Add tooling to support iOS build.

.github/workflows/wheels-dependencies.sh

@@ -1,31 +1,82 @@
 #!/bin/bash
 
-# Setup that needs to be done before multibuild utils are invoked
+# Safety check - Pillow builds require that CIBW_ARCHS is set, and that it only
+# contains a single value (even though cibuildwheel allows multiple values in
+# CIBW_ARCHS).
+if [[ -z "$CIBW_ARCHS" ]]; then
+    echo "ERROR: Pillow builds require CIBW_ARCHS be defined."
+    exit 1
+fi
+if [[ "$CIBW_ARCHS" == *" "* ]]; then
+    echo "ERROR: Pillow builds only support a single architecture in CIBW_ARCHS."
+    exit 1
+fi
+
+# Setup that needs to be done before multibuild utils are invoked. Process
+# potential cross-build platforms before native platforms to ensure that we pick
+# up the cross environment.
 PROJECTDIR=$(pwd)
-if [[ "$(uname -s)" == "Darwin" ]]; then
-    # Safety check - macOS builds require that CIBW_ARCHS is set, and that it
-    # only contains a single value (even though cibuildwheel allows multiple
-    # values in CIBW_ARCHS).
-    if [[ -z "$CIBW_ARCHS" ]]; then
-        echo "ERROR: Pillow macOS builds require CIBW_ARCHS be defined."
-        exit 1
-    fi
-    if [[ "$CIBW_ARCHS" == *" "* ]]; then
-        echo "ERROR: Pillow macOS builds only support a single architecture in CIBW_ARCHS."
-        exit 1
+if [[ "$CIBW_PLATFORM" == "ios" ]]; then
+    # On iOS, CIBW_ARCHS is actually a multi-arch - arm64_iphoneos,
+    # arm64_iphonesimulator or x86_64_iphonesimulator. Split into the CPU
+    # platform, and the iOS SDK.
+    PLAT=$(echo $CIBW_ARCHS | sed "s/\(.*\)_\(.*\)/\1/")
+    IOS_SDK=$(echo $CIBW_ARCHS | sed "s/\(.*\)_\(.*\)/\2/")
+
+    # Build iOS builds in `build/iphoneos` or `build/iphonesimulator/`
+    # (depending on the build target). Install them into `build/deps/iphoneos`
+    # or `build/deps/iphonesimulator`
+    WORKDIR=$(pwd)/build/$IOS_SDK
+    BUILD_PREFIX=$(pwd)/build/deps/$IOS_SDK
+    PATCH_DIR=$(pwd)/patches/iOS
+
+    # GNU tooling insists on using aarch64 rather than arm64
+    if [[ $PLAT == "arm64" ]]; then
+        GNU_ARCH=aarch64
+    else
+        GNU_ARCH=x86_64
     fi
 
+    IOS_SDK_PATH=$(xcrun --sdk $IOS_SDK --show-sdk-path)
+    if [[ "$IOS_SDK" == "iphonesimulator" ]]; then
+        CMAKE_SYSTEM_NAME=iOS
+        IOS_HOST_TRIPLE=$PLAT-apple-ios$IPHONEOS_DEPLOYMENT_TARGET-simulator
+    else
+        CMAKE_SYSTEM_NAME=iOS
+        IOS_HOST_TRIPLE=$PLAT-apple-ios$IPHONEOS_DEPLOYMENT_TARGET
+    fi
+
+    # GNU Autotools doesn't recognize the existence of arm64-apple-ios-simulator
+    # as a valid host. However, the only difference between arm64-apple-ios and
+    # arm64-apple-ios-simulator is the choice of sysroot, and that is
+    # coordinated by CC,CFLAGS etc. From the perspective of configure, the two
+    # platforms are identical, so we can use arm64-apple-ios consistently.
+    # This (mostly) avoids us needing to patch config.sub in dependency sources.
+    HOST_CONFIGURE_FLAGS="--disable-shared --enable-static --host=$GNU_ARCH-apple-ios --build=$GNU_ARCH-apple-darwin"
+
+    # Cmake has native support for iOS. However, most of that support is based
+    # on using the Xcode builder, which isn't very helpful for most of Pillow's
+    # dependencies. Therefore, we lean on the OSX configurations, plus CC/CFLAGS
+    # etc to ensure the right sysroot is selected.
+    HOST_CMAKE_FLAGS="-DCMAKE_SYSTEM_NAME=$CMAKE_SYSTEM_NAME -DCMAKE_SYSTEM_PROCESSOR=$GNU_ARCH -DCMAKE_OSX_DEPLOYMENT_TARGET=$IPHONEOS_DEPLOYMENT_TARGET -DCMAKE_OSX_SYSROOT=$IOS_SDK_PATH -DBUILD_SHARED_LIBS=NO"
+
+    # Meson needs to be pointed at a cross-platform configuration file
+    # This will be generated once CC etc have been evaluated.
+    HOST_MESON_FLAGS="--cross-file $WORKDIR/meson-cross.txt -Dprefer_static=true -Ddefault_library=static"
+
+elif [[ "$(uname -s)" == "Darwin" ]]; then
     # Build macOS dependencies in `build/darwin`
     # Install them into `build/deps/darwin`
+    PLAT="${CIBW_ARCHS:-$AUDITWHEEL_ARCH}"
     WORKDIR=$(pwd)/build/darwin
     BUILD_PREFIX=$(pwd)/build/deps/darwin
 else
     # Build prefix will default to /usr/local
+    PLAT="${CIBW_ARCHS:-$AUDITWHEEL_ARCH}"
     WORKDIR=$(pwd)/build
     MB_ML_LIBC=${AUDITWHEEL_POLICY::9}
     MB_ML_VER=${AUDITWHEEL_POLICY:9}
 fi
-PLAT="${CIBW_ARCHS:-$AUDITWHEEL_ARCH}"
 
