Add fallback fonts in pdfium

core/fpdfapi/fpdf_font/cpdf_font.cpp

 // Copyright 2016 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "core/fpdfapi/fpdf_font/include/cpdf_font.h"
 
 #include <memory>
 #include <vector>
@@ skipping 433 matching lines @@
   }
 
   if (!charnames.empty() && !charnames[charcode].IsEmpty())
     return charnames[charcode].c_str();
 
   const FX_CHAR* name = nullptr;
   if (iBaseEncoding)
     name = PDF_CharNameFromPredefinedCharSet(iBaseEncoding, charcode);
   return name && name[0] ? name : nullptr;
 }
+
+uint32_t CPDF_Font::FallbackFontFromCharcode(uint32_t charcode,
+                                             bool* pVertGlyph) {
+  if (m_FontFallbacks.size() < 1) {

[Lei Zhang, 2016/08/24 04:43:10]

m_FontFallbacks.empty()

[npm, 2016/08/24 14:39:22]

Done.

+    m_FontFallbacks.push_back(std::unique_ptr<CFX_Font>(new CFX_Font()));

[Lei Zhang, 2016/08/24 04:43:10]

We have our own WrapUnique() if you don't want to write out CFX_Font 2x.

[npm, 2016/08/24 14:39:22]

Done.

+    m_FontFallbacks[0]->LoadSubst("Arial", IsTrueTypeFont(), m_Flags,
+                                  m_StemV * 5, m_ItalicAngle, 0,
+                                  IsVertWriting());
+  }
+  return 0;

[Lei Zhang, 2016/08/24 04:43:10]

So always return 0?

[npm, 2016/08/24 14:39:22]

For now, just having a single fallback font

+}
+
+int CPDF_Font::FallbackGlyphFromCharcode(int fallbackFont,
+                                         uint32_t charcode,
+                                         bool* pVertGlyph) {

[Lei Zhang, 2016/08/24 04:43:10]

not used?

[npm, 2016/08/24 14:39:22]

The vert parameter is in GlyphFromCharcode so it might be needed later on. But
for now I see no use for it. Should I delete then?

+  int glyph =
+      FXFT_Get_Char_Index(m_FontFallbacks[fallbackFont]->GetFace(), charcode);

[Lei Zhang, 2016/08/24 04:43:10]

Can |fallbackFont| go out of bound?

[npm, 2016/08/24 14:39:22]

This should not happen if the two methods are implemented properly, but I've
added a check

+  if (glyph == 0 || glyph == 0xffff)
+    return -1;
+  return glyph;
+}