Don't read unecessary font files on Android.

src/ports/SkFontConfigParser_android.cpp

 /*
  * Copyright 2011 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkFontConfigParser_android.h"
 #include "SkTDArray.h"
 #include "SkTSearch.h"
@@ skipping 39 matching lines @@
  * The FamilyData structure is passed around by the parser so that each handler
  * can read these variables that are relevant to the current parsing.
  */
 struct FamilyData {
     FamilyData(XML_Parser parser, SkTDArray<FontFamily*> &families)
         : fParser(parser)
         , fFamilies(families)
         , fCurrentFamily(NULL)
         , fCurrentFontInfo(NULL)
         , fCurrentTag(NO_TAG)
-    { };
+        , fVersion(0)
+    { }
 
     XML_Parser fParser;                       // The expat parser doing the work, owned by caller
     SkTDArray<FontFamily*>& fFamilies;        // The array to append families, owned by caller
     SkAutoTDelete<FontFamily> fCurrentFamily; // The family being created, owned by this
     FontFileInfo* fCurrentFontInfo;           // The fontInfo being created, owned by currentFamily
     int fCurrentTag;                          // Flag to indicate when we're in nameset/fileset tags
+    int fVersion;                             // The version of the file parsed.
 };
 
 /** http://www.w3.org/TR/html-markup/datatypes.html#common.data.integer.non-negative-def */
 template <typename T> static bool parseNonNegativeInteger(const char* s, T* value) {
     SK_COMPILE_ASSERT(std::numeric_limits<T>::is_integer, T_must_be_integer);
     const T nMax = std::numeric_limits<T>::max() / 10;
     const T dMax = std::numeric_limits<T>::max() - (nMax * 10);
     T n = 0;
     for (; *s; ++s) {
         // Check if digit
@@ skipping 247 matching lines @@
         for (size_t i = 0; atts[i] != NULL &&
                            atts[i+1] != NULL; i += 2) {
             size_t nameLen = strlen(atts[i]);
             if (nameLen == 7 && strncmp(atts[i], "version", nameLen)) continue;
             const char* valueString = atts[i+1];
             int version;
             if (parseNonNegativeInteger(valueString, &version) && (version >= 21)) {
                 XML_SetElementHandler(familyData->fParser,
                                       lmpParser::startElementHandler,
                                       lmpParser::endElementHandler);
+                familyData->fVersion = version;
             }
         }
     } else if (len == 6 && strncmp(tag, "family", len) == 0) {
         familyData->fCurrentFamily.reset(new FontFamily());
         // The Family tag has an optional "order" attribute with an integer value >= 0
         // If this attribute does not exist, the default value is -1
         for (size_t i = 0; atts[i] != NULL &&
                            atts[i+1] != NULL; i += 2) {
             const char* valueString = atts[i+1];
             int value;
@@ skipping 36 matching lines @@
                 familyData->fCurrentTag == FILESET_TAG)) {
         // Disable the arbitrary text handler installed to load Name data
         XML_SetCharacterDataHandler(familyData->fParser, NULL);
     }
 }
 
 } // namespace jbParser
 
 /**
  * This function parses the given filename and stores the results in the given
- * families array.
+ * families array. Returns the version of the file, negative if the file does not exist.
  */
-static void parseConfigFile(const char* filename, SkTDArray<FontFamily*> &families) {
+static int parseConfigFile(const char* filename, SkTDArray<FontFamily*> &families) {
 
     FILE* file = fopen(filename, "r");
 
     // Some of the files we attempt to parse (in particular, /vendor/etc/fallback_fonts.xml)
     // are optional - failure here is okay because one of these optional files may not exist.
     if (NULL == file) {
-        return;
+        return -1;
     }
 
     XML_Parser parser = XML_ParserCreate(NULL);
     FamilyData familyData(parser, families);
     XML_SetUserData(parser, &familyData);
     // Start parsing oldschool; switch these in flight if we detect a newer version of the file.
     XML_SetElementHandler(parser, jbParser::startElementHandler, jbParser::endElementHandler);
 
     char buffer[512];
     bool done = false;
     while (!done) {
         fgets(buffer, sizeof(buffer), file);
         size_t len = strlen(buffer);
         if (feof(file) != 0) {
             done = true;
         }
         XML_Parse(parser, buffer, len, done);
     }
     XML_ParserFree(parser);
     fclose(file);
+    return familyData.fVersion;
 }
 
-static void getSystemFontFamilies(SkTDArray<FontFamily*> &fontFamilies) {
+/** Returns the version of the system font file actually found, negative if none. */
+static int appendSystemFontFamilies(SkTDArray<FontFamily*> &fontFamilies) {

[mtklein, 2015/02/02 16:55:49]

Let's update to static_function_name_style and T& foo while we're here?

