build: improve the Linux aspect of things (#75)

Improved, fixed and streamlined cmake files. Optionally use system libraries instead of vcpkg (-DENABLE_VCPKG=OFF)

cmake/FindZArchive.cmake

@@ -0,0 +1,20 @@
+# SPDX-FileCopyrightText: 2022 Andrea Pappacoda <andrea@pappacoda.it>
+# SPDX-License-Identifier: ISC
+
+find_package(PkgConfig)
+
+if (PKG_CONFIG_FOUND)
+	pkg_search_module(zarchive IMPORTED_TARGET GLOBAL zarchive)
+	if (zarchive_FOUND)
+		add_library(ZArchive::zarchive ALIAS PkgConfig::zarchive)
+	endif()
+endif()
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(ZArchive
+	REQUIRED_VARS
+		zarchive_LINK_LIBRARIES
+		zarchive_FOUND
+	VERSION_VAR
+		zarchive_VERSION
+)

cmake/Findimgui.cmake

@@ -0,0 +1,27 @@
+# SPDX-FileCopyrightText: 2022 Andrea Pappacoda <andrea@pappacoda.it>
+# SPDX-License-Identifier: ISC
+
+include(FindPackageHandleStandardArgs)
+
+find_package(imgui CONFIG)
+if (imgui_FOUND)
+	# Use upstream imguiConfig.cmake if possible
+	find_package_handle_standard_args(imgui CONFIG_MODE)
+else()
+	# Fallback to pkg-config otherwise
+	find_package(PkgConfig)
+	if (PKG_CONFIG_FOUND)
+		pkg_search_module(imgui IMPORTED_TARGET GLOBAL imgui)
+		if (imgui_FOUND)
+			add_library(imgui::imgui ALIAS PkgConfig::imgui)
+		endif()
+	endif()
+
+	find_package_handle_standard_args(imgui
+		REQUIRED_VARS
+			imgui_LINK_LIBRARIES
+			imgui_FOUND
+		VERSION_VAR
+			imgui_VERSION
+	)
+endif()

cmake/FindwxWidgets.cmake

@@ -0,0 +1,49 @@
+# SPDX-FileCopyrightText: 2022 Andrea Pappacoda <andrea@pappacoda.it>
+# SPDX-License-Identifier: ISC
+
+include(FindPackageHandleStandardArgs)
+find_package(wxWidgets CONFIG COMPONENTS ${wxWidgets_FIND_COMPONENTS})
+
+if (wxWidgets_FOUND)
+	# Use upstream wxWidgetsConfig.cmake if possible
+	find_package_handle_standard_args(wxWidgets CONFIG_MODE)
+else()
+	# Fall back to CMake's FindwxWidgets
+	# Temporarily unset CMAKE_MODULE_PATH to avoid calling the current find
+	# module recursively
+	set(_tmp_module_path "${CMAKE_MODULE_PATH}")
+	set(CMAKE_MODULE_PATH "")
+
+	find_package(wxWidgets MODULE QUIET COMPONENTS ${wxWidgets_FIND_COMPONENTS})
+
+	set(CMAKE_MODULE_PATH "${_tmp_module_path}")
+	unset(_tmp_module_path)
+
+	if (wxWidgets_FOUND)
+		add_library(wx::base IMPORTED INTERFACE)
+		target_include_directories(wx::base INTERFACE ${wxWidgets_INCLUDE_DIRS})
+		target_link_libraries(wx::base INTERFACE ${wxWidgets_LIBRARIES})
+		target_link_directories(wx::base INTERFACE ${wxWidgets_LIBRARY_DIRS})
+		target_compile_definitions(wx::base INTERFACE ${wxWidgets_DEFINITIONS})
+		target_compile_options(wx::base INTERFACE ${wxWidgets_CXX_FLAGS})
+
+		# FindwxWidgets sets everything into a single set of variables, so it is
+		# impossible to tell what libraries are required for what component.
+		# To be compatible with wxWidgetsConfig, we create an alias for each
+		# component so that the user can still use target_link_libraries(wx::gl)
+		foreach(component ${wxWidgets_FIND_COMPONENTS})
+			if (NOT component STREQUAL "base")
+				# don't alias base to itself
+				add_library(wx::${component} ALIAS wx::base)
+			endif()
+		endforeach()
+	endif()
+
+	find_package_handle_standard_args(wxWidgets
+		REQUIRED_VARS
+			wxWidgets_LIBRARIES
+			wxWidgets_FOUND
+		VERSION_VAR
+			wxWidgets_VERSION_STRING
+	)
+endif()

cmake/Findzstd.cmake

@@ -0,0 +1,33 @@
+# SPDX-FileCopyrightText: 2022 Andrea Pappacoda <andrea@pappacoda.it>
+# SPDX-License-Identifier: ISC
+
+include(FindPackageHandleStandardArgs)
+
+find_package(zstd CONFIG)
+if (zstd_FOUND)
+	# Use upstream zstdConfig.cmake if possible
+	if (NOT TARGET zstd::zstd)
+		if (TARGET zstd::libzstd_static)
+			add_library(zstd::zstd ALIAS zstd::libzstd_static)
+		elseif (TARGET zstd::libzstd_shared)
+			add_library(zstd::zstd ALIAS zstd::libzstd_shared)
+		endif()
+	endif()
+	find_package_handle_standard_args(zstd CONFIG_MODE)
+else()
+	# Fallback to pkg-config otherwise
+	find_package(PkgConfig)
+	if (PKG_CONFIG_FOUND)
+		pkg_search_module(libzstd IMPORTED_TARGET GLOBAL libzstd)
+		if (libzstd_FOUND)
+			add_library(zstd::zstd ALIAS PkgConfig::libzstd)
+		endif()
+	endif()
+
+	find_package_handle_standard_args(zstd
+		REQUIRED_VARS
+			libzstd_LINK_LIBRARIES
+			libzstd_FOUND
+		VERSION_VAR libzstd_VERSION
+	)
+endif()