MacViews: Fix behavior of move and select commands when selection direction changes.

ui/gfx/render_text.cc

 // Copyright (c) 2012 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/gfx/render_text.h"
 
 #include <limits.h>
 
 #include <algorithm>
 #include <climits>
@@ skipping 595 matching lines @@
     }
   }
 }
 
 void RenderText::SetCursorPosition(size_t position) {
   MoveCursorTo(position, false);
 }
 
 void RenderText::MoveCursor(BreakType break_type,
                             VisualCursorDirection direction,
-                            bool select) {
+                            SelectionBehavior selection_behavior) {
   SelectionModel cursor(cursor_position(), selection_model_.caret_affinity());
   // Cancelling a selection moves to the edge of the selection.
-  if (break_type != LINE_BREAK && !selection().is_empty() && !select) {
+  if (break_type != LINE_BREAK && !selection().is_empty() &&
+      selection_behavior == SELECTION_NONE) {
     SelectionModel selection_start = GetSelectionModelForSelectionStart();
     int start_x = GetCursorBounds(selection_start, true).x();
     int cursor_x = GetCursorBounds(cursor, true).x();
     // Use the selection start if it is left (when |direction| is CURSOR_LEFT)
     // or right (when |direction| is CURSOR_RIGHT) of the selection end.
     if (direction == CURSOR_RIGHT ? start_x > cursor_x : start_x < cursor_x)
       cursor = selection_start;
     // Use the nearest word boundary in the proper |direction| for word breaks.
     if (break_type == WORD_BREAK)
       cursor = GetAdjacentSelectionModel(cursor, break_type, direction);
     // Use an adjacent selection model if the cursor is not at a valid position.
     if (!IsValidCursorIndex(cursor.caret_pos()))
       cursor = GetAdjacentSelectionModel(cursor, CHARACTER_BREAK, direction);
   } else {
     cursor = GetAdjacentSelectionModel(cursor, break_type, direction);
   }
-  if (select)
-    cursor.set_selection_start(selection().start());
+
+  // |cursor| corresponds to the tentative end point of the new selection. The
+  // selection direction is reversed iff the current selection is non-empty and
+  // the old selection end point and |cursor| are at the opposite ends of the
+  // old selection start point.
+  uint32_t min_end = std::min(selection().end(), cursor.selection().end());
+  uint32_t max_end = std::max(selection().end(), cursor.selection().end());
+  uint32_t current_start = selection().start();
+
+  bool selection_reversed = !selection().is_empty() &&
+                            min_end <= current_start &&
+                            current_start <= max_end;
+
+  // Take |selection_behavior| into account.
+  switch (selection_behavior) {
+    case SELECTION_RETAIN:
+      cursor.set_selection_start(current_start);
+      break;
+    case SELECTION_EXTEND:
+      cursor.set_selection_start(selection_reversed ? selection().end()
+                                                    : current_start);
+      break;
+    case SELECTION_CARET:
+      if (selection_reversed) {
+        cursor =
+            SelectionModel(current_start, selection_model_.caret_affinity());
+      } else {
+        cursor.set_selection_start(current_start);
+      }
+      break;
+    case SELECTION_NONE:
+      // Do nothing.
+      break;
+  }
+
   MoveCursorTo(cursor);
 }
 
 bool RenderText::MoveCursorTo(const SelectionModel& model) {
   // Enforce valid selection model components.
   size_t text_length = text().length();
   Range range(std::min(model.selection().start(),
                        static_cast<uint32_t>(text_length)),
               std::min(model.caret_pos(), text_length));
   // The current model only supports caret positions at valid cursor indices.
@@ skipping 939 matching lines @@
 
   SetDisplayOffset(display_offset_.x() + delta_x);
 }
 
 void RenderText::DrawSelection(Canvas* canvas) {
   for (const Rect& s : GetSubstringBounds(selection()))
     canvas->FillRect(s, selection_background_focused_color_);
 }
 
 }  // namespace gfx