45 lines
1.2 KiB
Python
45 lines
1.2 KiB
Python
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"""
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Text layouting utilities.
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"""
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import dataclasses
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from .ft2font import KERNING_DEFAULT, LOAD_NO_HINTING
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LayoutItem = dataclasses.make_dataclass(
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"LayoutItem", ["char", "glyph_idx", "x", "prev_kern"])
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def layout(string, font, *, kern_mode=KERNING_DEFAULT):
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"""
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Render *string* with *font*. For each character in *string*, yield a
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(glyph-index, x-position) pair. When such a pair is yielded, the font's
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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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glyph_index : int
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x_position : float
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"""
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x = 0
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prev_glyph_idx = None
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for char in string:
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glyph_idx = font.get_char_index(ord(char))
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kern = (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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x += kern
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glyph = font.load_glyph(glyph_idx, flags=LOAD_NO_HINTING)
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yield LayoutItem(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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