 }
 
 base::TimeDelta TouchSelectionController::GetTapTimeout() const {
   return tap_timeout_;
 }
 
-float TouchSelectionController::GetTapSlop() const {
-  return tap_slop_;
+void TouchSelectionController::OnLongPressDragDetectionStateChanged() {

[mfomitchev, 2015/04/28 02:17:30]

I don't understand why we need this. TSC::OnSelectionChanged() sets the handle
visibility based on GetStartVisible()/GetEndVisible(), so it should already
choose the appropriate visibility. Am I missing something?

[jdduke (slow), 2015/04/28 20:37:48]

The problem is that we want the handles to reappear when they user lifts their
finger (after a longpress, but without any subsequent drag motion). We won't get
another OnSelectionChanged in that case, neither will we get a DragEnd as the
user hasn't initiated a drag after their longpress.

So the options are either get an explicit notification from the longpress
draggable, or have an implicit agreement that its state will change only due to
one of DragEnd or ACTION_UP. I almost went with the latter, don't have a strong
preference either way.

We could make the OnLongPressDragActiveStateChanged a more general method if you
prefer, though it would only be used for the longpress drag code (unless we try
to refresh visibility another way, in which case we don't even need this):

OnActiveStateChanged(const Draggable&) = 0;

Let me know either way, again, I don't have a strong opinion here.

[mfomitchev, 2015/04/29 00:34:28]

Ah, I see, thanks for explaining. I am fine with it the way it is. When you work
on tests, can you please add a test for this use case?

If/when we switch to using gestures to drive the drag selection, would
ET_GESTURE_LONG_TAP work for this case (so that we don't need to listen to
ACTION_UP)?

+  // 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() {
   if (activate_insertion_automatically_)
     return;
   activate_insertion_automatically_ = true;
   ResetCachedValuesIfInactive();
 }
 
 void TouchSelectionController::ShowSelectionHandlesAutomatically() {
@@ skipping 92 matching lines @@
   // intervening SELECTION_CLEARED update to avoid unnecessary state changes.
   if (!is_selection_active_ || response_pending_input_event_ == LONG_PRESS) {
     if (is_selection_active_) {
       // The active selection session finishes with the start of the new one.
       LogSelectionEnd();
     }
     is_selection_active_ = true;
     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);
   }
 }
 
 void TouchSelectionController::DeactivateSelection() {
   if (!is_selection_active_)
     return;
   DCHECK(start_selection_handle_);
   DCHECK(end_selection_handle_);
   LogSelectionEnd();
+  longpress_drag_selector_.OnSelectionDeactivated();
   start_selection_handle_->SetEnabled(false);
   end_selection_handle_->SetEnabled(false);
   is_selection_active_ = false;
   client_->OnSelectionEvent(SELECTION_CLEARED);
 }
 
 void TouchSelectionController::ResetCachedValuesIfInactive() {
   if (is_selection_active_ || is_insertion_active_)
     return;
   start_ = SelectionBound();
   end_ = SelectionBound();
   start_orientation_ = TouchHandleOrientation::UNDEFINED;
   end_orientation_ = TouchHandleOrientation::UNDEFINED;
 }
 
+void TouchSelectionController::RefreshHandleVisibility() {
+  TouchHandle::AnimationStyle animation_style = GetAnimationStyle(true);
+  if (is_selection_active_) {
+    start_selection_handle_->SetVisible(GetStartVisible(), animation_style);
+    end_selection_handle_->SetVisible(GetEndVisible(), animation_style);
+  }
+  if (is_insertion_active_)
+    insertion_handle_->SetVisible(GetStartVisible(), animation_style);
+}
+
 gfx::Vector2dF TouchSelectionController::GetStartLineOffset() const {
   return ComputeLineOffsetFromBottom(start_);
 }
 
 gfx::Vector2dF TouchSelectionController::GetEndLineOffset() const {
   return ComputeLineOffsetFromBottom(end_);
 }
 
 bool TouchSelectionController::GetStartVisible() const {
-  return start_.visible() && !temporarily_hidden_;
+  if (!start_.visible())
+    return false;
+
+  return !temporarily_hidden_ && !longpress_drag_selector_.IsDetectingDrag();
 }
 
 bool TouchSelectionController::GetEndVisible() const {
-  return end_.visible() && !temporarily_hidden_;
+  if (!end_.visible())
+    return false;
+
+  return !temporarily_hidden_ && !longpress_drag_selector_.IsDetectingDrag();
 }
 
 TouchHandle::AnimationStyle TouchSelectionController::GetAnimationStyle(
     bool was_active) const {
   return was_active && client_->SupportsAnimation()
              ? TouchHandle::ANIMATION_SMOOTH
              : TouchHandle::ANIMATION_NONE;
 }
 
 void TouchSelectionController::LogSelectionEnd() {
   // TODO(mfomitchev): Once we are able to tell the difference between
   // 'successful' and 'unsuccessful' selections - log
   // Event.TouchSelection.Duration instead and get rid of
   // Event.TouchSelectionD.WasDraggeduration.
   if (selection_handle_dragged_) {
     base::TimeDelta duration = base::TimeTicks::Now() - selection_start_time_;
     UMA_HISTOGRAM_CUSTOM_TIMES("Event.TouchSelection.WasDraggedDuration",
                                duration,
                                base::TimeDelta::FromMilliseconds(500),
                                base::TimeDelta::FromSeconds(60),
                                60);
   }
 }
 
 }  // namespace ui