Add squircle brand assets for desktop and web

scripts/generate-brand-assets.py

@@ -10,11 +10,12 @@
 
 from __future__ import annotations
 
+import math
 import sys
 from pathlib import Path
 
 try:
-    from PIL import Image
+    from PIL import Image, ImageDraw
 except ImportError as e:
     print("Install Pillow: python3 -m pip install pillow", file=sys.stderr)
     raise SystemExit(1) from e
@@ -26,11 +27,62 @@
 ICO_SIZES_WEB = (16, 32, 48)
 ICO_SIZES_DESKTOP = (16, 32, 48, 64, 128, 256)
 
+# macOS icon corner radius as a fraction of icon size (~22.37% matches Apple's squircle)
+MACOS_CORNER_RADIUS_FRACTION = 0.2237
+
 
 def resize(img: Image.Image, size: int) -> Image.Image:
     return img.resize((size, size), Image.Resampling.LANCZOS)
 
 
+def _superellipse_mask(size: int, radius_fraction: float = MACOS_CORNER_RADIUS_FRACTION) -> Image.Image:
+    """Create a macOS-style continuous-curvature rounded rectangle (squircle) mask.
+
+    Uses a superellipse approximation (n≈5) which closely matches Apple's
+    smoothed corner shape used in macOS Big Sur and later.
+    """
+    scale = 4  # supersampled for antialiasing
+    s = size * scale
+    r = int(s * radius_fraction)
+    mask = Image.new("L", (s, s), 0)
+    draw = ImageDraw.Draw(mask)
+    # Draw the main body (cross shape) and corner arcs
+    # Center rectangle (full width, excluding corner rows)
+    draw.rectangle([0, r, s - 1, s - 1 - r], fill=255)
+    # Top/bottom strips (excluding corner columns)
+    draw.rectangle([r, 0, s - 1 - r, r], fill=255)
+    draw.rectangle([r, s - 1 - r, s - 1 - r, s - 1], fill=255)
+
+    # Draw smooth corners using superellipse (n=5 for Apple-like smoothness)
+    n = 5.0
+    for cy, cx in [(r, r), (r, s - 1 - r), (s - 1 - r, r), (s - 1 - r, s - 1 - r)]:
+        for dy in range(-r, r + 1):
+            for dx in range(-r, r + 1):
+                # Normalise to [-1, 1] range within the corner radius
+                nx = abs(dx) / r if r > 0 else 0
+                ny = abs(dy) / r if r > 0 else 0
+                if nx ** n + ny ** n <= 1.0:
+                    px, py = cx + dx, cy + dy
+                    if 0 <= px < s and 0 <= py < s:
+                        mask.putpixel((px, py), 255)
+
+    # Downsample for antialiased edges
+    return mask.resize((size, size), Image.Resampling.LANCZOS)
+
+
+def apply_macos_mask(img: Image.Image) -> Image.Image:
+    """Apply the macOS squircle mask to an image, making corners transparent."""
+    size = img.width
+    img = img.convert("RGBA")
+    mask = _superellipse_mask(size)
+    # Apply mask to alpha channel
+    r, g, b, a = img.split()
+    # Composite: keep existing alpha where mask is white, transparent where mask is black
+    from PIL import ImageChops
+    a = ImageChops.multiply(a, mask.convert("L"))
+    return Image.merge("RGBA", (r, g, b, a))
+
+
 def save_ico(path: Path, source: Image.Image, sizes: tuple[int, ...]) -> None:
     path.parent.mkdir(parents=True, exist_ok=True)
     source.save(
@@ -59,10 +111,16 @@ def main() -> None:
     mark_1024.save(prod_dir / "okcode-mark-1024.png")
     mark_1024.save(dev_dir / "okcode-dev-mark-1024.png")
 
-    for name in ("okcode-macos-1024.png", "okcode-linux-1024.png", "okcode-ios-1024.png"):
-        mark_1024.save(prod_dir / name)
-    for name in ("okcode-dev-macos-1024.png", "okcode-dev-universal-1024.png", "okcode-dev-ios-1024.png"):
-        mark_1024.save(dev_dir / name)
+    # macOS & iOS icons get the squircle mask; Linux stays square
+    macos_1024 = apply_macos_mask(mark_1024)
+    macos_1024.save(prod_dir / "okcode-macos-1024.png")
+    macos_1024.save(prod_dir / "okcode-ios-1024.png")
+    mark_1024.save(prod_dir / "okcode-linux-1024.png")
+
+    macos_dev_1024 = apply_macos_mask(mark_1024)
+    macos_dev_1024.save(dev_dir / "okcode-dev-macos-1024.png")
+    macos_dev_1024.save(dev_dir / "okcode-dev-ios-1024.png")
+    mark_1024.save(dev_dir / "okcode-dev-universal-1024.png")
 
     # Web PNGs (match prior naming: 16/32 favicon + separate apple-touch)
     resize(img, 16).save(prod_dir / "okcode-web-favicon-16x16.png")