"{ Package: 'stx:libview2' }"

EventListener subclass:#ScreenLock
	instanceVariableNames:'workstation lastInactiveTime lockAfterSeconds lockChannel
		lockChannelOut processor lockedViews hiddenViews'
	classVariableNames:''
	poolDictionaries:''
	category:'Interface-Support'
!

!ScreenLock class methodsFor:'documentation'!

documentation
"
    documentation to be added.

    [author:]
	Stefan Vogel (stefan@nilpferd)

    [see also:]

    [instance variables:]

    [class variables:]
"
!

examples
"
                                                                [exBegin]
    |screenLock|

    screenLock := ScreenLock forDevice:Screen current.
    screenLock lock.
    Delay waitForSeconds:3.
    screenLock unlock.
    screenLock unlisten.
                                                                [exEnd]

                                                                [exBegin]
    |screenLock|

    screenLock := ScreenLock forDevice:Screen current.
    Delay waitForSeconds:1.
    screenLock checkTime.
    Delay waitForSeconds:12.
    screenLock checkTime.
    Delay waitForSeconds:3.
    screenLock unlock.
    screenLock unlisten.
                                                                [exEnd]
                                                                [exBegin]
    |screenLock channel running|

    screenLock := ScreenLock forDevice:Screen current.
    screenLock lockAfterSeconds:4.
    [
        channel := false asValue.
        channel onChangeEvaluate:[
            channel value ifTrue:[
                self information:'Application is locked\\Hit ok to unlock' withCRs.
                channel value:false.
            ].
        ].
        screenLock lockChannel:channel.

        [
            Delay waitForSeconds:2.
            screenLock checkTime.
        ] loop.
    ] valueNowOrOnUnwindDo:[
        screenLock unlisten.
    ].
                                                                [exEnd]
"
! !

!ScreenLock class methodsFor:'instance creation'!

forDevice:aWorkstation

    ^ self new initializeForDevice:aWorkstation

! !

!ScreenLock methodsFor:'accessing'!

lockAfterSeconds
    "return the value of the instance variable 'lockAfterSeconds' (automatically generated)"

    ^ lockAfterSeconds
!

lockAfterSeconds:something
    "set the value of the instance variable 'lockAfterSeconds' (automatically generated)"

    lockAfterSeconds := something.
!

lockChannel

    lockChannel isNil ifTrue:[
        self lockChannel:false asValue.
    ].
    ^ lockChannel
!

lockChannel:something

    lockChannel notNil ifTrue:[ 
        lockChannel removeDependent:self.
    ].

    lockChannel := something.
    lockChannel addDependent:self.
!

lockChannelOut

    lockChannelOut isNil ifTrue:[
        lockChannelOut := false asValue.
    ].
    ^ lockChannelOut
!

lockChannelOut:something
    "set the value of the instance variable 'lockChannelOut' (automatically generated)"

    lockChannelOut := something.
!

processor
    "return the value of the instance variable 'processor' (automatically generated)"

    ^ processor
!

processor:something
    "set the value of the instance variable 'processor' (automatically generated)"

    processor := something.
!

workstation
    "return the value of the instance variable 'workstation' (automatically generated)"

    ^ workstation
!

workstation:something
    "set the value of the instance variable 'workstation' (automatically generated)"

    workstation := something.
! !

!ScreenLock methodsFor:'change & update'!

update:aspect with:param from:anObject

    |lock|

    anObject == lockChannel ifTrue:[
        aspect == #value ifTrue:[
            "/ lockChannel is a value holder
            lock := lockChannel value.
        ] ifFalse:[
            "/ lockChannel is a block or something else
            lock := param.
        ].

        "lock or unlock the screen
         If a processor is defined, let the processor perform the unlock,
         so that posssible Display errors do not affect the sender"

        lock == true ifTrue:[
            processor isNil ifTrue:[
                self lockScreen.
            ] ifFalse:[
                processor enqueueMessage:#lockScreen for:self arguments:#().
            ].
        ] ifFalse:[
            processor isNil ifTrue:[
                self unlockScreen.
            ] ifFalse:[
                processor enqueueMessage:#unlockScreen for:self arguments:#().
            ].
        ]
    ].
! !

!ScreenLock methodsFor:'events'!

buttonMotion:state x:x y:y view:aView

    ^ self gotEventForView:aView.
!

buttonMultiPress:button x:x y:y view:aView
    ^ self gotEventForView:aView.

!

buttonPress:button x:x y:y view:aView
    ^ self gotEventForView:aView.

!

buttonRelease:button x:x y:y view:aView
    ^ self gotEventForView:aView.

!

keyPress:key x:x y:y view:aView
    ^ self gotEventForView:aView.

!

keyRelease:key x:x y:y view:aView
    ^ self gotEventForView:aView.

!

mouseWheelMotion:state x:x y:y amount:amount deltaTime:dTime view:aView
    ^ self gotEventForView:aView.

! !

!ScreenLock methodsFor:'lock interface'!

checkTime

    |now|

    lockedViews isNil ifTrue:[
        now := Timestamp now.
        lastInactiveTime notNil ifTrue:[
            (lastInactiveTime addSeconds:lockAfterSeconds value) < now ifTrue:[
                self lock
            ].
        ] ifFalse:[
            lastInactiveTime := now.
        ].
    ].
!

lock
   "trigger locking of screen"

    self lockChannel value:true.
!

unlisten
    "do not listen for events any longer.
     This must be called when a screen lock is detached from a
     screen."

    workstation removeEventListener:self
!

unlock
   "trigger unlocking of screen"

    self lockChannel value:false.
! !

!ScreenLock methodsFor:'private'!

gotEventForView:v
    "got an event.
     Reset the inactive timer.
     If locked, eat all user events (for security)"

    lockedViews isNil ifTrue:[
        lastInactiveTime := nil.        
        ^ false.
    ].
    ^ lockedViews includes:v.
!

initializeForDevice:aWorkstation

     lockAfterSeconds := 10.
     workstation := aWorkstation.
     workstation addEventListener:self.

!

lockScreen
    "lock the screen"

    lockedViews := workstation allViews.
    hiddenViews := lockedViews select:[:v|
        "close popupViews, they will leave the modal loop when 
         they are unmapped.
         This is a kludge, but invisible popUpViews are 
         currently not supported"

        v isPopUpView ifTrue:[
            v hide.
        ].
        v shown and:[v isTopView].
    ].

    hiddenViews do:[:v|
        v beInvisible.
    ].

    lockChannelOut notNil ifTrue:[      
        lockChannelOut value:true.
    ].
!

unlockScreen

    lastInactiveTime := nil.
    hiddenViews do:[:v|
        "don't try to restore views that have been closed while
         being invisible"
        v id notNil ifTrue:[
            v beVisible.
        ].
    ].
    hiddenViews := lockedViews := nil.

    lockChannelOut notNil ifTrue:[      
        lockChannelOut value:false.
    ].
! !

!ScreenLock methodsFor:'queries'!

isLocked

    ^ lockedViews notNil
! !

!ScreenLock class methodsFor:'documentation'!

version
    ^ '$Header: /cvs/stx/stx/libview2/ScreenLock.st,v 1.7 2004-03-20 19:20:31 stefan Exp $'
! !