[bungeman-skia, 2015/02/02 18:36:37]

Done.

     int initialCount = fontFamilies.count();
-    parseConfigFile(LMP_SYSTEM_FONTS_FILE, fontFamilies);
-
-    if (initialCount == fontFamilies.count()) {
-        parseConfigFile(OLD_SYSTEM_FONTS_FILE, fontFamilies);
+    int version = parseConfigFile(LMP_SYSTEM_FONTS_FILE, fontFamilies);
+    if (version < 0 || fontFamilies.count() == initialCount) {
+        version = parseConfigFile(OLD_SYSTEM_FONTS_FILE, fontFamilies);
     }
+    return version;
 }
 
 /**
  * In some versions of Android prior to Android 4.2 (JellyBean MR1 at API
  * Level 17) the fallback fonts for certain locales were encoded in their own
  * XML files with a suffix that identified the locale.  We search the provided
  * directory for those files,add all of their entries to the fallback chain, and
  * include the locale as part of each entry.
  */
-static void getFallbackFontFamiliesForLocale(SkTDArray<FontFamily*> &fallbackFonts, const char* dir) {
+static void appendFallbackFontFamiliesForLocale(SkTDArray<FontFamily*> &fallbackFonts,
+                                                const char* dir)
+{
 #if defined(SK_BUILD_FOR_ANDROID_FRAMEWORK)
     // The framework is beyond Android 4.2 and can therefore skip this function
     return;
 #endif
 
     DIR* fontDirectory = opendir(dir);
     if (fontDirectory != NULL){
         struct dirent* dirEntry = readdir(fontDirectory);
         while (dirEntry) {
 
@@ skipping 26 matching lines @@
             }
 
             // proceed to the next entry in the directory
             dirEntry = readdir(fontDirectory);
         }
         // cleanup the directory reference
         closedir(fontDirectory);
     }
 }
 
-static void getFallbackFontFamilies(SkTDArray<FontFamily*> &fallbackFonts) {
+static void appendSystemFallbackFontFamilies(SkTDArray<FontFamily*> &fallbackFonts) {
+    parseConfigFile(FALLBACK_FONTS_FILE, fallbackFonts);
+    appendFallbackFontFamiliesForLocale(fallbackFonts, LOCALE_FALLBACK_FONTS_SYSTEM_DIR);
+}
+
+static void mixinVendorFallbackFontFamilies(SkTDArray<FontFamily*> &fallbackFonts) {
     SkTDArray<FontFamily*> vendorFonts;
-    parseConfigFile(FALLBACK_FONTS_FILE, fallbackFonts);
     parseConfigFile(VENDOR_FONTS_FILE, vendorFonts);
-
-    getFallbackFontFamiliesForLocale(fallbackFonts, LOCALE_FALLBACK_FONTS_SYSTEM_DIR);
-    getFallbackFontFamiliesForLocale(vendorFonts, LOCALE_FALLBACK_FONTS_VENDOR_DIR);
+    appendFallbackFontFamiliesForLocale(vendorFonts, LOCALE_FALLBACK_FONTS_VENDOR_DIR);
 
     // This loop inserts the vendor fallback fonts in the correct order in the
     // overall fallbacks list.
     int currentOrder = -1;
     for (int i = 0; i < vendorFonts.count(); ++i) {
         FontFamily* family = vendorFonts[i];
         int order = family->fOrder;
         if (order < 0) {
             if (currentOrder < 0) {
                 // Default case - just add it to the end of the fallback list
@@ skipping 10 matching lines @@
             currentOrder = order + 1;
         }
     }
 }
 
 /**
  * Loads data on font families from various expected configuration files. The
  * resulting data is returned in the given fontFamilies array.
  */
 void SkFontConfigParser::GetFontFamilies(SkTDArray<FontFamily*> &fontFamilies) {
-
-    getSystemFontFamilies(fontFamilies);
+    // Version 21 of the system font configuration does not need any fallback configuration files.
+    if (appendSystemFontFamilies(fontFamilies) >= 21) {
+        return;
+    }
 
     // Append all the fallback fonts to system fonts
     SkTDArray<FontFamily*> fallbackFonts;
-    getFallbackFontFamilies(fallbackFonts);
+    appendSystemFallbackFontFamilies(fallbackFonts);
+    mixinVendorFallbackFontFamilies(fallbackFonts);
     for (int i = 0; i < fallbackFonts.count(); ++i) {
         fallbackFonts[i]->fIsFallbackFont = true;
         *fontFamilies.append() = fallbackFonts[i];
     }
 }
 
 void SkFontConfigParser::GetTestFontFamilies(SkTDArray<FontFamily*> &fontFamilies,
                                              const char* testMainConfigFile,
                                              const char* testFallbackConfigFile) {
     parseConfigFile(testMainConfigFile, fontFamilies);
@@ skipping 15 matching lines @@
     const char* tag = fTag.c_str();
 
     // strip off the rightmost "-.*"
     const char* parentTagEnd = strrchr(tag, '-');
     if (parentTagEnd == NULL) {
         return SkLanguage();
     }
     size_t parentTagLen = parentTagEnd - tag;
     return SkLanguage(tag, parentTagLen);
 }