"

 COPYRIGHT (c) 1989 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.

"

SimpleView subclass:#View

	instanceVariableNames:'model aspectMsg changeMsg menuMsg menuHolder menuPerformer'

	classVariableNames:''

	poolDictionaries:''

	category:'Views-Basic'

!

!View class methodsFor:'documentation'!

copyright

"

 COPYRIGHT (c) 1989 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

"

    this class adds provisions for views which show or work on a model.

    This functionality used to be in View, but has been extracted into SimpleView and

    this new View class, to take some of the stuff out of views which do not need

    this functionality (i.e. all views which do only geometry management).

    Instances of View are seldom used, most views in the system inherit 

    from this class. 

    [Instance variables:]

        model           <nil | any>         the model (if any)

        aspectMsg       <nil | Symbol>      the aspect; typically

                                            dependentViews react on changes

                                            of this aspect and update their contents.

        changeMsg       <nil | Symbol>      the changeMessage; typically

                                            dependentViews send this message to

                                            the model to tell it about changes.

        menuMsg         <nil | Symbol>      the menuMessage; typically

                                            dependentViews send this message to

                                            the model to ask for a popup menu.

        menuHolder      <any>               who has a menu 

                                            (default: nil i.e. model has menu)

        menuPerformer   <any>               who performs menu actions

                                            (default: nil i.e. model has menu)

    [see also:]

        StandardSystemView TopView DialogBox

        WindowGroup

        Model ValueHolder

        ( introduction to view programming :html: programming/viewintro.html )

    [author:]

        Claus Gittinger

"

!

examples

"

    a subView in a topView:

                                                                        [exBegin]

        |top v|

        v := View new.

        v origin:0.25 @ 0.25 corner:0.75 @ 0.75.

        top addSubView:v.

        top open

                                                                        [exEnd]

    the same, a bit more compact:

                                                                        [exBegin]

        |top v|

        top open

                                                                        [exEnd]

"

! !

!View class methodsFor:'instance creation'!

on:aModel aspect:aspectMsg

    "st-80 style view creation: create a new view, set its model

     and selectors for aspect"

    ^ self new 

	on:aModel

	aspect:aspectMsg

!

on:aModel aspect:aspectMsg change:changeMsg

    "st-80 style view creation: create a new view, set its model

     and selectors for aspect and change"

    ^ self new 

	on:aModel

	aspect:aspectMsg

	change:changeMsg

!

on:aModel aspect:aspectMsg change:changeMsg menu:menuMsg

    "st-80 style view creation: create a new view, set its model

     and selectors for aspect, change and menu"

    ^ self new 

	on:aModel

	aspect:aspectMsg

	change:changeMsg

	menu:menuMsg

!

on:aModel aspect:aspectMsg menu:menuMsg

    "st-80 style view creation: create a new view, set its model

     and selectors for aspect and menu"

    ^ self new 

	on:aModel

	aspect:aspectMsg

	menu:menuMsg

! !

!View class methodsFor:'defaults'!

defaultAspectMessage   

    "subclasses which by default do NOT want to be informed about changed

     models should redefine this to return nil"

    ^ #value

!

defaultChangeMessage   

    "subclasses which by default do NOT want to inform the model

     should redefine this to return nil"

    ^ #value:

!

defaultMenuMessage   

    "subclasses which by default do NOT want to send menu messages

     should return nil"

    ^ nil

    "Created: 3.1.1997 / 01:50:36 / stefan"

! !

!View methodsFor:'accessing-channels'!

setupChannel:newChannel for:changeSelector withOld:oldChannel

    "common code to change a channel.

     If changeSelector is non-nil, arrange for it to be sent when

     the channel changes its value; otherwise, arrange for a simple update.

     This is so common, that ist worth a helper method:

     release any old channel (if non-nil),

     arrange for changeSelector (or #update) to be sent for the new channel."

    |oldValue|

    oldChannel == newChannel ifTrue:[^ self].

    oldChannel notNil ifTrue:[

        changeSelector isNil ifTrue:[

            oldChannel removeDependent:self

        ] ifFalse:[

            oldChannel retractInterestsFor:self.

        ].

        oldValue := oldChannel value.

    ].

    newChannel notNil ifTrue:[

        changeSelector isNil ifTrue:[

            newChannel addDependent:self.

            newChannel value ~~ oldValue ifTrue:[

                self update:#value with:nil from:newChannel.

            ]

        ] ifFalse:[

            newChannel onChangeSend:changeSelector to:self.

            newChannel value ~~ oldValue ifTrue:[

                self perform:changeSelector.

            ]

        ]

    ].

    ^ newChannel

    "Modified: / 31.10.1997 / 14:47:21 / cg"

! !

!View methodsFor:'accessing-menus'!

menuHolder

    "who has the menu ? 

     If no explicit menuHolder was defined, its the model if I have one.

     Otherwise, its the menuHolder (if nonNil) or mySelf.

     The menuHolder is supposed to return a popUpMenu when asked via the

     menuMessage."

    menuHolder notNil ifTrue:[^ menuHolder].

    model notNil ifTrue:[^ model].

    ^ self

    "Modified: 23.12.1996 / 13:56:55 / cg"

!

menuHolder:anObject

    "change the one that provides the menu (via menuMsg)."

    "Created: 23.12.1996 / 13:54:33 / cg"

!

menuMessage

    "Return the symbol sent to the model to aquire the menu"

    ^ menuMsg

!

menuMessage:aSymbol

    "ST-80 style menus: If a views menuSymbol is nonNil, it

     will send it to its model when the middleButton is pressed.

