-string FileName::guessFormatFromContents() const
-{
- // the different filetypes and what they contain in one of the first lines
- // (dots are any characters). (Herbert 20020131)
- // AGR Grace...
- // BMP BM...
- // EPS %!PS-Adobe-3.0 EPSF...
- // FIG #FIG...
- // FITS ...BITPIX...
- // GIF GIF...
- // JPG JFIF
- // PDF %PDF-...
- // PNG .PNG...
- // PBM P1... or P4 (B/W)
- // PGM P2... or P5 (Grayscale)
- // PPM P3... or P6 (color)
- // PS %!PS-Adobe-2.0 or 1.0, no "EPSF"!
- // SGI \001\332... (decimal 474)
- // TGIF %TGIF...
- // TIFF II... or MM...
- // XBM ..._bits[]...
- // XPM /* XPM */ sometimes missing (f.ex. tgif-export)
- // ...static char *...
- // XWD \000\000\000\151 (0x00006900) decimal 105
- //
- // GZIP \037\213 http://www.ietf.org/rfc/rfc1952.txt
- // ZIP PK... http://www.halyava.ru/document/ind_arch.htm
- // Z \037\235 UNIX compress
- // paranoia check
-
- if (empty() || !isReadableFile())
- return string();
-
- ifstream ifs(toFilesystemEncoding().c_str());
- if (!ifs)
- // Couldn't open file...
- return string();
-
- // gnuzip
- static string const gzipStamp = "\037\213";
-
- // PKZIP
- static string const zipStamp = "PK";
-
- // compress
- static string const compressStamp = "\037\235";
-
- // Maximum strings to read
- int const max_count = 50;
- int count = 0;
-
- string str;
- string format;
- bool firstLine = true;
- while ((count++ < max_count) && format.empty()) {
- if (ifs.eof()) {
- LYXERR(Debug::GRAPHICS, "filetools(getFormatFromContents)\n"
- << "\tFile type not recognised before EOF!");
- break;
- }
-
- getline(ifs, str);
- string const stamp = str.substr(0, 2);
- if (firstLine && str.size() >= 2) {
- // at first we check for a zipped file, because this
- // information is saved in the first bytes of the file!
- // also some graphic formats which save the information
- // in the first line, too.
- if (prefixIs(str, gzipStamp)) {
- format = "gzip";
-
- } else if (stamp == zipStamp) {
- format = "zip";
-
- } else if (stamp == compressStamp) {
- format = "compress";
-
- // the graphics part
- } else if (stamp == "BM") {
- format = "bmp";
-
- } else if (stamp == "\001\332") {
- format = "sgi";
-
- // PBM family
- // Don't need to use str.at(0), str.at(1) because
- // we already know that str.size() >= 2
- } else if (str[0] == 'P') {
- switch (str[1]) {
- case '1':
- case '4':
- format = "pbm";
- break;
- case '2':
- case '5':
- format = "pgm";
- break;
- case '3':
- case '6':
- format = "ppm";
- }
- break;
-
- } else if ((stamp == "II") || (stamp == "MM")) {
- format = "tiff";
-
- } else if (prefixIs(str,"%TGIF")) {
- format = "tgif";
-
- } else if (prefixIs(str,"#FIG")) {
- format = "fig";
-
- } else if (prefixIs(str,"GIF")) {
- format = "gif";
-
- } else if (str.size() > 3) {
- int const c = ((str[0] << 24) & (str[1] << 16) &
- (str[2] << 8) & str[3]);
- if (c == 105) {
- format = "xwd";
- }
- }
-
- firstLine = false;
- }
-
- if (!format.empty())
- break;
- else if (contains(str,"EPSF"))
- // dummy, if we have wrong file description like
- // %!PS-Adobe-2.0EPSF"
- format = "eps";
-
- else if (contains(str, "Grace"))
- format = "agr";
-
- else if (contains(str, "JFIF"))
- format = "jpg";