 # Define custom utilities
 source wheels/multibuild/common_utils.sh
@@ -36,7 +87,9 @@ fi
 
 ARCHIVE_SDIR=pillow-depends-main
 
-# Package versions for fresh source builds
+# Package versions for fresh source builds. Version numbers with "Patched"
+# annotations have a source code patch that is required for some platforms. If
+# you change those versions, ensure the patch is also updated.
 FREETYPE_VERSION=2.13.3
 HARFBUZZ_VERSION=11.2.1
 LIBPNG_VERSION=1.6.49
@@ -47,31 +100,57 @@ TIFF_VERSION=4.7.0
 LCMS2_VERSION=2.17
 ZLIB_VERSION=1.3.1
 ZLIB_NG_VERSION=2.2.4
-LIBWEBP_VERSION=1.5.0
+LIBWEBP_VERSION=1.5.0  # Patched
 BZIP2_VERSION=1.0.8
 LIBXCB_VERSION=1.17.0
-BROTLI_VERSION=1.1.0
+BROTLI_VERSION=1.1.0  # Patched
 
 function build_pkg_config {
     if [ -e pkg-config-stamp ]; then return; fi
-    # This essentially duplicates the Homebrew recipe
-    CFLAGS="$CFLAGS -Wno-int-conversion" build_simple pkg-config 0.29.2 https://pkg-config.freedesktop.org/releases tar.gz \
+    # This essentially duplicates the Homebrew recipe.
+    # On iOS, we need a binary that can be executed on the build machine; but we
+    # can create a host-specific pc-path to store iOS .pc files. To ensure a
+    # macOS-compatible build, we temporarily clear environment flags that set
+    # iOS-specific values.
+    if [[ -n "$IOS_SDK" ]]; then
+        ORIGINAL_HOST_CONFIGURE_FLAGS=$HOST_CONFIGURE_FLAGS
+        ORIGINAL_IPHONEOS_DEPLOYMENT_TARGET=$IPHONEOS_DEPLOYMENT_TARGET
+        unset HOST_CONFIGURE_FLAGS
+        unset IPHONEOS_DEPLOYMENT_TARGET
+    fi
+
+    CFLAGS="$CFLAGS -Wno-int-conversion" CPPFLAGS="" build_simple pkg-config 0.29.2 https://pkg-config.freedesktop.org/releases tar.gz \
         --disable-debug --disable-host-tool --with-internal-glib \
         --with-pc-path=$BUILD_PREFIX/share/pkgconfig:$BUILD_PREFIX/lib/pkgconfig \
         --with-system-include-path=$(xcrun --show-sdk-path --sdk macosx)/usr/include
+
+    if [[ -n "$IOS_SDK" ]]; then
+        HOST_CONFIGURE_FLAGS=$ORIGINAL_HOST_CONFIGURE_FLAGS
+        IPHONEOS_DEPLOYMENT_TARGET=$ORIGINAL_IPHONEOS_DEPLOYMENT_TARGET
+    fi;
+
     export PKG_CONFIG=$BUILD_PREFIX/bin/pkg-config
     touch pkg-config-stamp
 }
 
 function build_zlib_ng {
     if [ -e zlib-stamp ]; then return; fi
+    # zlib-ng uses a "configure" script, but it's not a GNU autotools script, so
+    # it doesn't honor the usual flags. Temporarily disable any
+    # cross-compilation flags.
+    ORIGINAL_HOST_CONFIGURE_FLAGS=$HOST_CONFIGURE_FLAGS
+    unset HOST_CONFIGURE_FLAGS
+
     build_github zlib-ng/zlib-ng $ZLIB_NG_VERSION --zlib-compat
 
