kopia lustrzana https://github.com/peterhinch/micropython-font-to-py
Precise height determination. Binary file output option.
Peter Hinch
rodzic
7fa84269fd
commit
4058de707a
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@ -23,7 +23,8 @@ Example usage to produce a file ``myfont.py`` with height of 23 pixels:
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1. Font file path. Must be a ttf or otf file.
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2. Height in pixels.
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3. Output file path. Must have a .py extension.
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3. Output file path. Must have a .py extension otherwise a binary font file
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will be created; in this instance a warning message is output.
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### Optional arguments:
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@ -49,6 +50,16 @@ to render strings on demand. A practical example may be studied
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[here](https://github.com/peterhinch/micropython-samples/blob/master/SSD1306/ssd1306_test.py).
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The detailed layout of the Python file may be seen [here](./DRIVERS.md).
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### Binary font files
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If the output filename does not have a ``.py`` extension a binary font file is
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created. This is primarily intended for the e-paper driver. Specifically in
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applications where the file is to be stored on the display's internal flash
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memory rather than using frozen Python modules.
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The technique of accessing character data from a random access file is only
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applicable to devices such as e-paper where the update time is slow.
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# Dependencies, links and licence
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The code is released under the MIT licence. It requires Python 3.2 or later.
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100
font_to_py.py
100
font_to_py.py
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@ -2,6 +2,8 @@
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# -*- coding: utf-8 -*-
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# Needs freetype-py>=1.0
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# Implements multi-pass solution to setting an exact font height
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# Some code adapted from Daniel Bader's work at the following URL
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# http://dbader.org/blog/monochrome-font-rendering-with-freetype-and-python
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@ -258,26 +260,41 @@ class Font(dict):
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def __init__(self, filename, size, monospaced=False):
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super().__init__()
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self._face = freetype.Face(filename)
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self._face.set_pixel_sizes(0, size)
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self._max_descent = 0
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# For each character in the charset string we get the glyph
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# and update the overall dimensions of the resulting bitmap.
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self.max_width = 0
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max_ascent = 0
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for char in self.charset:
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glyph = self._glyph_for_character(char)
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max_ascent = max(max_ascent, int(glyph.ascent))
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self._max_descent = max(self._max_descent, int(glyph.descent))
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# for a few chars e.g. _ glyph.width > glyph.advance_width
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self.max_width = int(max(self.max_width, glyph.advance_width,
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glyph.width))
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self.height = max_ascent + self._max_descent
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self.max_width = self.get_dimensions(size)
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self.width = self.max_width if monospaced else 0
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for char in self.charset:
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for char in self.charset: # Populate dictionary
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self._render_char(char)
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# n-pass solution to setting a precise height.
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def get_dimensions(self, required_height):
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error = 0
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height = required_height
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for npass in range(10):
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height += error
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self._face.set_pixel_sizes(0, height)
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max_descent = 0
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# For each character in the charset string we get the glyph
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# and update the overall dimensions of the resulting bitmap.
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max_width = 0
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max_ascent = 0
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for char in self.charset:
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glyph = self._glyph_for_character(char)
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max_ascent = max(max_ascent, int(glyph.ascent))
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max_descent = max(max_descent, int(glyph.descent))
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# for a few chars e.g. _ glyph.width > glyph.advance_width
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max_width = int(max(max_width, glyph.advance_width,
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glyph.width))
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error = required_height - (max_ascent + max_descent)
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if error == 0:
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break
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print('Height set in {} passes'.format(npass))
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self.height = max_ascent + max_descent
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self._max_descent = max_descent
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return max_width
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def _glyph_for_character(self, char):
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# Let FreeType load the glyph for the given character and tell it to
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# render a monochromatic bitmap representation.
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@ -287,20 +304,18 @@ class Font(dict):
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def _render_char(self, char):
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glyph = self._glyph_for_character(char)
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if self.width: # Monospaced
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width = self.width
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else:
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width = int(max(glyph.width, glyph.advance_width))
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char_width = int(max(glyph.width, glyph.advance_width)) # Actual width
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width = self.width if self.width else char_width # Space required if monospaced
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outbuffer = Bitmap(width, self.height)
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# The vertical drawing position should place the glyph
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# on the baseline as intended.
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row = self.height - int(glyph.ascent) - self._max_descent
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outbuffer.bitblt(glyph.bitmap, row)
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self[char] = [outbuffer, width]
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self[char] = [outbuffer, width, char_width]
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def stream_char(self, char, hmap, reverse):
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outbuffer, _ = self[char]
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outbuffer, _, _ = self[char]
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if hmap:
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gen = outbuffer.get_hbyte(reverse)
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else:
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@ -317,6 +332,14 @@ class Font(dict):
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index += (len(data)).to_bytes(2, byteorder='little')
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return data, index
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def build_binary_array(self, hmap, reverse):
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data = bytearray((0x3f, 0xe7, self.max_width, self.height))
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for char in self.charset:
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width = self[char][2]
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data += bytes((width,))
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data += bytearray(self.stream_char(char, hmap, reverse))
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return data
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# PYTHON FILE WRITING
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STR01 = """# Code generated by font-to-py.py.
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@ -377,6 +400,22 @@ def write_data(stream, fnt, font_path, monospaced, hmap, reverse):
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bw_index.eot()
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stream.write(STR02.format(height, height))
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# BINARY OUTPUT
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def write_binary_font(op_path, font_path, height, hmap, reverse):
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try:
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fnt = Font(font_path, height, True) # All chars have same width
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except freetype.ft_errors.FT_Exception:
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print("Can't open", font_path)
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return False
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try:
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with open(op_path, 'wb') as stream:
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data = fnt.build_binary_array(hmap, reverse)
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stream.write(data)
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except OSError:
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print("Can't open", op_path, 'for writing')
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return False
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return True
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# PARSE COMMAND LINE ARGUMENTS
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@ -412,10 +451,13 @@ if __name__ == "__main__":
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if not os.path.splitext(args.infile)[1].upper() in ('.TTF', '.OTF'):
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print("Font file should be a ttf or otf file.")
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sys.exit(1)
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if not os.path.splitext(args.outfile)[1].upper() == '.PY':
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print("Output filename should have a .py extension.")
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sys.exit(1)
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if not write_font(args.outfile, args.infile, args.height, args.fixed,
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args.xmap, args.reverse):
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sys.exit(1)
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if os.path.splitext(args.outfile)[1].upper() == '.PY': # Emit Python
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if not write_font(args.outfile, args.infile, args.height, args.fixed,
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args.xmap, args.reverse):
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sys.exit(1)
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else:
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print('WARNING: output filename lacks .py extension. Writing binary font file.')
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if not write_binary_font(args.outfile, args.infile, args.height,
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args.xmap, args.reverse):
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sys.exit(1)
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print(args.outfile, 'written successfully.')
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