Source code for gpiozero.fonts

# GPIO Zero: a library for controlling the Raspberry Pi's GPIO pins
#
# Copyright (c) 2021 Dave Jones <dave@waveform.org.uk>
#
# SPDX-License-Identifier: BSD-3-Clause

from __future__ import (
    unicode_literals,
    absolute_import,
    print_function,
    division,
)
str = type('')

import io
from collections import Counter
from itertools import zip_longest


[docs]def load_segment_font(filename_or_obj, width, height, pins): """ A generic function for parsing segment font definition files. If you're working with "standard" `7-segment`_ or `14-segment`_ displays you *don't* want this function; see :func:`load_font_7seg` or :func:`load_font_14seg` instead. However, if you are working with another style of segmented display and wish to construct a parser for a custom format, this is the function you want. The *filename_or_obj* parameter is simply the file-like object or filename to load. This is typically passed in from the calling function. The *width* and *height* parameters give the width and height in characters of each character definition. For example, these are 3 and 3 for 7-segment displays. Finally, *pins* is a list of tuples that defines the position of each pin definition in the character array, and the character that marks that position "active". For example, for 7-segment displays this function is called as follows:: load_segment_font(filename_or_obj, width=3, height=3, pins=[ (1, '_'), (5, '|'), (8, '|'), (7, '_'), (6, '|'), (3, '|'), (4, '_')]) This dictates that each character will be defined by a 3x3 character grid which will be converted into a nine-character string like so: .. code-block:: text 012 345 ==> '012345678' 678 Position 0 is always assumed to be the character being defined. The *pins* list then specifies: the first pin is the character at position 1 which will be "on" when that character is "_". The second pin is the character at position 5 which will be "on" when that character is "|", and so on. .. _7-segment: https://en.wikipedia.org/wiki/Seven-segment_display .. _14-segment: https://en.wikipedia.org/wiki/Fourteen-segment_display """ assert 0 < len(pins) <= (width * height) - 1 if isinstance(filename_or_obj, bytes): filename_or_obj = filename_or_obj.decode('utf-8') opened = isinstance(filename_or_obj, str) if opened: filename_or_obj = io.open(filename_or_obj, 'r') try: lines = filename_or_obj.read() if isinstance(lines, bytes): lines = lines.decode('utf-8') lines = lines.splitlines() finally: if opened: filename_or_obj.close() # Strip out comments and blank lines, but remember the original line # numbers of each row for error reporting purposes rows = [ (index, line) for index, line in enumerate(lines, start=1) # Strip comments and blank (or whitespace) lines if line.strip() and not line.startswith('#') ] line_numbers = { row_index: line_index for row_index, (line_index, row) in enumerate(rows) } rows = [row for index, row in rows] if len(rows) % height: raise ValueError('number of definition lines is not divisible by ' '{height}'.format(height=height)) # Strip out blank columns then transpose back to rows, and make sure # everything is the right "shape" for n in range(0, len(rows), height): cols = [ col for col in zip_longest(*rows[n:n + height], fillvalue=' ') # Strip blank (or whitespace) columns if ''.join(col).strip() ] rows[n:n + height] = list(zip(*cols)) for row_index, row in enumerate(rows): if len(row) % width: raise ValueError( 'length of definitions starting on line {line} is not ' 'divisible by {width}'.format( line=line_numbers[row_index], width=width)) # Split rows up into character definitions. After this, chars will be a # list of strings each with width x height characters. The first character # in each string will be the character being defined chars = [ ''.join( char for row in rows[y::height] for char in row )[x::width] for y in range(height) for x in range(width) ] chars = [''.join(char) for char in zip(*chars)] # Strip out blank entries (a consequence of zip_longest above) and check # there're no repeat definitions chars = [char for char in chars if char.strip()] counts = Counter(char[0] for char in chars) for char, count in counts.most_common(): if count > 1: raise ValueError( 'multiple definitions for {char!r}'.format(char=char)) return { char[0]: tuple(int(char[pos] == on) for pos, on in pins) for char in chars }
[docs]def load_font_7seg(filename_or_obj): """ Given a filename or a file-like object, parse it as an font definition for a `7-segment display`_, returning a :class:`dict` suitable for use with :class:`~gpiozero.LEDCharDisplay`. The file-format is a simple text-based format in which blank and #-prefixed lines are ignored. All other lines are assumed to be groups of character definitions which are cells of 3x3 characters laid out as follows: .. code-block:: text Ca fgb edc Where C is the character being defined, and a-g define the states of the LEDs for that position. a, d, and g are on if they are "_". b, c, e, and f are on if they are "|". Any other character in these positions is considered off. For example, you might define the following characters: .. code-block:: text . 0_ 1. 2_ 3_ 4. 5_ 6_ 7_ 8_ 9_ ... |.| ..| ._| ._| |_| |_. |_. ..| |_| |_| ... |_| ..| |_. ._| ..| ._| |_| ..| |_| ._| In the example above, empty locations are marked with "." but could mostly be left as spaces. However, the first item defines the space (" ") character and needs *some* non-space characters in its definition as the parser also strips empty columns (as typically occur between character definitions). This is also why the definition for "1" must include something to fill the middle column. .. _7-segment display: https://en.wikipedia.org/wiki/Seven-segment_display """ return load_segment_font(filename_or_obj, width=3, height=3, pins=[ (1, '_'), (5, '|'), (8, '|'), (7, '_'), (6, '|'), (3, '|'), (4, '_')])
[docs]def load_font_14seg(filename_or_obj): """ Given a filename or a file-like object, parse it as a font definition for a `14-segment display`_, returning a :class:`dict` suitable for use with :class:`~gpiozero.LEDCharDisplay`. The file-format is a simple text-based format in which blank and #-prefixed lines are ignored. All other lines are assumed to be groups of character definitions which are cells of 5x5 characters laid out as follows: .. code-block:: text X.a.. fijkb .g.h. elmnc ..d.. Where X is the character being defined, and a-n define the states of the LEDs for that position. a, d, g, and h are on if they are "-". b, c, e, f, j, and m are on if they are "|". i and n are on if they are "\\". Finally, k and l are on if they are "/". Any other character in these positions is considered off. For example, you might define the following characters: .. code-block:: text .... 0--- 1.. 2--- 3--- 4 5--- 6--- 7---. 8--- 9--- ..... | /| /| | | | | | | / | | | | ..... | / | | --- -- ---| --- |--- | --- ---| ..... |/ | | | | | | | | | | | | ..... --- --- --- --- --- --- In the example above, several locations have extraneous characters. For example, the "/" in the center of the "0" definition, or the "-" in the middle of the "8". These locations are ignored, but filled in nonetheless to make the shape more obvious. These extraneous locations could equally well be left as spaces. However, the first item defines the space (" ") character and needs *some* non-space characters in its definition as the parser also strips empty columns (as typically occur between character definitions) and verifies that definitions are 5 columns wide and 5 rows high. This also explains why place-holder characters (".") have been inserted at the top of the definition of the "1" character. Otherwise the parser will strip these empty columns and decide the definition is invalid (as the result is only 3 columns wide). .. _14-segment display: https://en.wikipedia.org/wiki/Fourteen-segment_display """ return load_segment_font(filename_or_obj, width=5, height=5, pins=[ (2, '-'), (9, '|'), (19, '|'), (22, '-'), (15, '|'), (5, '|'), (11, '-'), (13, '-'), (6, '\\'), (7, '|'), (8, '/'), (16, '/'), (17, '|'), (18, '\\')])