Extract duplicated ASS writing code from libass provider

src/subtitle_format_ass.cpp

@@ -68,7 +68,7 @@ void AssSubtitleFormat::ReadFile(AssFile *target, agi::fs::path const& filename,
 #endif
 
 namespace {
-std::string format(AssEntryGroup group, bool ssa) {
+const char *format(AssEntryGroup group, bool ssa) {
 	if (group == AssEntryGroup::DIALOGUE) {
 		if (ssa)
 			return "Format: Marked, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text" LINEBREAK;
@@ -83,14 +83,18 @@ std::string format(AssEntryGroup group, bool ssa) {
 			return "Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding" LINEBREAK;
 	}
 
-	return "";
+	return nullptr;
 }
 
 struct Writer {
 	TextFileWriter file;
-	bool ssa;
+	bool ssa = false;
 	AssEntryGroup group = AssEntryGroup::INFO;
 
+	Writer(std::ostream &ostr) : file(ostr) {
+		file.WriteLineToFile("[Script Info]");
+	}
+
 	Writer(agi::fs::path const& filename, std::string const& encoding)
 	: file(filename, encoding)
 	, ssa(agi::fs::HasExtension(filename, "ssa"))
@@ -108,7 +112,8 @@ struct Writer {
 				file.WriteLineToFile("");
 
 				file.WriteLineToFile(line.GroupHeader(ssa));
-				file.WriteLineToFile(format(line.Group(), ssa), false);
+				if (const char *str = format(line.Group(), ssa))
+					file.WriteLineToFile(str, false);
 
 				group = line.Group();
 			}
@@ -135,9 +140,7 @@ struct Writer {
 				// the inline_string encoding grew the data by more than uuencoding would
 				// so base64 encode it instead
 				line += "u"; // marker for uuencoding
-				encoded_data = agi::ass::UUEncode(edi.second.second, false);
+				line += agi::ass::UUEncode(edi.second.second, false);
-				printf("did uuencoding, original size=%lu, encoded size=%lu\n", edi.second.second.size(), encoded_data.size());
-				line += encoded_data;
 			} else {
 				line += "e"; // marker for inline_string encoding (escaping)
 				line += encoded_data;
@@ -150,10 +153,16 @@ struct Writer {
 
 void AssSubtitleFormat::WriteFile(const AssFile *src, agi::fs::path const& filename, agi::vfr::Framerate const& fps, std::string const& encoding) const {
 	Writer writer(filename, encoding);
-
 	writer.Write(src->Info);
 	writer.Write(src->Styles);
 	writer.Write(src->Attachments);
 	writer.Write(src->Events);
 	writer.WriteExtradata(src->Extradata);
 }
+
+void AssSubtitleFormat::WriteToStream(const AssFile *src, std::ostream &ostr) {
+	Writer writer(ostr);
+	writer.Write(src->Info);
+	writer.Write(src->Styles);
+	writer.Write(src->Events);
+}

src/subtitle_format_ass.h

@@ -46,4 +46,5 @@ public:
 
 	void ReadFile(AssFile *target, agi::fs::path const& filename, agi::vfr::Framerate const& fps, std::string const& forceEncoding) const override;
 	void WriteFile(const AssFile *src, agi::fs::path const& filename, agi::vfr::Framerate const& fps, std::string const& encoding) const override;
+	static void WriteToStream(const AssFile *src, std::ostream &ostr);
 };

src/subtitles_provider_libass.cpp

@@ -40,6 +40,7 @@
 #include "ass_style.h"
 #include "compat.h"
 #include "include/aegisub/subtitles_provider.h"
+#include "subtitle_format_ass.h"
 #include "video_frame.h"
 
 #include <libaegisub/background_runner.h>
@@ -50,6 +51,7 @@
 
 #include <atomic>
 #include <boost/gil/gil_all.hpp>
+#include <boost/interprocess/streams/vectorstream.hpp>
 #include <boost/range/algorithm_ext/push_back.hpp>
 #include <memory>
 #include <mutex>
@@ -153,33 +155,13 @@ LibassSubtitlesProvider::~LibassSubtitlesProvider() {
 	if (ass_track) ass_free_track(ass_track);
 }
 
-struct Writer {
-	std::vector<char> data;
-	AssEntryGroup group = AssEntryGroup::GROUP_MAX;
-
-	template<typename T>
-	void Write(T const& list) {
-		for (auto const& line : list) {
-			if (group != line.Group()) {
-				group = line.Group();
-				boost::push_back(data, line.GroupHeader() + "\r\n");
-			}
-			boost::push_back(data, line.GetEntryData() + "\r\n");
-		}
-	}
-};
-
 void LibassSubtitlesProvider::LoadSubtitles(AssFile *subs) {
-	Writer writer;
+	boost::interprocess::basic_ovectorstream<std::vector<char>> ostr;
-
+	ostr.reserve(0x4000);
-	writer.data.reserve(0x4000);
+	AssSubtitleFormat::WriteToStream(subs, ostr);
-
-	writer.Write(subs->Info);
-	writer.Write(subs->Styles);
-	writer.Write(subs->Events);
 
 	if (ass_track) ass_free_track(ass_track);
-	ass_track = ass_read_memory(library, &writer.data[0], writer.data.size(), nullptr);
+	ass_track = ass_read_memory(library, const_cast<char *>(ostr.vector().data()), ostr.vector().size(), nullptr);
 	if (!ass_track) throw "libass failed to load subtitles.";
 }
 

src/text_file_writer.cpp

@@ -32,7 +32,7 @@
 
 TextFileWriter::TextFileWriter(agi::fs::path const& filename, std::string encoding)
 : file(new agi::io::Save(filename, true))
-, conv()
+, ostr(file->Get())
 {
 	if (encoding.empty())
 		encoding = OPT_GET("App/Save Charset")->GetString();
@@ -48,11 +48,15 @@ TextFileWriter::TextFileWriter(agi::fs::path const& filename, std::string encodi
 	}
 }
 
+TextFileWriter::TextFileWriter(std::ostream &ostr) : ostr(ostr) {
+	WriteLineToFile("\xEF\xBB\xBF", false);
+}
+
 TextFileWriter::~TextFileWriter() {
 	// Explicit empty destructor required with a unique_ptr to an incomplete class
 }
 
-void TextFileWriter::WriteLineToFile(std::string&& line, bool addLineBreak) {
+void TextFileWriter::WriteLineToFile(std::string line, bool addLineBreak) {
 	if (addLineBreak)
 #ifdef _WIN32
 		line += "\r\n";
@@ -62,5 +66,5 @@ void TextFileWriter::WriteLineToFile(std::string&& line, bool addLineBreak) {
 
 	if (conv)
 		line = conv->Convert(line);
-	file->Get().write(line.data(), line.size());
+	ostr.write(line.data(), line.size());
 }

src/text_file_writer.h

@@ -32,11 +32,12 @@ namespace agi {
 class TextFileWriter {
 	std::unique_ptr<agi::io::Save> file;
 	std::unique_ptr<agi::charset::IconvWrapper> conv;
+	std::ostream &ostr;
 
 public:
 	TextFileWriter(agi::fs::path const& filename, std::string encoding="");
+	TextFileWriter(std::ostream &ostr);
 	~TextFileWriter();
 
-	void WriteLineToFile(std::string const& line, bool addLineBreak=true) { WriteLineToFile(std::string(line), addLineBreak); }
+	void WriteLineToFile(std::string line, bool addLineBreak=true);
-	void WriteLineToFile(std::string&& line, bool addLineBreak=true);
 };