Circle CheckBox Without a library

Container(
                                width: 25,
                                height: 25,
                                decoration:  BoxDecoration(
                                    color: data.checkBox! ? t14_cBox_color : Colors.transparent,
                                    border: Border.all(
                                      width: 1,
                                      color: data.checkBox! ? white : t14_colorBlue,
                                    ),
                                    shape: BoxShape.circle),
                                child: Theme(
                                  data: ThemeData(
                                    unselectedWidgetColor: Colors.transparent,
                                  ),
                                  child: Checkbox(
                                    value: data.checkBox,
                                    onChanged: (state) {
                                     
                                    },
                                    activeColor: Colors.transparent,
                                    checkColor: t14_OppsColor,
                                    materialTapTargetSize: MaterialTapTargetSize.padded,
                                  ),
                                ),
                              )