docs: Add sphinx API docs

.gitignore

@@ -41,6 +41,12 @@ wheels/
 .installed.cfg
 *.egg
 
+# Sphinx docs
+api-docs/api
+api-docs/_build
+api-docs/_static
+api-docs/_preprocessed
+
 # PyInstaller
 # Usually these files are written by a Python script from a template
 # before PyInstaller builds the exe, so as to inject date/other infos into it.

Makefile

@@ -102,4 +102,8 @@ format:
 
 # Downloads the required native artifacts for the specified version
 download-native-artifacts:
-	python3 scripts/download_artifacts.py $(C2PA_VERSION)
+	python3 scripts/download_artifacts.py $(C2PA_VERSION)
+
+# Build API documentation with Sphinx
+docs:
+	python3 scripts/generate_api_docs.py

README.md

@@ -36,6 +36,10 @@ See the [`examples` directory](https://github.com/contentauth/c2pa-python/tree/m
 - `examples/sign.py` shows how to sign and verify an asset with a C2PA manifest.
 - `examples/training.py` demonstrates how to add a "Do Not Train" assertion to an asset and verify it.
 
+## API reference documentation
+
+See [the section in Contributing to the project](https://github.com/contentauth/c2pa-python/blob/main/docs/project-contributions.md#api-reference-documentation).
+
 ## Contributing
 
 Contributions are welcome!  For more information, see [Contributing to the project](https://github.com/contentauth/c2pa-python/blob/main/docs/project-contributions.md).

api-docs/conf.py

@@ -0,0 +1,64 @@
+import os
+from pathlib import Path
+
+# -- Project information -----------------------------------------------------
+
+project = "c2pa-python"
+author = "Content Authenticity Initiative (CAI)"
+
+# -- General configuration ---------------------------------------------------
+
+extensions = [
+    "myst_parser",
+    "autoapi.extension",
+    "sphinx.ext.napoleon",
+]
+
+myst_enable_extensions = [
+    "colon_fence",
+    "deflist",
+    "fieldlist",
+    "strikethrough",
+    "tasklist",
+    "attrs_block",
+    "attrs_inline",
+]
+
+templates_path = ["_templates"]
+exclude_patterns = ["_build", "Thumbs.db", ".DS_Store"]
+
+# -- AutoAPI configuration ---------------------------------------------------
+
+project_root = Path(__file__).resolve().parents[1]
+autoapi_type = "python"
+# Allow overriding the source path used by AutoAPI (for preprocessing)
+autoapi_dirs = [
+    os.environ.get(
+        "C2PA_DOCS_SRC",
+        str(project_root / "src" / "c2pa"),
+    )
+]
+autoapi_root = "api"
+autoapi_keep_files = True
+autoapi_add_toctree_entry = True
+autoapi_options = [
+    "members",
+    "undoc-members",
+    "show-inheritance",
+    "show-module-summary",
+    "imported-members",
+]
+
+# -- Options for HTML output -------------------------------------------------
+
+html_theme = "furo"
+html_static_path = ["_static"]
+
+# Avoid executing package imports during docs build
+autodoc_typehints = "description"
+
+# Napoleon (Google/Numpy docstring support)
+napoleon_google_docstring = True
+napoleon_numpy_docstring = False
+
+

api-docs/index.rst

@@ -0,0 +1,12 @@
+.. c2pa-python documentation master file
+
+Welcome to c2pa-python's documentation!
+=======================================
+
+.. toctree::
+   :maxdepth: 2
+   :caption: Contents:
+
+   api/index
+
+

