build_libpng

#!/bin/bash
#
# Cross-compiles libpng library for Android
#
# This script download libpng source code from libpng official website (https://www.libpng.net/)
#
# This script cross-compiles libpng library for Android (armeabi-v7a, arm64-v8a, x86, x86-64)
# using Android NDK and autoconf, as shown in [Use the NDK with other build systems]
# (https://developer.android.com/ndk/guides/other_build_systems#autoconf).
#
# Dependencies:
#   - Android NDK r22+
#   - curl
#   - make
#
# Android Arch Supported:
#   - arm   (armeabi-v7a)
#   - arm64 (arm64-v8a)
#   - x86
#   - x86-64

# Constants
readonly RED='\033[0;31m'
readonly NC='\033[0m'
readonly libpng_BASE_URL='https://download.sourceforge.net/libpng'
readonly OUTPUT_DIR="$PWD/output"
readonly DOWNLOADS_DIR='downloads'
readonly LOG_FILE='build.log'

print_usage() {
  echo 'usage:'
  echo '  build_libpng [-h | --help]          (Print this help)'
  echo '    [-c | --clean]                    (Clean output and download directories)'
  echo '    [--ndk-dir ANDROID_NDK_DIR]       (Default: $ANDROID_NDK)'
  echo '    [--android-abi ANDROID_ABI]       (Default: all, Values: all | arm | arm64 | x86 | x86-64)'
  echo '    [--android-api-level API_LEVEL]   (Default: 21)'
  echo '    [--with-zlib ZLIB_PREFIX]         (Build with zlib support)'
  echo '    [--libpng-version LIBPNG_VERSION] (Default: 1.6.37)'
  echo '    [--static-only]                   (Default: Build static and shared libs)'
  echo
  echo 'exmples:'
  echo '  # Build libpng-1.6.37 static and shared libs, for android-21, all supported architectures'
  echo '  build_libpng'
  echo
  echo '  # Build libpng-1.1.10 static and shared libs, for android-21, armeabi-v7a'
  echo '  build_libpng --ndk-dir /path/to/android-ndk --android-abi arm --libpng-version 1.1.10'
  echo
  echo '  # Build libpng-1.6.37 static libs, for android-24, arm64-v8a with zlib support'
  echo '  build_libpng --with-zlib /zlib/install/prefix  --android-abi arm64 --android-api-level 24 --static-only'
}

err() {
  echo -e "${RED}$*${NC}" >&2
}

cleanup() {
  echo "Cleaning ..."
  rm -rf $OUTPUT_DIR $DOWNLOADS_DIR $LOG_FILE
  rm -rf `find . -type d -name libpng-*`
  echo "Everything is clean."
}

check_error() {
  if [[ $? -ne 0 ]]; then
    err $@
    exit 1
  fi
}

############################################
# Download libpng source code
# Globals:
#   libpng_BASE_URL
#   DOWNLOADS_DIR
# Arguments:
#   libpng version to download (i.e., 1.6.37)
############################################
download_libpng() {
  local libpng=libpng-$1.tar.gz
  if [[ ! -d $DOWNLOADS_DIR || ! -f "$DOWNLOADS_DIR/$libpng" ]]; then
    echo "Downloading $libpng ..."
    mkdir -p $DOWNLOADS_DIR && cd $DOWNLOADS_DIR
    curl -sfSL $libpng_BASE_URL/$libpng -o $libpng 2>>"../$LOG_FILE"
    check_error "Failed to download $libpng. See '$LOG_FILE' for details."
    cd ..
  fi
}

############################################
# Extract libpng source code
# Globals:
#   DOWNLOADS_DIR
# Arguments:
#   libpng version to extract (i.e., 1.6.37)
############################################
extract_libpng() {
  local libpng=libpng-$1.tar.gz
  rm -rf $libpng
  echo "Extracting $libpng ..."
  tar -xzf "$DOWNLOADS_DIR/$libpng" 2>>$LOG_FILE
  check_error "Failed to extract $libpng. See '$LOG_FILE' for details."
}