-    if [ -n "$IS_MACOS" ]; then
+    HOST_CONFIGURE_FLAGS=$ORIGINAL_HOST_CONFIGURE_FLAGS
+
+    if [ -n "$IS_MACOS" ] && [ -z "$IOS_SDK" ]; then
         # Ensure that on macOS, the library name is an absolute path, not an
         # @rpath, so that delocate picks up the right library (and doesn't need
         # DYLD_LIBRARY_PATH to be set). The default Makefile doesn't have an
-        # option to control the install_name.
+        # option to control the install_name. This isn't needed on iOS, as iOS
+        # only builds the static library.
         install_name_tool -id $BUILD_PREFIX/lib/libz.1.dylib $BUILD_PREFIX/lib/libz.1.dylib
     fi
     touch zlib-stamp
@@ -79,20 +158,25 @@ function build_zlib_ng {
 
 function build_brotli {
     if [ -e brotli-stamp ]; then return; fi
+    local name=brotli
+    local version=$BROTLI_VERSION
     local out_dir=$(fetch_unpack https://github.com/google/brotli/archive/v$BROTLI_VERSION.tar.gz brotli-$BROTLI_VERSION.tar.gz)
     (cd $out_dir \
-        && cmake -DCMAKE_INSTALL_PREFIX=$BUILD_PREFIX -DCMAKE_INSTALL_LIBDIR=$BUILD_PREFIX/lib -DCMAKE_INSTALL_NAME_DIR=$BUILD_PREFIX/lib . \
+        && cmake -DCMAKE_INSTALL_PREFIX=$BUILD_PREFIX -DCMAKE_INSTALL_LIBDIR=$BUILD_PREFIX/lib -DCMAKE_INSTALL_NAME_DIR=$BUILD_PREFIX/lib $HOST_CMAKE_FLAGS  . \
         && make install)
     touch brotli-stamp
 }
 
 function build_harfbuzz {
     if [ -e harfbuzz-stamp ]; then return; fi
-    python3 -m pip install meson ninja
+    local name=harfbuzz
+    local version=$HARFBUZZ_VERSION
+
+    python3 -m pip install --disable-pip-version-check meson ninja
 
     local out_dir=$(fetch_unpack https://github.com/harfbuzz/harfbuzz/releases/download/$HARFBUZZ_VERSION/harfbuzz-$HARFBUZZ_VERSION.tar.xz harfbuzz-$HARFBUZZ_VERSION.tar.xz)
     (cd $out_dir \
-        && meson setup build --prefix=$BUILD_PREFIX --libdir=$BUILD_PREFIX/lib --buildtype=minsize -Dfreetype=enabled -Dglib=disabled -Dtests=disabled)
+        && meson setup build --prefix=$BUILD_PREFIX --libdir=$BUILD_PREFIX/lib --buildtype=minsize -Dfreetype=enabled -Dglib=disabled -Dtests=disabled $HOST_MESON_FLAGS)
     (cd $out_dir/build \
         && meson install)
     touch harfbuzz-stamp
@@ -110,19 +194,19 @@ function build {
     fi
 
     build_simple xcb-proto 1.17.0 https://xorg.freedesktop.org/archive/individual/proto
-    if [ -n "$IS_MACOS" ]; then
+    if [[ -n "$IS_MACOS" ]]; then
         build_simple xorgproto 2024.1 https://www.x.org/pub/individual/proto
         build_simple libXau 1.0.12 https://www.x.org/pub/individual/lib
         build_simple libpthread-stubs 0.5 https://xcb.freedesktop.org/dist
     else
-        sed s/\${pc_sysrootdir\}// $BUILD_PREFIX/share/pkgconfig/xcb-proto.pc > $BUILD_PREFIX/lib/pkgconfig/xcb-proto.pc
+        sed "s/\$\{pc_sysrootdir\}//" $BUILD_PREFIX/share/pkgconfig/xcb-proto.pc > $BUILD_PREFIX/lib/pkgconfig/xcb-proto.pc
     fi
     build_simple libxcb $LIBXCB_VERSION https://www.x.org/releases/individual/lib
 
     build_libjpeg_turbo
-    if [ -n "$IS_MACOS" ]; then
+    if [[ -n "$IS_MACOS" ]]; then
         # Custom tiff build to include jpeg; by default, configure won't include
-        # headers/libs in the custom macOS prefix. Explicitly disable webp,
+        # headers/libs in the custom macOS/iOS prefix. Explicitly disable webp,
         # libdeflate and zstd, because on x86_64 macs, it will pick up the
         # Homebrew versions of those libraries from /usr/local.
         build_simple tiff $TIFF_VERSION https://download.osgeo.org/libtiff tar.gz \
@@ -146,14 +230,44 @@ function build {
 
     build_brotli
 
-    if [ -n "$IS_MACOS" ]; then
+    if [[ -n "$IS_MACOS" ]]; then
         # Custom freetype build
         build_simple freetype $FREETYPE_VERSION https://download.savannah.gnu.org/releases/freetype tar.gz --with-harfbuzz=no
     else
         build_freetype
     fi
 
