Create image callback using Qt signal

Author: poljvd

include/grabber/V4L2Grabber.h

@@ -4,26 +4,27 @@
 #include <string>
 #include <vector>
 
+// Qt includes
+#include <QObject>
+#include <QSocketNotifier>
+
 // util includes
 #include <utils/Image.h>
 #include <utils/ColorRgb.h>
+#include <utils/VideoMode.h>
 
 /// Capture class for V4L2 devices
 ///
 /// @see http://linuxtv.org/downloads/v4l-dvb-apis/capture-example.html
-class V4L2Grabber
+class V4L2Grabber : public QObject
 {
-public:
-	typedef void (*ImageCallback)(void * arg, const Image<ColorRgb> & image);
+	Q_OBJECT
 
+public:
 	enum VideoStandard {
 		PAL, NTSC, NO_CHANGE
 	};
 
-	enum Mode3D {
-		MODE_NONE, MODE_3DSBS, MODE_3DTAB
-	};
-
 public:
 	V4L2Grabber(
 			const std::string & device,
@@ -36,21 +37,24 @@ class V4L2Grabber
 			int verticalPixelDecimation);
 	virtual ~V4L2Grabber();
 
+public slots:
 	void setCropping(int cropLeft,
 					 int cropRight,
 					 int cropTop,
 					 int cropBottom);
 
-	void set3D(Mode3D mode);
-
-	void setCallback(ImageCallback callback, void * arg);
+	void set3D(VideoMode mode);
 
 	void start();
 
-	void capture(int frameCount = -1);
-
 	void stop();
 
+signals:
+	void newFrame(const Image<ColorRgb> & image);
+
+private slots:
+	int read_frame();
+
 private:
 	void open_device();
 
@@ -70,8 +74,6 @@ class V4L2Grabber
 
 	void stop_capturing();
 
-	int read_frame();
-
 	bool process_image(const void *p, int size);
 
 	void process_image(const uint8_t *p);
@@ -111,10 +113,9 @@ class V4L2Grabber
 	int _horizontalPixelDecimation;
 	int _verticalPixelDecimation;
 
-	Mode3D _mode3D;
+	VideoMode _mode3D;
 
 	int _currentFrame;
 
-	ImageCallback _callback;
-	void * _callbackArg;
+	QSocketNotifier * _streamNotifier;
 };

libsrc/grabber/v4l2/CMakeLists.txt

@@ -2,18 +2,27 @@
 SET(CURRENT_HEADER_DIR ${CMAKE_SOURCE_DIR}/include/grabber)
 SET(CURRENT_SOURCE_DIR ${CMAKE_SOURCE_DIR}/libsrc/grabber/v4l2)
 
-SET(V4L2_HEADERS
+SET(V4L2_QT_HEADERS
 		${CURRENT_HEADER_DIR}/V4L2Grabber.h
 )
 
+SET(V4L2_HEADERS
+)
+
 SET(V4L2_SOURCES
 		${CURRENT_SOURCE_DIR}/V4L2Grabber.cpp
 )
 
+QT4_WRAP_CPP(V4L2_HEADERS_MOC ${V4L2_QT_HEADERS})
+
 add_library(v4l2-grabber
 		${V4L2_HEADERS}
 		${V4L2_SOURCES}
+		${V4L2_QT_HEADERS}
+		${V4L2_HEADERS_MOC}
 )
 
 target_link_libraries(v4l2-grabber
-	hyperion-utils)
+	hyperion
+	${QT_LIBRARIES}
+)

libsrc/grabber/v4l2/V4L2Grabber.cpp

@@ -59,10 +59,9 @@ V4L2Grabber::V4L2Grabber(
 	_frameDecimation(std::max(1, frameDecimation)),
 	_horizontalPixelDecimation(std::max(1, horizontalPixelDecimation)),
 	_verticalPixelDecimation(std::max(1, verticalPixelDecimation)),
-	_mode3D(MODE_NONE),
+	_mode3D(VIDEO_2D),
 	_currentFrame(0),
-	_callback(nullptr),
-	_callbackArg(nullptr)
+	_streamNotifier(nullptr)
 {
 	open_device();
 	init_device(videoStandard, input);
@@ -82,66 +81,21 @@ void V4L2Grabber::setCropping(int cropLeft, int cropRight, int cropTop, int crop
 	_cropBottom = cropBottom;
 }
 
