e418fd9ee3
Summary: Instead of using the metrics from our generated TTF files, use the fonts that TeX ships with. Pull the mapping out of the MathJax-dev repo from makeFF to get the correct mapping of metrics to font characters, and use our own tfm reader to extract metrics out of the tfm files into a useable format. Add a README and Makefile rule to make this process easier in the future. Also remove the silly 0.05em we put on supsubs because our italic correction works now. Test Plan: - Run huxley tests, see that changes are because of font metric changes. - See that the extension piece of `\bigl |` now extends above the top, as it is supposed to. Reviewers: alpert Reviewed By: alpert Differential Revision: http://phabricator.khanacademy.org/D12867
150 lines
4.2 KiB
Python
150 lines
4.2 KiB
Python
class CharInfoWord(object):
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def __init__(self, word):
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b1, b2, b3, b4 = (word >> 24,
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(word & 0xff0000) >> 16,
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(word & 0xff00) >> 8,
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word & 0xff)
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self.width_index = b1
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self.height_index = b2 >> 4
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self.depth_index = b2 & 0x0f
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self.italic_index = (b3 & 0b11111100) >> 2
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self.tag = b3 & 0b11
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self.remainder = b4
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class TfmCharMetrics(object):
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def __init__(self, width, height, depth, italic):
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self.width = width
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self.height = height
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self.depth = depth
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self.italic_correction = italic
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class TfmFile(object):
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def __init__(self, start_char, end_char, char_info, width_table,
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height_table, depth_table, italic_table):
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self.start_char = start_char
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self.end_char = end_char
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self.char_info = char_info
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self.width_table = width_table
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self.height_table = height_table
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self.depth_table = depth_table
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self.italic_table = italic_table
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def get_char_metrics(self, char_num):
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if char_num < self.start_char or char_num > self.end_char:
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raise RuntimeError("Invalid character number")
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info = self.char_info[char_num + self.start_char]
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return TfmCharMetrics(
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self.width_table[info.width_index],
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self.height_table[info.height_index],
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self.depth_table[info.depth_index],
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self.italic_table[info.italic_index])
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class TfmReader(object):
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def __init__(self, f):
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self.f = f
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def read_byte(self):
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return ord(self.f.read(1))
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def read_halfword(self):
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b1 = self.read_byte()
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b2 = self.read_byte()
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return (b1 << 8) | b2
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def read_word(self):
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b1 = self.read_byte()
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b2 = self.read_byte()
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b3 = self.read_byte()
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b4 = self.read_byte()
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return (b1 << 24) | (b2 << 16) | (b3 << 8) | b4
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def read_fixword(self):
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word = self.read_word()
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neg = False
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if word & 0x80000000:
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neg = True
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word = (-word & 0xffffffff)
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return (-1 if neg else 1) * word / float(1 << 20)
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def read_bcpl(self, length):
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str_length = self.read_byte()
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data = self.f.read(length - 1)
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return data[:str_length]
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def read_tfm_file(file_name):
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with open(file_name, 'rb') as f:
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reader = TfmReader(f)
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# file_size
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reader.read_halfword()
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header_size = reader.read_halfword()
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start_char = reader.read_halfword()
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end_char = reader.read_halfword()
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width_table_size = reader.read_halfword()
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height_table_size = reader.read_halfword()
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depth_table_size = reader.read_halfword()
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italic_table_size = reader.read_halfword()
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# ligkern_table_size
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reader.read_halfword()
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# kern_table_size
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reader.read_halfword()
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# extensible_table_size
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reader.read_halfword()
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# parameter_table_size
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reader.read_halfword()
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# checksum
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reader.read_word()
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# design_size
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reader.read_fixword()
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if header_size > 2:
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# coding_scheme
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reader.read_bcpl(40)
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if header_size > 12:
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# font_family
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reader.read_bcpl(20)
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for i in range(header_size - 17):
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reader.read_word()
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char_info = []
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for i in range(start_char, end_char + 1):
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char_info.append(CharInfoWord(reader.read_word()))
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width_table = []
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for i in range(width_table_size):
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width_table.append(reader.read_fixword())
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height_table = []
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for i in range(height_table_size):
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height_table.append(reader.read_fixword())
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depth_table = []
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for i in range(depth_table_size):
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depth_table.append(reader.read_fixword())
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italic_table = []
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for i in range(italic_table_size):
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italic_table.append(reader.read_fixword())
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# There is more information, like the ligkern, kern, extensible, and
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# param table, but we don't need these for now
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return TfmFile(start_char, end_char, char_info, width_table,
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height_table, depth_table, italic_table)
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