kopia lustrzana https://github.com/peterhinch/micropython-font-to-py
114 wiersze
4.9 KiB
Python
Executable File
114 wiersze
4.9 KiB
Python
Executable File
# Some code adapted from Daniel Bader's work at the following URL
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# https://dbader.org/blog/monochrome-font-rendering-with-freetype-and-python
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# With thanks to Stephen Irons @ironss for various improvements, also to
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# @enigmaniac for ideas around handling `bdf` and `pcf` files.
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# The MIT License (MIT)
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#
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# Copyright (c) 2016-2023 Peter Hinch
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#
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the "Software"), to deal
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# in the Software without restriction, including without limitation the rights
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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# copies of the Software, and to permit persons to whom the Software is
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# furnished to do so, subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be included in
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# all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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# THE SOFTWARE.
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from .bitmap import Bitmap
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class Glyph:
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def __init__( # noqa: PLR0913
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self, pixels, width, height, top, left, advance_width
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):
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self.bitmap = Bitmap(width, height, pixels)
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# The glyph bitmap's top-side bearing, i.e. the vertical distance from
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# the baseline to the bitmap's top-most scanline.
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self.top = top
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self.left = left
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# Ascent and descent determine how many pixels the glyph extends
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# above or below the baseline.
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self.descent = max(0, self.height - self.top)
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self.ascent = max(0, max(self.top, self.height) - self.descent)
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# The advance width determines where to place the next character
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# horizontally, that is, how many pixels we move to the right to
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# draw the next glyph.
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self.advance_width = advance_width
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@property
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def width(self):
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return self.bitmap.width
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@property
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def height(self):
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return self.bitmap.height
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@staticmethod
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def from_glyphslot(slot):
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"""Construct and return a Glyph object from a FreeType GlyphSlot."""
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pixels = Glyph.unpack_mono_bitmap(slot.bitmap)
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width, height = slot.bitmap.width, slot.bitmap.rows
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top = slot.bitmap_top
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left = slot.bitmap_left
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# The advance width is given in FreeType's 26.6 fixed point format,
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# which means that the pixel values are multiples of 64.
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advance_width = slot.advance.x / 64
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return Glyph(pixels, width, height, top, left, advance_width)
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@staticmethod
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def unpack_mono_bitmap(bitmap):
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"""
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Unpack a freetype FT_LOAD_TARGET_MONO glyph bitmap into a bytearray
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where each pixel is represented by a single byte.
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"""
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# Allocate a bytearray of sufficient size to hold the glyph bitmap.
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data = bytearray(bitmap.rows * bitmap.width)
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# Iterate over every byte in the glyph bitmap. Note that we're not
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# iterating over every pixel in the resulting unpacked bitmap --
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# we're iterating over the packed bytes in the input bitmap.
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for row in range(bitmap.rows):
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for byte_index in range(bitmap.pitch):
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# Read the byte that contains the packed pixel data.
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byte_value = bitmap.buffer[row * bitmap.pitch + byte_index]
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# We've processed this many bits (=pixels) so far. This
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# determines where we'll read the next batch of pixels from.
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num_bits_done = byte_index * 8
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# Pre-compute where to write the pixels that we're going
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# to unpack from the current byte in the glyph bitmap.
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rowstart = row * bitmap.width + byte_index * 8
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# Iterate over every bit (=pixel) that's still a part of the
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# output bitmap. Sometimes we're only unpacking a fraction of
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# a byte because glyphs may not always fit on a byte boundary.
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# So we make sure to stop if we unpack past the current row
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# of pixels.
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for bit_index in range(min(8, bitmap.width - num_bits_done)):
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# Unpack the next pixel from the current glyph byte.
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bit = byte_value & (1 << (7 - bit_index))
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# Write the pixel to the output bytearray. We ensure that
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# `off` pixels have a value of 0 and `on` pixels have a
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# value of 1.
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data[rowstart + bit_index] = 1 if bit else 0
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return data
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