Implement Uniscribe RenderText for Windows.

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 498bb3b42a3ad552208fee366dc42ec7de434b44..24753fcbd124c1dfaa4e0d435ec2cbbb3df5d70f 100644
--- a/ui/gfx/render_text.cc
+++ b/ui/gfx/render_text.cc
@@ -175,6 +175,11 @@ void RenderText::SetSelectionModel(const SelectionModel& sel) {
   cached_bounds_and_offset_valid_ = false;
 }
 
+void RenderText::ToggleInsertMode() {
+  insert_mode_ = !insert_mode_;
+  cached_bounds_and_offset_valid_ = false;
+}
+
 void RenderText::SetDisplayRect(const Rect& r) {
   display_rect_ = r;
   cached_bounds_and_offset_valid_ = false;
@@ -184,13 +189,8 @@ size_t RenderText::GetCursorPosition() const {
   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) {
@@ -237,6 +237,15 @@ void RenderText::MoveCursorRight(BreakType break_type, bool select) {
   MoveCursorTo(position);
 }
 
+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);

[xji, 2011/08/18 22:47:54]

hmm... the functionality seems different from previous version. Why is this
change?  Without the change, what is wrong? Is there any case that caret_pos
could be equal to position (which means index of previous grapheme is the same
as current) except when postion ==0 and caret is placed at leading?

[msw, 2011/08/19 10:55:30]

This has been reincarnated as a convenience function to set the caret trailing
the cursor's previous grapheme (or lead the cursor if there is no previous
grapheme). This seems to be the intended behavior in numerous cases.

Without the change, my primary hurdle was SetCursorPosition assuming there was a
previous grapheme, and no convenient way to SetCursorPosition while retaining
the selection start.

I opted to check for a non-equal previous grapheme rather than checking for a
cursor at 0, because if the first character is complex, the cursor could
theoretically be at 1 with no previous grapheme.

[xji, 2011/08/19 17:38:13]

make sense.

but I think for complex script, say first characters are "a" and "b" which are
in one grapheme,
if the text is "a", when cursor is at index 1, previous grapheme is "a", index
is 0.
if the text is "ab", we should not allow cursor at index 1, even if cursor at
index 1, previous grapheme index is 0. 
So, the only case that caret_placement is leading is when position==0.

[msw, 2011/08/19 18:03:33]

Interesting, I wonder how that works with the IMEs and composition text, we'll
have to do some good testing around that, I think it's okay to address that in
followup changes.

+}
+
 bool RenderText::MoveCursorTo(const SelectionModel& selection) {
   bool changed = !selection.Equals(selection_model_);
   SetSelectionModel(selection);
@@ -251,6 +260,8 @@ bool RenderText::MoveCursorTo(const Point& point, bool select) {
 }
 
 bool RenderText::IsPointInSelection(const Point& point) {
+  if (EmptySelection())
+    return false;
   // TODO(xji): should this check whether the point is inside the visual
   // selection bounds? In case of "abcFED", if "ED" is selected, |point| points
   // to the right half of 'c', is the point in selection?
@@ -308,12 +319,8 @@ void RenderText::SelectWord() {
       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);

[xji, 2011/08/18 22:47:54]

why this change?

[msw, 2011/08/19 10:55:30]

Convenience of built-in checking for s previous grapheme.

 }
 
 const ui::Range& RenderText::GetCompositionRange() const {
@@ -589,7 +596,6 @@ void RenderText::UpdateCachedBoundsAndOffset() {
   // function will set |cursor_bounds_| and |display_offset_| to correct values.
   cached_bounds_and_offset_valid_ = true;
   cursor_bounds_ = GetCursorBounds(selection_model_, insert_mode_);
-  cursor_bounds_.set_width(std::max(cursor_bounds_.width(), 1));
   // Update |display_offset_| to ensure the current cursor is visible.
   int display_width = display_rect_.width();
   int string_width = GetStringWidth();