Add fallback fonts in pdfium

core/fpdfapi/fpdf_font/cpdf_font.cpp

Index: core/fpdfapi/fpdf_font/cpdf_font.cpp
diff --git a/core/fpdfapi/fpdf_font/cpdf_font.cpp b/core/fpdfapi/fpdf_font/cpdf_font.cpp
index 8101bd49a65eab2364ec6cd611466b9eac8e87bc..fe44e539a1bbf5d0534a886276e6b7f9f091469f 100644
--- a/core/fpdfapi/fpdf_font/cpdf_font.cpp
+++ b/core/fpdfapi/fpdf_font/cpdf_font.cpp
@@ -451,3 +451,24 @@ const FX_CHAR* CPDF_Font::GetAdobeCharName(
     name = PDF_CharNameFromPredefinedCharSet(iBaseEncoding, charcode);
   return name && name[0] ? name : nullptr;
 }
+
+uint32_t CPDF_Font::FallbackFontFromCharcode(uint32_t charcode,

[dsinclair, 2016/08/23 19:41:18]

This only ever returns 1, can the return value just be removed?

[npm, 2016/08/23 20:36:57]

The intention is that the return value may be different once we use more than
one fallback font.

+                                             bool* pVertGlyph) {
+  if (m_FontPlusFallbacks.size() < 2) {
+    m_FontPlusFallbacks.push_back(new CFX_Font());

[dsinclair, 2016/08/23 19:41:18]

This font is going to end up leaking. The other font your adding is owned by
someone else. I think we need to work out the ownership here so that either, a)
this font is created elsewhere and added to the map, or b) the other font is
owned by this vector.

[npm, 2016/08/23 20:36:57]

Ok, a vector of unique pointers using only the fallbacks works.

+    m_FontPlusFallbacks[1]->LoadSubst("Arial", IsTrueTypeFont(), m_Flags,
+                                      m_StemV * 5, m_ItalicAngle, 0,
+                                      IsVertWriting());
+  }
+  return 1;
+}
+
+int CPDF_Font::FallbackGlyphFromCharcode(int fallbackFont,
+                                         uint32_t charcode,
+                                         bool* pVertGlyph) {
+  int glyph = FXFT_Get_Char_Index(m_FontPlusFallbacks[fallbackFont]->GetFace(),
+                                  charcode);
+  if (glyph == 0 || glyph == 0xffff)
+    return -1;
+  return glyph;
+}