146 lines
4.3 KiB
Python
146 lines
4.3 KiB
Python
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"""
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Common functionality between the PDF and PS backends.
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"""
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from io import BytesIO
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import functools
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from fontTools import subset
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import matplotlib as mpl
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from .. import font_manager, ft2font
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from .._afm import AFM
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from ..backend_bases import RendererBase
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@functools.lru_cache(50)
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def _cached_get_afm_from_fname(fname):
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with open(fname, "rb") as fh:
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return AFM(fh)
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def get_glyphs_subset(fontfile, characters):
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"""
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Subset a TTF font
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Reads the named fontfile and restricts the font to the characters.
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Returns a serialization of the subset font as file-like object.
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Parameters
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----------
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fontfile : str
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Path to the font file
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characters : str
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Continuous set of characters to include in subset
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"""
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options = subset.Options(glyph_names=True, recommended_glyphs=True)
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# Prevent subsetting extra tables.
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options.drop_tables += [
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'FFTM', # FontForge Timestamp.
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'PfEd', # FontForge personal table.
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'BDF', # X11 BDF header.
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'meta', # Metadata stores design/supported languages (meaningless for subsets).
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]
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# if fontfile is a ttc, specify font number
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if fontfile.endswith(".ttc"):
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options.font_number = 0
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with subset.load_font(fontfile, options) as font:
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subsetter = subset.Subsetter(options=options)
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subsetter.populate(text=characters)
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subsetter.subset(font)
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fh = BytesIO()
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font.save(fh, reorderTables=False)
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return fh
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class CharacterTracker:
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"""
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Helper for font subsetting by the pdf and ps backends.
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Maintains a mapping of font paths to the set of character codepoints that
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are being used from that font.
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"""
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def __init__(self):
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self.used = {}
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def track(self, font, s):
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"""Record that string *s* is being typeset using font *font*."""
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char_to_font = font._get_fontmap(s)
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for _c, _f in char_to_font.items():
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self.used.setdefault(_f.fname, set()).add(ord(_c))
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def track_glyph(self, font, glyph):
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"""Record that codepoint *glyph* is being typeset using font *font*."""
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self.used.setdefault(font.fname, set()).add(glyph)
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class RendererPDFPSBase(RendererBase):
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# The following attributes must be defined by the subclasses:
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# - _afm_font_dir
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# - _use_afm_rc_name
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def __init__(self, width, height):
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super().__init__()
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self.width = width
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self.height = height
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def flipy(self):
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# docstring inherited
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return False # y increases from bottom to top.
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def option_scale_image(self):
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# docstring inherited
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return True # PDF and PS support arbitrary image scaling.
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def option_image_nocomposite(self):
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# docstring inherited
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# Decide whether to composite image based on rcParam value.
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return not mpl.rcParams["image.composite_image"]
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def get_canvas_width_height(self):
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# docstring inherited
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return self.width * 72.0, self.height * 72.0
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def get_text_width_height_descent(self, s, prop, ismath):
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# docstring inherited
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if ismath == "TeX":
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return super().get_text_width_height_descent(s, prop, ismath)
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elif ismath:
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parse = self._text2path.mathtext_parser.parse(s, 72, prop)
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return parse.width, parse.height, parse.depth
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elif mpl.rcParams[self._use_afm_rc_name]:
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font = self._get_font_afm(prop)
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l, b, w, h, d = font.get_str_bbox_and_descent(s)
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scale = prop.get_size_in_points() / 1000
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w *= scale
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h *= scale
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d *= scale
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return w, h, d
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else:
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font = self._get_font_ttf(prop)
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font.set_text(s, 0.0, flags=ft2font.LOAD_NO_HINTING)
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w, h = font.get_width_height()
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d = font.get_descent()
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scale = 1 / 64
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w *= scale
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h *= scale
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d *= scale
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return w, h, d
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def _get_font_afm(self, prop):
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fname = font_manager.findfont(
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prop, fontext="afm", directory=self._afm_font_dir)
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return _cached_get_afm_from_fname(fname)
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def _get_font_ttf(self, prop):
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fnames = font_manager.fontManager._find_fonts_by_props(prop)
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font = font_manager.get_font(fnames)
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font.clear()
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font.set_size(prop.get_size_in_points(), 72)
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return font
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