CMake: make GeoRaster driver buildable in standalone mode

.github/workflows/ubuntu_20.04/build.sh

@@ -23,6 +23,12 @@ unset CFLAGS
 make "-j$(nproc)"
 make "-j$(nproc)" install
 
+# Download Oracle SDK
+wget https://download.oracle.com/otn_software/linux/instantclient/1923000/instantclient-basic-linux.x64-19.23.0.0.0dbru.zip
+wget https://download.oracle.com/otn_software/linux/instantclient/1923000/instantclient-sdk-linux.x64-19.23.0.0.0dbru.zip
+unzip -o instantclient-basic-linux.x64-19.23.0.0.0dbru.zip
+unzip -o instantclient-sdk-linux.x64-19.23.0.0.0dbru.zip
+
 # Test building MrSID driver in standalone mode
 mkdir build_mrsid
 cd build_mrsid
@@ -34,15 +40,19 @@ cd ..
 # Test building OCI driver in standalone mode
 mkdir build_oci
 cd build_oci
-wget https://download.oracle.com/otn_software/linux/instantclient/1923000/instantclient-basic-linux.x64-19.23.0.0.0dbru.zip
-wget https://download.oracle.com/otn_software/linux/instantclient/1923000/instantclient-sdk-linux.x64-19.23.0.0.0dbru.zip
-unzip -o instantclient-basic-linux.x64-19.23.0.0.0dbru.zip
-unzip -o instantclient-sdk-linux.x64-19.23.0.0.0dbru.zip
-cmake -S "${GDAL_SOURCE_DIR:=..}/ogr/ogrsf_frmts/oci" "-DOracle_ROOT=$PWD/instantclient_19_23" -DCMAKE_PREFIX_PATH=/tmp/install-gdal
+cmake -S "${GDAL_SOURCE_DIR:=..}/ogr/ogrsf_frmts/oci" "-DOracle_ROOT=$PWD/../instantclient_19_23" -DCMAKE_PREFIX_PATH=/tmp/install-gdal
 cmake --build . "-j$(nproc)"
 test -f ogr_OCI.so
 cd ..
 
+# Test building GeoRaster driver in standalone mode
+mkdir build_georaster
+cd build_georaster
+cmake -S "${GDAL_SOURCE_DIR:=..}/frmts/georaster" -DCMAKE_PREFIX_PATH=/tmp/install-gdal "-DOracle_ROOT=$PWD/../instantclient_19_23"
+cmake --build . "-j$(nproc)"
+test -f gdal_GEOR.so
+cd ..
+
 # Test building Parquet driver in standalone mode
 mkdir build_parquet
 cd build_parquet

cmake/helpers/CheckDependentLibraries.cmake

@@ -99,8 +99,7 @@ endif()
 
 gdal_check_package(XercesC "Read and write XML formats (needed for GMLAS and ILI drivers)" CAN_DISABLE)
 
-gdal_check_package(ZLIB "zlib (external)" CAN_DISABLE)
-gdal_internal_library(ZLIB REQUIRED)
+include(CheckDependentLibrariesZLIB)
 
 gdal_check_package(Deflate "Enable libdeflate compression library (complement to ZLib)" CAN_DISABLE)
 
@@ -168,46 +167,7 @@ include(CheckDependentLibrariesGeoTIFF)
 gdal_check_package(PNG "PNG compression library (external)" CAN_DISABLE RECOMMENDED VERSION "1.6")
 gdal_internal_library(PNG)
 
-gdal_check_package(JPEG "JPEG compression library (external)" CAN_DISABLE RECOMMENDED)
-if (GDAL_USE_JPEG AND (JPEG_LIBRARY MATCHES ".*turbojpeg\.(so|lib)"))
-  message(
-    FATAL_ERROR
-      "JPEG_LIBRARY should point to a library with libjpeg ABI, not TurboJPEG. See https://libjpeg-turbo.org/About/TurboJPEG for the difference"
-    )
-endif ()
-if (GDAL_USE_JPEG AND TARGET JPEG::JPEG)
-  set(EXPECTED_JPEG_LIB_VERSION "" CACHE STRING "Expected libjpeg version number")
-  mark_as_advanced(GDAL_CHECK_PACKAGE_${name}_NAMES)
-  if (EXPECTED_JPEG_LIB_VERSION)
-    get_property(_jpeg_old_icd TARGET JPEG::JPEG PROPERTY INTERFACE_COMPILE_DEFINITIONS)
-    set_property(TARGET JPEG::JPEG PROPERTY
-                 INTERFACE_COMPILE_DEFINITIONS "${_jpeg_old_icd};EXPECTED_JPEG_LIB_VERSION=${EXPECTED_JPEG_LIB_VERSION}")
-  endif()
-
-  # Check for jpeg12_read_scanlines() which has been added in libjpeg-turbo 2.2
-  # for dual 8/12 bit mode.
-  include(CheckCSourceCompiles)
-  include(CMakePushCheckState)
-  cmake_push_check_state(RESET)
-  set(CMAKE_REQUIRED_INCLUDES "${JPEG_INCLUDE_DIRS}")
-  set(CMAKE_REQUIRED_LIBRARIES "${JPEG_LIBRARIES}")
-  check_c_source_compiles(
-      "
-      #include <stddef.h>
-      #include <stdio.h>
-      #include \"jpeglib.h\"
-      int main()
-      {
-          jpeg_read_scanlines(0,0,0);
-          jpeg12_read_scanlines(0,0,0);
-          return 0;
-      }
-      "
-      HAVE_JPEGTURBO_DUAL_MODE_8_12)
-  cmake_pop_check_state()
-
-endif()
-gdal_internal_library(JPEG)
+include(CheckDependentLibrariesJpeg)
 
