more accurate

src/FPS.cpp

@@ -3,7 +3,7 @@
 
 FPS::FPS() {
 	previousFrame = high_resolution_clock::now();
-	timeSinceUpdate = milliseconds(0);
+	timeSinceUpdate = nanoseconds(0);
 	framesSinceUpdate = 0;
 	current = 0;
 
@@ -16,7 +16,7 @@ FPS::FPS() {
 void FPS::newFrame() {
 	framesSinceUpdate++;
 	auto thisFrame = high_resolution_clock::now();
-	timeSinceUpdate += duration_cast<milliseconds>(thisFrame - previousFrame);
+	timeSinceUpdate += thisFrame - previousFrame;
 	previousFrame = thisFrame;
 }
 
@@ -25,7 +25,7 @@ void FPS::setUpdateInterval(int milli) {
 }
 
 void FPS::updateCurrent() {
-	current = framesSinceUpdate * 1000 / timeSinceUpdate.count();
+	current = framesSinceUpdate * 1000 * 1000 * 1000 / timeSinceUpdate.count();
 	framesSinceUpdate = 0;
-	timeSinceUpdate = milliseconds(0);
+	timeSinceUpdate = nanoseconds(0);
 }

src/FPS.h

@@ -8,7 +8,7 @@ using namespace std::chrono;
 class FPS : public QObject {
 	QTimer * timer;
 	time_point<system_clock> previousFrame;
-	milliseconds timeSinceUpdate;
+	nanoseconds timeSinceUpdate;
 	size_t framesSinceUpdate;
 public:
 	FPS();