package/flutter-engine/flutter-engine.mk - buildroot - Git at Google

 ################################################################################
 #
 # flutter-engine
 #
 ################################################################################

 # Flutter-engine has a release on the GitHub page. However, that release is
 # only for Google. Its intended purpose is for the gclient tool provided by
 # Google in their depot-tools package. To use the source code, we must use
 # gclient to download the flutter-engine source code along with several other
 # projects. Unfortunately, the Buildroot download system does not have the
 # capability of using gclient, and considering this package is the only
 # package that uses gclient, we side-step the entire download process and
 # perform the following steps if a tarball does not exist already:
 #
 #  - Copy the pre-made gclient config file to a temporary scratch directory.
 #  - Run gclient sync to generate a source directory with the proper
 #    flutter-engine source code in the correct places.
 #  - Create a source tarball.
 #  - Copy the source tarball to the $(FLUTTER_ENGINE_DL_DIR) directory.
 #
 # There is no hash provided, as the gn binary (used for configuration) relies
 # on the .git directories. As such, a reproducible tarball is not possible.
 FLUTTER_ENGINE_VERSION = 3.24.0

 # There is nothing for Buildroot to download. This is handled by gclient.
 FLUTTER_ENGINE_SITE =
 FLUTTER_ENGINE_SOURCE =
 FLUTTER_ENGINE_LICENSE = BSD-3-Clause
 FLUTTER_ENGINE_LICENSE_FILES = LICENSE
 FLUTTER_ENGINE_TARBALL_PATH = $(FLUTTER_ENGINE_DL_DIR)/flutter-$(FLUTTER_ENGINE_VERSION).tar.gz
 FLUTTER_ENGINE_INSTALL_STAGING = YES
 FLUTTER_ENGINE_DOWNLOAD_DEPENDENCIES = host-depot-tools
 FLUTTER_ENGINE_DEPENDENCIES = \
 	host-flutter-sdk-bin \
 	host-ninja \
 	host-pkgconf \
 	freetype \
 	zlib

 # Dispatch all architectures of flutter
 # FLUTTER_ENGINE_TARGET_TRIPPLE must match the directory name found in
 # buildtools/linux-x64/clang/lib/clang/*/lib
 ifeq ($(BR2_aarch64),y)
 FLUTTER_ENGINE_TARGET_ARCH = arm64
 FLUTTER_ENGINE_TARGET_TRIPPLE = aarch64-unknown-linux-gnu
 else ifeq ($(BR2_arm)$(BR2_armeb),y)
 FLUTTER_ENGINE_TARGET_ARCH = arm
 FLUTTER_ENGINE_TARGET_TRIPPLE = armv7-unknown-linux-gnueabihf
 else ifeq ($(BR2_x86_64),y)
 FLUTTER_ENGINE_TARGET_ARCH = x64
 FLUTTER_ENGINE_TARGET_TRIPPLE = x86_64-unknown-linux-gnu
 endif

 ifeq ($(FLUTTER_ENGINE_RUNTIME_MODE_PROFILE),y)
 FLUTTER_ENGINE_RUNTIME_MODE=profile
 else ifeq ($(BR2_ENABLE_RUNTIME_DEBUG),y)
 FLUTTER_ENGINE_RUNTIME_MODE=debug
 else
 FLUTTER_ENGINE_RUNTIME_MODE=release
 endif

 FLUTTER_ENGINE_BUILD_DIR = \
 	$(@D)/out/linux_$(FLUTTER_ENGINE_RUNTIME_MODE)_$(FLUTTER_ENGINE_TARGET_ARCH)

 FLUTTER_ENGINE_INSTALL_FILES = libflutter_engine.so

 # Flutter engine includes a bundled patched clang that must be used for
 # compiling or else there are linking errors.
 FLUTTER_ENGINE_CLANG_PATH = $(@D)/flutter/buildtools/linux-x64/clang

