🎨 assets: add a logo, [0]

docs/_static/make_logo.py

@@ -0,0 +1,87 @@
+# /// script
+# requires-python = ">=3.11"
+# dependencies = ["resvg-py"]
+# ///
+"""Draw the zeroth logo: ``[0]``.
+
+Index zero between square brackets: the first element, for any iterable, in
+GalacticDynamics' navy and purple. The shapes are vector, so the logo is written
+as an SVG, sharp at any size; for a bitmap, name a .png and give its size::
+
+    uv run docs/_static/make_logo.py                     # favicon.svg
+    uv run docs/_static/make_logo.py --size 2048 big.png
+"""
+
+import argparse
+from pathlib import Path
+
+NAVY, PURPLE = "#030a23", "#7738eb"  # GalacticDynamics' colours
+
+# In a 64-unit square: the brackets' left and right x, their top and bottom, and
+# how far their ends turn in; the zero's centre and half-width and half-height.
+BRACKETS = (10, 54, 10, 54, 8)
+ZERO = (32, 32, 10, 16)
+
+SVG = """\
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64" width="512" height="512">
+  <g fill="none" stroke-linecap="round" stroke-linejoin="round">
+    <path d="{brackets}" stroke="{navy}" stroke-width="4.5"/>
+    <ellipse cx="{cx:g}" cy="{cy:g}" rx="{rx:g}" ry="{ry:g}"
+      stroke="{purple}" stroke-width="5"/>
+  </g>
+</svg>
+"""
+
+
+def brackets() -> str:
+    """Return the square brackets as an SVG path."""
+    left, right, top, bottom, end = BRACKETS
+    return (
+        f"M{left + end:g} {top:g}H{left:g}V{bottom:g}H{left + end:g}"
+        f"M{right - end:g} {top:g}H{right:g}V{bottom:g}H{right - end:g}"
+    )
+
+
+def svg() -> str:
+    """Return the logo as SVG text."""
+    cx, cy, rx, ry = ZERO
+    return SVG.format(
+        brackets=brackets(),
+        navy=NAVY,
+        purple=PURPLE,
+        cx=cx,
+        cy=cy,
+        rx=rx,
+        ry=ry,
+    )
+
+
+def main() -> None:
+    """Parse the command line and save the logo."""
+    parser = argparse.ArgumentParser(description=__doc__.split("\n")[0])
+    parser.add_argument(
+        "out",
+        nargs="?",
+        type=Path,
+        default=Path(__file__).with_name("favicon.svg"),
+        help="output file, SVG or PNG by its extension (default: favicon.svg)",
+    )
+    parser.add_argument(
+        "--size",
+        type=int,
+        default=512,
+        help="pixels per side, for a PNG",
+    )
+    args = parser.parse_args()
+
+    if args.out.suffix == ".svg":
+        args.out.write_text(svg())
+    else:
+        import resvg_py  # noqa: PLC0415  # only a PNG needs a renderer
+
+        png = resvg_py.svg_to_bytes(svg_string=svg(), width=args.size)
+        args.out.write_bytes(bytes(png))
+
+
+if __name__ == "__main__":
+    main()