316 lines
12 KiB
Python
316 lines
12 KiB
Python
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"""Fonts integration in PDF."""
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from math import ceil
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import pydyf
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from ..logger import LOGGER
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def build_fonts_dictionary(pdf, fonts, compress_pdf, subset, hinting):
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pdf_fonts = pydyf.Dictionary()
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fonts_by_file_hash = {}
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for font in fonts.values():
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fonts_by_file_hash.setdefault(font.hash, []).append(font)
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font_references_by_file_hash = {}
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for file_hash, file_fonts in fonts_by_file_hash.items():
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# TODO: find why we can have multiple fonts for one font file
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font = file_fonts[0]
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if font.bitmap:
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continue
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# Clean font, optimize and handle emojis
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cmap = {}
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if subset and not font.used_in_forms:
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for file_font in file_fonts:
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cmap = {**cmap, **file_font.cmap}
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font.clean(cmap, hinting)
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# Include font
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if font.type == 'otf':
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font_extra = pydyf.Dictionary({'Subtype': '/OpenType'})
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else:
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font_extra = pydyf.Dictionary({'Length1': len(font.file_content)})
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font_stream = pydyf.Stream(
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[font.file_content], font_extra, compress=compress_pdf)
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pdf.add_object(font_stream)
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font_references_by_file_hash[file_hash] = font_stream.reference
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for font in fonts.values():
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if subset and font.ttfont and not font.used_in_forms:
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# Only store widths and map for used glyphs
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font_widths = font.widths
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cmap = font.cmap
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else:
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# Store width and Unicode map for all glyphs
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font_widths, cmap = {}, {}
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for letter, key in font.ttfont.getBestCmap().items():
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glyph = font.ttfont.getGlyphID(key)
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if glyph not in cmap:
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cmap[glyph] = chr(letter)
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width = font.ttfont.getGlyphSet()[key].width
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font_widths[glyph] = width * 1000 / font.upem
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max_x = max(font_widths.values()) if font_widths else 0
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bbox = (0, font.descent, max_x, font.ascent)
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widths = pydyf.Array()
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for i in sorted(font_widths):
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if i - 1 not in font_widths:
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widths.append(i)
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current_widths = pydyf.Array()
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widths.append(current_widths)
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current_widths.append(font_widths[i])
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font_file = f'FontFile{3 if font.type == "otf" else 2}'
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to_unicode = pydyf.Stream([
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b'/CIDInit /ProcSet findresource begin',
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b'12 dict begin',
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b'begincmap',
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b'/CIDSystemInfo',
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b'<< /Registry (Adobe)',
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b'/Ordering (UCS)',
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b'/Supplement 0',
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b'>> def',
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b'/CMapName /Adobe-Identity-UCS def',
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b'/CMapType 2 def',
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b'1 begincodespacerange',
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b'<0000> <ffff>',
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b'endcodespacerange',
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f'{len(cmap)} beginbfchar'.encode()], compress=compress_pdf)
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for glyph, text in cmap.items():
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unicode_codepoints = ''.join(
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f'{letter.encode("utf-16-be").hex()}' for letter in text)
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to_unicode.stream.append(
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f'<{glyph:04x}> <{unicode_codepoints}>'.encode())
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to_unicode.stream.extend([
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b'endbfchar',
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b'endcmap',
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b'CMapName currentdict /CMap defineresource pop',
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b'end',
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b'end'])
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pdf.add_object(to_unicode)
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font_dictionary = pydyf.Dictionary({
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'Type': '/Font',
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'Subtype': f'/Type{3 if font.bitmap else 0}',
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'BaseFont': font.name,
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'ToUnicode': to_unicode.reference,
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})
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if font.bitmap:
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_build_bitmap_font_dictionary(
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font_dictionary, pdf, font, widths, compress_pdf, subset)
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else:
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font_descriptor = pydyf.Dictionary({
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'Type': '/FontDescriptor',
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'FontName': font.name,
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'FontFamily': pydyf.String(font.family),
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'Flags': font.flags,
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'FontBBox': pydyf.Array(bbox),
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'ItalicAngle': font.italic_angle,
