libcamera: Define a PixelFormat type for application-facing formats

Define a PixelFormat type as a simple typedef to an uint32_t. The usage
of a dedicated type creates a cleaner and more self-described API.

Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

include/libcamera/meson.build

@@ -9,6 +9,7 @@ libcamera_api = files([
     'geometry.h',
     'logging.h',
     'object.h',
+    'pixelformats.h',
     'request.h',
     'signal.h',
     'stream.h',

include/libcamera/pixelformats.h

@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * pixelformats.h - libcamera pixel formats
+ */
+#ifndef __LIBCAMERA_PIXEL_FORMATS_H__
+#define __LIBCAMERA_PIXEL_FORMATS_H__
+
+#include <stdint.h>
+
+namespace libcamera {
+
+using PixelFormat = uint32_t;
+
+} /* namespace libcamera */
+
+#endif /* __LIBCAMERA_PIXEL_FORMATS_H__ */

src/libcamera/meson.build

@@ -25,6 +25,7 @@ libcamera_sources = files([
     'message.cpp',
     'object.cpp',
     'pipeline_handler.cpp',
+    'pixelformats.cpp',
     'process.cpp',
     'request.cpp',
     'signal.cpp',

src/libcamera/pixelformats.cpp

@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * pixelformats.cpp - libcamera pixel formats
+ */
+
+#include <libcamera/pixelformats.h>
+
+/**
+ * \file pixelformats.h
+ * \brief libcamera pixel formats
+ */
+
+namespace libcamera {
+
+/**
+ * \typedef PixelFormat
+ * \brief libcamera image pixel format
+ *
+ * The PixelFormat type describes the format of images in the public libcamera
+ * API. It stores a FourCC value in a 32-bit unsigned integer. The values are
+ * defined in the Linux kernel V4L2 API (see linux/videodev2.h).
+ */
+
+} /* namespace libcamera */