Fixes vertical alignment of RenderTextWin.

ui/gfx/render_text_win.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_win.h"
 
 #include <algorithm>
 
 #include "base/i18n/break_iterator.h"
 #include "base/i18n/rtl.h"
@@ skipping 470 matching lines @@
     renderer.DrawPosText(&pos[0], run->glyphs.get(), run->glyph_count);
     renderer.DrawDecorations(x, y, run->width, run->underline, run->strike,
                              run->diagonal_strike);
 
     x = glyph_x;
   }
 }
 
 void RenderTextWin::ItemizeLogicalText() {
   runs_.clear();
-  string_size_ = Size(0, GetFont().GetHeight());
-  common_baseline_ = 0;
+  string_size_ = Size(0, font_list().GetHeight());
+  common_baseline_ = font_list().GetBaseline();

[Alexei Svitkine (slow), 2013/07/24 15:29:48]

This value will be clobbered unless the text is empty, so your CL is changing
the behaviour of GetBaseline() for when there is no text.

Which isn't necessarily bad, but we should have clear expectations for how that
works and accompanying tests.

[Yuki, 2013/07/25 14:32:41]

Done.

 
   // Set Uniscribe's base text direction.
   script_state_.uBidiLevel =
       (GetTextDirection() == base::i18n::RIGHT_TO_LEFT) ? 1 : 0;
 
   if (text().empty())
     return;
 
   HRESULT hr = E_OUTOFMEMORY;
   int script_items_count = 0;
@@ skipping 54 matching lines @@
   UndoCompositionAndSelectionStyles();
 }
 
 void RenderTextWin::LayoutVisualText() {
   DCHECK(!runs_.empty());
 
   if (!cached_hdc_)
     cached_hdc_ = CreateCompatibleDC(NULL);
 
   HRESULT hr = E_FAIL;
-  string_size_.set_height(0);
+  int ascent = font_list().GetBaseline();
+  int descent = font_list().GetHeight() - font_list().GetBaseline();

[Alexei Svitkine (slow), 2013/07/24 15:29:48]

I'm not sure it makes sense to start with the metrics of the font_list, after
all - none of the fonts in it may end up actually being used by the string due
to fallback.

Why not just use the fonts of the runs?

[msw, 2013/07/24 18:02:36]

Using just the fonts of the runs and not including the selected 'primary' font
is the bug. If you enter a character that uses a fallback font with a smaller
baseline/height, then enter a character that uses the primary font with a larger
baseline/height, it will shift the baseline. Granted, there are still other
related defects, since new fallback fonts can arrive on any keystroke; I'm not
sure how we'll fix that, but we should try, and this seems like a reasonable
step forward (always support the baseline/height of the primary font).

[Alexei Svitkine (slow), 2013/07/24 18:12:28]

Ah, I understand now. Thanks for the explanation - I think the code should have
a comment that also mentions this too (in addition to tests).

[Yuki, 2013/07/25 14:32:41]

Done.

   for (size_t i = 0; i < runs_.size(); ++i) {
     internal::TextRun* run = runs_[i];
     LayoutTextRun(run);
 
-    string_size_.set_height(std::max(string_size_.height(),
-                                     run->font.GetHeight()));
-    common_baseline_ = std::max(common_baseline_, run->font.GetBaseline());
+    ascent = std::max(ascent, run->font.GetBaseline());
+    descent = std::max(descent,
+                       run->font.GetHeight() - run->font.GetBaseline());
 
     if (run->glyph_count > 0) {
       run->advance_widths.reset(new int[run->glyph_count]);
       run->offsets.reset(new GOFFSET[run->glyph_count]);
       hr = ScriptPlace(cached_hdc_,
                        &run->script_cache,
                        run->glyphs.get(),
                        run->glyph_count,
                        run->visible_attributes.get(),
                        &(run->script_analysis),
                        run->advance_widths.get(),
                        run->offsets.get(),
                        &(run->abc_widths));
       DCHECK(SUCCEEDED(hr));
     }
   }
+  string_size_.set_height(ascent + descent);
+  common_baseline_ = ascent;
 
   // Build the array of bidirectional embedding levels.
   scoped_ptr<BYTE[]> levels(new BYTE[runs_.size()]);
   for (size_t i = 0; i < runs_.size(); ++i)
     levels[i] = runs_[i]->script_analysis.s.uBidiLevel;
 
   // Get the maps between visual and logical run indices.
   visual_to_logical_.reset(new int[runs_.size()]);
   logical_to_visual_.reset(new int[runs_.size()]);
   hr = ScriptLayout(runs_.size(),
@@ skipping 228 matching lines @@
   size_t position = LayoutIndexToTextIndex(run->range.end());
   position = IndexOfAdjacentGrapheme(position, CURSOR_BACKWARD);
   return SelectionModel(position, CURSOR_FORWARD);
 }
 
 RenderText* RenderText::CreateInstance() {
   return new RenderTextWin;
 }
 
 }  // namespace gfx