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'Ascent': font.ascent,
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'Descent': font.descent,
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'CapHeight': bbox[3],
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'StemV': font.stemv,
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'StemH': font.stemh,
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font_file: font_references_by_file_hash[font.hash],
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})
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if pdf.version <= b'1.4':
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cids = sorted(font.widths)
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padded_width = int(ceil((cids[-1] + 1) / 8))
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bits = ['0'] * padded_width * 8
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for cid in cids:
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bits[cid] = '1'
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stream = pydyf.Stream(
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(int(''.join(bits), 2).to_bytes(padded_width, 'big'),),
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compress=compress_pdf)
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pdf.add_object(stream)
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font_descriptor['CIDSet'] = stream.reference
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if font.type == 'otf':
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font_descriptor['Subtype'] = '/OpenType'
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pdf.add_object(font_descriptor)
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subfont_dictionary = pydyf.Dictionary({
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'Type': '/Font',
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'Subtype': f'/CIDFontType{0 if font.type == "otf" else 2}',
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'BaseFont': font.name,
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'CIDSystemInfo': pydyf.Dictionary({
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'Registry': pydyf.String('Adobe'),
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'Ordering': pydyf.String('Identity'),
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'Supplement': 0,
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}),
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'CIDToGIDMap': '/Identity',
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'W': widths,
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'FontDescriptor': font_descriptor.reference,
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})
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pdf.add_object(subfont_dictionary)
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font_dictionary['Encoding'] = '/Identity-H'
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font_dictionary['DescendantFonts'] = pydyf.Array(
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[subfont_dictionary.reference])
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pdf.add_object(font_dictionary)
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pdf_fonts[font.hash] = font_dictionary.reference
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return pdf_fonts
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def _build_bitmap_font_dictionary(font_dictionary, pdf, font, widths,
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compress_pdf, subset):
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# https://docs.microsoft.com/typography/opentype/spec/ebdt
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font_dictionary['FontBBox'] = pydyf.Array([0, 0, 1, 1])
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font_dictionary['FontMatrix'] = pydyf.Array([1, 0, 0, 1, 0, 0])
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if subset:
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chars = tuple(sorted(font.cmap))
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else:
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chars = tuple(range(256))
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first, last = chars[0], chars[-1]
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font_dictionary['FirstChar'] = first
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font_dictionary['LastChar'] = last
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differences = []
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for index, index_widths in zip(widths[::2], widths[1::2]):
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differences.append(index)
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for i in range(len(index_widths)):
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if i + index in chars:
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differences.append(f'/{i + index}')
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font_dictionary['Encoding'] = pydyf.Dictionary({
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'Type': '/Encoding',
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'Differences': pydyf.Array(differences),
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})
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char_procs = pydyf.Dictionary({})
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font_glyphs = font.ttfont['EBDT'].strikeData[0]
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widths = [0] * (last - first + 1)
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glyphs_info = {}
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for key, glyph in font_glyphs.items():
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glyph_format = glyph.getFormat()
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glyph_id = font.ttfont.getGlyphID(key)
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# Get and store glyph metrics
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if glyph_format == 5:
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data = glyph.data
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subtables = font.ttfont['EBLC'].strikes[0].indexSubTables
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for subtable in subtables:
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first_index = subtable.firstGlyphIndex
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last_index = subtable.lastGlyphIndex
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if first_index <= glyph_id <= last_index:
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height = subtable.metrics.height
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advance = width = subtable.metrics.width
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bearing_x = subtable.metrics.horiBearingX
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bearing_y = subtable.metrics.horiBearingY
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break
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else:
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LOGGER.warning(f'Unknown bitmap metrics for glyph: {glyph_id}')
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continue
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else:
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data_start = 5 if glyph_format in (1, 2, 8) else 8
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data = glyph.data[data_start:]
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height, width = glyph.data[0:2]
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bearing_x = int.from_bytes(glyph.data[2:3], 'big', signed=True)
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bearing_y = int.from_bytes(glyph.data[3:4], 'big', signed=True)
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advance = glyph.data[4]
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position_y = bearing_y - height
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if glyph_id in chars:
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widths[glyph_id - first] = advance
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stride = ceil(width / 8)
