Link the Arduino component automatically when built as an ESP-IDF component

CMakeLists.txt

@@ -29,12 +29,42 @@ else()
     set(COMPONENT_REQUIRES ${_m5gfx_name} esp_adc_cal)
 endif()
 
-### If you use arduino-esp32 components, please activate next comment line.
-# list(APPEND COMPONENT_REQUIRES arduino-esp32)
 
 
 message(STATUS "M5Unified use component = ${COMPONENT_REQUIRES}" )
 
 
 register_component()
 
+# Arduino as an ESP-IDF component: arduino-esp32 publishes -DARDUINO... as PUBLIC compile options, so
+# they only reach components that link against it, while the public headers of this library change
+# class layout with ARDUINO. Link the Arduino component publicly whenever it is part of the build so
+# this library is compiled in the same mode as the application. Only components already selected
+# for the build are considered; a build without Arduino is unaffected.
+#   M5UNIFIED_ARDUINO_COMPONENT=<name>  use a differently named Arduino component
+#   M5UNIFIED_ARDUINO_COMPONENT=OFF     disable the automatic dependency
+set(_m5unified_arduino_candidates arduino arduino-esp32 espressif__arduino-esp32)
+set(_m5unified_arduino_enabled ON)
+if(DEFINED M5UNIFIED_ARDUINO_COMPONENT AND NOT "${M5UNIFIED_ARDUINO_COMPONENT}" STREQUAL "")
+    if(M5UNIFIED_ARDUINO_COMPONENT)
+        set(_m5unified_arduino_candidates ${M5UNIFIED_ARDUINO_COMPONENT})
+    else()
+        set(_m5unified_arduino_enabled OFF)
+    endif()
+endif()
+if(_m5unified_arduino_enabled)
+    idf_build_get_property(_m5unified_arduino_build_components BUILD_COMPONENTS)
+    set(_m5unified_arduino_hits)
+    foreach(_m5unified_arduino_name ${_m5unified_arduino_candidates})
+        if(_m5unified_arduino_name IN_LIST _m5unified_arduino_build_components)
+            list(APPEND _m5unified_arduino_hits ${_m5unified_arduino_name})
+        endif()
+    endforeach()
+    list(LENGTH _m5unified_arduino_hits _m5unified_arduino_count)
+    if(_m5unified_arduino_count GREATER 1)
+        message(FATAL_ERROR "M5UNIFIED: several Arduino components are in the build (${_m5unified_arduino_hits}). Set M5UNIFIED_ARDUINO_COMPONENT to the one to use.")
+    elseif(_m5unified_arduino_count EQUAL 1)
+        idf_component_get_property(_m5unified_arduino_lib ${_m5unified_arduino_hits} COMPONENT_LIB)
+        target_link_libraries(${COMPONENT_LIB} PUBLIC ${_m5unified_arduino_lib})
+    endif()
+endif()

README.md

@@ -50,6 +50,7 @@ or have explicit support in the M5Unified library.  To use these functions, simp
  - ESP-IDF
  - Arduino IDE
 
+
 ## Supported devices (ESP32)
  - M5Stack Core (BASIC / GRAY / GO / FIRE)
  - M5Stack Core2 / Core2 v1.1 / Tough
@@ -128,6 +129,16 @@ or have explicit support in the M5Unified library.  To use these functions, simp
  - Unit IMU
 
 
+## Notes
+
+### Arduino as an ESP-IDF component
+When arduino-esp32 is used as an ESP-IDF component together with this library, the library links
+the Arduino component automatically (it looks for a component named `arduino`, `arduino-esp32` or
+`espressif__arduino-esp32` in the build) so that it is compiled with the same `ARDUINO` definitions
+as the application. Without that, the application and the library would see different layouts of the
+same classes. Set `M5UNIFIED_ARDUINO_COMPONENT=<name>` (CMake cache variable) if your Arduino component
+has another name, or `M5UNIFIED_ARDUINO_COMPONENT=OFF` to disable this.
+
 # Hardware information
 
 ### ESP32 GPIO list