"

 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

		lastHelpText'

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

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

    (actully, the view is first asked if it would like to display it itself

     - for example, in some information-view).

    The query for the helpText 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, Launcher 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

    [start with:]

        ActiveHelp start

        ActiveHelp stop

    [See also:]

        ActiveHelpView

        WindowGroup WindowEvent

        ApplicationModel StandardSystemView

"

!

examples

"

    (make certain that activeHelp is turned on ...

     ... otherwise, you will see nothing)

    the following example uses a Plug as a model replacement.

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

    query message.

                                                                        [exBegin]

        |app top button1 button2|

        app := Plug new.

        app respondTo:#helpTextFor:

                 with:[:view | 

                               view == button1 ifTrue:[

                                 'this is button1'

                               ] ifFalse:[

                                 view == button2 ifTrue:[

                                   'some help for button2'

                                 ] ifFalse:[

                                   nil

                                 ]

                               ]

                      ].

        top := StandardSystemView new.

        top extent:300@100.

        button1 := Button label:'b1' in:top.

        button1 origin:0.0@0.0 corner:0.5@30. 

        button2 := Button label:'b2' in:top.

        button2 origin:0.5@0.0 corner:1.0@30.

        top model:app. '<-- normally this would be: top application:app'.

        top open

                                                                        [exEnd]

    (make certain that activeHelp is turned on ...

     ... otherwise, you will see nothing)

    alternatively, display of the helpMessage in a local, private view:

                                                                        [exBegin]

        |app top button1 button2 infoView|

        app := Plug new.

        app respondTo:#helpTextFor:

                 with:[:view | infoView label:'info ...'.

                               view == button1 ifTrue:[

                                 infoView label:'this is button1'

                               ].

                               view == button2 ifTrue:[

                                 infoView label:'some help for button2'

                               ].

                               nil

                      ].

        top := StandardSystemView new.

        top extent:300@100.

        button1 := Button label:'b1' in:top.

        button1 origin:0.0@0.0 corner:0.5@30. 

        button2 := Button label:'b2' in:top.

        button2 origin:0.5@0.0 corner:1.0@30.

        infoView := Label label:'info ...' in:top.

        infoView level:-1; origin:0.0@1.0 corner:1.0@1.0.

        infoView topInset:(infoView preferredExtent y negated - 3);

                 leftInset:3; 

                 rightInset:3; 

                 bottomInset:3;

                 adjust:#left.

        top model:app. '<-- normally this would be: top application:app'.

        top open

                                                                        [exEnd]

"

! !

!ActiveHelp class methodsFor:'initialization'!

initialize

    "set default delay & help-display times"

    ShowTime := 15.

    DelayTime := 2.

    "

     ActiveHelp initialize

    "

    "Modified: 27.4.1996 / 15:07:27 / cg"

! !

!ActiveHelp class methodsFor:'queries'!

currentHelpListener

    "return the activeHelp listener if activeHelp is turned on, nil otherwise"

    ^ TheOneAndOnlyHelpListener

    "Created: 28.6.1997 / 13:59:44 / cg"

!

isActive

    "return true, if activeHelp is turned on"

    ^ TheOneAndOnlyHelpListener notNil

    "Modified: 27.4.1996 / 15:07:57 / cg"

! !

!ActiveHelp class methodsFor:'startup'!

start

    "start activeHelp"

    TheOneAndOnlyHelpListener isNil ifTrue:[

        TheOneAndOnlyHelpListener := self new.

    ].

    TheOneAndOnlyHelpListener listen

    "

     ActiveHelp start

    "

    "Modified: 27.4.1996 / 15:08:05 / cg"

!

stop

    "stop activeHelp"

    TheOneAndOnlyHelpListener notNil ifTrue:[

        TheOneAndOnlyHelpListener unlisten.

    ].

    TheOneAndOnlyHelpListener := nil

    "

     ActiveHelp stop

    "

    "Modified: 27.4.1996 / 15:08:11 / cg"

! !

