adding baseline options for super/sub scripting

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 <algorithm>
 #include <climits>
 
 #include "base/command_line.h"
@@ skipping 331 matching lines @@
     canvas_->DrawLine(start_, end, paint_);
 
     if (clipped)
       canvas_->Restore();
 
     x += pieces_[i].first;
   }
 }
 
 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());
 }
 
 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;
 }
 
 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);
 }
 
 LineSegment::LineSegment() : width(0), run(0) {}
 
 LineSegment::~LineSegment() {}
 
 Line::Line() : preceding_heights(0), baseline(0) {}
 
@@ skipping 35 matching lines @@
 RenderText* RenderText::CreateInstanceForEditing() {
   return new RenderTextHarfBuzz;
 }
 
 void RenderText::SetText(const base::string16& text) {
   DCHECK(!composition_range_.IsValid());
   if (text_ == text)
     return;
   text_ = text;
 
   // Adjust ranged styles and colors to accommodate a new text length.

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

nit: Adjust ranged styles, baselines, and colors...

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

Done.

   // Clear style ranges as they might break new text graphemes and apply
   // 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);
     break_list.SetMax(text_length);
   }
   cached_bounds_and_offset_valid_ = false;
 
   // Reset selection model. SetText should always followed by SetSelectionModel
   // or SetCursorPosition in upper layer.
   SetSelectionModel(SelectionModel());
@@ skipping 220 matching lines @@
 }
 
 void RenderText::SetColor(SkColor value) {
   colors_.SetValue(value);
 }
 
 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);
 
   cached_bounds_and_offset_valid_ = false;
   ResetLayout();
 }
 
 void RenderText::ApplyStyle(TextStyle style, bool value, const Range& range) {
   // Do not change styles mid-grapheme to avoid breaking ligatures.
   const size_t start = IsValidCursorIndex(range.start()) ? range.start() :
@@ skipping 237 matching lines @@
       text_direction_(base::i18n::UNKNOWN_DIRECTION),
       cursor_enabled_(true),
       cursor_visible_(false),
       insert_mode_(true),
       cursor_color_(kDefaultColor),
       selection_color_(kDefaultColor),
       selection_background_focused_color_(kDefaultSelectionBackgroundColor),
       focused_(false),
       composition_range_(Range::InvalidRange()),
       colors_(kDefaultColor),
+      baselines_(NORMAL_BASELINE),
       styles_(NUM_TEXT_STYLES),
       composition_and_selection_styles_applied_(false),
       obscured_(false),
       obscured_reveal_index_(-1),
       truncate_length_(0),
       elide_behavior_(NO_ELIDE),
       replace_newline_chars_with_symbols_(true),
       min_line_height_(0),
       multiline_(false),
       background_is_transparent_(false),
@@ skipping 314 matching lines @@
   if (behavior == ELIDE_EMAIL)
     return ElideEmail(text, available_width);
 
   // Create a RenderText copy with attributes that affect the rendering width.
   scoped_ptr<RenderText> render_text = CreateInstanceOfSameType();
   render_text->SetFontList(font_list_);
   render_text->SetDirectionalityMode(directionality_mode_);
   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)
     return text;
 
   const base::string16 ellipsis = base::string16(kEllipsisUTF16);
   const bool insert_ellipsis = (behavior != TRUNCATE);
   const bool elide_in_middle = (behavior == ELIDE_MIDDLE);
   const bool elide_at_beginning = (behavior == ELIDE_HEAD);
   StringSlicer slicer(text, ellipsis, elide_in_middle, elide_at_beginning);
 
   render_text->SetText(ellipsis);
   const float ellipsis_width = render_text->GetContentWidthF();
 
   if (insert_ellipsis && (ellipsis_width > available_width))
     return base::string16();
 
   // Use binary search to compute the elided text.
   size_t lo = 0;
   size_t hi = text.length() - 1;
   const base::i18n::TextDirection text_direction = GetTextDirection();
   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);
 
     // This has to be an additional step so that the ellipsis is rendered with
     // same style as trailing part of the text.
     if (insert_ellipsis && behavior == ELIDE_TAIL) {
       // When ellipsis follows text whose directionality is not the same as that
       // of the whole text, it will be rendered with the directionality of the
       // whole text. Since we want ellipsis to indicate continuation of the
@@ skipping 129 matching lines @@
   SetDisplayOffset(display_offset_.x() + delta_x);
 }
 
 void RenderText::DrawSelection(Canvas* canvas) {
   const std::vector<Rect> sel = GetSubstringBounds(selection());
   for (std::vector<Rect>::const_iterator i = sel.begin(); i < sel.end(); ++i)
     canvas->FillRect(*i, selection_background_focused_color_);
 }
 
 }  // namespace gfx