Merge commit 'e0b7d30fd437292c88141fb08d60681870b86c6e' as 'subprojects/pixpat'

1 files changed, 152 insertions, 0 deletions

diff --git a/subprojects/pixpat/setup.py b/subprojects/pixpat/setup.py
new file mode 100644
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--- /dev/null
+++ b/subprojects/pixpat/setup.py
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+"""setup.py overrides several setuptools commands to integrate the meson-built
+libpixpat.so into the Python wheel.
+
+Layout (where things land for each workflow):
+
+  meson setup build / meson compile -C build       — repo-root build/, the
+      C++ developer's meson dir. Python tooling never touches this.
+
+  pip install -e .                                  — DevEditableWheel
+      symlinks build/libpixpat.so into pixpat-python/pixpat/_lib/.
+      Requires the user to have built `build/` themselves.
+
+  pip install .                                     — MesonBuildPy invokes
+      meson into pixpat-python/build/native/, copies the .so straight into
+      setuptools' build_lib (pixpat-python/build/lib/pixpat/_lib/), and
+      bdist_wheel zips that into the wheel. The source tree's _lib/ is
+      never touched on this path, so wheel builds don't depend on (or
+      pollute) it.
+
+  scripts/build_wheel.sh <arch>                     — sets PIXPAT_TARGET_ARCH
+      and runs `python -m build`; meson lands in pixpat-python/build-<arch>/
+      native/, setuptools alongside.
+
+bdist_wheel: setuptools' default produces a `py3-none-any` (pure-Python) wheel
+when there's no compiled extension. We bundle a `.so` as package data, so we
+MUST tag the wheel for a specific platform — otherwise pip would
+install our x86_64 wheel on an arm64 box. Target arch is read from
+PIXPAT_TARGET_ARCH and falls back to the running machine's arch — important
+because setuptools' editable_wheel delegates wheel construction to whatever
+bdist_wheel is registered, so this class is invoked during `pip install -e .`
+too.
+"""
+
+import os
+import platform
+import shutil
+import subprocess
+from pathlib import Path
+
+from setuptools import setup
+from setuptools.command.bdist_wheel import bdist_wheel
+from setuptools.command.build import build
+from setuptools.command.build_py import build_py
+from setuptools.command.editable_wheel import editable_wheel
+
+REPO_ROOT = Path(__file__).resolve().parent
+LIB_DIR = REPO_ROOT / 'pixpat-python' / 'pixpat' / '_lib'
+
+
+def _target_arch() -> str:
+    return os.environ.get('PIXPAT_TARGET_ARCH') or platform.machine()
+
+
+def _wheel_build_root() -> Path:
+    """Top-level dir where setuptools and meson stage wheel-build output.
+
+    Plain `pip install .` uses pixpat-python/build/. Cross-compile via
+    PIXPAT_TARGET_ARCH gets a per-arch sibling so meson can keep arches
+    incrementally compiled side by side.
+    """
+    arch = os.environ.get('PIXPAT_TARGET_ARCH')
+    suffix = f'-{arch}' if arch else ''
+    return REPO_ROOT / 'pixpat-python' / f'build{suffix}'
+
+
+class ImpureBdistWheel(bdist_wheel):
+    def finalize_options(self):
+        super().finalize_options()
+        self.root_is_pure = False
+
+    def get_tag(self):
+        return ('py3', 'none', f'linux_{_target_arch()}')
+
+
+class WheelBuild(build):
+    """Direct setuptools' staging into pixpat-python/build[-<arch>]/."""
+
+    def initialize_options(self):
+        super().initialize_options()
+        self.build_base = str(_wheel_build_root())
+
+
+class MesonBuildPy(build_py):
+    """Compile libpixpat.so via meson and stage it into build_lib for the wheel."""
+
+    def run(self):
+        super().run()
+        # editable_mode is set by setuptools' editable_wheel command. In that
+        # path DevEditableWheel has already symlinked the user's repo-root
+        # build/ into the source _lib/, so meson must not run.
+        if not self.editable_mode:
+            self._build_native()
+
+    def _build_native(self):
+        meson_dir = _wheel_build_root() / 'native'
+        arch = _target_arch()
+        cross_args = []
+        if arch != platform.machine():
+            cross_file = REPO_ROOT / 'pixpat-native' / 'cross' / f'{arch}-linux-gnu.txt'
+            if not cross_file.exists():
+                raise SystemExit(f'no cross-file for {arch}: {cross_file}')
+            cross_args = ['--cross-file', str(cross_file)]
+
+        if not (meson_dir / 'meson-info').exists():
+            meson_dir.parent.mkdir(parents=True, exist_ok=True)
+            subprocess.check_call(
+                ['meson', 'setup', str(meson_dir), '--buildtype=release', *cross_args],
+                cwd=REPO_ROOT,
+            )
+        subprocess.check_call(['meson', 'compile', '-C', str(meson_dir)], cwd=REPO_ROOT)
+
+        out_dir = Path(self.build_lib) / 'pixpat' / '_lib'
+        out_dir.mkdir(parents=True, exist_ok=True)
+        # follow_symlinks resolves meson's libpixpat.so -> .so.<maj> -> .so.<maj>.<min>.<patch>
+        # chain into a regular file. The wheel ships only the unversioned name, so we
+        # don't have to track meson's project version here.
+        shutil.copy2(meson_dir / 'libpixpat.so', out_dir / 'libpixpat.so')
+
+
+class DevEditableWheel(editable_wheel):
+    """Symlink the user's repo-root meson build into _lib/ before installing."""
+
+    def run(self):
+        build_so = REPO_ROOT / 'build' / 'libpixpat.so'
+
+        if not build_so.exists():
+            raise SystemExit(
+                f'editable install needs {build_so}.\n'
+                'Configure and build first:\n'
+                '  meson setup build\n'
+                '  meson compile -C build'
+            )
+
+        LIB_DIR.mkdir(parents=True, exist_ok=True)
+        for old in LIB_DIR.glob('libpixpat.so*'):
+            old.unlink()
+        # Relative path so the symlink survives moves of the source tree.
+        (LIB_DIR / 'libpixpat.so').symlink_to(
+            Path('..') / '..' / '..' / 'build' / 'libpixpat.so'
+        )
+
+        super().run()
+
+
+setup(
+    cmdclass={
+        'bdist_wheel': ImpureBdistWheel,
+        'build': WheelBuild,
+        'build_py': MesonBuildPy,
+        'editable_wheel': DevEditableWheel,
+    }
+)