libcamera: Mark internal parts of public classes with \internal

The libcamera public API exposes classes that have parts considered
internal. They inherit the Extensible class, and their internal parts
are split into a Private class. Those classes are defined in public API
headers, and their Private counterparts are defined in internal headers
sharing a common file name (in a different directory). Both headers are
documented in the same source file.

For instance, include/libcamera/camera.h contains the public API of the
Camera class, and include/libcamera/internal/camera.h its internal
counterpart. Both are documented in src/libcamera/camera.cpp.

As the internal headers are not part of the public API, they need to be
hidden from the future public API builds. To prepare for doing so, mark
them with the \internal Doxygen directive. Hardcode the Doxygen
INTERNAL_DOCS option to YES to include the internal API. This will be
changed later for the public API documentation build.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

Documentation/Doxyfile.in

@@ -17,6 +17,7 @@ EXTENSION_MAPPING      = h=C++
 
 TOC_INCLUDE_HEADINGS   = 0
 
+INTERNAL_DOCS          = YES
 CASE_SENSE_NAMES       = YES
 
 QUIET                  = YES

src/libcamera/camera.cpp

@@ -118,6 +118,7 @@
  */
 
 /**
+ * \internal
  * \file libcamera/internal/camera.h
  * \brief Internal camera device handling
  */

src/libcamera/camera_manager.cpp

@@ -23,6 +23,7 @@
  */
 
 /**
+ * \internal
  * \file libcamera/internal/camera_manager.h
  * \brief Internal camera manager support
  */

src/libcamera/framebuffer.cpp

@@ -16,7 +16,10 @@
 /**
  * \file libcamera/framebuffer.h
  * \brief Frame buffer handling
- *
+ */
+
+/**
+ * \internal
  * \file libcamera/internal/framebuffer.h
  * \brief Internal frame buffer handling support
  */

src/libcamera/request.cpp

@@ -29,6 +29,7 @@
  */
 
 /**
+ * \internal
  * \file libcamera/internal/request.h
  * \brief Internal support for request handling
  */