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168 | """Paints axial and radial gradients, each into a clipped box.
The Python twin of the `write_gradient` example in Rust. Four panels: a
horizontal two-colour gradient, a diagonal one, a radial one whose outer colour
is extended to fill the corners, and a three-stop gradient built from a stitched
function. Each is added to the document once, then painted into a rectangle the
page clips to.
The title and the four labels are held in `Words`, once per language, and `HQF_PDF_LANG`
picks which set is drawn.
Usage: python examples/write_gradient.py [out.pdf] [font.ttf]
HQF_PDF_LANG=fr python examples/write_gradient.py
"""
from __future__ import annotations
from dataclasses import dataclass
from pathlib import Path
import _language
import _licence
import _out
import hqf_pdf
# The width and height of every panel, in points.
BOX = (210.0, 170.0)
@dataclass(frozen=True)
class Words:
"""Every word the page draws, in one language."""
# The title across the top of the page.
title: str
# The label under each of the four panels.
horizontal: str
diagonal: str
radial: str
three_stops: str
# The page in English.
ENGLISH = Words(
title="Axial and radial gradients",
horizontal="Axial, two colours",
diagonal="Axial, on the diagonal",
radial="Radial, outer extended",
three_stops="Axial, three stops",
)
# The page in French.
FRENCH = Words(
title="Dégradés en ligne droite et en cercle",
horizontal="En ligne droite, deux couleurs",
diagonal="En ligne droite, en diagonale",
radial="En cercle, couleur extérieure prolongée",
three_stops="En ligne droite, trois couleurs",
)
# 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 panel(content, font, shading, x, y, label):
"""Paint a gradient into the box at (x, y), sized BOX, and label it."""
content.save_state()
content.rect(x, y, BOX[0], BOX[1])
content.clip()
content.end_path()
content.draw_shading(shading)
content.restore_state()
content.draw_text(font, 10.0, x, y - 15.0, label)
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.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 column x, right column x, top row foot, bottom row foot.
left, right, top, bottom = 70.0, 315.0, 560.0, 320.0
# A horizontal two-colour gradient across the top-left box.
horizontal = document.add_shading(
hqf_pdf.Axial.rgb(
(left, top),
(left + BOX[0], top),
hqf_pdf.Rgb(0.85, 0.12, 0.12),
hqf_pdf.Rgb(0.12, 0.2, 0.8),
)
)
# A diagonal two-colour gradient across the top-right box.
diagonal = document.add_shading(
hqf_pdf.Axial.rgb(
(right, bottom + BOX[1]),
(right + BOX[0], top + BOX[1]),
hqf_pdf.Rgb(0.95, 0.8, 0.1),
hqf_pdf.Rgb(0.1, 0.55, 0.2),
)
)
# A radial gradient in the bottom-left box, its outer colour extended so it reaches
# the corners.
radial = document.add_shading(
hqf_pdf.Radial.rgb(
(left + BOX[0] / 2.0, bottom + BOX[1] / 2.0, 0.0),
(left + BOX[0] / 2.0, bottom + BOX[1] / 2.0, BOX[0] / 2.0),
hqf_pdf.Rgb(1.0, 1.0, 1.0),
hqf_pdf.Rgb(0.1, 0.15, 0.45),
).extend(False, True)
)
# A three-stop gradient in the bottom-right box, from a stitched function: red to
# green over the first half, green to blue over the second.
rainbow_function = 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, 0.6, 0.2])
),
hqf_pdf.Function.exponential(
(0.0, 1.0), 1.0, ([0.12, 0.6, 0.2], [0.12, 0.2, 0.8])
),
],
[0.5],
[(0.0, 1.0), (0.0, 1.0)],
)
rainbow = document.add_shading(
hqf_pdf.Axial(
(right, bottom),
(right + BOX[0], bottom),
hqf_pdf.DeviceSpace.Rgb,
rainbow_function,
)
)
content = hqf_pdf.Content()
content.draw_text(handle, 18.0, left, 770.0, words.title)
panel(content, handle, horizontal, left, top, words.horizontal)
panel(content, handle, diagonal, right, top, words.diagonal)
panel(content, handle, radial, left, bottom, words.radial)
panel(content, handle, rainbow, right, bottom, words.three_stops)
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()
|