qcam: Update window title with FPS

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.

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

3 files changed, 46 insertions, 2 deletions

diff --git a/src/qcam/main_window.cpp b/src/qcam/main_window.cpp
index d6136910..b2f3a1f3 100644
--- a/src/qcam/main_window.cpp
+++ b/src/qcam/main_window.cpp
@@ -28,6 +28,7 @@ MainWindow::MainWindow(const OptionsParser::Options &options)
 
 	title_ = "QCam " + QString::fromStdString(libcamera::version);
 	setWindowTitle(title_);
+	connect(&titleTimer_, SIGNAL(timeout()), this, SLOT(updateTitle()));
 
 	viewfinder_ = new ViewFinder(this);
 	setCentralWidget(viewfinder_);
@@ -54,6 +55,19 @@ 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 +162,10 @@ int MainWindow::startCapture()
 		requests.push_back(request);
 	}
 
+	titleTimer_.start(2000);
+	frameRateInterval_.start();
+	previousFrames_ = 0;
+	framesCaptured_ = 0;
 	lastBufferTime_ = 0;
 
 	ret = camera_->start();
@@ -188,6 +206,9 @@ void MainWindow::stopCapture()
 	isCapturing_ = false;
 
 	config_.reset();
+
+	titleTimer_.stop();
+	setWindowTitle(title_);
 }
 
 void MainWindow::requestComplete(Request *request,
@@ -196,6 +217,8 @@ 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 46a494a9..f58cb6a6 100644
--- a/src/qcam/main_window.h
+++ b/src/qcam/main_window.h
@@ -10,7 +10,10 @@
 #include <map>
 #include <memory>
 
+#include <QElapsedTimer>
 #include <QMainWindow>
+#include <QObject>
+#include <QTimer>
 
 #include <libcamera/camera.h>
 #include <libcamera/stream.h>
@@ -28,10 +31,15 @@ enum {
 
 class MainWindow : public QMainWindow
 {
+	Q_OBJECT
+
 public:
 	MainWindow(const OptionsParser::Options &options);
 	~MainWindow();
 
+private Q_SLOTS:
+	void updateTitle();
+
 private:
 	int openCamera();
 
@@ -43,6 +51,8 @@ private:
 	int display(Buffer *buffer);
 
 	QString title_;
+	QTimer titleTimer_;
+
 	const OptionsParser::Options &options_;
 
 	std::shared_ptr<Camera> camera_;
@@ -51,6 +61,10 @@ 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 9f1fa75f..21f91f25 100644
--- a/src/qcam/meson.build
+++ b/src/qcam/meson.build
@@ -7,14 +7,21 @@ qcam_sources = files([
     'viewfinder.cpp',
 ])
 
-import('qt5')
+qcam_moc_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()
-    qcam  = executable('qcam', qcam_sources,
+    moc_files = qt5.preprocess(moc_headers: qcam_moc_headers,
+                               dependencies: qt5_dep)
+
+    qcam  = executable('qcam', qcam_sources, moc_files,
                        install : true,
                        dependencies : [libcamera_dep, qt5_dep],
                        cpp_args : '-DQT_NO_KEYWORDS')