Fix CJK font linking size on Windows XP.

ui/gfx/render_text_win.cc

Index: ui/gfx/render_text_win.cc
===================================================================
--- ui/gfx/render_text_win.cc	(revision 133692)
+++ ui/gfx/render_text_win.cc	(working copy)
@@ -13,9 +13,10 @@
 #include "base/threading/thread_restrictions.h"
 #include "base/utf_string_conversions.h"
 #include "base/win/registry.h"
+#include "base/win/windows_version.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/font_smoothing_win.h"
-#include "ui/gfx/platform_font.h"
+#include "ui/gfx/platform_font_win.h"
 
 namespace {
 
@@ -116,16 +117,29 @@
   key.Close();
 }
 
-// Changes |font| to have the specified |font_size| and |font_style| if it does
-// not already. Only considers bold and italic styles, since the underlined
-// style has no effect on glyph shaping.
-void DeriveFontIfNecessary(int font_size, int font_style, gfx::Font* font) {
+// Changes |font| to have the specified |font_size| (or |font_height| on Windows
+// XP) and |font_style| if it is not the case already. Only considers bold and
+// italic styles, since the underlined style has no effect on glyph shaping.
+void DeriveFontIfNecessary(int font_size,

[msw, 2012/04/26 21:04:42]

It would be nice to have this function take a const Font& font for the target
size/height/style, then using the size/height per platform is more of an impl
detail.

[Alexei Svitkine (slow), 2012/04/26 21:45:56]

That won't work for the call site that applies the style to the font, the style
would have to come from a parameter and not the const font.

It would also be a bit confusing, because now it would take two fonts as
parameters - one for the reference size, and the other for the other
characteristics (e.g. font name) and the output parameter.

Right now, it's clear that the single font param is the font that may be changed
according to the other parameters. It's much less confusing than what you're
proposing.

[msw, 2012/04/26 22:14:13]

Fair enough, I agree :), the function comment suffices to explain why it takes a
height and a size, which is the minor confusing implementation detail i was
trying to encapsulate.

+                           int font_height,
+                           int font_style,
+                           gfx::Font* font) {
   const int kStyleMask = (gfx::Font::BOLD | gfx::Font::ITALIC);
+  const int target_style = (font_style & kStyleMask);
+
+  // On Windows XP, the font must be resized using |font_height| instead of
+  // |font_size| to match GDI behavior.
+  if (base::win::GetVersion() < base::win::VERSION_VISTA) {
+    gfx::PlatformFontWin* platform_font =
+        static_cast<gfx::PlatformFontWin*>(font->platform_font());
+    *font = platform_font->DeriveFontWithHeight(font_height, target_style);
+    return;
+  }
+
   const int current_style = (font->GetStyle() & kStyleMask);
-  const int target_style = (font_style & kStyleMask);
   const int current_size = font->GetFontSize();
-  if (current_style != target_style || current_size != font_size)
-    *font = font->DeriveFont(font_size - current_size, font_style);
+  if (current_style != target_style || current_size != font->GetFontSize())
+    *font = font->DeriveFont(font_size - font->GetFontSize(), font_style);
 }
 
 }  // namespace
@@ -562,7 +576,8 @@
     run->range.set_start(run_break);
     run->font = GetFont();
     run->font_style = style->font_style;
-    DeriveFontIfNecessary(run->font.GetFontSize(), run->font_style, &run->font);
+    DeriveFontIfNecessary(run->font.GetFontSize(), run->font.GetHeight(),
+                          run->font_style, &run->font);
     run->foreground = style->foreground;
     run->strike = style->strike;
     run->diagonal_strike = style->diagonal_strike;
@@ -746,8 +761,9 @@
 void RenderTextWin::ApplySubstituteFont(internal::TextRun* run,
                                         const Font& font) {
   const int font_size = run->font.GetFontSize();
+  const int font_height = run->font.GetHeight();
   run->font = font;
-  DeriveFontIfNecessary(font_size, run->font_style, &run->font);
+  DeriveFontIfNecessary(font_size, font_height, run->font_style, &run->font);
   ScriptFreeCache(&run->script_cache);
   SelectObject(cached_hdc_, run->font.GetNativeFont());
 }