[libcamera-devel] [PATCH v2 5/5] qcam: Update window title with FPS

[Kieran Bingham]

Provide an average FPS in the QCam title bar to show the current rate of
frame processing.

The QCam compilation is updated to process the QT MoC headers to support
signals and slots accordingly.

Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
---
 src/qcam/main_window.cpp | 22 ++++++++++++++++++++++
 src/qcam/main_window.h   | 11 +++++++++++
 src/qcam/meson.build     | 11 ++++++++++-
 3 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/src/qcam/main_window.cpp b/src/qcam/main_window.cpp
index d61369109d66..9f05ec05549f 100644
--- a/src/qcam/main_window.cpp
+++ b/src/qcam/main_window.cpp
@@ -29,6 +29,10 @@ MainWindow::MainWindow(const OptionsParser::Options &options)
 	title_ = "QCam " + QString::fromStdString(libcamera::version);
 	setWindowTitle(title_);
 
+	QTimer *timer = new QTimer(this);
+	connect(timer, SIGNAL(timeout()), this, SLOT(updateTitle()));
+	timer->start(2000);
+
 	viewfinder_ = new ViewFinder(this);
 	setCentralWidget(viewfinder_);
 	viewfinder_->setFixedSize(500, 500);
@@ -54,6 +58,19 @@ MainWindow::~MainWindow()
 	CameraManager::instance()->stop();
 }
 
+void MainWindow::updateTitle()
+{
+	unsigned int duration = frameRateInterval_.elapsed();
+	unsigned int frames = framesCaptured_ - previousFrames_;
+	double fps = frames * 1000.0 / duration;
+
+	/* Restart counters */
+	frameRateInterval_.start();
+	previousFrames_ = framesCaptured_;
+
+	setWindowTitle(title_ + " : " + QString::number(fps, 'f', 2) + " fps");
+}
+
 int MainWindow::openCamera()
 {
 	CameraManager *cm = CameraManager::instance();
@@ -148,6 +165,9 @@ int MainWindow::startCapture()
 		requests.push_back(request);
 	}
 
+	frameRateInterval_.start();
+	previousFrames_ = 0;
+	framesCaptured_ = 0;
 	lastBufferTime_ = 0;
 
 	ret = camera_->start();
@@ -196,6 +216,8 @@ void MainWindow::requestComplete(Request *request,
 	if (request->status() == Request::RequestCancelled)
 		return;
 
+	framesCaptured_++;
+
 	Buffer *buffer = buffers.begin()->second;
 
 	double fps = buffer->timestamp() - lastBufferTime_;
diff --git a/src/qcam/main_window.h b/src/qcam/main_window.h
index 46a494a9d783..6b3dcab6d490 100644
--- a/src/qcam/main_window.h
+++ b/src/qcam/main_window.h
@@ -10,7 +10,9 @@
 #include <map>
 #include <memory>
 
+#include <QElapsedTimer>
 #include <QMainWindow>
+#include <QObject>
 
 #include <libcamera/camera.h>
 #include <libcamera/stream.h>
@@ -28,10 +30,15 @@ enum {
 
 class MainWindow : public QMainWindow
 {
+	Q_OBJECT
+
 public:
 	MainWindow(const OptionsParser::Options &options);
 	~MainWindow();
 
+public Q_SLOTS:
+	void updateTitle();
+
 private:
 	int openCamera();
 
@@ -51,6 +58,10 @@ private:
 
 	uint64_t lastBufferTime_;
 
+	QElapsedTimer frameRateInterval_;
+	uint32_t previousFrames_;
+	uint32_t framesCaptured_;
+
 	ViewFinder *viewfinder_;
 };
 
diff --git a/src/qcam/meson.build b/src/qcam/meson.build
index 9f1fa75f9813..c2c4d7cc9787 100644
--- a/src/qcam/meson.build
+++ b/src/qcam/meson.build
@@ -7,13 +7,22 @@ qcam_sources = files([
     'viewfinder.cpp',
 ])
 
-import('qt5')
+qcam_headers = files([
+    'main_window.h',
+])
+
+qt5 = import('qt5')
 qt5_dep = dependency('qt5',
                      method : 'pkg-config',
                      modules : ['Core', 'Gui', 'Widgets'],
                      required : false)
 
 if qt5_dep.found()
+    moc_files = qt5.preprocess(moc_headers: qcam_headers,
+                               dependencies: qt5_dep)
+
+    qcam_sources += moc_files
+
     qcam  = executable('qcam', qcam_sources,
                        install : true,
                        dependencies : [libcamera_dep, qt5_dep],
-- 
2.20.1