Add wrappers for CPDF_Font::FT_UseTTCharmap().

Add wrappers with meaningful names, instead of calling FT_UseTTCharmap()
with cryptic values. Also rename FT_UseTTCharmap() to avoid confusion
because it is not a FreeType function.

Change-Id: Ia11d6c413579b922ee880402e2af756254d1325b
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/91794
Reviewed-by: Nigi <nigi@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/core/fpdfapi/font/cpdf_cidfont.cpp b/core/fpdfapi/font/cpdf_cidfont.cpp
index b460d57..25a8077 100644
--- a/core/fpdfapi/font/cpdf_cidfont.cpp
+++ b/core/fpdfapi/font/cpdf_cidfont.cpp
@@ -710,8 +710,8 @@
         return charcode ? static_cast<int>(charcode) : -1;
 
       charcode += 31;
-      bool bMSUnicode = FT_UseTTCharmap(face, 3, 1);
-      bool bMacRoman = !bMSUnicode && FT_UseTTCharmap(face, 1, 0);
+      bool bMSUnicode = UseTTCharmapMSUnicode(face);
+      bool bMacRoman = !bMSUnicode && UseTTCharmapMacRoman(face);
       int iBaseEncoding = PDFFONT_ENCODING_STANDARD;
       if (bMSUnicode)
         iBaseEncoding = PDFFONT_ENCODING_WINANSI;
diff --git a/core/fpdfapi/font/cpdf_font.cpp b/core/fpdfapi/font/cpdf_font.cpp
index 905f12e..a1c7d55 100644
--- a/core/fpdfapi/font/cpdf_font.cpp
+++ b/core/fpdfapi/font/cpdf_font.cpp
@@ -412,9 +412,9 @@
 }
 
 // static
-bool CPDF_Font::FT_UseTTCharmap(FXFT_FaceRec* face,
-                                int platform_id,
-                                int encoding_id) {
+bool CPDF_Font::UseTTCharmap(FXFT_FaceRec* face,
+                             int platform_id,
+                             int encoding_id) {
   for (int i = 0; i < face->num_charmaps; i++) {
     if (FXFT_Get_Charmap_PlatformID(face->charmaps[i]) == platform_id &&
         FXFT_Get_Charmap_EncodingID(face->charmaps[i]) == encoding_id) {
diff --git a/core/fpdfapi/font/cpdf_font.h b/core/fpdfapi/font/cpdf_font.h
index f7f9c36..8e7b694 100644
--- a/core/fpdfapi/font/cpdf_font.h
+++ b/core/fpdfapi/font/cpdf_font.h
@@ -131,9 +131,21 @@
   CPDF_Font(CPDF_Document* pDocument, CPDF_Dictionary* pFontDict);
 
   static int TT2PDF(FT_Pos m, FXFT_FaceRec* face);
-  static bool FT_UseTTCharmap(FXFT_FaceRec* face,
-                              int platform_id,
-                              int encoding_id);
+
+  // Commonly used wrappers for UseTTCharmap().
+  static bool UseTTCharmapMSUnicode(FXFT_FaceRec* face) {
+    return UseTTCharmap(face, 3, 1);
+  }
+  static bool UseTTCharmapMSSymbol(FXFT_FaceRec* face) {
+    return UseTTCharmap(face, 3, 0);
+  }
+  static bool UseTTCharmapMacRoman(FXFT_FaceRec* face) {
+    return UseTTCharmap(face, 1, 0);
+  }
+  static bool UseTTCharmap(FXFT_FaceRec* face,
+                           int platform_id,
+                           int encoding_id);
+
   static const char* GetAdobeCharName(int iBaseEncoding,
                                       const std::vector<ByteString>& charnames,
                                       uint32_t charcode);
diff --git a/core/fpdfapi/font/cpdf_truetypefont.cpp b/core/fpdfapi/font/cpdf_truetypefont.cpp
index 40222fc..e9a85c1 100644
--- a/core/fpdfapi/font/cpdf_truetypefont.cpp
+++ b/core/fpdfapi/font/cpdf_truetypefont.cpp
@@ -58,16 +58,16 @@
       SetGlyphIndicesFromFirstChar();
       return;
     }
-    bool bMSUnicode = FT_UseTTCharmap(face, 3, 1);
+    bool bMSUnicode = UseTTCharmapMSUnicode(face);
     bool bMacRoman = false;
     bool bMSSymbol = false;
     if (!bMSUnicode) {
       if (FontStyleIsNonSymbolic(m_Flags)) {
-        bMacRoman = FT_UseTTCharmap(face, 1, 0);
-        bMSSymbol = !bMacRoman && FT_UseTTCharmap(face, 3, 0);
+        bMacRoman = UseTTCharmapMacRoman(face);
+        bMSSymbol = !bMacRoman && UseTTCharmapMSSymbol(face);
       } else {
-        bMSSymbol = FT_UseTTCharmap(face, 3, 0);
-        bMacRoman = !bMSSymbol && FT_UseTTCharmap(face, 1, 0);
+        bMSSymbol = UseTTCharmapMSSymbol(face);
+        bMacRoman = !bMSSymbol && UseTTCharmapMacRoman(face);
       }
     }
     bool bToUnicode = m_pFontDict->KeyExist("ToUnicode");
@@ -121,7 +121,7 @@
     }
     return;
   }
-  if (FT_UseTTCharmap(face, 3, 0)) {
+  if (UseTTCharmapMSSymbol(face)) {
     bool bFound = false;
     for (int charcode = 0; charcode < 256; charcode++) {
       for (size_t j = 0; j < pdfium::size(kPrefix); j++) {
@@ -141,7 +141,7 @@
           if (name)
             m_Encoding.SetUnicode(charcode, PDF_UnicodeFromAdobeName(name));
         }
-      } else if (FT_UseTTCharmap(face, 1, 0)) {
+      } else if (UseTTCharmapMacRoman(face)) {
         for (int charcode = 0; charcode < 256; charcode++) {
           m_Encoding.SetUnicode(
               charcode,
@@ -151,7 +151,7 @@
       return;
     }
   }
-  if (FT_UseTTCharmap(face, 1, 0)) {
+  if (UseTTCharmapMacRoman(face)) {
     bool bFound = false;
     for (int charcode = 0; charcode < 256; charcode++) {
       m_GlyphIndex[charcode] = FT_Get_Char_Index(face, charcode);
diff --git a/core/fpdfapi/font/cpdf_type1font.cpp b/core/fpdfapi/font/cpdf_type1font.cpp
index a7fd61c..84d9e1f 100644
--- a/core/fpdfapi/font/cpdf_type1font.cpp
+++ b/core/fpdfapi/font/cpdf_type1font.cpp
@@ -137,7 +137,7 @@
   }
 #endif
   if (!IsEmbedded() && !IsSymbolicFont() && m_Font.IsTTFont()) {
-    if (FT_UseTTCharmap(m_Font.GetFaceRec(), 3, 0)) {
+    if (UseTTCharmapMSSymbol(m_Font.GetFaceRec())) {
       bool bGotOne = false;
       for (uint32_t charcode = 0; charcode < kInternalTableSize; charcode++) {
         const uint8_t prefix[4] = {0x00, 0xf0, 0xf1, 0xf2};