-    build_harfbuzz
+    if [[ -z "$IOS_SDK" ]]; then
+        # On iOS, there's no vendor-provided raqm, and we can't ship it due to
+        # licensing, so there's no point building harfbuzz.
+        build_harfbuzz
+    fi
+}
+
+function create_meson_cross_config {
+    cat << EOF > $WORKDIR/meson-cross.txt
+[binaries]
+pkg-config = '$BUILD_PREFIX/bin/pkg-config'
+cmake = '$(which cmake)'
+c = '$CC'
+cpp = '$CXX'
+strip = '$STRIP'
+
+[built-in options]
+c_args = '$CFLAGS -I$BUILD_PREFIX/include'
+cpp_args = '$CXXFLAGS -I$BUILD_PREFIX/include'
+c_link_args = '$CFLAGS -L$BUILD_PREFIX/lib'
+cpp_link_args = '$CFLAGS -L$BUILD_PREFIX/lib'
+
+[host_machine]
+system = 'darwin'
+subsystem = 'ios'
+kernel = 'xnu'
+cpu_family = '$(uname -m)'
+cpu = '$(uname -m)'
+endian = 'little'
+
+EOF
 }
 
 # Perform all dependency builds in the build subfolder.
@@ -172,24 +286,40 @@ if [[ ! -d $WORKDIR/pillow-depends-main ]]; then
 fi
 
 if [[ -n "$IS_MACOS" ]]; then
-    # Homebrew (or similar packaging environments) install can contain some of
-    # the libraries that we're going to build. However, they may be compiled
-    # with a MACOSX_DEPLOYMENT_TARGET that doesn't match what we want to use,
-    # and they may bring in other dependencies that we don't want. The same will
-    # be true of any other locations on the path. To avoid conflicts, strip the
-    # path down to the bare minimum (which, on macOS, won't include any
-    # development dependencies).
-    export PATH="$BUILD_PREFIX/bin:$(dirname $(which python3)):/usr/bin:/bin:/usr/sbin:/sbin:/Library/Apple/usr/bin"
-    export CMAKE_PREFIX_PATH=$BUILD_PREFIX
-
     # Ensure the basic structure of the build prefix directory exists.
     mkdir -p "$BUILD_PREFIX/bin"
     mkdir -p "$BUILD_PREFIX/lib"
 
-    # Ensure pkg-config is available
+    # Ensure pkg-config is available. This is done *before* setting CC, CFLAGS
+    # etc to ensure that the build is *always* a macOS build, even when building
+    # for iOS.
     build_pkg_config
-    # Ensure cmake is available
-    python3 -m pip install cmake
+
+    # Ensure cmake is available, and that the default prefix used by CMake is
+    # the build prefix
+    python3 -m pip install --disable-pip-version-check cmake
+    export CMAKE_PREFIX_PATH=$BUILD_PREFIX
+
+    if [[ -n "$IOS_SDK" ]]; then
+        export AR="$(xcrun --find --sdk $IOS_SDK ar)"
+        export CPP="$(xcrun --find --sdk $IOS_SDK clang) -E"
+        export CC=$(xcrun --find --sdk $IOS_SDK clang)
+        export CXX=$(xcrun --find --sdk $IOS_SDK clang++)
+        export LD=$(xcrun --find --sdk $IOS_SDK ld)
+        export STRIP=$(xcrun --find --sdk $IOS_SDK strip)
+
+        CPPFLAGS="$CPPFLAGS --sysroot=$IOS_SDK_PATH"
+        CFLAGS="-target $IOS_HOST_TRIPLE --sysroot=$IOS_SDK_PATH -mios-version-min=$IPHONEOS_DEPLOYMENT_TARGET"
+        CXXFLAGS="-target $IOS_HOST_TRIPLE --sysroot=$IOS_SDK_PATH -mios-version-min=$IPHONEOS_DEPLOYMENT_TARGET"
+
+        # Having IPHONEOS_DEPLOYMENT_TARGET in the environment causes problems
+        # with some cross-building toolchains, because it introduces implicit
+        # behavior into clang.
+        unset IPHONEOS_DEPLOYMENT_TARGET
+
+        # Now that we know CC etc, we can create a meson cross-configuration file
+        create_meson_cross_config
+    fi
 fi
 
 wrap_wheel_builder build

.github/workflows/wheels-test.ps1

@@ -23,7 +23,7 @@ cd $pillow
 if (!$?) { exit $LASTEXITCODE }
 & $venv\Scripts\$python selftest.py
 if (!$?) { exit $LASTEXITCODE }
-& $venv\Scripts\$python -m pytest -vx Tests\check_wheel.py
+& $venv\Scripts\$python -m pytest -vx checks\check_wheel.py
 if (!$?) { exit $LASTEXITCODE }
 & $venv\Scripts\$python -m pytest -vx Tests
 if (!$?) { exit $LASTEXITCODE }

.github/workflows/wheels-test.sh

@@ -25,8 +25,6 @@ else
     yum install -y fribidi
 fi
 
-python3 -m pip install numpy
-
 if [ ! -d "test-images-main" ]; then
     curl -fsSL -o pillow-test-images.zip https://github.com/python-pillow/test-images/archive/main.zip
     unzip pillow-test-images.zip
@@ -35,5 +33,5 @@ fi
 
 # Runs tests
 python3 selftest.py
-python3 -m pytest Tests/check_wheel.py
+python3 -m pytest checks/check_wheel.py
 python3 -m pytest

