[libcamera-devel] [PATCH v4 5/6] 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>

---
v4
 - Start and stop title timer with the stream
---
 src/qcam/main_window.cpp | 23 +++++++++++++++++++++++
 src/qcam/main_window.h   | 15 +++++++++++++++
 src/qcam/meson.build     | 11 +++++++++--
 3 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/src/qcam/main_window.cpp b/src/qcam/main_window.cpp
index d61369109d66..5693b9256a08 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 46a494a9d783..e97d92402f1e 100644
--- a/src/qcam/main_window.h
+++ b/src/qcam/main_window.h
@@ -10,7 +10,11 @@
 #include <map>
 #include <memory>
 
+
+#include <QElapsedTimer>
 #include <QMainWindow>
+#include <QObject>
+#include <QTimer>
 
 #include <libcamera/camera.h>
 #include <libcamera/stream.h>
@@ -28,10 +32,15 @@ enum {
 
 class MainWindow : public QMainWindow
 {
+	Q_OBJECT
+
 public:
 	MainWindow(const OptionsParser::Options &options);
 	~MainWindow();
 
+public Q_SLOTS:
+	void updateTitle();
+
 private:
 	int openCamera();
 
@@ -43,6 +52,8 @@ private:
 	int display(Buffer *buffer);
 
 	QString title_;
+	QTimer titleTimer_;
+
 	const OptionsParser::Options &options_;
 
 	std::shared_ptr<Camera> camera_;
@@ -51,6 +62,10 @@ 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..21f91f25cec0 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')
-- 
2.20.1