 gdal_check_package(GIF "GIF compression library (external)" CAN_DISABLE)
 gdal_internal_library(GIF)
@@ -502,8 +462,7 @@ gdal_check_package(PDFIUM "Enable PDF driver with Pdfium (read side)" CAN_DISABL
 gdal_check_package(Podofo "Enable PDF driver with Podofo (read side)" CAN_DISABLE)
 
 
-set(Oracle_CAN_USE_CLNTSH_AS_MAIN_LIBRARY ON)
-gdal_check_package(Oracle "Enable Oracle OCI driver" CAN_DISABLE)
+include(CheckDependentLibrariesOracle)
 gdal_check_package(TEIGHA "Enable DWG and DGNv8 drivers" CAN_DISABLE)
 gdal_check_package(FileGDB "Enable FileGDB (based on closed-source SDK) driver" CAN_DISABLE)
 

cmake/helpers/CheckDependentLibrariesJpeg.cmake

@@ -0,0 +1,40 @@
+gdal_check_package(JPEG "JPEG compression library (external)" CAN_DISABLE RECOMMENDED)
+if (GDAL_USE_JPEG AND (JPEG_LIBRARY MATCHES ".*turbojpeg\.(so|lib)"))
+  message(
+    FATAL_ERROR
+      "JPEG_LIBRARY should point to a library with libjpeg ABI, not TurboJPEG. See https://libjpeg-turbo.org/About/TurboJPEG for the difference"
+    )
+endif ()
+if (GDAL_USE_JPEG AND TARGET JPEG::JPEG)
+  set(EXPECTED_JPEG_LIB_VERSION "" CACHE STRING "Expected libjpeg version number")
+  mark_as_advanced(GDAL_CHECK_PACKAGE_${name}_NAMES)
+  if (EXPECTED_JPEG_LIB_VERSION)
+    get_property(_jpeg_old_icd TARGET JPEG::JPEG PROPERTY INTERFACE_COMPILE_DEFINITIONS)
+    set_property(TARGET JPEG::JPEG PROPERTY
+                 INTERFACE_COMPILE_DEFINITIONS "${_jpeg_old_icd};EXPECTED_JPEG_LIB_VERSION=${EXPECTED_JPEG_LIB_VERSION}")
+  endif()
+
+  # Check for jpeg12_read_scanlines() which has been added in libjpeg-turbo 2.2
+  # for dual 8/12 bit mode.
+  include(CheckCSourceCompiles)
+  include(CMakePushCheckState)
+  cmake_push_check_state(RESET)
+  set(CMAKE_REQUIRED_INCLUDES "${JPEG_INCLUDE_DIRS}")
+  set(CMAKE_REQUIRED_LIBRARIES "${JPEG_LIBRARIES}")
+  check_c_source_compiles(
+      "
+      #include <stddef.h>
+      #include <stdio.h>
+      #include \"jpeglib.h\"
+      int main()
+      {
+          jpeg_read_scanlines(0,0,0);
+          jpeg12_read_scanlines(0,0,0);
+          return 0;
+      }
+      "
+      HAVE_JPEGTURBO_DUAL_MODE_8_12)
+  cmake_pop_check_state()
+
+endif()
+gdal_internal_library(JPEG)

cmake/helpers/CheckDependentLibrariesOracle.cmake

@@ -0,0 +1,2 @@
+set(Oracle_CAN_USE_CLNTSH_AS_MAIN_LIBRARY ON)
+gdal_check_package(Oracle "Enable Oracle OCI and GeoRaster drivers" CAN_DISABLE)

cmake/helpers/CheckDependentLibrariesZLIB.cmake

@@ -0,0 +1,2 @@
+gdal_check_package(ZLIB "zlib (external)" CAN_DISABLE)
+gdal_internal_library(ZLIB REQUIRED)

doc/source/drivers/raster/georaster.rst

@@ -490,3 +490,28 @@ system so one alternative is to create VRT to represent the GeoRaster descriptio
 
