library UnitDamaged initializer InitRect
{
    private region Region
    private trigger Trigger
    
    private nothing Adder()
    {
        if(GetEnteringUnit()!=null)
        {
            TriggerRegisterUnitEvent(GetTriggeringTrigger(),GetEnteringUnit(),EVENT_UNIT_DAMAGED)
        }
    }
    
    void OnDamage(code actionFunc)
    {
        TriggerAddAction(Trigger, actionFunc)
    }
    
    private nothing AnyUnitDamagedEvent(trigger trg)
    {
        group CurrentUnits = CreateGroup()
        unit Picked
        GroupEnumUnitsInRect(CurrentUnits,bj_mapInitialPlayableArea,null)
        loop
        {
            Picked = FirstOfGroup(CurrentUnits)
            exitwhen Picked == null
            TriggerRegisterUnitEvent(trg,Picked,EVENT_UNIT_DAMAGED)
            GroupRemoveUnit(CurrentUnits,Picked)
        }
        TriggerRegisterEnterRegion(trg,Region,null)
        TriggerAddAction(trg,function Adder)
        DestroyGroup(CurrentUnits)
        CurrentUnits=null
    }

    private nothing InitRect()
    {
        Region = CreateRegion()
        Trigger = CreateTrigger()
        AnyUnitDamagedEvent(Trigger)
        RegionAddRect(Region, bj_mapInitialPlayableArea)
    }
}