determine font pixel-heights

[lenny]

what is the easiest way to determine the pixel-height of a font?

[bk]

http://www.rockbox.org/twiki/bin/view/Main/FontFormat

The height (16 bit value) is stored at an offset of 6 bytes.

edit: misread, actually 16 bit value

[lenny]

I don't have the knowledge of how to read the 32 bit value offset 6 bytes in the header... How would I do that? All I'm trying to do is find an alternative to counting the pixels on the screen

[Yotto]

I always look to see how many lines fit on the screen, and divide the screen height by that.

Not much better than counting pixels, but hey.

[bk]

Here's a little program that outputs all the header information from a rockbox font file.

Compile with any ANSI C compiler (GCC on any platform should work) and use as follows:
fntinfo font.fnt



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[bascule]

Forgive my ignorance, but doesn't the name give it away?

Nimbus 14 = 14 pixel-high font, no?

[Yotto]

I think you're right, assuming the font has a number in it.  Many of the fonts in my folder are lacking numbers.

[lenny]

Wow that's awsome. I've never had anybody respond to me with a program!

Anyway...
used on rockbox_default.fnt

Output:

Code: [Select]

Max width: 1536
Height: 2048
Ascent (baseline): 1792
Total characters: 65536

That can't be right
(I'm on mac 10.4 fyi)

[bk]

Hmmm, Macs are 64 bit arch, right? That'll screw fntinfo up.

This version should work but may not be ANSI compatible (gcc -ansi doesn't complain though). I'm not totally sure how to write portable C that handles variable int sizes but this should be a decent quick and dirty fix.


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[lenny]

well, thanks. unfortunately the new fntinfo generates the same output for me. I have an old powerpc g4. I tried wikipedia to find out bit architecture info for ya but it's over my head. good news is when I run either fntinfo program on a font file with a number, the output for height is always 256 times the expected answer. For now that will work just fine for me.

Still, it seems like waaaayyy too much work to accomplish such a small thing. Oh well!

Perhaps:
1) all font names should be ended with the pixel height number
2) a chart should exist somewhere in the wiki

I vote for number 1

[NsN]

PowerPC macs are big endian and some are 64 Bit.
Shouldn't be very problematic though, i can try to whip something up by tomorrow.

EDIT:
I had some old endian check code lying around. The attached program should work on pretty much any architecture. If for some reason your int is not 4 Bytes you might need to edit the defines at the beginning.

Tested on Pentium M linux and windows and on a G4 Power PC Mac OS 10.4



Bye,
NsN

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