############################################
# Export cross build environment variables
# Arguments:
#   Android NDK path
#   Android ABI (i.e., arm, arm64, x86, x86-64)
#   Android API Level (i.e., 21)
############################################
setup_env() {
  local uname=`(uname -s || echo unknown) 2>>$LOG_FILE`
  local ndk_toolchain
  local ndk_target
  
  case "$uname" in
    Linux* | linux* | GNU | GNU/* | solaris*) ndk_toolchain=linux-x86_64 ;;
    Darwin* | darwin*) ndk_toolchain=darwin-x86_64 ;;
    unknown) err 'Failed to get device OS name.'; exit 1 ;;
    *) err "OS \'$uname\' is not supported."; exit 1 ;;
  esac
  
  case "$2" in
    arm) ndk_target=armv7a-linux-androideabi ;;
    arm64) ndk_target=aarch64-linux-android ;;
    x86) ndk_target=i686-linux-android ;;
    x86-64) ndk_target=x86_64-linux-android ;;
    *) err "ABI \'$2\' is not supported."; exit 1 ;;
  esac
  
  export NDK=$1
  export TOOLCHAIN=$NDK/toolchains/llvm/prebuilt/$ndk_toolchain
  export TARGET=$ndk_target
  export API=$3
  export AR=$TOOLCHAIN/bin/llvm-ar
  export CC=$TOOLCHAIN/bin/$TARGET$API-clang
  export AS=$CC
  export CXX=$TOOLCHAIN/bin/$TARGET$API-clang++
  export LD=$TOOLCHAIN/bin/ld
  export RANLIB=$TOOLCHAIN/bin/llvm-ranlib
  export STRIP=$TOOLCHAIN/bin/llvm-strip
}

############################################
# Build libpng
# Globals:
#   OUTPUT_DIR
# Arguments:
#   libpng version to build
#   Android ABI (i.e., arm, arm64, x86, x86-64)
#   Optional zlib prefix
#   Build type argument (i.e., --enable-shared=no)
############################################
build_libpng() {
  local src_dir=libpng-$1
  local out_dir
  local zlib_options=''
  local abi
  
  case "$2" in
    arm) abi='armeabi-v7a' ;;
    arm64) abi='arm64-v8a' ;;
    x86) abi='x86' ;;
    x86-64) abi='x86-64' ;;
    *) err "ABI \'$2\' is not supported."; exit 1 ;;
  esac
  
  out_dir="$OUTPUT_DIR/$src_dir/$abi"

  if [[ ! -z $3 ]]; then
    zlib_options = "--with-zlib-prefix=$3/$abi"
  fi
  
  cd $src_dir
  echo "Building $src_dir for $abi ..."
  echo "Target: $TARGET Prefix: $out_dir"
  ./configure --host $TARGET --prefix=$out_dir $zlib_options $4 1>/dev/null 2>>"../$LOG_FILE"
  check_error "Error building $src_dir. See '$LOG_FILE' for details."
  make -s 1>/dev/null 2>>"../$LOG_FILE"
  check_error "Error building $src_dir. See '$LOG_FILE' for details."
  make -s install 1>/dev/null 2>>"../$LOG_FILE"
  check_error "Error building $src_dir. See '$LOG_FILE' for details."
  cd ..
  rm -rf $src_dir
  echo "Done."
}

############################################
# Entry point
# Arguments:
#   Program arguments (See usage)
############################################
main() {
  local android_ndk=$ANDROID_NDK
  local android_abi='all'
  local android_api_level='21'
  local libpng_version='1.6.37'
  local zlib_prefix=''
  local build_type=''
  
  while [[ $# -ge 1 ]]; do
    case "$1" in
      -h | --help) print_usage; exit 0 ;;
      -c | --clean) cleanup; exit 0 ;;
      --ndk-dir) android_ndk="$2"; shift; shift ;;
      --android-abi) android_abi="$2"; shift; shift ;;
      --android-api-level) android_api_level="$2"; shift; shift ;;
      --libpng-version) libpng_version="$2"; shift; shift ;;
      --with-zlib) zlib_prefix=$2; shift; shift ;;
      --static-only) build_type='--enable-shared=no'; shift ;;
      *) err "Unknown argument $1"; print_usage; exit 1 ;;
    esac
  done
  
  download_libpng $libpng_version
  
  if [[ $android_abi -eq 'all' ]]; then
    for abi in arm arm64 x86 x86-64; do
      extract_libpng $libpng_version
      setup_env $android_ndk $abi $android_api_level
      build_libpng $libpng_version $abi $zlib_prefix $build_type
    done
  else
    extract_libpng $libpng_version
    setup_env $android_ndk $android_abi $android_api_level
    build_libpng $libpng_version $android_abi $zlib_prefix $build_type
  fi
  exit 0
}

main $@