.github/workflows/wheels.yml

@@ -51,40 +51,66 @@ jobs:
       matrix:
         include:
           - name: "macOS 10.10 x86_64"
+            platform: macos
             os: macos-13
             cibw_arch: x86_64
             build: "cp3{9,10,11}*"
             macosx_deployment_target: "10.10"
           - name: "macOS 10.13 x86_64"
+            platform: macos
             os: macos-13
             cibw_arch: x86_64
             build: "cp3{12,13}*"
             macosx_deployment_target: "10.13"
           - name: "macOS 10.15 x86_64"
+            platform: macos
             os: macos-13
             cibw_arch: x86_64
             build: "pp3*"
             macosx_deployment_target: "10.15"
           - name: "macOS arm64"
+            platform: macos
             os: macos-latest
             cibw_arch: arm64
             macosx_deployment_target: "11.0"
           - name: "manylinux2014 and musllinux x86_64"
+            platform: linux
             os: ubuntu-latest
             cibw_arch: x86_64
           - name: "manylinux_2_28 x86_64"
+            platform: linux
             os: ubuntu-latest
             cibw_arch: x86_64
             build: "*manylinux*"
             manylinux: "manylinux_2_28"
           - name: "manylinux2014 and musllinux aarch64"
+            platform: linux
             os: ubuntu-24.04-arm
             cibw_arch: aarch64
           - name: "manylinux_2_28 aarch64"
+            platform: linux
             os: ubuntu-24.04-arm
             cibw_arch: aarch64
             build: "*manylinux*"
             manylinux: "manylinux_2_28"
+          - name: "iOS arm64 device"
+            platform: ios
+            os: macos-13
+            cibw_arch: arm64
+            build: "*iphoneos"
+            iphoneos_deployment_target: "13.0"
+          - name: "iOS arm64 simulator"
+            platform: ios
+            os: macos-13
+            cibw_arch: arm64
+            build: "*iphonesimulator"
+            iphoneos_deployment_target: "13.0"
+          - name: "iOS x86_64 simulator"
+            platform: ios
+            os: macos-latest
+            cibw_arch: x86_64
+            build: "*iphonesimulator"
+            iphoneos_deployment_target: "13.0"
     steps:
       - uses: actions/checkout@v4
         with:
@@ -103,6 +129,7 @@ jobs:
         run: |
           python3 -m cibuildwheel --output-dir wheelhouse
         env:
+          CIBW_PLATFORM: ${{ matrix.platform }}
           CIBW_ARCHS: ${{ matrix.cibw_arch }}
           CIBW_BUILD: ${{ matrix.build }}
           CIBW_ENABLE: cpython-prerelease cpython-freethreading pypy
@@ -111,10 +138,11 @@ jobs:
           CIBW_MANYLINUX_PYPY_X86_64_IMAGE: ${{ matrix.manylinux }}
           CIBW_MANYLINUX_X86_64_IMAGE: ${{ matrix.manylinux }}
           MACOSX_DEPLOYMENT_TARGET: ${{ matrix.macosx_deployment_target }}
+          IPHONEOS_DEPLOYMENT_TARGET: ${{ matrix.iphoneos_deployment_target }}
 
       - uses: actions/upload-artifact@v4
         with:
-          name: dist-${{ matrix.os }}${{ matrix.macosx_deployment_target && format('-{0}', matrix.macosx_deployment_target) }}-${{ matrix.cibw_arch }}${{ matrix.manylinux && format('-{0}', matrix.manylinux) }}
+          name: dist-${{ matrix.name }}
           path: ./wheelhouse/*.whl
 
   windows:

.gitignore

@@ -80,6 +80,10 @@ docs/_build/
 # JetBrains
 .idea
 
+# Files downloaded as part of the build process
+pillow-depends-main.zip
+pillow-test-images.zip
+
 # Extra test images installed from python-pillow/test-images
 Tests/images/README.md
 Tests/images/crash_1.tif

.pre-commit-config.yaml

@@ -21,7 +21,7 @@ repos:
     rev: v1.5.5
     hooks:
       - id: remove-tabs
-        exclude: (Makefile$|\.bat$|\.cmake$|\.eps$|\.fits$|\.gd$|\.opt$)
+        exclude: (Makefile$|\.bat$|\.cmake$|\.eps$|\.fits$|\.gd$|\.opt$|\.patch$)
 
   - repo: https://github.com/pre-commit/mirrors-clang-format
     rev: v20.1.5
@@ -46,9 +46,9 @@ repos:
       - id: check-yaml
         args: [--allow-multiple-documents]
       - id: end-of-file-fixer
-        exclude: ^Tests/images/
+        exclude: ^Tests/images/|\.patch$
       - id: trailing-whitespace
-        exclude: ^.github/.*TEMPLATE|^Tests/(fonts|images)/
+        exclude: ^.github/.*TEMPLATE|^Tests/(fonts|images)/|\.patch$
 
   - repo: https://github.com/python-jsonschema/check-jsonschema
     rev: 0.33.0

Tests/oss-fuzz/test_fuzzers.py

@@ -10,8 +10,12 @@ import pytest
 from PIL import Image, features
 from Tests.helper import skip_unless_feature
 
