Hi all. I've spent the last two weeks writing an open-source Rust BMFont parser that works with text, XML, and binary BMFont formats.

The homepage is here: https://github.com/shampoofactory/bmfont_rs

However, I have a question that I need help with.

Based on the `Bitmap Font Generator - Documentation` my understanding is that the binary file is the de facto standard when it comes to defining the content and the other formats reflect this. For example, common::lineHeight is a size 2 unsigned integer, and not a string, a boolean, an elephant, or anything else.

However, I've noted that some tools, like Hiero (https://github.com/libgdx/libgdx/wiki/Hiero) produce output like this:

`info face="Arial Black" size=33 bold=0 italic=0 charset="" unicode=0 stretchH=100 smooth=1 aa=1 padding=0,0,0,1 spacing=-2,-2`

Here `spacing` is negative, whereas the binary format defines it as a size 1 unsigned integer. This line cannot be encoded into a valid BMFont binary info block.

Question: Is Hiero incorrect, or am I incorrect in my interpretation. If Heiro is incorrect, I think there is already a ticket about this, I can try and assist in submitting a patch. If I am incorrect, then how do I determine the parameter types for text format files?

Thank you for the prompt feedback Gotanod. I did come across that ticket in my travels. My concern is that Hiero produces invalid BMFont output, in that it just doesn't obey the rules. My understanding, as stated above, is that negative spacing is not a thing in BMFont format. Hence the question at clarifying the format.

http://www.angelcode.com/products/bmfont/doc/file_format.html

Block type 1: info

field        size    type    pos    comment
fontSize     2       int     0     
bitField     1       bits    2      bit 0: smooth, bit 1: unicode, bit 2: italic, bit 3: bold, bit 4: fixedHeigth, bits 5-7: reserved
charSet      1       uint    3     
stretchH     2       uint    4     
aa           1       uint    6     
paddingUp    1       uint    7     
paddingRight 1       uint    8     
paddingDown  1       uint    9     
paddingLeft  1       uint    10    
spacingHoriz 1       uint    11    
spacingVert  1       uint    12    
outline      1       uint    13     added with version 2
fontName     n+1     string  14     null terminated string with length n

Spacing (horizontal/ vertical) is encoded as an unsigned char type. It can hold a value of 0 to 255. It cannot hold a negative value

Additional discussion here:

https://github.com/libgdx/libgdx/issues/5125​​

@gotanod Hi again. I'll try to be clearer. Hiero is just an example, we can put it to one side.

Let me rephrase my question:

If we take http://www.angelcode.com/products/bmfont/doc/file_format.html​ then:

Are the text file parameter types defined by the binary standard, e.g. info::stretchH is an unsigned short (size: 2 uint). If not, how do we determine the parameter types?

@witchlord Thank you! That's helped me enormously. I was uncertain as to whether I'd correctly interpreted the format as written. Due to its popularity, I can make a note on my repo about Hiero's particular take on the BMFont format and how one might work around it.

On further reflection, the Hiero situation is a can of worms. Whilst unequivocal interoperability with different BMFont format applications would be a wonderful thing, changing a core mode of Hiero's operation and potentially breaking existing downstream applications would not. I can understand why its maintainers are reluctant to make changes.

I have one more question, but it's not that important. Would it be possible to re-upload BMFont version 1.9c as mentioned here:

https://www.gamedev.net/forums/topic/682933-bmfont-v19c/5314268/​

I would like to support BMFont format v1 and v2, but I cannot find any information on the mysterious v2 common block encoded field. In particular, its binary format details. I was hoping to pull the code apart to figure it out.

@witchlord Thank you again.