Build wheels as a github action (#957)

Co-Authored by: @JeanChristopheMorinPerso 

* Added pyproject.toml for python build environment

* Added python wheel build action

* Added workaround to setup.py disabling PYBIND11_FINDPYTHON for the cibuildwheel linux environment

Author: reinecke

.github/workflows/python-package.yml

@@ -26,7 +26,7 @@ jobs:
     env:
       OTIO_CXX_COVERAGE_BUILD: ON
       OTIO_CXX_BUILD_TMP_DIR: ${{ github.workspace }}/build
-      
+
     steps:
     - uses: actions/[email protected]
       with:
@@ -64,3 +64,34 @@ jobs:
         flags: unittests
         name: opentimelineio-codecov
         fail_ci_if_error: true
+
+  package_wheels:
+    name: Package wheels on ${{ matrix.os }}
+    needs: build
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macOS-latest]
+        python-build: [cp27*, cp37*, cp38*]
+
+    steps:
+      - uses: actions/checkout@v2
+
+      # Used to host cibuildwheel
+      - uses: actions/setup-python@v2
+
+      - name: Install cibuildwheel
+        run: python -m pip install cibuildwheel==1.10.0
+
+      - name: Build wheels
+        run: python -m cibuildwheel --output-dir wheelhouse
+        # TODO: Solve for the 32-bit errors in windows python 2.7:
+        #   https://github.com/pybind/cmake_example/blob/master/.github/workflows/wheels.yml#L66
+        env:
+          CIBW_SKIP: cp27-win*
+          CIBW_BUILD: ${{ matrix.python-build }}
+
+      - uses: actions/upload-artifact@v2
+        with:
+          name: wheels
+          path: ./wheelhouse/*.whl

pyproject.toml

@@ -0,0 +1,7 @@
+[build-system]
+requires = [
+    "setuptools",
+    "wheel",
+    "cmake>=3.12",
+]
+build-backend = "setuptools.build_meta"

setup.py

@@ -112,8 +112,14 @@ def cmake_generate(self):
             '-DOTIO_PYTHON_INSTALL:BOOL=ON',
             '-DOTIO_CXX_INSTALL:BOOL=ON',
             '-DCMAKE_BUILD_TYPE=' + self.build_config,
-            '-DPYBIND11_FINDPYTHON=ON',  # Smart tool to find python's libs
-        ]  # https://pybind11.readthedocs.io/en/latest/compiling.html#findpython-mode
+        ]
+
+        # Within the manylinux docker containers used for linux wheel builds
+        # pybind's findpython does not work for some reason
+        if not os.environ.get("CIBUILDWHEEL") or platform.system() != "Linux":
+            # Smart tool to find python's libs
+            # https://pybind11.readthedocs.io/en/latest/compiling.html#findpython-mode
+            cmake_args.append('-DPYBIND11_FINDPYTHON=ON')
 
         # install the C++ into the opentimelineio/cxx-sdk directory under the
         # python installation