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141 | """Fills text and a shape with a gradient, through a shading pattern.
The Python twin of the `write_gradient_fill` example in Rust. Where
`write_gradient` paints a gradient into a clipped box, this makes a gradient the
colour something is filled with: a headline whose letters are windows onto a
three-stop blend, and a panel filled with a radial one. The gradient lives in
the page's own space, so the letters show the part of it behind them.
The two captions are held in `Words`, once per language, and `HQF_PDF_LANG` picks which
set is drawn. The headline is the library's own name and reads the same in every
language.
Usage: python examples/write_gradient_fill.py [out.pdf] [font.ttf]
HQF_PDF_LANG=fr python examples/write_gradient_fill.py
"""
from __future__ import annotations
from dataclasses import dataclass
from pathlib import Path
import _language
import _licence
import _out
import hqf_pdf
# The headline the gradient fills, which is the library's own name.
HEADLINE = "hqf-pdf"
@dataclass(frozen=True)
class Words:
"""Every word the page draws, in one language."""
# The caption under the headline.
letters: str
# The caption under the panel.
shape: str
# The page in English.
ENGLISH = Words(
letters="Text filled with a gradient, through a shading pattern.",
shape="A shape filled with a radial gradient.",
)
# The page in French.
FRENCH = Words(
letters="Du texte rempli par un dégradé, au moyen d'un motif.",
shape="Une forme remplie par un dégradé en cercle.",
)
# Every language the example is written in. A language is added by writing its own set
# of words and naming it here.
WORDS = {_language.ENGLISH: ENGLISH, _language.FRENCH: FRENCH}
def main() -> None:
language = _language.from_environment()
words = _language.words_of(WORDS, language)
# A named file is written as named; the default one carries the language, so the two
# languages do not overwrite each other in `tmp/`.
out = _out.output_path(Path(_language.file_name("gradient_fill.pdf", language)).stem)
document = hqf_pdf.Document()
document.set_license(_licence.licensed())
handle = document.add_font(hqf_pdf.Font.from_path(_out.font_path()))
left = 70.0
# A three-stop gradient spanning the width of the headline, set as a fill pattern so
# the letters show it through their shapes.
headline_size = 84.0
headline_baseline = 660.0
headline_width = handle.measure(HEADLINE, headline_size)
ramp = hqf_pdf.Function.stitching(
(0.0, 1.0),
[
hqf_pdf.Function.exponential(
(0.0, 1.0), 1.0, ([0.85, 0.12, 0.12], [0.12, 0.55, 0.2])
),
hqf_pdf.Function.exponential(
(0.0, 1.0), 1.0, ([0.12, 0.55, 0.2], [0.12, 0.2, 0.8])
),
],
[0.5],
[(0.0, 1.0), (0.0, 1.0)],
)
letters = document.add_shading_pattern(
hqf_pdf.Axial(
(left, headline_baseline),
(left + headline_width, headline_baseline),
hqf_pdf.DeviceSpace.Rgb,
ramp,
)
)
# A radial gradient filling a panel below the headline.
px, py, pw, ph = left, 350.0, 455.0, 190.0
panel = document.add_shading_pattern(
hqf_pdf.Radial.rgb(
(px + pw / 2.0, py + ph / 2.0, 0.0),
(px + pw / 2.0, py + ph / 2.0, pw / 2.0),
hqf_pdf.Rgb(1.0, 1.0, 1.0),
hqf_pdf.Rgb(0.1, 0.15, 0.45),
).extend(False, True)
)
content = hqf_pdf.Content()
# The headline, its letters filled with the gradient.
content.save_state()
content.set_fill_pattern(letters)
content.draw_text(handle, headline_size, left, headline_baseline, HEADLINE)
content.restore_state()
# A caption, in plain black.
content.draw_text(handle, 13.0, left, headline_baseline - 26.0, words.letters)
# The panel, filled with the radial gradient.
content.save_state()
content.set_fill_pattern(panel)
content.rect(px, py, pw, ph)
content.fill()
content.restore_state()
content.draw_text(handle, 12.0, px, py - 16.0, words.shape)
page = hqf_pdf.Page.a4()
page.set_content(content)
document.add_page(page)
written = document.write(out)
print(f"wrote {out}: {written} bytes")
if __name__ == "__main__":
main()
|