CaltechOpticalObservatories · astronomerdave · Sep 28, 2026 · Sep 28, 2026 · Sep 28, 2026 · Sep 28, 2026
@@ -121,3 +121,70 @@ jobs:
         shell: bash
         run: |
           cmake --build build -j"$(nproc)"
+
+  cmake-3-24-subproject:
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+
+    env:
+      CMAKE_324: cmake-3.24.4-linux-x86_64
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Install dependencies
+        shell: bash
+        run: |
+          bash .github/workflows/install-deps.sh
+
+      - name: Build and install zmqpp from source
+        shell: bash
+        run: |
+          git clone --depth 1 https://github.com/zeromq/zmqpp.git /tmp/zmqpp
+          cmake -S /tmp/zmqpp -B /tmp/zmqpp/build
+          cmake --build /tmp/zmqpp/build -j"$(nproc)"
+          sudo cmake --install /tmp/zmqpp/build
+          sudo ldconfig
+
+      # The declared minimum is only true if something builds with it
+      - name: Install CMake 3.24.4
+        shell: bash
+        run: |
+          cd "$RUNNER_TEMP"
+          curl -sSLO "https://github.com/Kitware/CMake/releases/download/v3.24.4/${CMAKE_324}.tar.gz"
+          echo "cac77d28fb8668c179ac02c283b058aeb846fe2133a57d40b503711281ed9f19  ${CMAKE_324}.tar.gz" | sha256sum -c
+          tar xzf "${CMAKE_324}.tar.gz"
+          echo "$RUNNER_TEMP/${CMAKE_324}/bin" >> "$GITHUB_PATH"
+
+      - name: Build the core as a top-level project
+        shell: bash
+        run: |
+          cmake --version
+          cmake -G Ninja -S . -B build -DCONTROLLER=archon
+          cmake --build build -j"$(nproc)"
+
+      # Stands in for an instrument's build: the core composed as a subproject,
+      # and a translation unit of the consumer's own that includes its headers
+      - name: Build the core as a subproject
+        shell: bash
+        run: |
+          mkdir -p "$RUNNER_TEMP/consumer"
+          cd "$RUNNER_TEMP/consumer"
+          cat > CMakeLists.txt <<'EOF'
+          cmake_minimum_required(VERSION 3.24)
+          project(consumer CXX)
+          # Below the core's C++17, so the core has to raise it for its headers
+          set(CMAKE_CXX_STANDARD 14)
+          set(CONTROLLER archon CACHE STRING "")
+          include(FetchContent)
+          FetchContent_Declare(camerad SOURCE_DIR ${CAMERAD_SOURCE_DIR})
+          FetchContent_MakeAvailable(camerad)
+          add_library(consumer OBJECT consumer.cpp)
+          target_link_libraries(consumer PRIVATE camerad_base)
+          EOF
+          cat > consumer.cpp <<'EOF'
+          #include "camera_interface.h"
+          EOF
+          cmake -G Ninja -S . -B build -DCAMERAD_SOURCE_DIR="$GITHUB_WORKSPACE"
+          cmake --build build -j"$(nproc)"
@@ -22,7 +22,7 @@ jobs:
         sudo apt-get install -y \
           libccfits-dev libcfitsio-dev libcurl4-openssl-dev \
           nlohmann-json3-dev libzmq3-dev \
-          libopencv-dev libboost-thread-dev libboost-chrono-dev
+          libboost-thread-dev libboost-chrono-dev
 
     - name: Build and install zmqpp from source
       run: |
@@ -131,7 +131,7 @@ jobs:
         sudo apt-get install -y \
           libccfits-dev libcfitsio-dev libcurl4-openssl-dev \
           nlohmann-json3-dev libzmq3-dev \
-          libopencv-dev libboost-thread-dev libboost-chrono-dev \
+          libboost-thread-dev libboost-chrono-dev \
           python3-dev python3-pip
         python3 -m pip install --upgrade pybind11
 
