debugNeedsPaint property
Whether this render object's paint information is dirty.
This is only set in debug mode. In general, render objects should not need to condition their runtime behavior on whether they are dirty or not, since they should only be marked dirty immediately prior to being laid out and painted.
It is intended to be used by tests and asserts.
It is possible (and indeed, quite common) for debugNeedsPaint to be false and debugNeedsLayout to be true. The render object will still be repainted in the next frame when this is the case, because the markNeedsPaint method is implicitly called by the framework after a render object is laid out, prior to the paint phase.
Implementation
bool get debugNeedsPaint {
bool result;
assert(() {
result = _needsPaint;
return true;
}());
return result;
}