Add PNG-to-RLE with libdeflate and CI support

Direct PNG-to-RLE conversion for 8-bit grayscale PNGs using libdeflate,
bypassing intermediate numpy arrays. Includes from_png, from_label_map_png,
and rlesFromLabelMapPng for single-pass label map extraction from PNG.

Updates setup.py with libdeflate linking (pkg-config + MSVC fallback),
LIBDEFLATE_DIR env var, and removes standalone png_to_rle_cython extension.
CI workflows install libdeflate on all platforms for builds and tests.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: isarandi

.github/workflows/python-publish.yml

@@ -29,6 +29,24 @@ jobs:
           CIBW_SKIP: "*-musllinux_* pp*"
           CIBW_TEST_SKIP: "cp38-macosx_*:arm64"
           CIBW_TEST_COMMAND: python -c "import rlemasklib; print(rlemasklib.__version__)"
+          CIBW_BEFORE_ALL_LINUX: >
+            yum install -y cmake gcc gcc-c++ make &&
+            cd /tmp &&
+            curl -L https://github.com/ebiggers/libdeflate/archive/refs/tags/v1.22.tar.gz | tar xz &&
+            cd libdeflate-1.22 &&
+            cmake -B build -DCMAKE_BUILD_TYPE=Release &&
+            cmake --build build --parallel &&
+            cmake --install build
+          CIBW_BEFORE_ALL_MACOS: brew install libdeflate
+          CIBW_BEFORE_ALL_WINDOWS: >
+            cd /d %TEMP% &&
+            curl -L -o libdeflate.tar.gz https://github.com/ebiggers/libdeflate/archive/refs/tags/v1.22.tar.gz &&
+            tar xzf libdeflate.tar.gz &&
+            cd libdeflate-1.22 &&
+            cmake -B build -DCMAKE_BUILD_TYPE=Release &&
+            cmake --build build --config Release --parallel &&
+            cmake --install build --prefix C:/libdeflate
+          CIBW_ENVIRONMENT_WINDOWS: LIBDEFLATE_DIR=C:/libdeflate
 
       - uses: actions/upload-artifact@v4
         with:
@@ -68,4 +86,4 @@ jobs:
           merge-multiple: true
 
       - name: Publish to PyPI
-        uses: pypa/gh-action-pypi-publish@release/v1
+        uses: pypa/gh-action-pypi-publish@release/v1

.github/workflows/test.yml

@@ -26,11 +26,32 @@ jobs:
         with:
           python-version: ${{ matrix.python-version }}
 
+      - name: Install libdeflate (Linux)
+        if: runner.os == 'Linux'
+        run: sudo apt-get update && sudo apt-get install -y libdeflate-dev
+
+      - name: Install libdeflate (macOS)
+        if: runner.os == 'macOS'
+        run: brew install libdeflate
+
+      - name: Install libdeflate (Windows)
+        if: runner.os == 'Windows'
+        shell: bash
+        run: |
+          cd "$TEMP"
+          curl -L -o libdeflate.tar.gz https://github.com/ebiggers/libdeflate/archive/refs/tags/v1.22.tar.gz
+          tar xzf libdeflate.tar.gz
+          cd libdeflate-1.22
+          cmake -B build -DCMAKE_BUILD_TYPE=Release
+          cmake --build build --config Release --parallel
+          cmake --install build --prefix "C:/libdeflate"
+          echo "LIBDEFLATE_DIR=C:/libdeflate" >> "$GITHUB_ENV"
+
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
           pip install "numpy${{ matrix.numpy-version }}"
           pip install .[test-headless]
 
       - name: Run tests
-        run: pytest tests/ -v
+        run: pytest tests/ -v

setup.py

@@ -1,3 +1,5 @@
+import os
+import subprocess
 import sys
 import numpy as np
 from setuptools import setup, Extension
@@ -21,21 +23,52 @@
         "/O2",
         "/wd4505",
     ]  # /O2=optimize, /wd4505=disable unused function warning
+    extra_link_args = []
 else:
     extra_compile_args = ["-Wno-cpp", "-Wno-unused-function", "-std=c99", "-O3"]
+    extra_link_args = []
+
+include_dirs = [np.get_include(), "src/rlemasklib/c"]
+library_dirs = []
+
+# Support custom libdeflate install location via LIBDEFLATE_DIR env var
+libdeflate_dir = os.environ.get("LIBDEFLATE_DIR")
+if libdeflate_dir:
+    include_dirs.append(os.path.join(libdeflate_dir, "include"))
+    library_dirs.append(os.path.join(libdeflate_dir, "lib"))
+
+# Check for libdeflate (required for PNG-to-RLE)
+try:
+    deflate_cflags = subprocess.check_output(
+        ["pkg-config", "--cflags", "libdeflate"], stderr=subprocess.DEVNULL
+    ).decode().strip().split()
+    deflate_libs = subprocess.check_output(
+        ["pkg-config", "--libs", "libdeflate"], stderr=subprocess.DEVNULL
+    ).decode().strip().split()
+    extra_compile_args.extend(deflate_cflags)
+    extra_link_args.extend(deflate_libs)
+except (subprocess.CalledProcessError, FileNotFoundError):
+    if sys.platform == "win32":
+        extra_link_args.append("deflate.lib")
+    else:
+        extra_link_args.append("-ldeflate")
 
 ext_modules = [
     Extension(
         "rlemasklib.rlemasklib_cython",
         sources=["src/rlemasklib/rlemasklib_cython.pyx"] + c_files,
-        include_dirs=[np.get_include(), "src/rlemasklib/c"],
+        include_dirs=include_dirs,
+        library_dirs=library_dirs,
         extra_compile_args=extra_compile_args,
+        extra_link_args=extra_link_args,
     ),
     Extension(
         "rlemasklib.oop_cython",
         sources=["src/rlemasklib/oop_cython.pyx"] + c_files,
-        include_dirs=[np.get_include(), "src/rlemasklib/c"],
+        include_dirs=include_dirs,
+        library_dirs=library_dirs,
         extra_compile_args=extra_compile_args,
+        extra_link_args=extra_link_args,
     ),
 ]