 FLUTTER_ENGINE_CONF_OPTS = \
 	--clang \
 	--embedder-for-target \
 	--linux-cpu $(FLUTTER_ENGINE_TARGET_ARCH) \
 	--no-build-embedder-examples \
 	--no-clang-static-analyzer \
 	--no-enable-unittests \
 	--no-goma \
 	--no-prebuilt-dart-sdk \
 	--no-stripped \
 	--runtime-mode $(FLUTTER_ENGINE_RUNTIME_MODE) \
 	--target-os linux \
 	--target-sysroot $(STAGING_DIR) \
 	--target-toolchain $(FLUTTER_ENGINE_CLANG_PATH) \
 	--target-triple $(FLUTTER_ENGINE_TARGET_TRIPPLE)

 ifeq ($(BR2_arm)$(BR2_armeb),y)
 FLUTTER_ENGINE_CONF_OPTS += \
 	--arm-float-abi $(call qstrip,$(BR2_GCC_TARGET_FLOAT_ABI))
 endif

 # We must specify a full path to ccache and a full path to the flutter-engine
 # provided clang in order to use ccache, or else flutter-engine will error out
 # attempting to find ccache in the target-toolchain provided path.
 ifeq ($(BR2_CCACHE),y)
 define FLUTTER_ENGINE_COMPILER_PATH_FIXUP
 	$(SED) "s%cc =.*%cc = \"$(HOST_DIR)/bin/ccache $(FLUTTER_ENGINE_CLANG_PATH)/bin/clang\""%g \
 		$(@D)/build/toolchain/custom/BUILD.gn

 	$(SED) "s%cxx =.*%cxx = \"$(HOST_DIR)/bin/ccache $(FLUTTER_ENGINE_CLANG_PATH)/bin/clang++\""%g \
 		$(@D)/build/toolchain/custom/BUILD.gn
 endef
 FLUTTER_ENGINE_PRE_CONFIGURE_HOOKS += FLUTTER_ENGINE_COMPILER_PATH_FIXUP
 endif

 ifeq ($(BR2_ENABLE_LTO),y)
 FLUTTER_ENGINE_CONF_OPTS += --lto
 else
 FLUTTER_ENGINE_CONF_OPTS += --no-lto
 endif

 ifeq ($(BR2_OPTIMIZE_0),y)
 FLUTTER_ENGINE_CONF_OPTS += --unoptimized
 endif

 # There is no --disable-fontconfig option.
 ifeq ($(BR2_PACKAGE_FONTCONFIG),y)
 FLUTTER_ENGINE_DEPENDENCIES += fontconfig
 FLUTTER_ENGINE_CONF_OPTS += --enable-fontconfig
 endif

 ifeq ($(BR2_PACKAGE_HAS_LIBGL),y)
 FLUTTER_ENGINE_DEPENDENCIES += libgl
 endif

 ifeq ($(BR2_PACKAGE_HAS_LIBGLES),y)
 FLUTTER_ENGINE_DEPENDENCIES += libgles
 FLUTTER_ENGINE_CONF_OPTS += --enable-impeller-3d
 endif

 ifeq ($(BR2_PACKAGE_LIBGLFW),y)
 FLUTTER_ENGINE_DEPENDENCIES += libglfw
 FLUTTER_ENGINE_CONF_OPTS += --build-glfw-shell
 else
 FLUTTER_ENGINE_CONF_OPTS += --no-build-glfw-shell
 endif

 ifeq ($(BR2_PACKAGE_LIBGTK3),y)
 FLUTTER_ENGINE_DEPENDENCIES += libgtk3
 FLUTTER_ENGINE_INSTALL_FILES += libflutter_linux_gtk.so
 else
 FLUTTER_ENGINE_CONF_OPTS += --disable-desktop-embeddings
 endif

 # There is no --disable-vulkan option
 ifeq ($(BR2_PACKAGE_MESA3D_VULKAN_DRIVER),y)
 FLUTTER_ENGINE_CONF_OPTS += --enable-vulkan --enable-impeller-vulkan
 endif

 ifeq ($(BR2_PACKAGE_XORG7)$(BR2_PACKAGE_LIBXCB),yy)
 FLUTTER_ENGINE_DEPENDENCIES += libxcb
 else
 define FLUTTER_ENGINE_VULKAN_X11_SUPPORT_FIXUP
 	$(SED) "s%vulkan_use_x11.*%vulkan_use_x11 = false%g" -i \
 		$(@D)/flutter/build_overrides/vulkan_headers.gni

