Update cmake target export

CMakeLists.txt

@@ -31,26 +31,37 @@ endif()
 # Installation
 ################################################
 # Export package for use from the build tree
-set(TRANSFORMS_GRAPH_CMAKE_EXPORT_DIR lib/cmake/TransformsGraph)
+set(CMAKE_EXPORT_DIR lib/cmake/TransformsGraph)
+set(TARGETS_NAME "TransformsGraph")
+set(TARGETS_NAMESPACE "TransformsGraph")
+set(TARGETS_CONFIG_FILENAME "${TARGETS_NAME}Config.cmake.in")
 
-install(TARGETS TransformsGraph
-        EXPORT  TransformsGraphTargets
-        ARCHIVE DESTINATION lib
-        LIBRARY DESTINATION lib
+install(
+  TARGETS "${TARGETS_NAME}"
+  EXPORT  "${TARGETS_NAME}Targets"
+  ARCHIVE DESTINATION lib
+  LIBRARY DESTINATION lib 
 )
-install(EXPORT TransformsGraphTargets 
-  NAMESPACE TransformsGraph::
-  DESTINATION ${TRANSFORMS_GRAPH_CMAKE_EXPORT_DIR}
+install(EXPORT "${TARGETS_NAME}Targets" 
+  NAMESPACE "${TARGETS_NAMESPACE}::"
+  DESTINATION ${CMAKE_EXPORT_DIR}
 )
 
 # Install the include directory
-install(DIRECTORY ${PROJECT_SOURCE_DIR}/include/
-      DESTINATION include)
-
+install(
+  DIRECTORY ${PROJECT_SOURCE_DIR}/include/
+  DESTINATION include
+)
 include(CMakePackageConfigHelpers)
 configure_package_config_file(
-	"TransformsGraphConfig.cmake.in" "${CMAKE_CURRENT_BINARY_DIR}/TransformsGraphConfig.cmake"
-	INSTALL_DESTINATION "lib/cmake/TransformsGraph"
+  "${TARGETS_CONFIG_FILENAME}" "${CMAKE_CURRENT_BINARY_DIR}/${TARGETS_NAME}Config.cmake"
+  INSTALL_DESTINATION "${CMAKE_EXPORT_DIR}"
 )
-install(FILES "${CMAKE_CURRENT_BINARY_DIR}/TransformsGraphConfig.cmake" DESTINATION "lib/cmake/TransformsGraph")
+install(FILES "${CMAKE_CURRENT_BINARY_DIR}/${TARGETS_NAME}Config.cmake" DESTINATION "${CMAKE_EXPORT_DIR}")
 
+# Export without installing
+export(
+  EXPORT "${TARGETS_NAME}Targets"
+  FILE "${CMAKE_CURRENT_BINARY_DIR}/${TARGETS_NAME}Targets.cmake"
+  NAMESPACE "${TARGETS_NAMESPACE}::"
+)

README.md

@@ -16,7 +16,10 @@ This is similar to the [tf2 ROS package](http://wiki.ros.org/tf2), but this pack
     * [Using `enum` for `Frame`](#using-enum-for-frame)
 * [Transforms storage](#transforms-storage)
     * [Mermaid graphs](#mermaid-graphs)
-* [Installation](#installation)
+Building and installing](#building-and-installing)
+    * [Copy include files locally](#copy-include-files-locally)
+    * [Link package to the downstream project](#link-package-to-the-downstream-project)
+    * [Install the package globally](#install-the-package-globally)
 * [FAQ](#faq)
 
 <!-- vim-markdown-toc -->
@@ -163,14 +166,38 @@ graph TD
 
 The transforms can be visualized for this option as well by passing `true` as the second argument to `GetMermaidGraph`.
 
-# Installation
-This is a header-only library.
-It can be used by directly including the `include/transforms_graph/transforms_graph.h` into your folder, or it can be installed on your system by running the following from the root of this repo.
+# Building and installing
+This is a header-only library, so it doesn't need to be built. However, the examples and tests need to be built:
 ```bash
-cmake -S . --build build
+cmake -S . --build build -DBUILD_EXAMPLES=ON
 cmake --build build
-sudo cmake --install build
 ```
+There are various ways to use the package downstream, which are listed below:
+## Copy include files locally
+Since the library is header-only, the header files can be included in the downstream project by copying `include/transforms_graph/transforms_graph.h` into the downstream project and including it into the CMake targets.
+
+## Link package to the downstream project
+The TransformsGraph exports the `TransformsGraph::TransformsGraph` library.
+The library can be imported downstream by adding the following to the `CMakeLists.txt`
+```bash
+# In the downstream CMakeLists.txt
+find_package(TransformsGraph REQUIRED)
+...
+target_link_libraries(main TransformsGraph::TransformsGraph)
+```
+The TransformsGraph *build* directory `<transforms-graph-build-directory>` then needs to be passed as an argument when building the CMake project:
+Then, the downstream 
+```bash
+# In the downstream project
+cmake -S . -B build -DTransformsGraph_DIR=<path-to-transforms-graph-build-directory>
+```
+
+## Install the package globally
+The TransformsGraph package can be installed globally by running
+```bash
+cmake --install build  # May require `sudo` privileges
+```
+The `CMakeLists.txt` downstream can then be used as shown in the [previous section](#link-package-to-the-downstream-project)
 
 # FAQ
 - Why use a graph instead of a tree or a forest?

TransformsGraphConfig.cmake.in

@@ -1,3 +1,5 @@
 @PACKAGE_INIT@
 
 include("${CMAKE_CURRENT_LIST_DIR}/TransformsGraphTargets.cmake")
+
+check_required_components(TransformsGraph)