From 1d10a165c5962a744eeca7a72a0c1fa087cc6ba9 Mon Sep 17 00:00:00 2001
From: "asvitkine@chromium.org"
 <asvitkine@chromium.org@0039d316-1c4b-4281-b951-d872f2087c98>
Date: Thu, 3 May 2012 20:19:30 +0000
Subject: Cache successful substitute fonts in RenderTextWin.

This is both a performance win (avoids trying all fonts
in the chain in the common case) and fixes the issue in
http://crbug.com/126109.

BUG=126109, 105550
TEST=Set Chrome's UI language to Chinese and restart Chrome.
Look through various text in the UI. The font used for all
Chinese text should be the same.

Review URL: http://codereview.chromium.org/10342018

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@135200 0039d316-1c4b-4281-b951-d872f2087c98
---
 ui/gfx/render_text_win.cc | 21 ++++++++++++++++++++-
 ui/gfx/render_text_win.h  |  3 +++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/ui/gfx/render_text_win.cc b/ui/gfx/render_text_win.cc
index c0a8277..4093047 100644
--- a/ui/gfx/render_text_win.cc
+++ b/ui/gfx/render_text_win.cc
@@ -191,6 +191,9 @@ HDC RenderTextWin::cached_hdc_ = NULL;
 // static
 std::map<std::string, std::vector<Font> > RenderTextWin::cached_linked_fonts_;
 
+// static
+std::map<std::string, Font> RenderTextWin::successful_substitute_fonts_;
+
 RenderTextWin::RenderTextWin()
     : RenderText(),
       common_baseline_(0),
@@ -608,6 +611,7 @@ void RenderTextWin::LayoutVisualText() {
     internal::TextRun* run = runs_[i];
     size_t run_length = run->range.length();
     const wchar_t* run_text = &(text()[run->range.start()]);
+    bool tried_cached_font = false;
     bool tried_fallback = false;
     size_t linked_font_index = 0;
     const std::vector<Font>* linked_fonts = NULL;
@@ -656,8 +660,23 @@ void RenderTextWin::LayoutVisualText() {
       }
 
       // Skip font substitution if there are no missing glyphs.
-      if (!glyphs_missing)
+      if (!glyphs_missing) {
+        // Save the successful fallback font that was chosen.
+        if (tried_fallback)
+          successful_substitute_fonts_[original_font.GetFontName()] = run->font;
         break;
+      }
+
+      // First, try the cached font from previous runs, if any.
+      if (!tried_cached_font) {
+        tried_cached_font = true;
+        std::map<std::string, Font>::const_iterator it =
+            successful_substitute_fonts_.find(original_font.GetFontName());
+        if (it != successful_substitute_fonts_.end()) {
+          ApplySubstituteFont(run, it->second);
+          continue;
+        }
+      }
 
       // If there are missing glyphs, first try finding a fallback font using a
       // meta file, if it hasn't yet been attempted for this run.
diff --git a/ui/gfx/render_text_win.h b/ui/gfx/render_text_win.h
index 6e9059e..7fb8d86 100644
--- a/ui/gfx/render_text_win.h
+++ b/ui/gfx/render_text_win.h
@@ -118,6 +118,9 @@ class RenderTextWin : public RenderText {
   // Cached map from font names to vectors of linked fonts.
   static std::map<std::string, std::vector<Font> > cached_linked_fonts_;
 
+  // Cached map from font name to the last successful substitute font used.
+  static std::map<std::string, Font> successful_substitute_fonts_;
+
   SCRIPT_CONTROL script_control_;
   SCRIPT_STATE script_state_;
 
-- 
cgit v1.1