-if sys.platform.startswith("win32"):
-    pytest.skip("Fuzzer is linux only", allow_module_level=True)
+if sys.platform.startswith("win32") or sys.platform in {"ios", "android"}:
+    pytest.skip(
+        "Fuzzer doesn't run on Windows or mobile",
+        allow_module_level=True,
+    )
+
 libjpeg_turbo_version = features.version("libjpeg_turbo")
 if libjpeg_turbo_version is not None:
     version = packaging.version.parse(libjpeg_turbo_version)

Tests/test_main.py

@@ -7,6 +7,10 @@ import sys
 import pytest
 
 
+@pytest.mark.skipif(
+    sys.platform in {"ios", "android"},
+    reason="Not required on mobile",
+)
 @pytest.mark.parametrize(
     "args, report",
     ((["PIL"], False), (["PIL", "--report"], True), (["PIL.report"], True)),

Tests/test_pyroma.py

@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+from importlib.metadata import metadata
+
 import pytest
 
 from PIL import __version__
@@ -9,7 +11,7 @@ pyroma = pytest.importorskip("pyroma", reason="Pyroma not installed")
 
 def test_pyroma() -> None:
     # Arrange
-    data = pyroma.projectdata.get_data(".")
+    data = pyroma.projectdata.map_metadata_keys(metadata("Pillow"))
 
     # Act
     rating = pyroma.ratings.rate(data)

checks/check_wheel.py

@@ -5,7 +5,7 @@ import sys
 
 from PIL import features
 
-from .helper import is_pypy
+from Tests.helper import is_pypy
 
 
 def test_wheel_modules() -> None:
@@ -19,6 +19,9 @@ def test_wheel_modules() -> None:
             assert tkinter
         except ImportError:
             expected_modules.remove("tkinter")
+    elif sys.platform == "ios":
+        # tkinter is not available on iOS
+        expected_modules.remove("tkinter")
 
     assert set(features.get_supported_modules()) == expected_modules
 
@@ -46,5 +49,11 @@ def test_wheel_features() -> None:
         expected_features.remove("xcb")
     elif sys.platform == "darwin" and not is_pypy() and platform.processor() != "arm":
         expected_features.remove("zlib_ng")
+    elif sys.platform == "ios":
+        # Can't distribute raqm due to licensing, and there's no system version;
+        # fribid and harfbuzz won't be available if raqm isn't available.
+        expected_features.remove("fribidi")
+        expected_features.remove("raqm")
+        expected_features.remove("harfbuzz")
 
     assert set(features.get_supported_features()) == expected_features

patches/README.md

@@ -0,0 +1,14 @@
+Although we try to use official sources for dependencies, sometimes the official
+sources don't support a platform (especially mobile platforms), or there's a bug
+fix/feature that is required to support Pillow's usage.
+
+This folder contains patches that must be applied to official sources, organized
+by the platforms that need those patches.
+
+Each patch is against the root of the unpacked official tarball, and is named by
+appending `.patch` to the end of the tarball that is to be patched. This
+includes the full version number; so if the version is bumped, the patch will
+at a minimum require a filename change.
+
+Wherever possible, these patches should be contributed upstream, in the hope that
+future Pillow versions won't need to maintain these patches.

patches/iOS/brotli-1.1.0.tar.gz.patch

@@ -0,0 +1,43 @@
+# Brotli doesn't have explicit support for iOS as a CMAKE_SYSTEM_NAME.
+#
+diff -ru brotli-1.1.0-orig/CMakeLists.txt brotli-1.1.0/CMakeLists.txt
+--- brotli-1.1.0-orig/CMakeLists.txt	2023-08-29 19:00:29
++++ brotli-1.1.0/CMakeLists.txt	2024-11-07 10:46:26
+@@ -114,6 +114,8 @@
+   add_definitions(-DOS_MACOSX)
+   set(CMAKE_MACOS_RPATH TRUE)
+   set(CMAKE_INSTALL_NAME_DIR "${CMAKE_INSTALL_PREFIX}/lib")
++elseif(${CMAKE_SYSTEM_NAME} MATCHES "iOS")
++  add_definitions(-DOS_IOS)
+ endif()
+ 
+ if(BROTLI_EMSCRIPTEN)
+@@ -174,10 +176,12 @@
+ 
+ # Installation
+ if(NOT BROTLI_BUNDLED_MODE)
+-  install(
+-    TARGETS brotli
+-    RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
+-  )
++  if(NOT ${CMAKE_SYSTEM_NAME} MATCHES "iOS")
++    install(
++      TARGETS brotli
++      RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
++    )
++  endif()
+ 
+   install(
+     TARGETS ${BROTLI_LIBRARIES_CORE}
+diff -ru brotli-1.1.0-orig/c/common/platform.h brotli-1.1.0/c/common/platform.h
+--- brotli-1.1.0-orig/c/common/platform.h	2023-08-29 19:00:29
++++ brotli-1.1.0/c/common/platform.h	2024-11-07 10:47:28
+@@ -33,7 +33,7 @@
+ #include <endian.h>
+ #elif defined(OS_FREEBSD)
+ #include <machine/endian.h>
+-#elif defined(OS_MACOSX)
++#elif defined(OS_MACOSX) || defined(OS_IOS)
+ #include <machine/endian.h>
+ /* Let's try and follow the Linux convention */
+ #define BROTLI_X_BYTE_ORDER BYTE_ORDER

