libcamera: virtual: Avoid some copies

There is no reason make copies, these functions return
const lvalue references, access the data through those.

Signed-off-by: Barnabás Pőcze <pobrn@protonmail.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/libcamera/pipeline/virtual/image_frame_generator.cpp

@@ -129,7 +129,7 @@ int ImageFrameGenerator::generateFrame(const Size &size, const FrameBuffer *buff
 
 	MappedFrameBuffer mappedFrameBuffer(buffer, MappedFrameBuffer::MapFlag::Write);
 
-	auto planes = mappedFrameBuffer.planes();
+	const auto &planes = mappedFrameBuffer.planes();
 
 	/* Loop only around the number of images available */
 	frameIndex_ %= imageFrameDatas_.size();

src/libcamera/pipeline/virtual/test_pattern_generator.cpp

@@ -25,7 +25,7 @@ int TestPatternGenerator::generateFrame(const Size &size,
 	MappedFrameBuffer mappedFrameBuffer(buffer,
 					    MappedFrameBuffer::MapFlag::Write);
 
-	auto planes = mappedFrameBuffer.planes();
+	const auto &planes = mappedFrameBuffer.planes();
 
 	shiftLeft(size);
 

src/libcamera/pipeline/virtual/virtual.cpp

@@ -275,8 +275,7 @@ int PipelineHandlerVirtual::exportFrameBuffers([[maybe_unused]] Camera *camera,
 		return -ENOBUFS;
 
 	const StreamConfiguration &config = stream->configuration();
-
-	auto info = PixelFormatInfo::info(config.pixelFormat);
+	const PixelFormatInfo &info = PixelFormatInfo::info(config.pixelFormat);
 
 	std::vector<unsigned int> planeSizes;
 	for (size_t i = 0; i < info.planes.size(); ++i)