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171 lines
6.5 KiB
Python
171 lines
6.5 KiB
Python
5 years ago
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"""XGLCD Font Utility."""
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from math import ceil, floor
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class XglcdFont(object):
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"""Font data in X-GLCD format.
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Attributes:
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letters: A bytearray of letters (columns consist of bytes)
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width: Maximum pixel width of font
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height: Pixel height of font
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start_letter: ASCII number of first letter
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height_bytes: How many bytes comprises letter height
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Note:
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Font files can be generated with the free version of MikroElektronika
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GLCD Font Creator: www.mikroe.com/glcd-font-creator
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The font file must be in X-GLCD 'C' format.
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To save text files from this font creator program in Win7 or higher
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you must use XP compatibility mode or you can just use the clipboard.
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"""
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# Dict to tranlate bitwise values to byte position
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BIT_POS = {1: 0, 2: 2, 4: 4, 8: 6, 16: 8, 32: 10, 64: 12, 128: 14, 256: 16}
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def __init__(self, path, width, height, start_letter=32, letter_count=96):
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"""Constructor for X-GLCD Font object.
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Args:
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path (string): Full path of font file
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width (int): Maximum width in pixels of each letter
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height (int): Height in pixels of each letter
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start_letter (int): First ACII letter. Default is 32.
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letter_count (int): Total number of letters. Default is 96.
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"""
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self.width = width
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self.height = height
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self.start_letter = start_letter
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self.letter_count = letter_count
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self.bytes_per_letter = (floor(
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(self.height - 1) / 8) + 1) * self.width + 1
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self.__load_xglcd_font(path)
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def __load_xglcd_font(self, path):
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"""Load X-GLCD font data from text file.
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Args:
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path (string): Full path of font file.
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"""
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bytes_per_letter = self.bytes_per_letter
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# Buffer to hold letter byte values
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self.letters = bytearray(bytes_per_letter * self.letter_count)
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mv = memoryview(self.letters)
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offset = 0
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with open(path, 'r') as f:
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for line in f:
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# Skip lines that do not start with hex values
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line = line.strip()
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if len(line) == 0 or line[0:2] != '0x':
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continue
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# Remove comments
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comment = line.find('//')
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if comment != -1:
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line = line[0:comment].strip()
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# Remove trailing commas
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if line.endswith(','):
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line = line[0:len(line) - 1]
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# Convert hex strings to bytearray and insert in to letters
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mv[offset: offset + bytes_per_letter] = bytearray(
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int(b, 16) for b in line.split(','))
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offset += bytes_per_letter
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def lit_bits(self, n):
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"""Return positions of 1 bits only."""
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while n:
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b = n & (~n+1)
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yield self.BIT_POS[b]
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n ^= b
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def get_letter(self, letter, color, background=0, landscape=False):
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"""Convert letter byte data to pixels.
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Args:
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letter (string): Letter to return (must exist within font).
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color (int): RGB565 color value.
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background (int): RGB565 background color (default: black).
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landscape (bool): Orientation (default: False = portrait)
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Returns:
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(bytearray): Pixel data.
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(int, int): Letter width and height.
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"""
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# Get index of letter
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letter_ord = ord(letter) - self.start_letter
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# Confirm font contains letter
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if letter_ord >= self.letter_count:
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print('Font does not contain character: ' + letter)
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return b'', 0, 0
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bytes_per_letter = self.bytes_per_letter
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offset = letter_ord * bytes_per_letter
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mv = memoryview(self.letters[offset:offset + bytes_per_letter])
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# Get width of letter (specified by first byte)
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letter_width = mv[0]
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letter_height = self.height
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# Get size in bytes of specified letter
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letter_size = letter_height * letter_width
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# Create buffer (double size to accommodate 16 bit colors)
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if background:
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buf = bytearray(background.to_bytes(2, 'big') * letter_size)
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else:
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buf = bytearray(letter_size * 2)
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msb, lsb = color.to_bytes(2, 'big')
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if landscape:
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# Populate buffer in order for landscape
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pos = (letter_size * 2) - (letter_height * 2)
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lh = letter_height
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# Loop through letter byte data and convert to pixel data
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for b in mv[1:]:
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# Process only colored bits
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for bit in self.lit_bits(b):
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buf[bit + pos] = msb
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buf[bit + pos + 1] = lsb
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if lh > 8:
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# Increment position by double byte
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pos += 16
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lh -= 8
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else:
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# Descrease position to start of previous column
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pos -= (letter_height * 4) - (lh * 2)
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lh = letter_height
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else:
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# Populate buffer in order for portrait
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col = 0 # Set column to first column
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bytes_per_letter = ceil(letter_height / 8)
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letter_byte = 0
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# Loop through letter byte data and convert to pixel data
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for b in mv[1:]:
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# Process only colored bits
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segment_size = letter_byte * letter_width * 16
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for bit in self.lit_bits(b):
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pos = (bit * letter_width) + (col * 2) + segment_size
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buf[pos] = msb
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pos = (bit * letter_width) + (col * 2) + 1 + segment_size
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buf[pos] = lsb
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letter_byte += 1
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if letter_byte + 1 > bytes_per_letter:
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col += 1
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letter_byte = 0
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return buf, letter_width, letter_height
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def measure_text(self, text, spacing=1):
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"""Measure length of text string in pixels.
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Args:
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text (string): Text string to measure
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spacing (optional int): Pixel spacing between letters. Default: 1.
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Returns:
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int: length of text
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"""
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length = 0
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for letter in text:
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# Get index of letter
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letter_ord = ord(letter) - self.start_letter
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offset = letter_ord * self.bytes_per_letter
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# Add length of letter and spacing
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length += self.letters[offset] + spacing
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return length
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