How Long Does It Take for a QQuickItem to Become Visible?
2 days ago
- #Performance Measurement
- #Frame Timing
- #Qt Quick
- Measuring time for a Qt Quick item to become visible after loading to detect perceived frame drops.
- Items must inherit from QQuickItem with visible set false initially; visibleChanged signal triggers measurement.
- Use ensurePolished and updatePolish to ensure measurement occurs only when the item's frame is swapped.
- Connect to QQuickWindow::afterFrameEnd for precise timing; disconnect after capturing the measurement.
- Calculate dropped frames by dividing elapsed time by frame duration (e.g., 16 ms for 60 Hz).
- Setting visible false in C++ constructor guarantees visibleChanged signal emission during QML initialization.
- Code example provided: TimedItem subclass with properties and methods for time measurement.