 	$(SED) "s%ozone_platform_x11.*%ozone_platform_x11 = false%g" \
 		$(@D)/build/config/BUILDCONFIG.gn
 endef
 FLUTTER_ENGINE_PRE_CONFIGURE_HOOKS += FLUTTER_ENGINE_VULKAN_X11_SUPPORT_FIXUP
 endif

 ifeq ($(BR2_PACKAGE_WAYLAND),y)
 FLUTTER_ENGINE_DEPENDENCIES += wayland
 else
 define FLUTTER_ENGINE_VULKAN_WAYLAND_SUPPORT_FIXUP
 	$(SED) "s%vulkan_use_wayland.*%vulkan_use_wayland = false%g" \
 		$(@D)/flutter/build_overrides/vulkan_headers.gni

 	$(SED) "s%ozone_platform_wayland.*%ozone_platform_wayland = false%g" \
 		$(@D)/build/config/BUILDCONFIG.gn
 endef
 FLUTTER_ENGINE_PRE_CONFIGURE_HOOKS += FLUTTER_ENGINE_VULKAN_WAYLAND_SUPPORT_FIXUP
 endif

 # Generate a tarball if one does not already exist.
 define FLUTTER_ENGINE_GENERATE_TARBALL
 	TAR="$(TAR)" \
 	PATH=$(HOST_DIR)/share/depot_tools:$(BR_PATH) \
 	PYTHONPATH=$(HOST_DIR)/lib/python$(PYTHON3_VERSION_MAJOR) \
 	PUB_CACHE=$(FLUTTER_SDK_BIN_PUB_CACHE) \
 	$(FLUTTER_ENGINE_PKGDIR)/gen-tarball \
 		--dot-gclient $(TOPDIR)/$(FLUTTER_ENGINE_PKGDIR)/dot-gclient \
 		--jobs $(PARALLEL_JOBS) \
 		--scratch-dir $(@D)/dl-tmp \
 		--tarball-dl-path $(FLUTTER_ENGINE_TARBALL_PATH) \
 		--version $(FLUTTER_ENGINE_VERSION)
 endef
 FLUTTER_ENGINE_POST_DOWNLOAD_HOOKS += FLUTTER_ENGINE_GENERATE_TARBALL

 define FLUTTER_ENGINE_EXTRACT_CMDS
 	$(call suitable-extractor,$(FLUTTER_ENGINE_TARBALL_PATH)) $(FLUTTER_ENGINE_TARBALL_PATH) \
 	| $(TAR) --strip-components=1 -C $(@D) $(TAR_OPTIONS) -
 endef

 # We must set the home directory to the sdk directory or else flutter will
 # place .dart, and .flutter in ~/.
 define FLUTTER_ENGINE_CONFIGURE_CMDS
 	cd $(@D) && \
 		rm -rf $(FLUTTER_ENGINE_BUILD_DIR) && \
 		PATH=$(HOST_DIR)/share/depot_tools:$(BR_PATH) \
 		PUB_CACHE=$(FLUTTER_SDK_BIN_PUB_CACHE) \
 		HOME=$(HOST_FLUTTER_SDK_BIN_SDK) \
 		./flutter/tools/gn \
 			$(FLUTTER_ENGINE_CONF_OPTS)
 endef

 define FLUTTER_ENGINE_BUILD_CMDS
 	cd $(@D) && \
 		PATH=$(HOST_DIR)/share/depot_tools:$(BR_PATH) \
 		PUB_CACHE=$(FLUTTER_SDK_BIN_PUB_CACHE) \
 		HOME=$(HOST_FLUTTER_SDK_BIN_SDK) \
 		$(HOST_DIR)/bin/ninja \
 			-j $(PARALLEL_JOBS) \
 			-C $(FLUTTER_ENGINE_BUILD_DIR)
 endef

