Split LayoutSelecton::ClearSelection() out from SetSelection()

third_party/WebKit/Source/core/editing/LayoutSelection.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights
  * reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 195 matching lines @@
       runner->SetSelectionStateIfNeeded(SelectionInside);
   }
 }
 
 void LayoutSelection::SetSelection(
     LayoutObject* start,
     int start_pos,
     LayoutObject* end,
     int end_pos,
     SelectionPaintInvalidationMode block_paint_invalidation_mode) {
-  // This code makes no assumptions as to if the layout tree is up to date or
-  // not and will not try to update it. Currently clearSelection calls this
-  // (intentionally) without updating the layout tree as it doesn't care.
-  // Other callers may want to force recalc style before calling this.
-
-  // Make sure both our start and end objects are defined.
-  // Check www.msnbc.com and try clicking around to find the case where this
-  // happened.
-  if ((start && !end) || (end && !start))
-    return;
+  DCHECK(start);
+  DCHECK(end);
 
   // Just return if the selection hasn't changed.
   if (selection_start_ == start && selection_start_pos_ == start_pos &&
       selection_end_ == end && selection_end_pos_ == end_pos)
     return;
 
   DCHECK(frame_selection_->GetDocument().GetLayoutView()->GetFrameView());
+  DCHECK(!frame_selection_->GetDocument().NeedsLayoutTreeUpdate());
 
   SelectedMap old_selected_map =
       CollectSelectedMap(selection_start_, selection_end_, selection_end_pos_,
                          block_paint_invalidation_mode);
 
   // Now clear the selection.
   for (auto layout_object : old_selected_map.object_map.Keys())
     layout_object->SetSelectionStateIfNeeded(SelectionNone);
 
   SetSelectionState(start, end, end_pos);
@@ skipping 51 matching lines @@
   Commit();
   return std::make_pair(selection_start_pos_, selection_end_pos_);
 }
 
 void LayoutSelection::ClearSelection() {
   // For querying Layer::compositingState()
   // This is correct, since destroying layout objects needs to cause eager paint
   // invalidations.
   DisableCompositingQueryAsserts disabler;
 
-  SetSelection(0, -1, 0, -1, kPaintInvalidationNewMinusOld);
+  // Just return if the selection hasn't changed.
+  if (!selection_start_) {
+    DCHECK_EQ(selection_end_, nullptr);
+    DCHECK_EQ(selection_start_pos_, -1);
+    DCHECK_EQ(selection_end_pos_, -1);
+    return;
+  }
+
+  const SelectedMap& old_selected_map =
+      CollectSelectedMap(selection_start_, selection_end_, selection_end_pos_,
+                         kPaintInvalidationNewMinusOld);
+  // Clear SelectionState and invalidation.
+  for (auto layout_object : old_selected_map.object_map.Keys()) {
+    const SelectionState old_state = layout_object->GetSelectionState();
+    layout_object->SetSelectionStateIfNeeded(SelectionNone);
+    if (layout_object->GetSelectionState() == old_state)
+      continue;
+    layout_object->SetShouldInvalidateSelection();
+  }
+
+  // Reset selection start and end.
+  selection_start_ = nullptr;
+  selection_start_pos_ = -1;
+  selection_end_ = nullptr;
+  selection_end_pos_ = -1;
 }
 
 void LayoutSelection::Commit() {
   if (!HasPendingSelection())
     return;
   has_pending_selection_ = false;
 
   const VisibleSelectionInFlatTree& original_selection =
       frame_selection_->ComputeVisibleSelectionInFlatTree();
 
@@ skipping 106 matching lines @@
 
     o->SetShouldInvalidateSelection();
   }
 }
 
 DEFINE_TRACE(LayoutSelection) {
   visitor->Trace(frame_selection_);
 }
 
 }  // namespace blink