@@ -212,7 +212,7 @@ jobs:
         sudo apt-get install -y \
           libccfits-dev libcfitsio-dev libcurl4-openssl-dev \
           nlohmann-json3-dev libzmq3-dev \
-          libopencv-dev libboost-thread-dev libboost-chrono-dev
+          libboost-thread-dev libboost-chrono-dev
 
     - name: Build and install zmqpp from source
       run: |

@@ -13,7 +13,6 @@ packages=(
   libgtest-dev
   nlohmann-json3-dev
   libzmq3-dev
-  libopencv-dev
   libboost-thread-dev
   libboost-chrono-dev
 )

@@ -4,7 +4,7 @@
 # @author  David Hale <dhale@caltech.edu>
 # ----------------------------------------------------------------------------
 
-cmake_minimum_required( VERSION 3.12 )
+cmake_minimum_required( VERSION 3.24 )
 
 add_definitions( -std=c++17 -O3 -Wall -c -fmessage-length=0 -fPIC -MMD -MP -MF )
 

@@ -4,7 +4,7 @@
 # @author  David Hale <dhale@caltech.edu>
 # ----------------------------------------------------------------------------
 
-cmake_minimum_required( VERSION 3.12 )
+cmake_minimum_required( VERSION 3.24 )
 
 include_directories( ${ARC_DIR}/CArcBase/inc )
 include_directories( ${CARC_DEVICE_DIR}/inc )

@@ -4,7 +4,7 @@
 # @author  David Hale <dhale@caltech.edu>
 # ----------------------------------------------------------------------------
 
-cmake_minimum_required( VERSION 3.12 )
+cmake_minimum_required( VERSION 3.24 )
 
 add_definitions( -std=c++17 -O0 -Wall -c -fmessage-length=0 -D_REENTRANT -fPIC -MMD -MP -MF )
 

@@ -4,7 +4,7 @@
 # @author  David Hale <dhale@caltech.edu>
 # ----------------------------------------------------------------------------
 
-cmake_minimum_required( VERSION 3.12 )
+cmake_minimum_required( VERSION 3.24 )
 
 set( ARC_DIR ${PROJECT_BASE_DIR}/ARC )
 

@@ -34,7 +34,7 @@ option(ENABLE_SHM_OUTPUT "Build shared-memory output support (requires ImageStre
 # un-comment the following to log verbose debug messages
 #add_definitions(-DLOGLEVEL_DEBUG)
 
-cmake_minimum_required(VERSION 3.12)
+cmake_minimum_required(VERSION 3.24)
 
 # Choosing the compiler belongs to whoever owns the build. A parent project has
 # already detected a compiler by the time it descends into this file, and
@@ -62,7 +62,7 @@ set(PROJECT_BASE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
 # A wheel build has nowhere to put a source-tree bin/, so let CMake keep its
 # outputs in the build directory. A project that add_subdirectory()s this one
 # has nowhere to put them either, and its source tree is not ours to write into
-if (NOT SKBUILD AND CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
+if (NOT SKBUILD AND PROJECT_IS_TOP_LEVEL)
   set(EXECUTABLE_OUTPUT_PATH ${PROJECT_BASE_DIR}/bin)
   set(LIBRARY_OUTPUT_PATH ${PROJECT_BASE_DIR}/lib)
 endif()
@@ -88,8 +88,15 @@ if (BUILD_PYTHON_MODULE)
   set(CMAKE_POSITION_INDEPENDENT_CODE ON)
 endif()
 
