if compressed:
byte 3,4: size of compressed graphic data
byte 5-n: compressed linear graphic data (ZX0 with special SymbOS -specific header, see below)
</pre>
</pre>
===Extended 4 and 16 colour graphicpart===
<pre>
if compressed:
byte 8,9: size of compressed graphic data
byte 10-n: compressed linear graphic data (ZX0 with special SymbOS -specific header, see below)
</pre>
Please note, that currently there are some limitations:
* the maximum width for a 4 colour graphics graphic part is 1020 pixel* the maximum width for a 16 colour graphics graphic part is 508 pixel* 16 colour graphics graphic parts must always have an even width in bytes (2,4,...,254)
===Line feed===
This chunk has a length of 3 bytes and can be recognized with 255 in the first byte. Usually every graphic part will be linked right to the previous part. After a line feed the next graphic part will be linked below the first graphic of the previous "line".
===EOF===
[[Image:symbosSGX.jpg]]
==Graphic data compression==
Both simple and extended graphic parts can be stored in a compressed way.
Compressed data has to be stored in the following SymbOS-specific way, which is used for all kind of compressed data in SymbOS:
<pre>
00 4B last 4 bytes of the data (not compressed)
04 1W size of non compressed part at the beginning (always 0 for SGX files)
06 ?B not compressed part of the data (not existing in SGX files)
?? ?B compressed part of the data without the last 4 bytes
using the "ZX0 data compressor" by Einar Saukas, see
https://github.com/einar-saukas/ZX0
</pre>
==See also==
==Web links==
* [httphttps://www.symbos.deorg/downloadmedia.htm#marke3 ?1 SGX file downloads]
[[Category:SymbOS]]
[[Category:Programming]]