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glyph_info = glyphs_info[glyph_id] = {
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'width': width,
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'height': height,
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'x': bearing_x,
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'y': position_y,
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'stride': stride,
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'bitmap': None,
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'subglyphs': None,
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}
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# Decode bitmaps
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if 0 in (width, height) or not data:
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glyph_info['bitmap'] = b''
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elif glyph_format in (1, 6):
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glyph_info['bitmap'] = data
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elif glyph_format in (2, 5, 7):
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padding = (8 - (width % 8)) % 8
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bits = bin(int(data.hex(), 16))[2:]
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bits = bits.zfill(8 * len(data))
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bitmap_bits = ''.join(
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bits[i * width:(i + 1) * width] + padding * '0'
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for i in range(height))
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glyph_info['bitmap'] = int(bitmap_bits, 2).to_bytes(
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height * stride, 'big')
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elif glyph_format in (8, 9):
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subglyphs = glyph_info['subglyphs'] = []
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i = 0 if glyph_format == 9 else 1
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number_of_components = int.from_bytes(data[i:i+2], 'big')
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for j in range(number_of_components):
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index = (i + 2) + (j * 4)
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subglyph_id = int.from_bytes(data[index:index+2], 'big')
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x = int.from_bytes(data[index+2:index+3], 'big', signed=True)
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y = int.from_bytes(data[index+3:index+4], 'big', signed=True)
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subglyphs.append({'id': subglyph_id, 'x': x, 'y': y})
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else: # pragma: no cover
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LOGGER.warning(f'Unsupported bitmap glyph format: {glyph_format}')
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glyph_info['bitmap'] = bytes(height * stride)
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for glyph_id, glyph_info in glyphs_info.items():
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# Don’t store glyph not in cmap
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if glyph_id not in chars:
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continue
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# Draw glyph
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stride = glyph_info['stride']
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width = glyph_info['width']
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height = glyph_info['height']
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x = glyph_info['x']
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y = glyph_info['y']
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if glyph_info['bitmap'] is None:
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length = height * stride
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bitmap_int = int.from_bytes(bytes(length), 'big')
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for subglyph in glyph_info['subglyphs']:
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sub_x = subglyph['x']
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sub_y = subglyph['y']
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sub_id = subglyph['id']
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if sub_id not in glyphs_info:
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LOGGER.warning(f'Unknown subglyph: {sub_id}')
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continue
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subglyph = glyphs_info[sub_id]
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if subglyph['bitmap'] is None:
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# TODO: support subglyph in subglyph
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LOGGER.warning(
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f'Unsupported subglyph in subglyph: {sub_id}')
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continue
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for row_y in range(subglyph['height']):
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row_slice = slice(
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row_y * subglyph['stride'],
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(row_y + 1) * subglyph['stride'])
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row = subglyph['bitmap'][row_slice]
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row_int = int.from_bytes(row, 'big')
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shift = stride * 8 * (height - sub_y - row_y - 1)
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stride_difference = stride - subglyph['stride']
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if stride_difference > 0:
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row_int <<= stride_difference * 8
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elif stride_difference < 0:
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row_int >>= -stride_difference * 8
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if sub_x > 0:
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row_int >>= sub_x
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elif sub_x < 0:
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row_int <<= -sub_x
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row_int %= 1 << stride * 8
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row_int <<= shift
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bitmap_int |= row_int
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bitmap = bitmap_int.to_bytes(length, 'big')
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else:
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bitmap = glyph_info['bitmap']
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bitmap_stream = pydyf.Stream([
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b'0 0 d0',
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f'{width} 0 0 {height} {x} {y} cm'.encode(),
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b'BI',
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b'/IM true',
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b'/W', width,
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b'/H', height,
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b'/BPC 1',
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b'/D [1 0]',
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b'ID', bitmap, b'EI'
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], compress=compress_pdf)
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pdf.add_object(bitmap_stream)
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char_procs[glyph_id] = bitmap_stream.reference
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pdf.add_object(char_procs)
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font_dictionary['Widths'] = pydyf.Array(widths)
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font_dictionary['CharProcs'] = char_procs.reference
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