Attempt to fallback to some matching font in the GetMatchingDirectWriteFontForTypeface function in …

ui/gfx/platform_font_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/platform_font_win.h"
 
 #include <algorithm>
 #include <dwrite.h>
 #include <math.h>
 #include <windows.h>
 
+#include "base/debug/alias.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/strings/string_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/win/scoped_comptr.h"
 #include "base/win/scoped_gdi_object.h"
 #include "base/win/scoped_hdc.h"
 #include "base/win/scoped_select_object.h"
 #include "base/win/win_util.h"
@@ skipping 96 matching lines @@
     return hr;
   }
 
   DWRITE_FONT_WEIGHT weight = (font_style & SkTypeface::kBold)
                             ? DWRITE_FONT_WEIGHT_BOLD
                             : DWRITE_FONT_WEIGHT_NORMAL;
   DWRITE_FONT_STRETCH stretch = DWRITE_FONT_STRETCH_NORMAL;
   DWRITE_FONT_STYLE italic = (font_style & SkTypeface::kItalic)
                             ? DWRITE_FONT_STYLE_ITALIC
                             : DWRITE_FONT_STYLE_NORMAL;
+
+  // The IDWriteFontFamily::GetFirstMatchingFont call fails on certain machines
+  // for fonts like MS UI Gothic, Segoe UI, etc. It is not clear why these
+  // fonts could be accessible to GDI and not to DirectWrite.
+  // The code below adds some debug fields to help track down these failures.
+  // 1. We get the matching font list for the font attributes passed in.
+  // 2. We get the font count in the family with a debug alias variable.
+  // 3. If we fail to get the font via the GetFirstMatchingFont call then we
+  //    try to get the first matching font in the IDWriteFontList.
+  // 4. If GetFirstMatchingFont and IDWriteFontList both fail then we CHECK as
+  //    before.
+  // Next step would be to remove the CHECKs in this function and fallback to
+  // GDI.

[scottmg, 2014/11/19 22:15:36]

add crbug link

[ananta, 2014/11/19 22:21:30]

Done.

+  uint32 matching_font_count = 0;
+  base::debug::Alias(&matching_font_count);
+
+  base::win::ScopedComPtr<IDWriteFontList> matching_font_list;
+  hr = font_family->GetMatchingFonts(weight, stretch, italic,
+                                     matching_font_list.Receive());
+  if (SUCCEEDED(hr))
+    matching_font_count = matching_font_list->GetFontCount();

[scottmg, 2014/11/19 22:15:36]

is it necessary to debug::Alias again after the assignment?

[ananta, 2014/11/19 22:21:30]

Done.

+
+  bool fallback_to_matching_font = false;
+  base::debug::Alias(&fallback_to_matching_font);
+
   hr = font_family->GetFirstMatchingFont(weight, stretch, italic,
                                          dwrite_font);
+  if (FAILED(hr)) {
+    if (matching_font_list) {
+      hr = matching_font_list->GetFont(0, dwrite_font);
+      if (SUCCEEDED(hr))
+        fallback_to_matching_font = true;

[scottmg, 2014/11/19 22:15:36]

same

[ananta, 2014/11/19 22:21:30]

Done.

+    }
+  }
   if (FAILED(hr))
     CHECK(false);
   return hr;
 }
 
 }  // namespace
 
 namespace gfx {
 
 // static
@@ skipping 300 matching lines @@
   const int baseline = std::max<int>(1, std::round(-skia_metrics.fAscent));
   const int cap_height = std::round(-font_info.lfHeight *
       dwrite_font_metrics.capHeight / dwrite_font_metrics.designUnitsPerEm);
 
   // The metrics retrieved from skia don't have the average character width. In
   // any case if we get the average character width from skia then use that or
   // use the text extent technique as documented by microsoft. See
   // GetAverageCharWidthInDialogUnits for details.
   const int ave_char_width =
       skia_metrics.fAvgCharWidth == 0 ?
-          HFontRef::GetAverageCharWidthInDialogUnits(gdi_font)
+          HFontRef::GetAverageCharWidthInDialogUnits(gdi_font) - 1
               : skia_metrics.fAvgCharWidth;
 
   // tmAscent - tmInternalLeading in gdi font land gives us the cap height.
   // We can use fAscent - cap_height in DirectWrite land to get the internal
   // leading value.
   const int internal_leading = -skia_metrics.fAscent - cap_height;
   const int font_size = std::max<int>(1, height - internal_leading);
 
   int style = 0;
   if (skia_style & SkTypeface::kItalic)
@@ skipping 81 matching lines @@
   return new PlatformFontWin(native_font);
 }
 
 // static
 PlatformFont* PlatformFont::CreateFromNameAndSize(const std::string& font_name,
                                                   int font_size) {
   return new PlatformFontWin(font_name, font_size);
 }
 
 }  // namespace gfx