android: Add CameraMetadata helper class

The new CameraMetadata helper class wraps the Android camera_metadata_t
to simplify its usage.

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

src/android/camera_metadata.h

@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * camera_metadata.h - libcamera Android Camera Metadata Helper
+ */
+#ifndef __ANDROID_CAMERA_METADATA_H__
+#define __ANDROID_CAMERA_METADATA_H__
+
+#include <stdint.h>
+
+#include <system/camera_metadata.h>
+
+class CameraMetadata
+{
+public:
+	CameraMetadata(size_t entryCapacity, size_t dataCapacity);
+	~CameraMetadata();
+
+	bool isValid() { return valid_; }
+	bool addEntry(uint32_t tag, const void *data, size_t data_count);
+
+	camera_metadata_t *get();
+
+private:
+	camera_metadata_t *metadata_;
+	bool valid_;
+};
+
+#endif /* __ANDROID_CAMERA_METADATA_H__ */