debugEmptyFrameDiagnosis static method

@visibleForTesting ({String? message, bool warned}) debugEmptyFrameDiagnosis({ required bool warned, required bool drewSomething, required bool regionEmpty, required bool noViews, required bool noScreenViews, required int meshCount, required int visibleMeshCount, required bool anyLayerMaskZero, required List<int> screenViewMasks, required int visibleLayersUnion, })

Diagnoses a frame that issued zero draw calls, for renderViews.

Returns the message to print (null when nothing should print) and the next state of the once-only latch. A frame that drew (drewSomething) clears the latch so a later regression prints again; a blank frame prints one message the first time and stays silent until a frame draws. The caller invokes this inside an assert, so neither it nor the scan feeding it costs anything in a release build.

Implementation

@visibleForTesting
static ({String? message, bool warned}) debugEmptyFrameDiagnosis({
  required bool warned,
  required bool drewSomething,
  required bool regionEmpty,
  required bool noViews,
  required bool noScreenViews,
  required int meshCount,
  required int visibleMeshCount,
  required bool anyLayerMaskZero,
  required List<int> screenViewMasks,
  required int visibleLayersUnion,
}) {
  if (drewSomething) return (message: null, warned: false);
  if (warned) return (message: null, warned: true);
  final cause = _blankFrameCause(
    regionEmpty: regionEmpty,
    noViews: noViews,
    noScreenViews: noScreenViews,
    meshCount: meshCount,
    visibleMeshCount: visibleMeshCount,
    anyLayerMaskZero: anyLayerMaskZero,
    screenViewMasks: screenViewMasks,
    visibleLayersUnion: visibleLayersUnion,
  );
  return (
    message: 'Flutter Scene rendered a blank frame (zero draw calls). $cause',
    warned: true,
  );
}