"

 COPYRIGHT (c) 1995 by Claus Gittinger

	      All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

EventListener subclass:#ActiveHelp

	instanceVariableNames:'currentView currentHelpView currentFrame showProcess closeProcess'

	classVariableNames:'DelayTime ShowTime TheOneAndOnlyHelpListener'

	poolDictionaries:''

	category:'Interface-Help'

!

!ActiveHelp class methodsFor:'documentation'!

copyright

"

 COPYRIGHT (c) 1995 by Claus Gittinger

	      All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

!

documentation

"

    The active help listener.

    The one and only instance of myself intercepts incoming mouse & keyboard 

    events for the display device, being especially interested in view-enter/

    leave enents. When such an event arrives, it asks the corresponding view

    or its model for a help message and display it via an ActiveHelpView.

    This query is repeated along the views superView chain, until any model or

    view returns a nonNil answer for the #helpTextFor:at or #helpTextFor

    message.

    All I need for automatic help is some model/view/applicationModel along

    the superview chain of the entered component, which responds to the

    #helpTextFor: message with a non-nil (string-) answer.

    I close down the help view after a while, if a key is pressed or the mouse

    moved to another view.

    Who should provide the helpText:

        the best place is the application object (an instance of ApplicationModel)

        or the topView, if its a derived class of StandardSystemView.

        This should know about its components and return the string

        when asked via #helpTextFor:aComponent.

        See examples in FileBrowser, NewLauncher etc.

    Be aware, that for applicationModels, there must be a link from the

    topView to this applicationModel 

    (set via: aTopView application:anApplicationModel)

    otherwise, the helpManager has no means of finding the application which

    corresponds to a view.

    Who should display the helpText:

        by default, the helpListener opens a little popup view, which displays the

        returned help message. However, a nice trick which can be used by applications

        is to create an infoLabel as a subview of the topFrame (a la windows)

        and display the text right in the #helpTextFor: method. To cheat the

        help listener, this method should then return nil, to keep it silent.

    [author:]

        Claus Gittinger

    [See also:]

        ActiveHelp

"

!

examples

"

    (make certain that activeHelp is turned on ...)

    the following example uses a Plug as a model replacement.

    In concrete application, you would create a method to implement the helpText

    query message.

"

! !

!ActiveHelp class methodsFor:'initialization'!

initialize

    ShowTime := 15.

    DelayTime := 2.

    "

     ActiveHelp initialize

    "

! !

!ActiveHelp class methodsFor:'startup'!

isActive 

    ^ TheOneAndOnlyHelpListener notNil

!

start

    TheOneAndOnlyHelpListener isNil ifTrue:[

	TheOneAndOnlyHelpListener := self new.

    ].

    TheOneAndOnlyHelpListener listen

    "

     ActiveHelp start

    "

!

stop

    TheOneAndOnlyHelpListener notNil ifTrue:[

	TheOneAndOnlyHelpListener unlisten.

    ].

    TheOneAndOnlyHelpListener := nil

    "

     ActiveHelp stop

    "

! !

!ActiveHelp class methodsFor:'times'!

delayTime:numberOfSeconds

    "set the delay (the time, the cursor has to be in the view

     before help is shown). The default is 2 seconds."

    DelayTime := numberOfSeconds

    "

     ActiveHelp delayTime:0.5

     ActiveHelp delayTime:2

     ActiveHelp delayTime:10

    "

!

showTime:numberOfSeconds

    "set the number of seconds, a help messages is to be shown.

     The default is 15 seconds."

    ShowTime := numberOfSeconds

    "

     ActiveHelp showTime:10

     ActiveHelp showTime:99999 

     ActiveHelp showTime:30

    "

! !

!ActiveHelp methodsFor:'listening'!

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

    self hideIfPointerLeft:view.

    ^ false

!

buttonPress:state x:x y:y view:view

    self hideHelp.

    ^ false

!

keyPress:state x:x y:y view:view

    self hideHelp.

    ^ false

!

pointerEnter:state x:x y:y view:aView

    |text p|

    showProcess notNil ifTrue:[

	p := showProcess. showProcess := nil.

	p terminate.

    ].

    self hideIfPointerLeft:aView.

    aView topView == currentHelpView ifTrue:[

	^ true

    ].

    self initiateHelpFor:aView atX:x y:y.

    ^ false

!

pointerLeave:state view:view

    self hideIfPointerLeft:view.

    ^ false

! !

!ActiveHelp methodsFor:'private'!

helpTextFor:aView atX:x y:y

    "pointer entered aView; 

     walk along the views superView chain,

     asking models and views encountered while walking.

     The first one who understands and returns a nonNil answer to the

     #helpTextFor:at: or #helpTextFor: message ends this walk and the

     returned string is returned."

    |model text view org found v sv|

    view := aView.

    (model := aView model) notNil ifTrue:[

	(model respondsTo:#helpTextFor:at:) ifTrue:[

	    text := model helpTextFor:aView at:x@y.

	    text notNil ifTrue:[^ text].

	].

	(model respondsTo:#helpTextFor:) ifTrue:[

	    text := model helpTextFor:aView.

	    text notNil ifTrue:[^ text].

	]

    ].

