libcamera: buffer: Add an accessor to the BufferMemory

Buffer instances reference memory, which is modelled internally by a
BufferMemory instance. Store a pointer to the BufferMemory in the Buffer
class, and populate it when the buffer is queued to the camera through a
request. This is useful for applications to access the buffer memory in
the buffer or request completion handler.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

src/cam/capture.cpp

@@ -154,7 +154,6 @@ void Capture::requestComplete(Request *request, const std::map<Stream *, Buffer
 	for (auto it = buffers.begin(); it != buffers.end(); ++it) {
 		Stream *stream = it->first;
 		Buffer *buffer = it->second;
-		BufferMemory *mem = &stream->buffers()[buffer->index()];
 		const std::string &name = streamName_[stream];
 
 		info << " " << name
@@ -163,7 +162,7 @@ void Capture::requestComplete(Request *request, const std::map<Stream *, Buffer
 		     << " bytesused: " << buffer->bytesused();
 
 		if (writer_)
-			writer_->write(buffer, mem, name);
+			writer_->write(buffer, name);
 	}
 
 	std::cout << info.str() << std::endl;