 # Flutter-engine builds several host applications use for flutter development.
 # One of those applications is gen_snapshot, which turns applications into
 # usable .so files for the target architecture. Compiling a host version of
 # flutter-engine would result in binaries producing host-architecture
 # flutter applications .so files. As such, copy gen_snapshot to the host
 # directory here and name it flutter_gen_snapshot for clarity.
 FLUTTER_ENGINE_GEN_SNAPSHOT = $(HOST_DIR)/bin/flutter_gen_snapshot
 define FLUTTER_ENGINE_INSTALL_GEN_SNAPSHOT
 	$(INSTALL) -D -m 0755 $(FLUTTER_ENGINE_BUILD_DIR)/clang_x64/gen_snapshot \
 		$(HOST_DIR)/bin/flutter_gen_snapshot
 endef
 FLUTTER_ENGINE_POST_INSTALL_STAGING_HOOKS += FLUTTER_ENGINE_INSTALL_GEN_SNAPSHOT

 define FLUTTER_ENGINE_INSTALL_STAGING_CMDS
 	$(foreach i,$(FLUTTER_ENGINE_INSTALL_FILES),
 		$(INSTALL) -D -m 0755 $(FLUTTER_ENGINE_BUILD_DIR)/so.unstripped/$(i) \
 			$(STAGING_DIR)/usr/lib/$(i); \
 	)
 	$(INSTALL) -D -m 0755 $(FLUTTER_ENGINE_BUILD_DIR)/flutter_embedder.h \
 		$(STAGING_DIR)/usr/include/flutter_embedder.h

 	$(INSTALL) -D -m 0755 $(FLUTTER_ENGINE_BUILD_DIR)/icudtl.dat \
 		$(STAGING_DIR)/usr/share/flutter/$(FLUTTER_ENGINE_RUNTIME_MODE)/data/icudtl.dat
 endef

 define FLUTTER_ENGINE_INSTALL_TARGET_CMDS
 	$(foreach i,$(FLUTTER_ENGINE_INSTALL_FILES),
 		$(INSTALL) -D -m 0755 $(FLUTTER_ENGINE_BUILD_DIR)/so.unstripped/$(i) \
 			$(TARGET_DIR)/usr/lib/$(i); \
 	)
 	$(INSTALL) -D -m 0755 $(FLUTTER_ENGINE_BUILD_DIR)/icudtl.dat \
 		$(TARGET_DIR)/usr/share/flutter/$(FLUTTER_ENGINE_RUNTIME_MODE)/data/icudtl.dat
 endef

 $(eval $(generic-package))
	################################################################################
	#
	# flutter-engine
	#
	################################################################################

	# Flutter-engine has a release on the GitHub page. However, that release is
	# only for Google. Its intended purpose is for the gclient tool provided by
	# Google in their depot-tools package. To use the source code, we must use
	# gclient to download the flutter-engine source code along with several other
	# projects. Unfortunately, the Buildroot download system does not have the
	# capability of using gclient, and considering this package is the only
	# package that uses gclient, we side-step the entire download process and
	# perform the following steps if a tarball does not exist already:
	#
	# - Copy the pre-made gclient config file to a temporary scratch directory.
	# - Run gclient sync to generate a source directory with the proper
	# flutter-engine source code in the correct places.
	# - Create a source tarball.
	# - Copy the source tarball to the $(FLUTTER_ENGINE_DL_DIR) directory.
	#
	# There is no hash provided, as the gn binary (used for configuration) relies
	# on the .git directories. As such, a reproducible tarball is not possible.
	FLUTTER_ENGINE_VERSION = 3.24.0

	# There is nothing for Buildroot to download. This is handled by gclient.
	FLUTTER_ENGINE_SITE =
	FLUTTER_ENGINE_SOURCE =
	FLUTTER_ENGINE_LICENSE = BSD-3-Clause
	FLUTTER_ENGINE_LICENSE_FILES = LICENSE
	FLUTTER_ENGINE_TARBALL_PATH = $(FLUTTER_ENGINE_DL_DIR)/flutter-$(FLUTTER_ENGINE_VERSION).tar.gz
	FLUTTER_ENGINE_INSTALL_STAGING = YES
	FLUTTER_ENGINE_DOWNLOAD_DEPENDENCIES = host-depot-tools
	FLUTTER_ENGINE_DEPENDENCIES = \
	host-flutter-sdk-bin \
	host-ninja \
	host-pkgconf \
	freetype \
	zlib

