Implement Pango RenderText for Linux.

ui/gfx/render_text.cc

Index: ui/gfx/render_text.cc
===================================================================
--- ui/gfx/render_text.cc	(revision 97884)
+++ ui/gfx/render_text.cc	(working copy)
@@ -162,6 +162,10 @@
   CheckStyleRanges(style_ranges_, text_.length());
 #endif
   cached_bounds_and_offset_valid_ = false;
+
+  // Reset selection model. SetText should always followed by SetSelectionModel
+  // or SetCursorPosition in upper layer.
+  SetSelectionModel(SelectionModel(0, 0, SelectionModel::LEADING));
 }
 
 void RenderText::SetSelectionModel(const SelectionModel& sel) {
@@ -184,13 +188,8 @@
   return selection_model_.selection_end();
 }
 
-void RenderText::SetCursorPosition(const size_t position) {
-  SelectionModel sel(selection_model());
-  sel.set_selection_start(position);
-  sel.set_selection_end(position);
-  sel.set_caret_pos(GetIndexOfPreviousGrapheme(position));
-  sel.set_caret_placement(SelectionModel::TRAILING);
-  SetSelectionModel(sel);
+void RenderText::SetCursorPosition(size_t position) {
+  MoveCursorTo(position, false);
 }
 
 void RenderText::MoveCursorLeft(BreakType break_type, bool select) {
@@ -199,8 +198,7 @@
   // Cancelling a selection moves to the edge of the selection.
   if (break_type != LINE_BREAK && !EmptySelection() && !select) {
     // Use the selection start if it is left of the selection end.
-    SelectionModel selection_start(GetSelectionStart(), GetSelectionStart(),
-                                   SelectionModel::LEADING);
+    SelectionModel selection_start = GetSelectionModelForSelectionStart();
     if (GetCursorBounds(selection_start, false).x() <
         GetCursorBounds(position, false).x())
       position = selection_start;
@@ -221,8 +219,7 @@
   // Cancelling a selection moves to the edge of the selection.
   if (break_type != LINE_BREAK && !EmptySelection() && !select) {
     // Use the selection start if it is right of the selection end.
-    SelectionModel selection_start(GetSelectionStart(), GetSelectionStart(),
-                                   SelectionModel::LEADING);
+    SelectionModel selection_start = GetSelectionModelForSelectionStart();
     if (GetCursorBounds(selection_start, false).x() >
         GetCursorBounds(position, false).x())
       position = selection_start;
@@ -308,12 +305,8 @@
       break;
   }
 
-  SelectionModel sel(selection_model());
-  sel.set_selection_start(selection_start);
-  sel.set_selection_end(cursor_position);
-  sel.set_caret_pos(GetIndexOfPreviousGrapheme(cursor_position));
-  sel.set_caret_placement(SelectionModel::TRAILING);
-  SetSelectionModel(sel);
+  MoveCursorTo(selection_start, false);
+  MoveCursorTo(cursor_position, true);
 }
 
 const ui::Range& RenderText::GetCompositionRange() const {
@@ -349,9 +342,9 @@
   cached_bounds_and_offset_valid_ = false;
 }
 
-base::i18n::TextDirection RenderText::GetTextDirection() const {
-  // TODO(msw): Bidi implementation, intended to replace the functionality added
-  //  in crrev.com/91881 (discussed in codereview.chromium.org/7324011).
+base::i18n::TextDirection RenderText::GetTextDirection() {
+  if (base::i18n::IsRTL())
+    return base::i18n::RIGHT_TO_LEFT;
   return base::i18n::LEFT_TO_RIGHT;
 }
 
@@ -426,7 +419,7 @@
   if (x >= right) return SelectionModel(right_pos);
   // binary searching the cursor position.
   // TODO(oshima): use the center of character instead of edge.
-  // Binary search may not work for language like arabic.
+  // Binary search may not work for language like Arabic.
   while (std::abs(static_cast<long>(right_pos - left_pos)) > 1) {
     int pivot_pos = left_pos + (right_pos - left_pos) / 2;
     int pivot = font.GetStringWidth(text().substr(0, pivot_pos));
@@ -497,7 +490,7 @@
   if (break_type == CHARACTER_BREAK)
     return SelectionModel(pos, pos, SelectionModel::LEADING);
 