docs/project-contributions.md

@@ -127,3 +127,28 @@ To rebuild and test, enter these commands:
 make build-python
 make test
 ```
+
+## API reference documentation
+
+We use Sphinx autodoc to generate API docs.
+
+Install development dependencies:
+
+```
+cd c2pa-python
+python3 -m pip install -r requirements-dev.txt
+```
+
+Build docs by entering `make -C docs` or:
+
+```
+python3 scripts/generate_api_docs.py
+```
+
+View the output by loading `api-docs/build/html/index.html` in a web browser.
+
+This uses `sphinx-autoapi` to parse `src/c2pa` directly, avoiding imports of native libs.
+- Entry script: `scripts/generate_api_docs.py`
+- Config: `api-docs/conf.py`; index: `api-docs/index.rst`
+
+Sphinx config is in `api-docs/conf.py`, which uses `index.rst`.

requirements-dev.txt

@@ -16,4 +16,10 @@ autopep8==2.0.4  # For automatic code formatting
 flake8==7.3.0
 
 # Test dependencies (for callback signers)
-cryptography==45.0.6
+cryptography==45.0.6
+
+# Documentation
+Sphinx>=7.3.0
+sphinx-autoapi>=3.0.0
+myst-parser>=2.0.0
+furo>=2024.0.0

scripts/generate_api_docs.py

@@ -0,0 +1,124 @@
+#!/usr/bin/env python3
+"""
+Generate API documentation using Sphinx + AutoAPI.
+
+This script builds HTML docs into docs/_build/html.
+It avoids importing the package by relying on sphinx-autoapi
+to parse source files directly.
+"""
+
+import shutil
+import os
+import sys
+from pathlib import Path
+import importlib
+
+
+def ensure_tools_available() -> None:
+    try:
+        importlib.import_module("sphinx")
+        importlib.import_module("autoapi")
+        importlib.import_module("myst_parser")
+    except Exception as exc:
+        root = Path(__file__).resolve().parents[1]
+        req = root / "requirements-dev.txt"
+        print(
+            "Missing documentation dependencies. "
+            f"Install with: python3 -m pip install -r {req}",
+            file=sys.stderr,
+        )
+        raise SystemExit(1) from exc
+
+
+def build_docs() -> None:
+    root = Path(__file__).resolve().parents[1]
+    docs_dir = root / "api-docs"
+    build_dir = docs_dir / "_build" / "html"
+    api_dir = docs_dir / "api"
+
+    # Preprocess sources: convert Markdown code fences in docstrings to reST
+    src_pkg_dir = root / "src" / "c2pa"
+    pre_dir = docs_dir / "_preprocessed"
+    pre_pkg_dir = pre_dir / "c2pa"
+    if pre_dir.exists():
+        shutil.rmtree(pre_dir)
+    pre_pkg_dir.mkdir(parents=True, exist_ok=True)
+
+    def convert_fences_to_rst(text: str) -> str:
+        lines = text.splitlines()
+        out: list[str] = []
+        i = 0
+        while i < len(lines):
+            line = lines[i]
+            stripped = line.lstrip()
+            indent = line[: len(line) - len(stripped)]
+            if stripped.startswith("```"):
+                fence = stripped
+                lang = fence[3:].strip() or "text"
+                # Start directive
+                out.append(f"{indent}.. code-block:: {lang}")
+                out.append("")
+                i += 1
+                # Emit indented code until closing fence
+                while i < len(lines):
+                    l2 = lines[i]
+                    if l2.lstrip().startswith("```"):
+                        i += 1
+                        break
+                    out.append(f"{indent}    {l2}")
+                    i += 1
+                continue
+            out.append(line)
+            i += 1
+        return "\n".join(out) + ("\n" if text.endswith("\n") else "")
+
+    for src_path in src_pkg_dir.rglob("*.py"):
+        rel = src_path.relative_to(src_pkg_dir)
+        dest = pre_pkg_dir / rel
+        dest.parent.mkdir(parents=True, exist_ok=True)
+        content = src_path.read_text(encoding="utf-8")
+        dest.write_text(convert_fences_to_rst(content), encoding="utf-8")
+
+    # Point AutoAPI to preprocessed sources
+    os.environ["C2PA_DOCS_SRC"] = str(pre_pkg_dir)
+
+    # Clean AutoAPI output to avoid stale pages
+    if api_dir.exists():
+        shutil.rmtree(api_dir)
+
+    build_dir.mkdir(parents=True, exist_ok=True)
+
+    try:
+        sphinx_build_mod = importlib.import_module("sphinx.cmd.build")
+        sphinx_main = getattr(sphinx_build_mod, "main")
+        code = sphinx_main([
+            "-b",
+            "html",
+            str(docs_dir),
+            str(build_dir),
+        ])
+        if code != 0:
+            raise SystemExit(code)
+    except Exception:
+        # Fallback to subprocess if needed
+        import subprocess
+
+        cmd = [
+            sys.executable,
+            "-m",
+            "sphinx",
+            "-b",
+            "html",
+            str(docs_dir),
+            str(build_dir),
+        ]
+        subprocess.run(cmd, check=True)
+
+    print(f"API docs generated at: {build_dir}")
+
+
+if __name__ == "__main__":
+    ensure_tools_available()
+    build_docs()
+
+

src/c2pa/build.py

@@ -13,7 +13,7 @@
 
 import os
 import sys
-import requests
+import requests  # type: ignore
 from pathlib import Path
 import zipfile
 import io
@@ -53,8 +53,7 @@ def download_artifact(url: str, platform_name: str) -> None:
         # Extract all files to the platform directory
         zip_ref.extractall(platform_dir)
 
-    print(f"Successfully downloaded and extracted artifacts for {
-          platform_name}")
+    print(f"Successfully downloaded and extracted artifacts for {platform_name}")
 
 
 def download_artifacts() -> None:
@@ -95,7 +94,7 @@ def download_artifacts() -> None:
 def inject_version():
     """Inject the version from pyproject.toml
     into src/c2pa/__init__.py as __version__."""
-    import toml
+    import toml  # type: ignore
     pyproject_path = os.path.abspath(
         os.path.join(
             os.path.dirname(__file__),