Moved compress/uncompress code across to using gzip compatible methods

src/osgPlugins/gz/ReaderWriterGZ.cpp

@@ -103,6 +103,11 @@ class ReaderWriterGZ : public osgDB::ReaderWriter
         
         WriteResult writeFile(ObjectType objectType, const osg::Object* object, const std::string& fullFileName, const osgDB::ReaderWriter::Options* options) const;
 
+
+        bool read(std::istream& fin, std::string& destination) const;
+        bool write(std::ostream& fout, const std::string& source) const;
+        
+
 };
 
 ReaderWriterGZ::ReaderWriterGZ()
@@ -169,30 +174,9 @@ osgDB::ReaderWriter::ReadResult ReaderWriterGZ::readFile(ObjectType objectType,
     std::ifstream fin(fileName.c_str());
     if (!fin) return ReadResult::ERROR_IN_READING_FILE;
     
-    std::streampos start = fin.tellg();
-    fin.seekg(0, std::ios::end);
-    std::streampos end = fin.tellg();
-    fin.seekg(start, std::ios::beg);
-    std::streampos sourceLen = end - start;
-
-    /* empty stream into memory, open that, and keep the pointer in a FreeTypeFont for cleanup */
-    char* buffer = new char[sourceLen];
-    fin.read(reinterpret_cast<char*>(buffer), sourceLen);
-    if (!fin || (static_cast<std::streampos>(fin.gcount()) != sourceLen))
-    {
-        osg::notify(osg::WARN)<<" .... the compressed file could not be read from its stream"<<std::endl;
-        return 0;
-    }
-    
-    uLongf destLen = 1000000;
 
     std::string dest;
-    dest.resize(destLen);
-        
-    int result = uncompress ((Bytef *)(&(*dest.begin())), &destLen,
-                             (const Bytef *)buffer, sourceLen);
-                                   
-    delete [] buffer;
+    read(fin, dest);
 
     std::stringstream strstream(dest);
 
@@ -241,35 +225,137 @@ osgDB::ReaderWriter::WriteResult ReaderWriterGZ::writeFile(ObjectType objectType
     std::stringstream strstream;
     osgDB::ReaderWriter::WriteResult writeResult = writeFile(objectType, object, rw, strstream, options);
     
-    
-    std::string str(strstream.str());
-    
-    uLong destLen = compressBound(str.size());
-    
-    osg::notify(osg::NOTICE)<<"compressBound("<<str.size()<<") = "<<destLen<<std::endl;
-    
-    std::string output;
-    output.resize(destLen);
-    
-    int level = 6;
-    
-    char* source = new char[str.size()];
-    char* dest = new char[destLen];
-
-    int result = compress2( (Bytef *)(&(*output.begin())), &destLen,
-                            (const Bytef *)(&(*str.begin())), str.size(),
-                             level);
-
-    osg::notify(osg::NOTICE)<<"compress2()"<<result<<", destLen="<<destLen<<std::endl;
-    
-    output.resize(destLen);
-    
     std::ofstream fout(fullFileName.c_str());
-    fout<<output;
+    
+    write(fout,strstream.str());
     
     return writeResult;
 }
 
+#define CHUNK 16384
+
+bool ReaderWriterGZ::read(std::istream& fin, std::string& destination) const
+{
+    int ret;
+    unsigned have;
+    z_stream strm;
+    unsigned char in[CHUNK];
+    unsigned char out[CHUNK];
+
+    /* allocate inflate state */
+    strm.zalloc = Z_NULL;
+    strm.zfree = Z_NULL;
+    strm.opaque = Z_NULL;
+    strm.avail_in = 0;
+    strm.next_in = Z_NULL;
+    ret = inflateInit2(&strm,
+                       15 + 32 // autodected zlib or gzip header
+                       );
+    if (ret != Z_OK)
+        return ret;
+
+    /* decompress until deflate stream ends or end of file */
+    do {
+
+        osg::notify(osg::NOTICE)<<"Doing readsome"<<std::endl;
+
+        strm.avail_in = fin.readsome((char*)in, CHUNK);
+
+        if (fin.fail())
+        {
+            (void)inflateEnd(&strm);
+            return false;
+        }
+        if (strm.avail_in == 0)
+            break;
+        strm.next_in = in;
+
+        /* run inflate() on input until output buffer not full */
+        do {
+            strm.avail_out = CHUNK;
+            strm.next_out = out;
+            ret = inflate(&strm, Z_NO_FLUSH);
+
+            switch (ret) {
+            case Z_NEED_DICT:
+            case Z_DATA_ERROR:
+            case Z_MEM_ERROR:
+                (void)inflateEnd(&strm);
+                return false;
+            }
+            have = CHUNK - strm.avail_out;
+
+            destination.append((char*)out, have);
+            
+        } while (strm.avail_out == 0);
+
+        /* done when inflate() says it's done */
+    } while (ret != Z_STREAM_END);
+
+    /* clean up and return */
+    (void)inflateEnd(&strm);
+    return ret == Z_STREAM_END ? true : false;
+}
+
+bool ReaderWriterGZ::write(std::ostream& fout, const std::string& source) const
+{
+    int ret, flush = Z_FINISH;
+    unsigned have;
+    z_stream strm;
+    unsigned char out[CHUNK];
+    
+    int level = 6;
+    int stategy = Z_DEFAULT_STRATEGY; // looks to be the best for .osg/.ive files
+    //int stategy = Z_FILTERED;
+    //int stategy = Z_HUFFMAN_ONLY;
+    //int stategy = Z_RLE;
+
+    /* allocate deflate state */
+    strm.zalloc = Z_NULL;
+    strm.zfree = Z_NULL;
+    strm.opaque = Z_NULL;
+    ret = deflateInit2(&strm, 
+                       level,
+                       Z_DEFLATED,
+                       15+16, // +16 to use gzip encoding
+                       8, // default
+                       stategy);
+    if (ret != Z_OK)
+    return false;
+
+    strm.avail_in = source.size();
+    strm.next_in = (Bytef*)(&(*source.begin()));
+
+    /* run deflate() on input until output buffer not full, finish
+       compression if all of source has been read in */
+    do {
+        strm.avail_out = CHUNK;
+        strm.next_out = out;
+        ret = deflate(&strm, flush);    /* no bad return value */
+
+        if (ret == Z_STREAM_ERROR)
+        {
+            osg::notify(osg::NOTICE)<<"Z_STREAM_ERROR"<<std::endl;
+            return false;
+        }
+
+        have = CHUNK - strm.avail_out;
+
+        if (have>0) fout.write((const char*)out, have);
+        
+        if (fout.fail())
+        {
+            (void)deflateEnd(&strm);
+            return false;
+        }
+    } while (strm.avail_out == 0);
+
+    /* clean up and return */
+    (void)deflateEnd(&strm);
+    return true;
+}
+
+
 // now register with Registry to instantiate the above
 // reader/writer.
 REGISTER_OSGPLUGIN(GZ, ReaderWriterGZ)