-void V4L2Grabber::set3D(Mode3D mode)
+void V4L2Grabber::set3D(VideoMode mode)
 {
 	_mode3D = mode;
 }
 
-void V4L2Grabber::setCallback(V4L2Grabber::ImageCallback callback, void *arg)
-{
-	_callback = callback;
-	_callbackArg = arg;
-}
-
 void V4L2Grabber::start()
 {
+	_streamNotifier->setEnabled(true);
 	start_capturing();
 }
 
-void V4L2Grabber::capture(int frameCount)
-{
-	for (int count = 0; count < frameCount || frameCount < 0; ++count)
-	{
-		for (;;)
-		{
-			// the set of file descriptors for select
-			fd_set fds;
-			FD_ZERO(&fds);
-			FD_SET(_fileDescriptor, &fds);
-
-			// timeout
-			struct timeval tv;
-			tv.tv_sec = 2;
-			tv.tv_usec = 0;
-
-			// block until data is available
-			int r = select(_fileDescriptor + 1, &fds, NULL, NULL, &tv);
-
-			if (-1 == r)
-			{
-				if (EINTR == errno)
-					continue;
-				throw_errno_exception("select");
-			}
-
-			if (0 == r)
-			{
-				throw_exception("select timeout");
-			}
-
-			if (read_frame())
-			{
-				break;
-			}
-
-			/* EAGAIN - continue select loop. */
-		}
-	}
-}
-
 void V4L2Grabber::stop()
 {
 	stop_capturing();
+	_streamNotifier->setEnabled(false);
 }
 
 void V4L2Grabber::open_device()
@@ -170,6 +124,10 @@ void V4L2Grabber::open_device()
 		oss << "Cannot open '" << _deviceName << "'";
 		throw_errno_exception(oss.str());
 	}
+
+	// create the notifier for when a new frame is available
+	_streamNotifier = new QSocketNotifier(_fileDescriptor, QSocketNotifier::Read);
+	connect(_streamNotifier, SIGNAL(activated(int)), this, SLOT(read_frame()));
 }
 
 void V4L2Grabber::close_device()
@@ -178,6 +136,12 @@ void V4L2Grabber::close_device()
 		throw_errno_exception("close");
 
 	_fileDescriptor = -1;
+
+	if (_streamNotifier != nullptr)
+	{
+		delete _streamNotifier;
+		_streamNotifier = nullptr;
+	}
 }
 
 void V4L2Grabber::init_read(unsigned int buffer_size)
@@ -674,10 +638,10 @@ void V4L2Grabber::process_image(const uint8_t * data)
 
 	switch (_mode3D)
 	{
-	case MODE_3DSBS:
+	case VIDEO_3DSBS:
 		width = _width/2;
 		break;
-	case MODE_3DTAB:
+	case VIDEO_3DTAB:
 		height = _height/2;
 		break;
 	default:
@@ -717,10 +681,7 @@ void V4L2Grabber::process_image(const uint8_t * data)
 		}
 	}
 
-	if (_callback != nullptr)
-	{
-		(*_callback)(_callbackArg, image);
-	}
+	emit newFrame(image);
 }
 
 int V4L2Grabber::xioctl(int request, void *arg)

src/hyperion-v4l2/CMakeLists.txt

@@ -14,16 +14,21 @@ include_directories(
 	${QT_INCLUDES}
 )
 