	# Dispatch all architectures of flutter
	# FLUTTER_ENGINE_TARGET_TRIPPLE must match the directory name found in
	# buildtools/linux-x64/clang/lib/clang/*/lib
	ifeq ($(BR2_aarch64),y)
	FLUTTER_ENGINE_TARGET_ARCH = arm64
	FLUTTER_ENGINE_TARGET_TRIPPLE = aarch64-unknown-linux-gnu
	else ifeq ($(BR2_arm)$(BR2_armeb),y)
	FLUTTER_ENGINE_TARGET_ARCH = arm
	FLUTTER_ENGINE_TARGET_TRIPPLE = armv7-unknown-linux-gnueabihf
	else ifeq ($(BR2_x86_64),y)
	FLUTTER_ENGINE_TARGET_ARCH = x64
	FLUTTER_ENGINE_TARGET_TRIPPLE = x86_64-unknown-linux-gnu
	endif

	ifeq ($(FLUTTER_ENGINE_RUNTIME_MODE_PROFILE),y)
	FLUTTER_ENGINE_RUNTIME_MODE=profile
	else ifeq ($(BR2_ENABLE_RUNTIME_DEBUG),y)
	FLUTTER_ENGINE_RUNTIME_MODE=debug
	else
	FLUTTER_ENGINE_RUNTIME_MODE=release
	endif

	FLUTTER_ENGINE_BUILD_DIR = \
	$(@D)/out/linux_$(FLUTTER_ENGINE_RUNTIME_MODE)_$(FLUTTER_ENGINE_TARGET_ARCH)

	FLUTTER_ENGINE_INSTALL_FILES = libflutter_engine.so

	# Flutter engine includes a bundled patched clang that must be used for
	# compiling or else there are linking errors.
	FLUTTER_ENGINE_CLANG_PATH = $(@D)/flutter/buildtools/linux-x64/clang

	FLUTTER_ENGINE_CONF_OPTS = \
	--clang \
	--embedder-for-target \
	--linux-cpu $(FLUTTER_ENGINE_TARGET_ARCH) \
	--no-build-embedder-examples \
	--no-clang-static-analyzer \
	--no-enable-unittests \
	--no-goma \
	--no-prebuilt-dart-sdk \
	--no-stripped \
	--runtime-mode $(FLUTTER_ENGINE_RUNTIME_MODE) \
	--target-os linux \
	--target-sysroot $(STAGING_DIR) \
	--target-toolchain $(FLUTTER_ENGINE_CLANG_PATH) \
	--target-triple $(FLUTTER_ENGINE_TARGET_TRIPPLE)

	ifeq ($(BR2_arm)$(BR2_armeb),y)
	FLUTTER_ENGINE_CONF_OPTS += \
	--arm-float-abi $(call qstrip,$(BR2_GCC_TARGET_FLOAT_ABI))
	endif

	# We must specify a full path to ccache and a full path to the flutter-engine
	# provided clang in order to use ccache, or else flutter-engine will error out
	# attempting to find ccache in the target-toolchain provided path.
	ifeq ($(BR2_CCACHE),y)
	define FLUTTER_ENGINE_COMPILER_PATH_FIXUP
	$(SED) "s%cc =.*%cc = \"$(HOST_DIR)/bin/ccache $(FLUTTER_ENGINE_CLANG_PATH)/bin/clang\""%g \
	$(@D)/build/toolchain/custom/BUILD.gn

	$(SED) "s%cxx =.*%cxx = \"$(HOST_DIR)/bin/ccache $(FLUTTER_ENGINE_CLANG_PATH)/bin/clang++\""%g \
	$(@D)/build/toolchain/custom/BUILD.gn
	endef
	FLUTTER_ENGINE_PRE_CONFIGURE_HOOKS += FLUTTER_ENGINE_COMPILER_PATH_FIXUP
	endif

	ifeq ($(BR2_ENABLE_LTO),y)
	FLUTTER_ENGINE_CONF_OPTS += --lto
	else
	FLUTTER_ENGINE_CONF_OPTS += --no-lto
	endif