-  // Notes: We always iterate words from the begining.
+  // Notes: We always iterate words from the beginning.
   // This is probably fast enough for our usage, but we may
   // want to modify WordIterator so that it can start from the
   // middle of string and advance backwards.
@@ -529,6 +522,8 @@
 
 SelectionModel RenderText::GetRightSelectionModel(const SelectionModel& current,
                                                   BreakType break_type) {
+  if (text_.empty())
+    return SelectionModel(0, 0, SelectionModel::LEADING);
   if (break_type == LINE_BREAK)
     return SelectionModel(text().length(),
         GetIndexOfPreviousGrapheme(text().length()), SelectionModel::TRAILING);
@@ -576,6 +571,31 @@
   }
 }
 
+Point RenderText::ToTextPoint(const Point& point) {
+  Point p(point.Subtract(display_rect_.origin()));
+  p = p.Subtract(GetUpdatedDisplayOffset());
+  if (base::i18n::IsRTL())
+    p.Offset(GetStringWidth() - display_rect_.width() + 1, 0);
+  return p;
+}
+
+Point RenderText::ToViewPoint(const Point& point) {
+  Point p(point.Add(display_rect_.origin()));
+  p = p.Add(GetUpdatedDisplayOffset());
+  if (base::i18n::IsRTL())
+    p.Offset(display_rect_.width() - GetStringWidth() - 1, 0);
+  return p;
+}
+
+void RenderText::MoveCursorTo(size_t position, bool select) {
+  size_t caret_pos = GetIndexOfPreviousGrapheme(position);
+  SelectionModel::CaretPlacement placement = (caret_pos == position) ?
+      SelectionModel::LEADING : SelectionModel::TRAILING;
+  size_t selection_start = select ? GetSelectionStart() : position;
+  SelectionModel sel(selection_start, position, caret_pos, placement);
+  SetSelectionModel(sel);
+}
+
 bool RenderText::IsPositionAtWordSelectionBoundary(size_t pos) {
   return pos == 0 || (u_isalnum(text()[pos - 1]) && !u_isalnum(text()[pos])) ||
       (!u_isalnum(text()[pos - 1]) && u_isalnum(text()[pos]));
@@ -598,9 +618,16 @@
     // Show all text whenever the text fits to the size.
     delta_offset = -display_offset_.x();
   } else if (cursor_bounds_.right() > display_rect_.right()) {
+    // TODO(xji): when the character overflow is a RTL character, currently, if
+    // we pan cursor at the rightmost position, the entered RTL character is not
+    // displayed. Should pan cursor to show the last logical characters.
+    //
     // Pan to show the cursor when it overflows to the right,
     delta_offset = display_rect_.right() - cursor_bounds_.right();
   } else if (cursor_bounds_.x() < display_rect_.x()) {
+    // TODO(xji): have similar problem as above when overflow character is a
+    // LTR character.
+    //
     // Pan to show the cursor when it overflows to the left.
     delta_offset = display_rect_.x() - cursor_bounds_.x();
   }
@@ -608,4 +635,18 @@
   cursor_bounds_.Offset(delta_offset, 0);
 }
 
+SelectionModel RenderText::GetSelectionModelForSelectionStart() {
+  size_t selection_start = GetSelectionStart();
+  size_t selection_end = GetCursorPosition();
+  if (selection_start < selection_end)
+    return SelectionModel(selection_start,
+                          selection_start,
+                          SelectionModel::LEADING);
+  else if (selection_start > selection_end)
+    return SelectionModel(selection_start,
+                          GetIndexOfPreviousGrapheme(selection_start),
+                          SelectionModel::TRAILING);
+  return selection_model_;
+}
+
 }  // namespace gfx