     % gdal_translate -of VRT geor:scott/tiger@dbdemo,landsat,scene,id=54 view_54.vrt
     % openenv view_54.vrt
+
+Standalone plugin compilation
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. versionadded:: 3.10
+
+While this driver may be built as part of a whole GDAL build, either in libgdal
+itself, or as a plugin, it is also possible to only build this driver as a plugin,
+against an already built libgdal.
+
+The version of the GDAL sources used to build the driver must match the version
+of the libgdal it is built against.
+
+For example, from a "build_georaster" directory under the root of the GDAL source tree:
+
+::
+
+    cmake -S ../frmts/georaster -DCMAKE_PREFIX_PATH=/path/to/GDAL_installation_prefix -DOracle_ROOT=/path/to/instantclient_sdk_root
+    cmake --build .
+
+
+Note that such a plugin, when used against a libgdal not aware of it, will be
+systematically loaded at GDAL driver initialization time, and will not benefit from
+`deferred plugin loading capabilities <rfc-96>`. For that, libgdal itself must be built with the
+CMake variable GDAL_REGISTER_DRIVER_GEOR_FOR_LATER_PLUGIN=ON set.

frmts/CMakeLists.txt

@@ -165,7 +165,7 @@ gdal_dependent_format(jp2lura "JPEG-2000 (based on Luratech)" "GDAL_USE_LURATECH
 gdal_dependent_format(sde "ESRI ArcSDE Raster" "HAVE_SDE")
 # LizardTech's decoding software development kit (DSDK)
 include(mrsid/driver_declaration.cmake)
-gdal_dependent_format(georaster "Oracle Spatial GeoRaster" "GDAL_USE_ORACLE" DRIVER_NAME_OPTION GEOR)
+include(georaster/driver_declaration.cmake)
 include(ecw/driver_declaration.cmake)
 
 # Register all frmt drivers according to FRMT_<driver> flags

frmts/georaster/CMakeLists.txt

@@ -1,3 +1,22 @@
+include("${CMAKE_CURRENT_SOURCE_DIR}/../../cmake/helpers/GdalCMakeMinimumRequired.cmake")
+cmake_minimum_required(VERSION ${GDAL_CMAKE_VERSION_MIN}...${GDAL_CMAKE_VERSION_MAX})
+
+if(NOT DEFINED PROJECT_SOURCE_DIR)
+    # Standalone plugin building
+    project(gdal_GEOR)
+    include("${PROJECT_SOURCE_DIR}/../../cmake/helpers/SetupStandalonePlugin.cmake")
+    include(CheckDependentLibrariesZLIB)
+    include(CheckDependentLibrariesJpeg)
+    include(CheckDependentLibrariesOracle)
+    if (GDAL_USE_ZLIB_INTERNAL)
+        message(FATAL_ERROR "Internal zlib not supported for GeoRaster standalone plugin build")
+    endif()
+    if (GDAL_USE_JPEG_INTERNAL)
+        message(FATAL_ERROR "Internal libjpeg not supported for GeoRaster standalone plugin build")
+    endif()
+    standalone_driver_finalize(GDAL_ENABLE_DRIVER_GEOR)
+endif()
+
 add_gdal_driver(
   TARGET gdal_GEOR
   SOURCES georaster_dataset.cpp georaster_priv.h georaster_rasterband.cpp georaster_wrapper.cpp oci_wrapper.cpp

frmts/georaster/driver_declaration.cmake

@@ -0,0 +1 @@
+gdal_dependent_format(georaster "Oracle Spatial GeoRaster" "GDAL_USE_ORACLE" DRIVER_NAME_OPTION GEOR)

ogr/ogrsf_frmts/oci/CMakeLists.txt

@@ -5,7 +5,7 @@ if(NOT DEFINED PROJECT_SOURCE_DIR)
     # Standalone plugin building
     project(ogr_OCI)
     include("${PROJECT_SOURCE_DIR}/../../../cmake/helpers/SetupStandalonePlugin.cmake" )
-    include(CheckDependentLibrariesOCI)
+    include(CheckDependentLibrariesOracle)
     standalone_driver_finalize(OGR_ENABLE_DRIVER_OCI)
 endif()