    (aView respondsTo:#helpText) ifTrue:[

	text := aView helpText.

	text notNil ifTrue:[^ text].

    ].

    "walk up the chain - maybe someone knows about its subview ..."

    v := aView.

    [(sv := v superView) notNil] whileTrue:[

	(model := sv model) notNil ifTrue:[

	    (model respondsTo:#helpTextFor:at:) ifTrue:[

		text := model helpTextFor:aView at:x@y.

		text notNil ifTrue:[^ text].

	    ].

	    (model respondsTo:#helpTextFor:) ifTrue:[

		text := model helpTextFor:aView.

		text notNil ifTrue:[^ text].

	    ]

	].

	(sv respondsTo:#helpTextFor:) ifTrue:[

	    text := sv helpTextFor:aView.

	    text notNil ifTrue:[^ text].

	    text := sv helpTextFor:v.

	    text notNil ifTrue:[^ text].

	 ].

	 v := sv.

    ].

    (v notNil and:[v respondsTo:#application]) ifTrue:[

	(model := v application) notNil ifTrue:[

	    (model respondsTo:#helpTextFor:at:) ifTrue:[

		text := model helpTextFor:aView at:x@y.

		text notNil ifTrue:[^ text].

	    ].

	    (model respondsTo:#helpTextFor:) ifTrue:[

		text := model helpTextFor:aView.

		text notNil ifTrue:[^ text].

	    ]

	]

    ].

    (v notNil and:[v respondsTo:#model]) ifTrue:[

	(model := v model) notNil ifTrue:[

	    (model respondsTo:#helpTextFor:at:) ifTrue:[

		text := model helpTextFor:aView at:x@y.

		text notNil ifTrue:[^ text].

	    ].

	    (model respondsTo:#helpTextFor:) ifTrue:[

		text := model helpTextFor:aView.

		text notNil ifTrue:[^ text].

	    ]

	]

    ].

    (view class respondsTo:#helpText) ifTrue:[

	text := view class helpText.

	text notNil ifTrue:[^ text].

    ].

    ^ nil

    "Modified: 31.8.1995 / 20:38:00 / claus"

!

hideIfPointerLeft:aView

    |whereOnScreen p|

"/    showProcess notNil ifTrue:[

"/        p := showProcess. showProcess := nil.

"/        p terminate.

"/    ].

    whereOnScreen := aView device pointerPosition.

    (currentFrame notNil

    and:[(currentFrame insetBy:1@1) containsPoint:whereOnScreen]) ifFalse:[

	self hideHelp.

	currentView := nil

    ].

!

initiateHelpFor:aView atX:x y:y

    |text p|

    text := self helpTextFor:aView atX:x y:y.

    text notNil ifTrue:[

	DelayTime > 0 ifTrue:[

	    showProcess notNil ifTrue:[

		p := showProcess. showProcess := nil.

		p terminate.

	    ].

	    showProcess := [

		    (Delay forSeconds:DelayTime) wait.

		    showProcess := nil.

		    self showHelp:text for:aView

	    ] forkAt:(Processor userSchedulingPriority + 1).

	] ifFalse:[

	    self showHelp:text for:aView

	]

    ].

! !

!ActiveHelp methodsFor:'show / hide help'!

hideHelp

    |p|

    showProcess notNil ifTrue:[

	p := showProcess. showProcess := nil.

	p terminate.

    ].

    currentHelpView notNil ifTrue:[

	[

	    currentHelpView destroy.

	    currentHelpView := nil.

	    currentView := nil.

	] valueUninterruptably

    ].

    currentFrame := nil.

    closeProcess notNil ifTrue:[

	p := closeProcess. closeProcess := nil.

	p terminate.

    ]

!

showHelp:aHelpText for:view

    |org p v|

    view == currentView ifTrue:[^ self].

    closeProcess notNil ifTrue:[

	p := closeProcess. closeProcess := nil.

	p terminate.

    ].

    currentHelpView notNil ifTrue:[

	self hideHelp

    ].

    org := view originRelativeTo:nil.

    currentFrame := org extent:view extent.

    org :=org + (view extent // 2).

    v := ActiveHelpView for:aHelpText withCRs.

    org := view device pointerPosition.

    org := org + (10@10).

    (org x + v width) > view device width ifTrue:[

	org := (org x - v width) @ org y

    ].

    (org y + v height) > view device height ifTrue:[

	org := org x @ (org y - v height).

    ].

    v origin:org.

"/    currentHelpView open.

    v realize.

    v enableButtonMotionEvents.

    v enableMotionEvents.

    currentHelpView := v.

    currentView := view.

    closeProcess := [

	Process terminateSignal handle:[:ex |

	    closeProcess := nil.

	] do:[

	    (Delay forSeconds:ShowTime) wait.

	    [

		currentHelpView notNil ifTrue:[

		    currentHelpView destroy.

		    currentHelpView := nil.

		]

	    ] valueUninterruptably

	].

    ] forkAt:(Processor userSchedulingPriority + 1).

    "Modified: 31.8.1995 / 19:20:45 / claus"

! !

!ActiveHelp class methodsFor:'documentation'!

version

! !

ActiveHelp initialize!