android: camera_device: Create struct to track per stream buffer

The Camera3RequestDescriptor structure stores, for each stream, the
camera3_stream_buffer_t and the libcamera FrameBuffer in two separate
vectors. This complicates buffer handling, as the code needs to keep
both vectors in sync. Create a new structure to group all data about
per-stream buffers to simplify this.

As a side effect, we need to create a local vector of
camera3_stream_buffer_t in CameraDevice::sendCaptureResults() as the
camera3_stream_buffer_t instances stored in the new structure in
Camera3RequestDescriptor are not contiguous anymore. This is a small
price to pay for easier handling of buffers, and will be refactored in
subsequent commits anyway.

Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Hirokazu Honda <hiroh@chromium.org>

src/android/camera_request.h

@@ -29,6 +29,16 @@ public:
 		Error,
 	};
 
+	struct StreamBuffer {
+		camera3_stream_buffer_t buffer;
+		/*
+		 * FrameBuffer instances created by wrapping a camera3 provided
+		 * dmabuf are emplaced in this vector of unique_ptr<> for
+		 * lifetime management.
+		 */
+		std::unique_ptr<libcamera::FrameBuffer> frameBuffer;
+	};
+
 	Camera3RequestDescriptor(libcamera::Camera *camera,
 				 const camera3_capture_request_t *camera3Request);
 	~Camera3RequestDescriptor();
@@ -36,8 +46,9 @@ public:
 	bool isPending() const { return status_ == Status::Pending; }
 
 	uint32_t frameNumber_ = 0;
-	std::vector<camera3_stream_buffer_t> buffers_;
-	std::vector<std::unique_ptr<libcamera::FrameBuffer>> frameBuffers_;
+
+	std::vector<StreamBuffer> buffers_;
+
 	CameraMetadata settings_;
 	std::unique_ptr<CaptureRequest> request_;
 	std::unique_ptr<CameraMetadata> resultMetadata_;