-set(Hyperion_V4L2_HEADERS
-	ProtoConnection.h
+set(Hyperion_V4L2_QT_HEADERS
 	ImageHandler.h
+	ScreenshotHandler.h
+)
+
+set(Hyperion_V4L2_HEADERS
 	VideoStandardParameter.h
+	ProtoConnection.h
 )
 
 set(Hyperion_V4L2_SOURCES
 	hyperion-v4l2.cpp
 	ProtoConnection.cpp
 	ImageHandler.cpp
+	ScreenshotHandler.cpp
 )
 
 set(Hyperion_V4L2_PROTOS
@@ -34,9 +39,13 @@ protobuf_generate_cpp(Hyperion_V4L2_PROTO_SRCS Hyperion_V4L2_PROTO_HDRS
 	${Hyperion_V4L2_PROTOS}
 )
 
+QT4_WRAP_CPP(Hyperion_V4L2_MOC_SOURCES ${Hyperion_V4L2_QT_HEADERS})
+
 add_executable(hyperion-v4l2
 	${Hyperion_V4L2_HEADERS}
 	${Hyperion_V4L2_SOURCES}
+	${Hyperion_V4L2_QT_HEADERS}
+	${Hyperion_V4L2_MOC_SOURCES}
 	${Hyperion_V4L2_PROTO_SRCS}
 	${Hyperion_V4L2_PROTO_HDRS}
 )
@@ -48,5 +57,5 @@ target_link_libraries(hyperion-v4l2
 	hyperion-utils
 	${PROTOBUF_LIBRARIES}
 	pthread
-    ${QT_LIBRARIES}
+	${QT_LIBRARIES}
 )

src/hyperion-v4l2/ImageHandler.cpp

@@ -10,6 +10,10 @@ ImageHandler::ImageHandler(const std::string & address, int priority, double sig
 	_connection.setSkipReply(skipProtoReply);
 }
 
+ImageHandler::~ImageHandler()
+{
+}
+
 void ImageHandler::receiveImage(const Image<ColorRgb> & image)
 {
 	// check if we should do signal detection
@@ -32,10 +36,3 @@ void ImageHandler::receiveImage(const Image<ColorRgb> & image)
 		}
 	}
 }
-
-void ImageHandler::imageCallback(void *arg, const Image<ColorRgb> &image)
-{
-	ImageHandler * handler = static_cast<ImageHandler *>(arg);
-	handler->receiveImage(image);
-}
-

src/hyperion-v4l2/ImageHandler.h

@@ -1,24 +1,30 @@
+// Qt includes
+#include <QObject>
+
+// hyperion includes
+#include <utils/Image.h>
+#include <utils/ColorRgb.h>
+
 // blackborder includes
 #include <blackborder/BlackBorderProcessor.h>
 
-// hyperion-v4l includes
+// hyperion v4l2 includes
 #include "ProtoConnection.h"
 
 /// This class handles callbacks from the V4L2 grabber
-class ImageHandler
+class ImageHandler : public QObject
 {
+	Q_OBJECT
+
 public:
 	ImageHandler(const std::string & address, int priority, double signalThreshold, bool skipProtoReply);
+	virtual ~ImageHandler();
 
+public slots:
 	/// Handle a single image
 	/// @param image The image to process
 	void receiveImage(const Image<ColorRgb> & image);
 
-	/// static function used to direct callbacks to a ImageHandler object
-	/// @param arg This should be an ImageHandler instance
-	/// @param image The image to process
-	static void imageCallback(void * arg, const Image<ColorRgb> & image);
-
 private:
 	/// Priority for calls to Hyperion
 	const int _priority;

src/hyperion-v4l2/ScreenshotHandler.cpp

@@ -0,0 +1,25 @@
+// Qt includes
+#include <QImage>
+#include <QCoreApplication>
+
+// hyperion-v4l2 includes
+#include "ScreenshotHandler.h"
+
+ScreenshotHandler::ScreenshotHandler(const std::string & filename) :
+		_filename(filename)
+{
+}
+
+ScreenshotHandler::~ScreenshotHandler()
+{
+}
+
+void ScreenshotHandler::receiveImage(const Image<ColorRgb> & image)
+{
+	// store as PNG
+	QImage pngImage((const uint8_t *) image.memptr(), image.width(), image.height(), 3*image.width(), QImage::Format_RGB888);
+	pngImage.save(_filename.c_str());
+
+	// Quit the application after the first image
+	QCoreApplication::quit();
+}