GRAPHICS INTERCHANGE FORMAT

GrafX2 format of predilection is GIF.

GrafX2 uses the GIF89a spec for saving : ​https://www.w3.org/Graphics/GIF/spec-gif89a.txt

it supports a few extensions :

• NETSCAPE animation extension
• GFX2PATH original path saving extension
• GFX2MODE Special Drawing mode saving extension
• CRNG Color cycling extension

NETSCAPE animation extension

see ​http://www.vurdalakov.net/misc/gif/netscape-looping-application-extension

GFX2PATH

Stores the original file path. This is used by the backup system.

The format is :

0x21       Extension Label
0xFF       Application Extension Label
0x0B       Block Size
"GFX2PATH" Application Identifier (8 bytes)
"\0\0\0"   Application Authentication Code (3 bytes)
0xll       Sub-block Data Size : path size (including null)
"..path.." path (null-terminated)
0xll       Sub-block Data Size : filename size (including null)
"..file.." file name (null-terminated)
0x00       Block terminator

GFX2MODE

extension to store ::IMAGE_MODES :

0x21       Extension Label
0xFF       Application Extension Label
0x0B       Block Size
"GFX2MODE" Application Identifier (8 bytes)
"2.6"      Application Authentication Code (3 bytes)
0xll       Sub-block Data Size
string     label
...        More sub blocks can be added in the future
0x00 Block terminator

Supported values (as of GrafX2 2.6) :

• "LAYERED" (not written)
• "ANIMATION" (not written)
• "ZX_SPECTRUM"
• "GAMEBOYCOLOR"
• "THOMSON40COL"
• "CPC_EGX"
• "CPC_EGX2"
• "CPC_MODE5"
• "CPC_RASTER"
• "C64_HIRES"
• "C64_MULTICOLOR"
• "C64_FLI"
• "APPLE2_HGR"
• "APPLE2_DHGR"

CRNG color cycling extension

Same content as a CRNG IFF chunk

0x21       Extension Label
0xFF       Application Extension Label
0x0B       Block Size
"CRNG\0\0\0\0" "CRNG" Application Identifier (8 bytes)
"1.0"      Application Authentication Code (3 bytes)
0xll       Sub-block Data Size (6 bytes per color cycle)
For each color cycle :
  0xRRRR   (big endian) Rate
  0xFFFF   (big endian) Flags
  0xSS     start (lower color index)
  0xEE     end (higher color index)
0x00       Block terminator