addPerformanceOverlay method

void addPerformanceOverlay (int enabledOptions, Rect bounds)

Adds an object to the scene that displays performance statistics.

Useful during development to assess the performance of the application. The enabledOptions controls which statistics are displayed. The bounds controls where the statistics are displayed.

enabledOptions is a bit field with the following bits defined:

  • 0x01: displayRasterizerStatistics - show GPU thread frame time
  • 0x02: visualizeRasterizerStatistics - graph GPU thread frame times
  • 0x04: displayEngineStatistics - show UI thread frame time
  • 0x08: visualizeEngineStatistics - graph UI thread frame times Set enabledOptions to 0x0F to enable all the currently defined features.

The "UI thread" is the thread that includes all the execution of the main Dart isolate (the isolate that can call Window.render). The UI thread frame time is the total time spent executing the Window.onBeginFrame callback. The "GPU thread" is the thread (running on the CPU) that subsequently processes the Scene provided by the Dart code to turn it into GPU commands and send it to the GPU.

See also the PerformanceOverlayOption enum in the rendering library. for more details.

Implementation 

// Values above must match constants in //engine/src/sky/compositor/performance_overlay_layer.h
void addPerformanceOverlay(int enabledOptions, Rect bounds) {
  _addPerformanceOverlay(enabledOptions,
                         bounds.left,
                         bounds.right,
                         bounds.top,
                         bounds.bottom);
}