Glyph decoding, encoding and traversal

The glyph module provides several functions for encoding, decoding and iterating over glyphs. Together, they can be used for easy glyph manipulation.

Glyphs are usually encoded in 8 bytes, each byte representing one row of the glyph. The decode_glyph function can be used to transform a glyph to a human readable format.

from retrofont.glyph import decode_glyph

glyph = b'B$~\xdb\xff~\x81\xe7'
text_glyph = decode_glyph(glyph)
print('\n'.join(text_glyph))

The text representation of the glyph looks as follows.

 #    #
  #  #
 ######
## ## ##
########
 ######
#      #
###  ###

This representation can easily be manipulated.

text_glyph[0] = '  #  #  '
print('\n'.join(text_glyph))

The modified text glyph now looks as follows.

  #  #
  #  #
 ######
## ## ##
########
 ######
#      #
###  ###

A text glyph can be encoded with encode_glyph to a glyph again.

from retrofont.glyph import encode_glyph

glyph = encode_glyph(text_glyph)
print(glyph)

Notice that the first byte ($) now differs from what we started with (B).

b'$$~\xdb\xff~\x81\xe7'

Glyphs frequently need to be traversed (e.g., for printing). The traverse_glyph generator can be used for this purpose.

from retrofont.glyph import traverse_glyph

pixels = traverse_glyph(glyph)
for pixel in pixels:
    (r, c), v = pixel
    print(f'row: {r}, column: {c}, value: {v}')

The generator produces 2-tuples, consisting of a coordinate (also a 2-tuple) and a value.

row: 0, column: 0, value: Pixel.empty
row: 0, column: 1, value: Pixel.empty
row: 0, column: 2, value: Pixel.filled
...