patches/iOS/libwebp-1.5.0.tar.gz.patch

@@ -0,0 +1,39 @@
+# libwebp example binaries require dependencies that aren't available for iOS builds.
+# There's also no easy way to invoke the build to *exclude* the example builds.
+# Since we don't need the examples anyway, remove them from the makefile.
+#
+# As a point of reference, libwebp provides an XCframework build script that involves
+# 7 separate invocations of make to avoid building the examples. Patching the makefile
+# to remove the examples is a simpler approach, and one that is more compatible with
+# the existing multibuild infrastructure.
+#
+diff -ur libwebp-1.5.0-orig/Makefile.am libwebp-1.5.0/Makefile.am
+--- libwebp-1.5.0-orig/Makefile.am	2024-12-20 09:17:50
++++ libwebp-1.5.0/Makefile.am	2025-01-09 11:24:17
+@@ -5,5 +5,3 @@
+ if BUILD_EXTRAS
+   SUBDIRS += extras
+ endif
+-
+-SUBDIRS += examples
+diff -ur libwebp-1.5.0-orig/Makefile.in libwebp-1.5.0/Makefile.in
+--- libwebp-1.5.0-orig/Makefile.in	2024-12-20 09:52:53
++++ libwebp-1.5.0/Makefile.in	2025-01-09 11:24:17
+@@ -156,7 +156,7 @@
+   unique=`for i in $$list; do \
+     if test -f "$$i"; then echo $$i; else echo $(srcdir)/$$i; fi; \
+   done | $(am__uniquify_input)`
+-DIST_SUBDIRS = sharpyuv src imageio man extras examples
++DIST_SUBDIRS = sharpyuv src imageio man extras
+ am__DIST_COMMON = $(srcdir)/Makefile.in \
+ 	$(top_srcdir)/src/webp/config.h.in AUTHORS COPYING ChangeLog \
+ 	NEWS README.md ar-lib compile config.guess config.sub \
+@@ -351,7 +351,7 @@
+ top_srcdir = @top_srcdir@
+ webp_libname_prefix = @webp_libname_prefix@
+ ACLOCAL_AMFLAGS = -I m4
+-SUBDIRS = sharpyuv src imageio man $(am__append_1) examples
++SUBDIRS = sharpyuv src imageio man $(am__append_1)
+ EXTRA_DIST = COPYING autogen.sh
+ all: all-recursive
+ 

pyproject.toml

@@ -103,15 +103,49 @@ before-all = ".github/workflows/wheels-dependencies.sh"
 build-verbosity = 1
 
 config-settings = "raqm=enable raqm=vendor fribidi=vendor imagequant=disable"
-# Disable platform guessing on macOS
-macos.config-settings = "raqm=enable raqm=vendor fribidi=vendor imagequant=disable platform-guessing=disable"
 
 test-command = "cd {project} && .github/workflows/wheels-test.sh"
 test-extras = "tests"
+test-requires = [
+  "numpy",
+]
+xbuild-tools = [  ]
+
+[tool.cibuildwheel.macos]
+# Disable platform guessing on macOS to avoid picking up homebrew etc
+config-settings = "raqm=enable raqm=vendor fribidi=vendor imagequant=disable platform-guessing=disable"
 
 [tool.cibuildwheel.macos.environment]
+# Isolate macOS build environment from homebrew etc
 PATH = "$(pwd)/build/deps/darwin/bin:$(dirname $(which python3)):/usr/bin:/bin:/usr/sbin:/sbin:/Library/Apple/usr/bin"
 
+[tool.cibuildwheel.ios]
+# Disable platform guessing on iOS, and disable raqm (since there won't be a
+# vendor version, and we can't distribute it due to licensing)
+config-settings = "raqm=disable imagequant=disable platform-guessing=disable"
+
+# iOS needs to be given a specific pytest invocation and list of test sources.
+test-sources = [
+  "checks",
+  "Tests",
+  "pyproject.toml",
+  "selftest.py",
+]
+test-command = "python -m pytest -vv selftest.py checks/check_wheel.py Tests"
+
+# There's no numpy wheel for iOS (yet...)
+test-requires = [  ]
+
+[[tool.cibuildwheel.overrides]]
+# iOS environment is isolated by cibuildwheel, but needs the dependencies
+select = "*_iphoneos"
+environment.PATH = "$(pwd)/build/deps/iphoneos/bin:$PATH"
+
+[[tool.cibuildwheel.overrides]]
+# iOS simulator environment is isolated by cibuildwheel, but needs the dependencies
+select = "*_iphonesimulator"
+environment.PATH = "$(pwd)/build/deps/iphonesimulator/bin:$PATH"
+
 [tool.black]
 exclude = "wheels/multibuild"
 
