Dynamix Font Format v2-v3

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Dynamix Font Format v2-v3
Dynamix Font v3.png
Format typeFont
Max glyph count255
Minimum glyph size (pixels)0×0 (global)
Maximum glyph size (pixels)127×127 (global)
Access modeIndexed
Metadata?None
Bitmap glyphs?Yes
Vector glyphs?No
Compressed glyphs?No
Hidden data?No
Games

A 1-bpp font with the file header specifying the global width and height for all symbols, the start symbol and the amount of symbols. The existence of the start symbol means it is optimized by only saving the used range of symbols. Typically, the first symbol code is 0x20 (32), the space character. A font with a full uppercase set has a count of at least 0x40 (64) while a font with an upper/lowercase set has a count of at least 0x60 (96).

The v2 and v3 types are identical, except that the v3 one is embedded in a "FNT" chunk of the typical Dynamix chunk format: a 3-character ID string, followed by a ':', followed by the chunk size in UINT32LE format, in which the highest bit is reserved for a flag indicating whether the chunk embeds chunks inside itself (which this "FNT" one does not), followed by the chunk data. The following explanation details the structures inside that chunk data, meaning all calculations of offsets should compensate for the extra 8 bytes at the start when reading a v3 font.

File format

Header

The font format starts with the following 4-byte header:

Offset Data type Name Description
0x00 UINT8 FontWidth Font symbol width, in pixels.
0x01 UINT8 FontHeight Font symbol height, in pixels.
0x02 UINT8 StartSymbol Start symbol. Symbols lower than this are not saved in the font file. Usually 0x20
0x03 UINT8 NrOfSymbols Number of symbols in the font file. Since this is a byte, the font is limited to a maximum of only 255 symbols, and not the full 256. However, since C-style strings end with byte 0x00, index 0 is technically useless, and can be skipped to get the full real range.

This is followed by raw blocks of 1-bpp data for the actual symbols, as determined by the header. Each line of a symbol is the width in bits rounded up to the next full byte, in bytes, which can be calculated as stride = ((FontWidth + 7) / 8). Multiply that by the FontHeight to get the size of one symbol. There should be NrOfSymbols of these blocks, meaning the file size can perfectly be calculated as HeaderSize + (stride * FontHeight * NrOfSymbols), with HeaderSize being 4, as detailed above.

Note that the stride may exceed one byte if the width in the header is greater than 8. Some existing systems simply interpret the symbol size as being equal to the height, but since the format supports widths greater than 8 pixels this is a dangerous simplification that should never be used.

To validate the font and correctly identify it, some other simple checks can be done. The most obvious one is that the amount of symbols plus the start symbol cannot exceed 256. Another one is that the later Dynamix fonts use the first byte as version, using values 0xFF and 0xFD to indicate respectively v4 and v5. This means that, for convenience, and because no officially released files ever have a width exceeding 127, the font dimensions could be interpreted as signed bytes.

Image data

The actual font data is 1 bit per pixel. To find a particular symbol, look at the following position in the data array: 

(symbolCode - start) * symbolSize

The 6x6.FNT font included in Heart of China starts at symbol code 0x20 and has a size of 6x6 pixels, giving it a symbol size of 0x06. For symbol code 0x42 (66, letter B) the position would be: 

0x04 + (0x42 - 0x20) * 0x06 = 0xD0 (208)

The data at this location is: 

70 48 70 48 70 00

The font is just a basic raster bitmap using 1 bit per pixel: 

70: .111....
48: .1..1...
70: .111....
48: .1..1...
70: .111....
00: ........

If the width is less than the full 8 bits shown here, the remaining bits on the line are simply ignored, and the graphics are cut off at the actual width specified in the header. The format does not use partial bytes to compact the data; as mentioned before, lines are always rounded up to the next full byte.

Tools

The following tools are able to work with files in this format.

Name PlatformView images in this format? Convert/export to another file/format? Import from another file/format? Access hidden data? Edit metadata? Notes
Westwood Font Editor WindowsYesYesYesN/AN/A
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