	ifeq ($(BR2_OPTIMIZE_0),y)
	FLUTTER_ENGINE_CONF_OPTS += --unoptimized
	endif

	# There is no --disable-fontconfig option.
	ifeq ($(BR2_PACKAGE_FONTCONFIG),y)
	FLUTTER_ENGINE_DEPENDENCIES += fontconfig
	FLUTTER_ENGINE_CONF_OPTS += --enable-fontconfig
	endif

	ifeq ($(BR2_PACKAGE_HAS_LIBGL),y)
	FLUTTER_ENGINE_DEPENDENCIES += libgl
	endif

	ifeq ($(BR2_PACKAGE_HAS_LIBGLES),y)
	FLUTTER_ENGINE_DEPENDENCIES += libgles
	FLUTTER_ENGINE_CONF_OPTS += --enable-impeller-3d
	endif

	ifeq ($(BR2_PACKAGE_LIBGLFW),y)
	FLUTTER_ENGINE_DEPENDENCIES += libglfw
	FLUTTER_ENGINE_CONF_OPTS += --build-glfw-shell
	else
	FLUTTER_ENGINE_CONF_OPTS += --no-build-glfw-shell
	endif

	ifeq ($(BR2_PACKAGE_LIBGTK3),y)
	FLUTTER_ENGINE_DEPENDENCIES += libgtk3
	FLUTTER_ENGINE_INSTALL_FILES += libflutter_linux_gtk.so
	else
	FLUTTER_ENGINE_CONF_OPTS += --disable-desktop-embeddings
	endif

	# There is no --disable-vulkan option
	ifeq ($(BR2_PACKAGE_MESA3D_VULKAN_DRIVER),y)
	FLUTTER_ENGINE_CONF_OPTS += --enable-vulkan --enable-impeller-vulkan
	endif

	ifeq ($(BR2_PACKAGE_XORG7)$(BR2_PACKAGE_LIBXCB),yy)
	FLUTTER_ENGINE_DEPENDENCIES += libxcb
	else
	define FLUTTER_ENGINE_VULKAN_X11_SUPPORT_FIXUP
	$(SED) "s%vulkan_use_x11.*%vulkan_use_x11 = false%g" -i \
	$(@D)/flutter/build_overrides/vulkan_headers.gni

	$(SED) "s%ozone_platform_x11.*%ozone_platform_x11 = false%g" \
	$(@D)/build/config/BUILDCONFIG.gn
	endef
	FLUTTER_ENGINE_PRE_CONFIGURE_HOOKS += FLUTTER_ENGINE_VULKAN_X11_SUPPORT_FIXUP
	endif

	ifeq ($(BR2_PACKAGE_WAYLAND),y)
	FLUTTER_ENGINE_DEPENDENCIES += wayland
	else
	define FLUTTER_ENGINE_VULKAN_WAYLAND_SUPPORT_FIXUP
	$(SED) "s%vulkan_use_wayland.*%vulkan_use_wayland = false%g" \
	$(@D)/flutter/build_overrides/vulkan_headers.gni

	$(SED) "s%ozone_platform_wayland.*%ozone_platform_wayland = false%g" \
	$(@D)/build/config/BUILDCONFIG.gn
	endef
	FLUTTER_ENGINE_PRE_CONFIGURE_HOOKS += FLUTTER_ENGINE_VULKAN_WAYLAND_SUPPORT_FIXUP
	endif

	# Generate a tarball if one does not already exist.
	define FLUTTER_ENGINE_GENERATE_TARBALL
	TAR="$(TAR)" \
	PATH=$(HOST_DIR)/share/depot_tools:$(BR_PATH) \
	PYTHONPATH=$(HOST_DIR)/lib/python$(PYTHON3_VERSION_MAJOR) \
	PUB_CACHE=$(FLUTTER_SDK_BIN_PUB_CACHE) \
	$(FLUTTER_ENGINE_PKGDIR)/gen-tarball \
	--dot-gclient $(TOPDIR)/$(FLUTTER_ENGINE_PKGDIR)/dot-gclient \
	--jobs $(PARALLEL_JOBS) \
	--scratch-dir $(@D)/dl-tmp \
	--tarball-dl-path $(FLUTTER_ENGINE_TARBALL_PATH) \
	--version $(FLUTTER_ENGINE_VERSION)
	endef
	FLUTTER_ENGINE_POST_DOWNLOAD_HOOKS += FLUTTER_ENGINE_GENERATE_TARBALL

	define FLUTTER_ENGINE_EXTRACT_CMDS
	$(call suitable-extractor,$(FLUTTER_ENGINE_TARBALL_PATH)) $(FLUTTER_ENGINE_TARBALL_PATH) \
	\| $(TAR) --strip-components=1 -C $(@D) $(TAR_OPTIONS) -
	endef

