pre-commit: Check for images exceeding 4096×4096 (#2207)

As documented in

https://github.com/endlessm/threadbare/wiki/Visual-Style-Guide#image-file-format
this is a limitation of mobile GPUs.

Check all PNGs, JPEGs and WebPs against this limit using a small Python
program using Pillow.

Update the GitHub Actions workflow to check out objects from LFS.

Author: wjt

.github/workflows/checks.yaml

@@ -19,6 +19,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v6
+    - uses: ./.github/actions/lfs-cached-checkout
     - uses: tox-dev/action-pre-commit-uv@v1
 
   reuse:

.pre-commit-config.yaml

@@ -39,6 +39,15 @@ repos:
             scenes/quests/story_quests/(?!stella/)
           )
 
+  - repo: local
+    hooks:
+      - id: check-image-size
+        name: check image dimensions
+        entry: python tools/check-image-size.py
+        language: python
+        additional_dependencies: [Pillow]
+        types_or: [png, jpeg, webp]
+
   - repo: https://github.com/Scony/godot-gdscript-toolkit
     rev: 4.5.0
     hooks:

tools/check-image-size.py

@@ -0,0 +1,52 @@
+#!/usr/bin/env python3
+# /// script
+# dependencies = [
+#     "pillow>=12.2.0",
+# ]
+# ///
+
+# SPDX-FileCopyrightText: The Threadbare Authors
+# SPDX-License-Identifier: MPL-2.0
+"""
+Fail if any given image file exceeds 4096px wide or 4096px high.
+"""
+
+import argparse
+import sys
+
+from PIL import Image, UnidentifiedImageError
+
+# https://docs.godotengine.org/en/stable/tutorials/3d/3d_rendering_limitations.html
+# “if you want your texture to display correctly on all platforms, you should
+# avoid using textures larger than 4096×4096”
+MAX_SIZE = 4096
+
+
+def check(path) -> bool:
+    try:
+        with Image.open(path) as im:
+            width, height = im.size
+    except (UnidentifiedImageError, OSError) as e:
+        print(f"{path}: could not read image ({e})", file=sys.stderr)
+        return False
+
+    if width > MAX_SIZE or height > MAX_SIZE:
+        print(
+            f"{path}: {width}x{height} exceeds {MAX_SIZE}x{MAX_SIZE}",
+            file=sys.stderr,
+        )
+        return False
+
+    return True
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("files", nargs="*")
+    args = parser.parse_args()
+
+    return not all([check(path) for path in args.files])
+
+
+if __name__ == "__main__":
+    sys.exit(main())