[libcamera-devel] [PATCH 4/4] 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.

Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
---
 src/qcam/main_window.cpp | 23 ++++++++++++++++++++---
 src/qcam/main_window.h   |  4 +++-
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/src/qcam/main_window.cpp b/src/qcam/main_window.cpp
index 61d7aa9469f0..c093bd0c809e 100644
--- a/src/qcam/main_window.cpp
+++ b/src/qcam/main_window.cpp
@@ -26,7 +26,7 @@ MainWindow::MainWindow(const OptionsParser::Options &options)
 {
 	int ret;
 
-	setWindowTitle();
+	setWindowTitle("");
 	viewfinder_ = new ViewFinder(this);
 	setCentralWidget(viewfinder_);
 	viewfinder_->setFixedSize(500, 500);
@@ -52,10 +52,11 @@ MainWindow::~MainWindow()
 	CameraManager::instance()->stop();
 }
 
-void MainWindow::setWindowTitle()
+void MainWindow::setWindowTitle(QString fps)
 {
 	QMainWindow::setWindowTitle("QCam : "
-		+ QString::fromStdString(libcamera::version.toString()));
+		+ QString::fromStdString(libcamera::version.toString())
+		+ " (" + fps + ")");
 }
 
 int MainWindow::openCamera()
@@ -152,6 +153,9 @@ int MainWindow::startCapture()
 		requests.push_back(request);
 	}
 
+	firstFrameTime = 0;
+	framesCaptured = 0;
+
 	ret = camera_->start();
 	if (ret) {
 		std::cout << "Failed to start capture" << std::endl;
@@ -215,6 +219,19 @@ void MainWindow::requestComplete(Request *request,
 
 	display(buffer);
 
+	if (firstFrameTime == 0)
+		firstFrameTime = buffer->timestamp();
+
+	uint64_t duration = buffer->timestamp() - firstFrameTime;
+	if (duration)
+		fps = framesCaptured * 1000000000.0 / duration;
+	else
+		fps = 0.0;
+
+	setWindowTitle(QString::number(fps, 'f', 2) + " fps");
+
+	framesCaptured++;
+
 	request = camera_->createRequest();
 	if (!request) {
 		std::cerr << "Can't create request" << std::endl;
diff --git a/src/qcam/main_window.h b/src/qcam/main_window.h
index b30a86768efc..792f89c2d831 100644
--- a/src/qcam/main_window.h
+++ b/src/qcam/main_window.h
@@ -33,7 +33,7 @@ public:
 	~MainWindow();
 
 private:
-	void setWindowTitle();
+	void setWindowTitle(QString info);
 
 	int openCamera();
 
@@ -49,6 +49,8 @@ private:
 	std::shared_ptr<Camera> camera_;
 	bool isCapturing_;
 	std::unique_ptr<CameraConfiguration> config_;
+	uint64_t firstFrameTime;
+	uint32_t framesCaptured;
 
 	ViewFinder *viewfinder_;
 };
-- 
2.20.1