setValue method
Implementation
void setValue(double value) {
if (value > _initOffset) {
_opacity = value;
} else {
_opacity = value - _initOffset;
}
notifyListeners();
if (callback != null) {
if (_isCollapsed && opacity < 1) {
_isCollapsed = false;
callback!(_isCollapsed);
} else if (!_isCollapsed && opacity >= 1) {
_isCollapsed = true;
callback!(_isCollapsed);
}
}
}