qcam: Replace MappedBuffer with Span<uint8_t>

The MappedBuffer structure is a custom container that binds a data
pointer with a length. This is exactly what Span is. Use it instead.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/qcam/main_window.cpp

@@ -474,7 +474,8 @@ int MainWindow::startCapture()
 			const FrameBuffer::Plane &plane = buffer->planes().front();
 			void *memory = mmap(NULL, plane.length, PROT_READ, MAP_SHARED,
 					    plane.fd.fd(), 0);
-			mappedBuffers_[buffer.get()] = { memory, plane.length };
+			mappedBuffers_[buffer.get()] = { static_cast<uint8_t *>(memory),
+							 plane.length };
 
 			/* Store buffers on the free list. */
 			freeBuffers_[stream].enqueue(buffer.get());
@@ -537,8 +538,8 @@ error:
 	requests_.clear();
 
 	for (auto &iter : mappedBuffers_) {
-		const MappedBuffer &buffer = iter.second;
+		const Span<uint8_t> &buffer = iter.second;
-		munmap(buffer.memory, buffer.size);
+		munmap(buffer.data(), buffer.size());
 	}
 	mappedBuffers_.clear();
 
@@ -573,8 +574,8 @@ void MainWindow::stopCapture()
 	camera_->requestCompleted.disconnect(this, &MainWindow::requestComplete);
 
 	for (auto &iter : mappedBuffers_) {
-		const MappedBuffer &buffer = iter.second;
+		const Span<uint8_t> &buffer = iter.second;
-		munmap(buffer.memory, buffer.size);
+		munmap(buffer.data(), buffer.size());
 	}
 	mappedBuffers_.clear();
 
@@ -673,10 +674,10 @@ void MainWindow::processRaw(FrameBuffer *buffer,
 							"DNG Files (*.dng)");
 
 	if (!filename.isEmpty()) {
-		const MappedBuffer &mapped = mappedBuffers_[buffer];
+		const Span<uint8_t> &mapped = mappedBuffers_[buffer];
 		DNGWriter::write(filename.toStdString().c_str(), camera_.get(),
 				 rawStream_->configuration(), metadata, buffer,
-				 mapped.memory);
+				 mapped.data());
 	}
 #endif
 
@@ -753,7 +754,7 @@ void MainWindow::processViewfinder(FrameBuffer *buffer)
 		<< "fps:" << Qt::fixed << qSetRealNumberPrecision(2) << fps;
 
 	/* Render the frame on the viewfinder. */
-	viewfinder_->render(buffer, &mappedBuffers_[buffer]);
+	viewfinder_->render(buffer, mappedBuffers_[buffer]);
 }
 
 void MainWindow::queueRequest(FrameBuffer *buffer)

src/qcam/main_window.h

@@ -106,7 +106,7 @@ private:
 	FrameBufferAllocator *allocator_;
 
 	std::unique_ptr<CameraConfiguration> config_;
-	std::map<FrameBuffer *, MappedBuffer> mappedBuffers_;
+	std::map<FrameBuffer *, Span<uint8_t>> mappedBuffers_;
 
 	/* Capture state, buffers queue and statistics */
 	bool isCapturing_;

src/qcam/viewfinder.h

@@ -11,14 +11,11 @@
 #include <QList>
 #include <QSize>
 
+#include <libcamera/base/span.h>
+
 #include <libcamera/formats.h>
 #include <libcamera/framebuffer.h>
 
-struct MappedBuffer {
-	void *memory;
-	size_t size;
-};
-
 class ViewFinder
 {
 public:
@@ -27,7 +24,7 @@ public:
 	virtual const QList<libcamera::PixelFormat> &nativeFormats() const = 0;
 
 	virtual int setFormat(const libcamera::PixelFormat &format, const QSize &size) = 0;
-	virtual void render(libcamera::FrameBuffer *buffer, MappedBuffer *map) = 0;
+	virtual void render(libcamera::FrameBuffer *buffer, libcamera::Span<uint8_t> mem) = 0;
 	virtual void stop() = 0;
 
 	virtual QImage getCurrentImage() = 0;

src/qcam/viewfinder_gl.cpp

@@ -110,7 +110,8 @@ QImage ViewFinderGL::getCurrentImage()
 	return grabFramebuffer();
 }
 
-void ViewFinderGL::render(libcamera::FrameBuffer *buffer, MappedBuffer *map)
+void ViewFinderGL::render(libcamera::FrameBuffer *buffer,
+			  libcamera::Span<uint8_t> mem)
 {
 	if (buffer->planes().size() != 1) {
 		qWarning() << "Multi-planar buffers are not supported";
@@ -120,7 +121,7 @@ void ViewFinderGL::render(libcamera::FrameBuffer *buffer, MappedBuffer *map)
 	if (buffer_)
 		renderComplete(buffer_);
 
-	data_ = static_cast<unsigned char *>(map->memory);
+	data_ = mem.data();
 	/*
 	 * \todo Get the stride from the buffer instead of computing it naively
 	 */

src/qcam/viewfinder_gl.h

@@ -39,7 +39,7 @@ public:
 	const QList<libcamera::PixelFormat> &nativeFormats() const override;
 
 	int setFormat(const libcamera::PixelFormat &format, const QSize &size) override;
-	void render(libcamera::FrameBuffer *buffer, MappedBuffer *map) override;
+	void render(libcamera::FrameBuffer *buffer, libcamera::Span<uint8_t> mem) override;
 	void stop() override;
 
 	QImage getCurrentImage() override;

src/qcam/viewfinder_qt.cpp

@@ -78,14 +78,15 @@ int ViewFinderQt::setFormat(const libcamera::PixelFormat &format,
 	return 0;
 }
 
-void ViewFinderQt::render(libcamera::FrameBuffer *buffer, MappedBuffer *map)
+void ViewFinderQt::render(libcamera::FrameBuffer *buffer,
+			  libcamera::Span<uint8_t> mem)
 {
 	if (buffer->planes().size() != 1) {
 		qWarning() << "Multi-planar buffers are not supported";
 		return;
 	}
 
-	unsigned char *memory = static_cast<unsigned char *>(map->memory);
+	unsigned char *memory = mem.data();
 	size_t size = buffer->metadata().planes[0].bytesused;
 
 	{

src/qcam/viewfinder_qt.h

@@ -32,7 +32,7 @@ public:
 	const QList<libcamera::PixelFormat> &nativeFormats() const override;
 
 	int setFormat(const libcamera::PixelFormat &format, const QSize &size) override;
-	void render(libcamera::FrameBuffer *buffer, MappedBuffer *map) override;
+	void render(libcamera::FrameBuffer *buffer, libcamera::Span<uint8_t> mem) override;
 	void stop() override;
 
 	QImage getCurrentImage() override;