	# We must set the home directory to the sdk directory or else flutter will
	# place .dart, and .flutter in ~/.
	define FLUTTER_ENGINE_CONFIGURE_CMDS
	cd $(@D) && \
	rm -rf $(FLUTTER_ENGINE_BUILD_DIR) && \
	PATH=$(HOST_DIR)/share/depot_tools:$(BR_PATH) \
	PUB_CACHE=$(FLUTTER_SDK_BIN_PUB_CACHE) \
	HOME=$(HOST_FLUTTER_SDK_BIN_SDK) \
	./flutter/tools/gn \
	$(FLUTTER_ENGINE_CONF_OPTS)
	endef

	define FLUTTER_ENGINE_BUILD_CMDS
	cd $(@D) && \
	PATH=$(HOST_DIR)/share/depot_tools:$(BR_PATH) \
	PUB_CACHE=$(FLUTTER_SDK_BIN_PUB_CACHE) \
	HOME=$(HOST_FLUTTER_SDK_BIN_SDK) \
	$(HOST_DIR)/bin/ninja \
	-j $(PARALLEL_JOBS) \
	-C $(FLUTTER_ENGINE_BUILD_DIR)
	endef

	# Flutter-engine builds several host applications use for flutter development.
	# One of those applications is gen_snapshot, which turns applications into
	# usable .so files for the target architecture. Compiling a host version of
	# flutter-engine would result in binaries producing host-architecture
	# flutter applications .so files. As such, copy gen_snapshot to the host
	# directory here and name it flutter_gen_snapshot for clarity.
	FLUTTER_ENGINE_GEN_SNAPSHOT = $(HOST_DIR)/bin/flutter_gen_snapshot
	define FLUTTER_ENGINE_INSTALL_GEN_SNAPSHOT
	$(INSTALL) -D -m 0755 $(FLUTTER_ENGINE_BUILD_DIR)/clang_x64/gen_snapshot \
	$(HOST_DIR)/bin/flutter_gen_snapshot
	endef
	FLUTTER_ENGINE_POST_INSTALL_STAGING_HOOKS += FLUTTER_ENGINE_INSTALL_GEN_SNAPSHOT

	define FLUTTER_ENGINE_INSTALL_STAGING_CMDS
	$(foreach i,$(FLUTTER_ENGINE_INSTALL_FILES),
	$(INSTALL) -D -m 0755 $(FLUTTER_ENGINE_BUILD_DIR)/so.unstripped/$(i) \
	$(STAGING_DIR)/usr/lib/$(i); \
	)
	$(INSTALL) -D -m 0755 $(FLUTTER_ENGINE_BUILD_DIR)/flutter_embedder.h \
	$(STAGING_DIR)/usr/include/flutter_embedder.h

	$(INSTALL) -D -m 0755 $(FLUTTER_ENGINE_BUILD_DIR)/icudtl.dat \
	$(STAGING_DIR)/usr/share/flutter/$(FLUTTER_ENGINE_RUNTIME_MODE)/data/icudtl.dat
	endef

	define FLUTTER_ENGINE_INSTALL_TARGET_CMDS
	$(foreach i,$(FLUTTER_ENGINE_INSTALL_FILES),
	$(INSTALL) -D -m 0755 $(FLUTTER_ENGINE_BUILD_DIR)/so.unstripped/$(i) \
	$(TARGET_DIR)/usr/lib/$(i); \
	)
	$(INSTALL) -D -m 0755 $(FLUTTER_ENGINE_BUILD_DIR)/icudtl.dat \
	$(TARGET_DIR)/usr/share/flutter/$(FLUTTER_ENGINE_RUNTIME_MODE)/data/icudtl.dat
	endef

	$(eval $(generic-package))