adding baseline options for super/sub scripting

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 50d29e83fe14585dc6002bc9b2a502b49d5c0b31..873cd47452c137daee715e08fa797e0cb1189c4f 100644
--- a/ui/gfx/render_text.cc
+++ b/ui/gfx/render_text.cc
@@ -349,10 +349,13 @@ void SkiaTextRenderer::DiagonalStrike::Draw() {
 }
 
 StyleIterator::StyleIterator(const BreakList<SkColor>& colors,
+                             const BreakList<BaselineStyle>& baselines,
                              const std::vector<BreakList<bool> >& styles)
     : colors_(colors),
+      baselines_(baselines),
       styles_(styles) {
   color_ = colors_.breaks().begin();
+  baseline_ = baselines_.breaks().begin();
   for (size_t i = 0; i < styles_.size(); ++i)
     style_.push_back(styles_[i].breaks().begin());
 }
@@ -361,6 +364,7 @@ StyleIterator::~StyleIterator() {}
 
 Range StyleIterator::GetRange() const {
   Range range(colors_.GetRange(color_));
+  range = range.Intersect(baselines_.GetRange(baseline_));
   for (size_t i = 0; i < NUM_TEXT_STYLES; ++i)
     range = range.Intersect(styles_[i].GetRange(style_[i]));
   return range;
@@ -368,6 +372,7 @@ Range StyleIterator::GetRange() const {
 
 void StyleIterator::UpdatePosition(size_t position) {
   color_ = colors_.GetBreak(position);
+  baseline_ = baselines_.GetBreak(position);
   for (size_t i = 0; i < NUM_TEXT_STYLES; ++i)
     style_[i] = styles_[i].GetBreak(position);
 }
@@ -428,6 +433,7 @@ void RenderText::SetText(const base::string16& text) {
   // the first style to the whole text instead.
   const size_t text_length = text_.length();
   colors_.SetMax(text_length);
+  baselines_.SetMax(text_length);

[msw, 2015/02/18 17:07:23]

You'll need to clear the baseline values here, like we do for |styles_| below.
Changes in text content need to clear any ranged styling that breaks runs,
otherwise the old ranges might attempt to split multi-character graphemes
(surrogate pairs, etc.) into different runs.

[dschuyler, 2015/02/18 22:36:02]

Done.

   for (size_t style = 0; style < NUM_TEXT_STYLES; ++style) {
     BreakList<bool>& break_list = styles_[style];
     break_list.SetValue(break_list.breaks().begin()->second);
@@ -668,6 +674,14 @@ void RenderText::ApplyColor(SkColor value, const Range& range) {
   colors_.ApplyValue(value, range);
 }
 
+void RenderText::SetBaselineStyle(BaselineStyle value) {
+  baselines_.SetValue(value);
+}
+
+void RenderText::ApplyBaselineStyle(BaselineStyle value, const Range& range) {
+  baselines_.ApplyValue(value, range);
+}
+
 void RenderText::SetStyle(TextStyle style, bool value) {
   styles_[style].SetValue(value);
 
@@ -925,6 +939,7 @@ RenderText::RenderText()
       focused_(false),
       composition_range_(Range::InvalidRange()),
       colors_(kDefaultColor),
+      baselines_(NORMAL_BASELINE),
       styles_(NUM_TEXT_STYLES),
       composition_and_selection_styles_applied_(false),
       obscured_(false),
@@ -1259,6 +1274,7 @@ base::string16 RenderText::Elide(const base::string16& text,
   render_text->SetCursorEnabled(cursor_enabled_);
   render_text->set_truncate_length(truncate_length_);
   render_text->styles_ = styles_;
+  render_text->baselines_ = baselines_;
   render_text->colors_ = colors_;
   render_text->SetText(text);
   if (render_text->GetContentWidthF() <= available_width)
@@ -1283,6 +1299,7 @@ base::string16 RenderText::Elide(const base::string16& text,
   for (size_t guess = (lo + hi) / 2; lo <= hi; guess = (lo + hi) / 2) {
     // Restore colors. They will be truncated to size by SetText.
     render_text->colors_ = colors_;
+    render_text->baselines_ = baselines_;

[msw, 2015/02/18 17:07:23]

With the change to clear the baseline values on SetText, you'll need to restore
baselines below, like we do for |styles_|, ensuring that the breaks fall on
valid cursor positions... I suggest making an improvement here: Create a helper
function (from the contents of the style loop below) to fix-up a breaklist given
a render text instance, ensuring the breaks fall on valid cursor indices. Then
we can just call that helper for each of the |styles_| breaklists, and for the
new |baselines_| breaklist.

That said, this helper code is a bit naive and overly-cautious, the ranges
should take the specific eliding into account. We should adjust ranges for
ELIDE_MIDDLE and ELIDE_HEAD (shifting indices for text that was removed, so the
ranges continue applying to the same characters)... But fixing that is a bit
beyond what I'd ask of you in this CL.

[dschuyler, 2015/02/18 22:36:02]

I moved the restore break list code out to a separate function.
I left the last bit that sounds like some decent optimization opportunities for
a later day.  :)

Done.

     base::string16 new_text =
         slicer.CutString(guess, insert_ellipsis && behavior != ELIDE_TAIL);
     render_text->SetText(new_text);