+# A project that composes this one gets the libraries; the programs and the
+# install rules are built only if it asks for them
+option(CAMERAD_BUILD_TOOLS "Build the emulator, listener, socksend and shm_reader" ${PROJECT_IS_TOP_LEVEL})
+option(CAMERAD_INSTALL "Generate install rules" ${PROJECT_IS_TOP_LEVEL})
+
 add_subdirectory(${PROJECT_BASE_DIR}/utils)
 add_subdirectory(${PROJECT_BASE_DIR}/common)
 add_subdirectory(${PROJECT_BASE_DIR}/camerad)
-add_subdirectory(${PROJECT_BASE_DIR}/emulator)
+if (CAMERAD_BUILD_TOOLS)
+  add_subdirectory(${PROJECT_BASE_DIR}/emulator)
+endif()
 add_subdirectory(${PROJECT_BASE_DIR}/tests EXCLUDE_FROM_ALL)
@@ -15,7 +15,7 @@ If you encounter any problems or have questions about this project, please open
 
 ## Requirements
 
-- **CMake** 3.12 or higher
+- **CMake** 3.24 or higher
 - **cfitsio** and **CCFits** libraries (expected in `/usr/local/lib`)
 - **gtest** (Google Test) library (needed to run unit tests)
 
@@ -81,7 +81,7 @@ If you encounter any problems or have questions about this project, please open
 
    pybind11 is located by asking the interpreter CMake selected, so pass `-DPython3_EXECUTABLE=...` to build against a specific one (a virtualenv, say). The module and that interpreter then always agree on the ABI.
 
-   pybind11 is header-only and needed only to compile: the built module links cfitsio, CCfits and OpenCV but not pybind11, so it does not have to be present where the module is imported.
+   pybind11 is header-only and needed only to compile: the built module links cfitsio and CCfits but not pybind11, so it does not have to be present where the module is imported.
 
 4. **Compile the sources:**
 

@@ -4,7 +4,7 @@
 # @author  David Hale <dhale@caltech.edu>
 # ----------------------------------------------------------------------------
 
-cmake_minimum_required( VERSION 3.12 )
+cmake_minimum_required( VERSION 3.24 )
 
 set( CAMERAD_DIR ${PROJECT_BASE_DIR}/camerad )
 
@@ -146,6 +146,9 @@ target_link_libraries(camerad_base PUBLIC
                       logentry
                       frame_output_factory
                       )
+# The public headers need C++17. The standard set for this directory is not
+# inherited by a project consuming this one, so it has to travel with the target
+target_compile_features(camerad_base PUBLIC cxx_std_17)
 
 # ----------------------------------------------------------------------------
 # controller implementation, linking the base PUBLIC so that anything
@@ -181,11 +184,6 @@ find_library(CFITS_LIB cfitsio NAMES libcfitsio  PATHS /usr/local/lib)
 find_library( ZMQPP_LIB zmqpp NAMES libzmqpp PATHS /usr/local/lib )
 find_library( ZMQ_LIB zmq NAMES libzmq PATHS /usr/local/lib )
 
-# OpenCV
-#
-find_package( OpenCV REQUIRED )
-include_directories( ${OpenCV_INCLUDE_DIRS} )
-
 # Boost
 #
 find_package(Boost REQUIRED COMPONENTS thread chrono)
@@ -215,15 +213,16 @@ target_link_libraries(camerad
   ${CMAKE_THREAD_LIBS_INIT}
   ${CCFITS_LIB}
   ${CFITS_LIB}
-  ${OpenCV_LIBS}
   ${BOOST_INCLUDES}
   Boost::thread
   Boost::chrono
   ${ZMQPP_LIB}
   ${ZMQ_LIB}
   )
 
-install(TARGETS camerad RUNTIME DESTINATION ${CAMERAD_INSTALL_BINDIR})
+if (CAMERAD_INSTALL)
+  install(TARGETS camerad RUNTIME DESTINATION ${CAMERAD_INSTALL_BINDIR})
+endif()
 
 # ----------------------------------------------------------------------------
 # optional Python module

@@ -4,7 +4,7 @@
 # @author  David Hale <dhale@caltech.edu>
 # ----------------------------------------------------------------------------
 
-cmake_minimum_required(VERSION 3.12)
+cmake_minimum_required(VERSION 3.24)
 
 set(PROJECT_UTILS_DIR ${PROJECT_BASE_DIR}/common)
 

@@ -5,10 +5,10 @@ emulator stands in for the hardware.
 
