83 lines
2.5 KiB
Python
83 lines
2.5 KiB
Python
"""
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Low-level text helper utilities.
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"""
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from __future__ import annotations
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import dataclasses
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from . import _api
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from .ft2font import KERNING_DEFAULT, LOAD_NO_HINTING, FT2Font
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@dataclasses.dataclass(frozen=True)
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class LayoutItem:
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ft_object: FT2Font
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char: str
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glyph_idx: int
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x: float
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prev_kern: float
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def warn_on_missing_glyph(codepoint, fontnames):
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_api.warn_external(
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f"Glyph {codepoint} "
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f"({chr(codepoint).encode('ascii', 'namereplace').decode('ascii')}) "
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f"missing from font(s) {fontnames}.")
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block = ("Hebrew" if 0x0590 <= codepoint <= 0x05ff else
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"Arabic" if 0x0600 <= codepoint <= 0x06ff else
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"Devanagari" if 0x0900 <= codepoint <= 0x097f else
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"Bengali" if 0x0980 <= codepoint <= 0x09ff else
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"Gurmukhi" if 0x0a00 <= codepoint <= 0x0a7f else
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"Gujarati" if 0x0a80 <= codepoint <= 0x0aff else
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"Oriya" if 0x0b00 <= codepoint <= 0x0b7f else
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"Tamil" if 0x0b80 <= codepoint <= 0x0bff else
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"Telugu" if 0x0c00 <= codepoint <= 0x0c7f else
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"Kannada" if 0x0c80 <= codepoint <= 0x0cff else
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"Malayalam" if 0x0d00 <= codepoint <= 0x0d7f else
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"Sinhala" if 0x0d80 <= codepoint <= 0x0dff else
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None)
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if block:
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_api.warn_external(
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f"Matplotlib currently does not support {block} natively.")
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def layout(string, font, *, kern_mode=KERNING_DEFAULT):
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"""
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Render *string* with *font*.
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For each character in *string*, yield a LayoutItem instance. When such an instance
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is yielded, the font's glyph is set to the corresponding character.
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Parameters
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----------
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string : str
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The string to be rendered.
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font : FT2Font
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The font.
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kern_mode : int
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A FreeType kerning mode.
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Yields
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------
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LayoutItem
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"""
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x = 0
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prev_glyph_idx = None
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char_to_font = font._get_fontmap(string)
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base_font = font
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for char in string:
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# This has done the fallback logic
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font = char_to_font.get(char, base_font)
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glyph_idx = font.get_char_index(ord(char))
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kern = (
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base_font.get_kerning(prev_glyph_idx, glyph_idx, kern_mode) / 64
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if prev_glyph_idx is not None else 0.
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)
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x += kern
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glyph = font.load_glyph(glyph_idx, flags=LOAD_NO_HINTING)
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yield LayoutItem(font, char, glyph_idx, x, kern)
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x += glyph.linearHoriAdvance / 65536
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prev_glyph_idx = glyph_idx
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