!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

    "handle motion events - if the mousepointer left the 

     previous helped view, hide the help"

    self hideIfPointerLeft:view.

    ^ false

    "Modified: 27.4.1996 / 15:09:48 / cg"

!

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

    "handle button press - unconditionally hide the help"

    self hideHelp.

    ^ false

    "Modified: 27.4.1996 / 15:09:45 / cg"

!

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

    "handle key press - unconditionally hide the help"

    self hideHelp.

    ^ false

    "Modified: 27.4.1996 / 15:09:57 / cg"

!

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

    "handle pointer entering a view; setup timeOut to show help"

    self stopHelpDisplayProcess.

    self hideIfPointerLeft:aView.

    aView topView == currentHelpView ifTrue:[

        ^ true

    ].

    self initiateHelpFor:aView atX:x y:y.

    ^ false

    "Modified: 28.6.1997 / 14:04:09 / cg"

!

pointerLeave:state view:view

    "handle pointer leaving a view; hide help text"

    self hideIfPointerLeft:view.

    ^ false

    "Modified: 27.4.1996 / 15:10:41 / cg"

! !

!ActiveHelp methodsFor:'private'!

helpTextFor:aView atX:x y:y

    "retrieve helptext for aView as a string; 

     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 search and the

     returned string is returned."

    |model app text view 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 container) 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.

    ].

    (aView respondsTo:#application) ifTrue:[

        (app := aView application) notNil ifTrue:[

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

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

                text notNil ifTrue:[^ text].

            ].

            (app respondsTo:#helpTextFor:) ifTrue:[

                text := app helpTextFor:aView.

                text notNil ifTrue:[^ text].

            ]

        ]

    ].

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

        (app := v application) notNil ifTrue:[

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

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

                text notNil ifTrue:[^ text].

            ].

            (app respondsTo:#helpTextFor:) ifTrue:[

                text := app 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"

    "Modified: 5.6.1996 / 14:18:23 / cg"

!

hideIfPointerLeft:aView

    "hide help, if the pointer is not in aView"

    |whereOnScreen|

    whereOnScreen := aView graphicsDevice pointerPosition.

    (currentFrame notNil

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

        self hideHelp.

        currentView := nil

    ].

    "Modified: 28.5.1996 / 20:18:28 / cg"

!

stopHelpDisplayProcess

    |p|

    showProcess notNil ifTrue:[

        p := showProcess. showProcess := nil.

        p terminate.

    ].

    "Created: 28.6.1997 / 14:03:17 / cg"

! !

!ActiveHelp methodsFor:'show / hide help'!

hideHelp

    "hide the help text"

    |p|

    self stopHelpDisplayProcess.

    currentHelpView notNil ifTrue:[

        [

            currentHelpView destroy.

            currentHelpView := nil.

            currentView := nil.

        ] valueUninterruptably

    ].

    currentFrame := nil.

    closeProcess notNil ifTrue:[

        p := closeProcess. closeProcess := nil.

        p terminate.

    ]

    "Modified: 28.6.1997 / 14:03:50 / cg"

!

initiateHelpFor:aView atX:x y:y

    "ask aView for helpText, passing x/y coordinates;

     start a timeout process to display this helpText after some delay;

     Normally used internally, but can also be used by widgets to force 

     re-negotiation of the displayed helpText 

     (for example in a menu, when the selection changes)"

    self

        initiateHelpFor:aView atX:x y:y now:false

    "Modified: 28.6.1997 / 14:45:57 / cg"

!

initiateHelpFor:aView atX:x y:y now:showItNow

    "ask aView for helpText, passing x/y coordinates;

     start a timeout process to display this helpText after some delay;

     Normally used internally, but can also be used by widgets to force 

     re-negotiation of the displayed helpText 

     (for example in a menu, when the selection changes)"

    |text top app|