embed fonts in deterministic order

(fixes #288)

Author: mgieseki

src/DVIToSVG.cpp

@@ -351,22 +351,25 @@ void DVIToSVG::embedFonts () {
 	if (!_actions) // no dvi actions => no chars written => no fonts to embed
 		return;
 
+	auto usedFonts = FontManager::instance().getUniqueFonts();
 	auto &usedCharsMap = FontManager::instance().getUsedChars();
 	collect_chars(usedCharsMap);
 
 	GlyphTracerMessages messages;
 	unordered_set<const Font*> tracedFonts;  // collect unique fonts already traced
-	for (const auto &fontchar : usedCharsMap) {
-		const Font *font = fontchar.first;
+	for (auto font : usedFonts) {
 		if (auto ph_font = font_cast<const PhysicalFont*>(font)) {
 			// Check if glyphs should be traced. Only trace the glyphs of unique fonts, i.e.
 			// avoid retracing the same glyphs again if they are referenced in various sizes.
 			if (TRACE_MODE != 0 && tracedFonts.find(ph_font->uniqueFont()) == tracedFonts.end()) {
 				ph_font->traceAllGlyphs(TRACE_MODE == 'a', &messages);
 				tracedFonts.insert(ph_font->uniqueFont());
 			}
-			if (font->path())  // does font file exist?
-				_svg.append(*ph_font, fontchar.second, &messages);
+			if (font->path()) { // does font file exist?
+				auto it = usedCharsMap.find(font);
+				if (it != usedCharsMap.end())
+					_svg.append(*ph_font, it->second, &messages);
+			}
 			else
 				Message::wstream(true) << "can't embed font '" << font->name() << "'\n";
 		}

src/FontManager.cpp

@@ -159,6 +159,18 @@ Font* FontManager::getFontById (int id) const {
 }
 
 
+vector<const Font*> FontManager::getUniqueFonts () const {
+	vector<const Font*> fonts;
+	fonts.reserve(_fonts.size());
+	for (auto &font : _fonts) {
+		auto it = _usedChars.find(font.get());
+		if (it != _usedChars.end())
+			fonts.push_back(font.get());
+	}
+	return fonts;
+}
+
+
 /** Returns the current active virtual font. */
 const VirtualFont* FontManager::getVF () const {
 	return _vfStack.empty() ? nullptr : _vfStack.top();

src/FontManager.hpp

@@ -62,6 +62,7 @@ class FontManager {
 		Font* getFont (const std::string &name) const;
 		Font* getFont (const std::string &name, double ptsize);
 		Font* getFontById (int id) const;
+		std::vector<const Font*> getUniqueFonts () const;
 		const VirtualFont* getVF () const;
 		int fontID (int n) const;
 		int fontID (const Font *font) const;