From 3e8111aaee070dc9b5d51cab3fd44ff88841f63e Mon Sep 17 00:00:00 2001
From: Thomas Vanbesien <tvanbesi@proton.me>
Date: Tue, 24 Feb 2026 17:41:35 +0100
Subject: Make build system usable as a git submodule

Replace CMAKE_SOURCE_DIR/CMAKE_BINARY_DIR with PROJECT_SOURCE_DIR/
PROJECT_BINARY_DIR so paths resolve correctly from add_subdirectory().
Guard global settings (CMAKE_CXX_STANDARD, CMAKE_BUILD_RPATH,
qt_standard_project_setup, demo) behind PROJECT_IS_TOP_LEVEL.
Export OPEN62541_INSTALL_DIR and QTOPCUA_INSTALL_DIR as CACHE INTERNAL
so parent projects can set up RPATH and plugin paths.
---
 CMakeLists.txt | 46 +++++++++++++++++++++++++++-------------------
 1 file changed, 27 insertions(+), 19 deletions(-)

(limited to 'CMakeLists.txt')

diff --git a/CMakeLists.txt b/CMakeLists.txt
index f35b498..51b90e8 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,9 +1,11 @@
 cmake_minimum_required(VERSION 3.16)
 project(BobinkQtOpcUa LANGUAGES CXX)
 
-set(CMAKE_CXX_STANDARD 17)
-set(CMAKE_CXX_STANDARD_REQUIRED ON)
-set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+if(PROJECT_IS_TOP_LEVEL)
+  set(CMAKE_CXX_STANDARD 17)
+  set(CMAKE_CXX_STANDARD_REQUIRED ON)
+  set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+endif()
 
 # Build external dependencies (open62541, qtopcua) if not already built
 include(cmake/BuildDeps.cmake)
@@ -19,21 +21,27 @@ set(Qt6DeclarativeOpcua_DIR "${QTOPCUA_INSTALL_DIR}/lib/cmake/Qt6DeclarativeOpcu
 list(PREPEND CMAKE_PREFIX_PATH "${OPEN62541_INSTALL_DIR}")
 
 find_package(Qt6 6.10.2 REQUIRED COMPONENTS Core Qml Quick OpcUa)
-qt_standard_project_setup(REQUIRES 6.10.2)
-
-# Set path for qmllint
-set(QML_IMPORT_PATH
-    "${CMAKE_CURRENT_BINARY_DIR}/qml"
-    CACHE STRING "Path to locally built qml")
-# Generate .qmlls.ini for QML Language Server. Useful once QtOpcUa is installed
-# globally (qt-cmake --install build/deps/qtopcua-build) so qmlls can resolve
-# all Qt QML imports without extra importPaths. set(QT_QML_GENERATE_QMLLS_INI ON
-# CACHE BOOL "")
-
-# Ensure the local QtOpcUa and open62541 libs are findable at runtime (needed
-# because the Qt plugin loader dlopen's the open62541 backend).
-set(CMAKE_BUILD_RPATH "${QTOPCUA_INSTALL_DIR}/lib"
-                      "${OPEN62541_INSTALL_DIR}/lib")
+
+if(PROJECT_IS_TOP_LEVEL)
+  qt_standard_project_setup(REQUIRES 6.10.2)
+
+  # Set path for qmllint
+  set(QML_IMPORT_PATH
+      "${CMAKE_CURRENT_BINARY_DIR}/qml"
+      CACHE STRING "Path to locally built qml")
+  # Generate .qmlls.ini for QML Language Server. Useful once QtOpcUa is installed
+  # globally (qt-cmake --install build/deps/qtopcua-build) so qmlls can resolve
+  # all Qt QML imports without extra importPaths. set(QT_QML_GENERATE_QMLLS_INI ON
+  # CACHE BOOL "")
+
+  # Ensure the local QtOpcUa and open62541 libs are findable at runtime (needed
+  # because the Qt plugin loader dlopen's the open62541 backend).
+  set(CMAKE_BUILD_RPATH "${QTOPCUA_INSTALL_DIR}/lib"
+                        "${OPEN62541_INSTALL_DIR}/lib")
+endif()
 
 add_subdirectory(src)
-add_subdirectory(demo)
+
+if(PROJECT_IS_TOP_LEVEL)
+  add_subdirectory(demo)
+endif()
-- 
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