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

ui/gfx/render_text.cc

Index: ui/gfx/render_text.cc
diff --git a/ui/gfx/render_text.cc b/ui/gfx/render_text.cc
index f2f691ee9e283f214f5606dc22edb72a7ecd425d..3b94ef4cc3564ac4e667320e80f932b0c2eb9d37 100644
--- a/ui/gfx/render_text.cc
+++ b/ui/gfx/render_text.cc
@@ -205,6 +205,18 @@ void RestoreBreakList(RenderText* render_text, BreakList<T>* break_list) {
   }
 }
 
+// Merges |range1| and |range2|, with the directionality of the result same as
+// |range2|. |range1| and |range2| must at least share a point.
+gfx::Range MergeRangesWithDirection(const Range& range1, const Range& range2) {
+  DCHECK(!(range1.GetMax() < range2.GetMin() ||
+           range2.GetMax() < range1.GetMin()));
+  const uint32_t min = std::min(range1.GetMin(), range2.GetMin());
+  const uint32_t max = std::max(range1.GetMax(), range2.GetMax());
+  bool reversed =
+      range2.is_empty() ? !range1.is_reversed() : range2.is_reversed();

[tapted, 2016/05/25 04:31:06]

Comment about the logic here

+  return reversed ? Range(max, min) : Range(min, max);
+}
+
 }  // namespace
 
 namespace internal {
@@ -604,7 +616,16 @@ void RenderText::SetCursorPosition(size_t position) {
 
 void RenderText::MoveCursor(BreakType break_type,
                             VisualCursorDirection direction,
-                            bool select) {
+                            bool select,
+                            SelectionReversedBehavior select_behavior) {
+  // |select_behavior| is not relevant for CHARACTER_BREAK. Verify
+  // |select_behavior| has the default value for this case.
+  if (break_type == CHARACTER_BREAK)
+    DCHECK_EQ(SELECTION_DEFAULT, select_behavior);
+
+  if (break_type == WORD_BREAK)
+    DCHECK_NE(SELECTION_EXTEND, select_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) {
@@ -624,8 +645,26 @@ void RenderText::MoveCursor(BreakType break_type,
   } else {
     cursor = GetAdjacentSelectionModel(cursor, break_type, direction);
   }
-  if (select)
+  if (select) {
     cursor.set_selection_start(selection().start());
+
+    // cursor now corresponds to the new selection. Take |select_behavior| into

[tapted, 2016/05/25 04:31:06]

nit: cursor -> Cursor

+    // account.
+    bool selection_direction_changed =
+        !selection().is_empty() && !cursor.selection().is_empty() &&
+        selection().is_reversed() != cursor.selection().is_reversed();
+
+    if (select_behavior == SELECTION_EXTEND) {
+      cursor = SelectionModel(
+          MergeRangesWithDirection(selection(), cursor.selection()),
+          selection_model_.caret_affinity());
+    } else if (selection_direction_changed &&
+               select_behavior == SELECTION_CARET) {
+      cursor = SelectionModel(selection().start(),
+                              selection_model_.caret_affinity());
+    }
+  }
+
   MoveCursorTo(cursor);
 }