 ## Dependencies
 
-`camerad` needs a C++20 compiler, CMake 3.12 or newer, and:
+`camerad` needs a C++20 compiler, CMake 3.24 or newer, and:
 
 - cfitsio and CCfits, for FITS output
-- OpenCV, Boost (thread and chrono), nlohmann-json
+- Boost (thread and chrono), nlohmann-json
 - ZeroMQ and [zmqpp](https://github.com/zeromq/zmqpp), which is not usually packaged and is built from source
 - gtest, to run the unit tests
 - [ImageStreamIO](https://github.com/milk-org/ImageStreamIO), only for the shared-memory output
@@ -18,7 +18,7 @@ On Debian or Ubuntu the packaged ones are what CI installs:
 ```bash
 sudo apt-get install -y build-essential cmake ninja-build \
   libccfits-dev libcfitsio-dev libcurl4-openssl-dev libgtest-dev \
-  nlohmann-json3-dev libzmq3-dev libopencv-dev \
+  nlohmann-json3-dev libzmq3-dev \
   libboost-thread-dev libboost-chrono-dev
 ```
 

@@ -2,7 +2,7 @@
 # emulator/CMakeLists.txt
 # ----------------------------------------------------------------------------
 
-cmake_minimum_required( VERSION 3.12 )
+cmake_minimum_required( VERSION 3.24 )
 
 set( EMULATOR_DIR ${PROJECT_BASE_DIR}/emulator )
 
@@ -52,7 +52,9 @@ target_link_directories(emulator PRIVATE ${CFITSIO_LIBRARY_DIRS})
 # Prefixed because "emulator" is too generic for a shared bin directory
 set_target_properties(emulator PROPERTIES OUTPUT_NAME camerad-emulator)
 
-install(TARGETS emulator RUNTIME DESTINATION ${CAMERAD_INSTALL_BINDIR})
+if( CAMERAD_INSTALL )
+        install(TARGETS emulator RUNTIME DESTINATION ${CAMERAD_INSTALL_BINDIR})
+endif()
 elseif( ${INTERFACE_TYPE} STREQUAL "AstroCam" )
         message( STATUS "emulator not implemented for AstroCam" )
 else()

@@ -9,7 +9,7 @@ description = "camera_interface built for the HISPEC tracking camera"
 requires-python = ">=3.10"
 
 [tool.scikit-build]
-cmake.version = ">=3.15"
+cmake.version = ">=3.24"
 cmake.source-dir = "../.."
 wheel.packages = []
 

@@ -9,7 +9,7 @@ description = "Python bindings for the camera-interface detector controller soft
 requires-python = ">=3.10"
 
 [tool.scikit-build]
-cmake.version = ">=3.15"
+cmake.version = ">=3.24"
 
 # The wheel carries camerad and its tools as well as the module, so installing
 # the Python side gives a working command line too

@@ -62,11 +62,12 @@ target_link_libraries(camera_interface PRIVATE
   ${CMAKE_THREAD_LIBS_INIT}
   ${CCFITS_LIB}
   ${CFITS_LIB}
-  ${OpenCV_LIBS}
   Boost::thread
   Boost::chrono
   ${ZMQPP_LIB}
   ${ZMQ_LIB}
 )
 
-install(TARGETS camera_interface LIBRARY DESTINATION ${CAMERAD_INSTALL_LIBDIR})
+if (CAMERAD_INSTALL)
+  install(TARGETS camera_interface LIBRARY DESTINATION ${CAMERAD_INSTALL_LIBDIR})
+endif()
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.12)
+cmake_minimum_required(VERSION 3.24)
 
 set(PROJECT_TESTS_DIR ${PROJECT_BASE_DIR}/tests)