markDirty method
Implementation
void markDirty(Rect region) {
_dirtyRegion = _dirtyRegion == null
? region
: _dirtyRegion!.expandToInclude(region);
}
void markDirty(Rect region) {
_dirtyRegion = _dirtyRegion == null
? region
: _dirtyRegion!.expandToInclude(region);
}