RmlUi/CMake/Modules/Emscripten/FindFreetype.cmake

#[[
	Custom find module for Freetype for Emscripten compilation.

	Input variables:
		none
	Output variables:
		Freetype_FOUND
		FREETYPE_VERSION_STRING

	Resulting targets:
		Freetype::Freetype

	More info:
	https://emscripten.org/docs/porting/multimedia_and_graphics/OpenGL-support.html
]]

include(FindPackageHandleStandardArgs)
include(FindPackageMessage)

if(NOT TARGET Freetype::Freetype)
	# If no version was specified, set default
	if(NOT DEFINED Freetype_FIND_VERSION)
		set(Freetype_FIND_VERSION "2")
	endif()

	# Check if requested Freetype version is valid
	# Emscripten SDK only provides Freetype 2.x
	if((Freetype_FIND_VERSION VERSION_LESS "2") OR (Freetype_FIND_VERSION VERSION_GREATER_EQUAL "3"))
		message(FATAL_ERROR "The requested Freetype version ${Freetype_FIND_VERSION} is invalid.")
	endif()

	# Emscripten includes Freetype support as part of it's SDK, meaning there's no need to find it
	set(Freetype_FOUND TRUE)
	add_library(Freetype::Freetype INTERFACE IMPORTED)

	# Set found Freetype version
	# Version set based on latest Emscripten SDK at the time of writing this file
	set(FREETYPE_VERSION_STRING "2.6")

	# Enable compilation and linking against Freetype
	target_compile_options(Freetype::Freetype INTERFACE "-sUSE_FREETYPE=1")
	target_link_libraries(Freetype::Freetype INTERFACE "-sUSE_FREETYPE=1")

	# Get final compiler and linker flags to print them
	get_target_property(Freetype_COMPILE_FLAGS Freetype::Freetype "INTERFACE_COMPILE_OPTIONS")
	get_target_property(Freetype_LINK_FLAGS Freetype::Freetype "INTERFACE_LINK_OPTIONS")

	find_package_message(
		"Freetype"
		"Freetype ${FREETYPE_VERSION_STRING} has been found as part of the Emscripten SDK."
		"[${Freetype_COMPILE_FLAGS}][${Freetype_LINK_FLAGS}]"
	)

	# Clean scope
	unset(Freetype_COMPILE_FLAGS)
	unset(Freetype_LINK_FLAGS)
else()
	# Since the target already exists, we declare it as found
	set(Freetype_FOUND TRUE)
	if(NOT DEFINED FREETYPE_VERSION_STRING)
		set(FREETYPE_VERSION_STRING "UNKNOWN")
	endif()
endif()