@@ -168,7 +202,7 @@ lint.isort.required-imports = [
 max_supported_python = "3.13"
 
 [tool.pytest.ini_options]
-addopts = "-ra --color=yes"
+addopts = "-ra --color=auto"
 testpaths = [
   "Tests",
 ]

setup.py

@@ -474,6 +474,19 @@ class pil_build_ext(build_ext):
                 sdk_path = commandlinetools_sdk_path
         return sdk_path
 
+    def get_ios_sdk_path(self) -> str:
+        try:
+            sdk = sys.implementation._multiarch.split("-")[-1]
+            _dbg("Using %s SDK", sdk)
+            return (
+                subprocess.check_output(["xcrun", "--show-sdk-path", "--sdk", sdk])
+                .strip()
+                .decode("latin1")
+            )
+        except Exception:
+            msg = "Unable to identify location of iOS SDK."
+            raise ValueError(msg)
+
     def build_extensions(self) -> None:
         library_dirs: list[str] = []
         include_dirs: list[str] = []
@@ -615,14 +628,6 @@ class pil_build_ext(build_ext):
                 _add_directory(library_dirs, "/usr/X11/lib")
                 _add_directory(include_dirs, "/usr/X11/include")
 
-            # Add the macOS SDK path.
-            sdk_path = self.get_macos_sdk_path()
-            if sdk_path:
-                _add_directory(library_dirs, os.path.join(sdk_path, "usr", "lib"))
-                _add_directory(include_dirs, os.path.join(sdk_path, "usr", "include"))
-
-                for extension in self.extensions:
-                    extension.extra_compile_args = ["-Wno-nullability-completeness"]
         elif sys.platform.startswith(("linux", "gnu", "freebsd")):
             for dirname in _find_library_dirs_ldconfig():
                 _add_directory(library_dirs, dirname)
@@ -677,6 +682,27 @@ class pil_build_ext(build_ext):
                 _add_directory(library_dirs, os.path.join(best_path, "lib"))
                 _add_directory(include_dirs, os.path.join(best_path, "include"))
 
+        elif sys.platform == "darwin":
+            # Alwasy include the macOS SDK path.
+            sdk_path = self.get_macos_sdk_path()
+            if sdk_path:
+                _add_directory(library_dirs, os.path.join(sdk_path, "usr", "lib"))
+                _add_directory(include_dirs, os.path.join(sdk_path, "usr", "include"))
+
+                for extension in self.extensions:
+                    extension.extra_compile_args = ["-Wno-nullability-completeness"]
+
+        elif sys.platform == "ios":
+            # Always include the iOS SDK path.
+            sdk_path = self.get_ios_sdk_path()
+
+            # Add the iOS SDK path.
+            _add_directory(library_dirs, os.path.join(sdk_path, "usr", "lib"))
+            _add_directory(include_dirs, os.path.join(sdk_path, "usr", "include"))
+
+            for extension in self.extensions:
+                extension.extra_compile_args = ["-Wno-nullability-completeness"]
+
         #
         # insert new dirs *before* default libs, to avoid conflicts
         # between Python PYD stub libs and real libraries
@@ -878,6 +904,9 @@ class pil_build_ext(build_ext):
                 # so we have to guess; by default it is defined in all Windows builds.
                 # See #4237, #5243, #5359 for more information.
                 defs.append(("USE_WIN32_FILEIO", None))
+            elif sys.platform == "ios":
+                # Ensure transitive dependencies are linked.
+                libs.append("lzma")
         if feature.get("jpeg"):
             libs.append(feature.get("jpeg"))
             defs.append(("HAVE_LIBJPEG", None))
@@ -894,6 +923,9 @@ class pil_build_ext(build_ext):
             defs.append(("HAVE_LIBIMAGEQUANT", None))
         if feature.get("xcb"):
             libs.append(feature.get("xcb"))
+            if sys.platform == "ios":
+                # Ensure transitive dependencies are linked.
+                libs.append("Xau")
             defs.append(("HAVE_XCB", None))
         if sys.platform == "win32":
             libs.extend(["kernel32", "user32", "gdi32"])
@@ -925,6 +957,11 @@ class pil_build_ext(build_ext):
                         libs.append(feature.get("fribidi"))
                     else:  # building FriBiDi shim from src/thirdparty
                         srcs.append("src/thirdparty/fribidi-shim/fribidi.c")
+
+            if sys.platform == "ios":
+                # Ensure transitive dependencies are linked.
+                libs.extend(["z", "bz2", "brotlicommon", "brotlidec", "png"])
+
             self._update_extension("PIL._imagingft", libs, defs, srcs)
 
         else:
@@ -941,6 +978,9 @@ class pil_build_ext(build_ext):
         webp = feature.get("webp")
         if isinstance(webp, str):
             libs = [webp, webp + "mux", webp + "demux"]
+            if sys.platform == "ios":
+                # Ensure transitive dependencies are linked.
+                libs.append("sharpyuv")
             self._update_extension("PIL._webp", libs)
         else:
             self._remove_extension("PIL._webp")