Bitmap Font File Structure

ant512 · 12 October 2007, 15:28

Does anyone know anything about the structure of Amiga bitmap font files? I'm guessing that they're more or less standard IFF ILBM files with extra information specifying character width and height - is this correct? Can anyone point me in the direction of a complete spec for the file format that I could use to implement a font loader?

Thanks!

girv · 12 October 2007, 16:08

There is a font loader source buried in some of the WHDLoad example slave sources, it's pretty straightforward.

You're basically right about the format. There is a header, which I believe is specified in a system include file somewhere (textfont.[ih] ?), then the font glyphs follow it as one big bitmap. You need to shift & mask to cut out the raw data for the glyph you need.

Minuous · 12 October 2007, 20:02

They are nothing like IFF files.

They are documented in the Amiga ROM Kernel Reference Manual: Libraries. More specifically:

http://cataclysm.cx/random/amiga/ref.../node03E0.html

ant512 · 13 October 2007, 00:15

Thanks guys. Looks like fonts *are* IFF files, but they come with the extra .font file that contains the font descripton info.

Minuous · 13 October 2007, 15:00

"For each font size described in a FontContents (or TFontContents)
structure, there is a corresponding file in that font's directory whose
name is its size. For example, for the font size Sapphire-19, there is a
file in the Sapphire directory called 19. That file is basically a
DiskFontHeader disguised as a loadable DOS hunk and is known as a font
descriptor file. This allows the diskfont.library to use the dos.library
to load the module just like it was a hunk of relocatable 680x0
instructions. It even contains two instructions before the real
DiskFontHeader structure that will cause the 680x0 to stop running the
DiskFontHeader if it does inadvertently get executed."

"If it doesn't start with "FORM", "LIST", or "CAT ", it's not an IFF-85 file."

ant512 · 13 October 2007, 17:13

Yeah, I read through in a rush and made some stupid assumptions. Thanks for your patience!

YoJoe! · 14 October 2007, 10:05

I figured out the plain monochrome font file structure years ago but I never could figure out how in the name of Jay to create or use a ColorFont

redblade · 20 October 2007, 08:33

like minuous said, their mentioned in the Amiga RKM.

you can find it on the Kick 1.3 rkm that comes on the fish disks.

Comes with full source and a description to a example font.

12 October 2007, 15:28	#1
ant512 Registered User Join Date: Dec 2002 Location: California Posts: 965	Bitmap Font File Structure Does anyone know anything about the structure of Amiga bitmap font files? I'm guessing that they're more or less standard IFF ILBM files with extra information specifying character width and height - is this correct? Can anyone point me in the direction of a complete spec for the file format that I could use to implement a font loader? Thanks!

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12 October 2007, 16:08	#2
girv Mostly Harmless Join Date: Aug 2004 Location: Northern Ireland Posts: 1,115	There is a font loader source buried in some of the WHDLoad example slave sources, it's pretty straightforward. You're basically right about the format. There is a header, which I believe is specified in a system include file somewhere (textfont.[ih] ?), then the font glyphs follow it as one big bitmap. You need to shift & mask to cut out the raw data for the glyph you need.

12 October 2007, 20:02	#3
Minuous Coder/webmaster/gamer Join Date: Oct 2001 Location: Canberra/Australia Posts: 2,651	They are nothing like IFF files. They are documented in the Amiga ROM Kernel Reference Manual: Libraries. More specifically: http://cataclysm.cx/random/amiga/ref.../node03E0.html

13 October 2007, 00:15	#4
ant512 Registered User Join Date: Dec 2002 Location: California Posts: 965	Thanks guys. Looks like fonts are IFF files, but they come with the extra .font file that contains the font descripton info.

13 October 2007, 15:00	#5
Minuous Coder/webmaster/gamer Join Date: Oct 2001 Location: Canberra/Australia Posts: 2,651	"For each font size described in a FontContents (or TFontContents) structure, there is a corresponding file in that font's directory whose name is its size. For example, for the font size Sapphire-19, there is a file in the Sapphire directory called 19. That file is basically a DiskFontHeader disguised as a loadable DOS hunk and is known as a font descriptor file. This allows the diskfont.library to use the dos.library to load the module just like it was a hunk of relocatable 680x0 instructions. It even contains two instructions before the real DiskFontHeader structure that will cause the 680x0 to stop running the DiskFontHeader if it does inadvertently get executed." "If it doesn't start with "FORM", "LIST", or "CAT ", it's not an IFF-85 file."

13 October 2007, 17:13	#6
ant512 Registered User Join Date: Dec 2002 Location: California Posts: 965	Yeah, I read through in a rush and made some stupid assumptions. Thanks for your patience!

14 October 2007, 10:05	#7
YoJoe! Amiga Enthusiast Join Date: Oct 2007 Location: USA Posts: 217	I figured out the plain monochrome font file structure years ago but I never could figure out how in the name of Jay to create or use a ColorFont

20 October 2007, 08:33	#8
redblade Zone Friend Join Date: Mar 2004 Location: Middle Earth Age: 40 Posts: 2,127	like minuous said, their mentioned in the Amiga RKM. you can find it on the Kick 1.3 rkm that comes on the fish disks. Comes with full source and a description to a example font.

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