     That method should return nil or the menu to be shown.

     This is useful for very dynamic menus, where it does not

     make sense to define an initial menu.

     This is the same as #menu: which was added for ST-80 compatibility."

    menuMsg := aSymbol

!

menuPerformer

    "who should perform the menu actions ? 

     If no menuPerformer was defined, its the model if I have one.

     Otherwise its the menuPerformer (if nonNil), or myself.

     The menuPerformer get messages from the menu"

    menuPerformer notNil ifTrue:[^ menuPerformer].

    model notNil ifTrue:[^ model].

    ^ self

    "Modified: 23.12.1996 / 13:57:18 / cg"

!

menuPerformer:anObject

    "change the one that does the menu actions.

     See the comment in SimpleView>>activateMenu on who gets the menus

     message."

    menuPerformer := anObject

    "

     |top textV plug|

     plug := Plug new.

     plug respondTo:#textMenu

               with:[ |m|

                        m := PopUpMenu

                                  labels:#('copy' 'foo' '-' 'others')

                                  selectors:#(copySelection foo nil others).

                        m subMenuAt:#others

                                put:(PopUpMenu 

                                        labels:#('bar' 'goto')

                                        selectors:#(bar gotoLine))        

                    ].

     top := StandardSystemView new.

     top extent:300@300.

     textV := TextView origin:0.0@0.0 corner:1.0@1.0 in:top.

     textV menuHolder:plug; menuMessage:#textMenu; menuPerformer:plug.

     textV contents:'hello world'.

     top open.

    "

    "Created: 23.12.1996 / 13:57:28 / cg"

! !

!View methodsFor:'accessing-mvc'!

addModelInterfaceTo:aDictionary

    "this adds entries for all messages sent to my model

     to aDictionary"

    aDictionary at:#aspectMessage put:aspectMsg.

    aDictionary at:#changeMessage put:changeMsg.

    aDictionary at:#menuMessage put:menuMsg.

    "

     Button new modelInterface 

    "

!

aspect

    "Return the aspect used with changes from/to the model"

    ^ aspectMsg

!

aspectMessage

    "Return the aspect used with changes from/to the model"

    ^ aspectMsg

!

aspectMessage:aspectSymbol

    "ST-80 style updating: If a views aspectSymbol is nonNil, 

     it will respond to changes of this aspect from the model."

    aspectMsg := aspectSymbol

!

change:changeSymbol

    "ST-80 style change notification: If a views changeSymbol is nonNil, 

     it will send it to its model when something changes.

     Alias for changeMessage: for ST-80 compatibility."

    self changeMessage:changeSymbol

!

changeMessage

    "Return the symbol sent to the model if nonNil when something changes."

    ^ changeMsg

!

changeMessage:aSymbol

    "ST-80 style change notification: If a views changeSymbol is nonNil, 

     it will send it to its model when something changes.

     This is the same as change: which was added for ST-80 compatibility."

    changeMsg := aSymbol

!

controller:aController

    "set the controller"

    super controller:aController.

    controller notNil ifTrue:[

	controller model:model

    ]

!

menu:menuSymbol

    "ST-80 style menus: If a views menuSymbol is nonNil, it

     will send it to its model when the middleButton is pressed.

     That method should return nil or the menu to be shown.

     This is useful for very dynamic menus, where it does not

     make sense to define an initial menu.

     Alias for #menuMessage:, for ST-80 compatibility."

    menuMsg := menuSymbol

!

model

    "return the model, for non-MVC views,

     this is nil or the receiver"

    ^ model

!

model:aModel

    "Set the model.

     Here, if I am my own menuPerformer/menuHolder,

     set the menuHolder and menuPerformer to the model. 

     This is a compatibility kludge,

     since typically, ST-80 code expects the model to provide a menu

     and perform it. If the model does not support a menu message,

     it will be forwarded to the view.

     Those apps which want the view to provide the (default) menu have to reset

     this by sending #menuHolder: message (again)"

    model notNil ifTrue:[

        model removeDependent:self

    ].

    model := aModel.

    (menuPerformer == self and:[menuHolder == self]) ifTrue:[

        menuPerformer := menuHolder := model

    ].

    model notNil ifTrue:[

        aModel addDependent:self

    ].

    controller notNil ifTrue:[

        controller model:aModel

    ].

    "Modified: 28.2.1997 / 19:23:06 / cg"

!

modelInterface

    "this returns a dictionary of messages sent to my model.

     It can be used for builders and wrappers to get information

     about the messages sent to my model.

     The returned dictionary contains one entry for each get-Msg,

     and the recevier will implement corresponding messages (with a colon)

     to set the message symbol."

    |d|

    d := IdentityDictionary new.

    self addModelInterfaceTo:d.

    ^ d

    "

     Button new modelInterface

     Label new modelInterface 

    "

    "

     does the view support setting the menuMessage ?

     SelectionInListView new modelInterface includesKey:#menuMessage 

    "

    "

     turn off all interaction to the model:

     |m v if|

     m := SelectionInList new.

     m list:#('one' 'two' 'tree' 'four') asValue.

     m selection:1 asValue.

     v := SelectionInListView on:m.

     v open.

     v inspect.

     if := v modelInterface.

     if inspect.

     if keysAndValuesDo:[:what :msg |

	 v perform:(what , ':') asSymbol with:nil.

     ].

    "

!

on:aModel aspect:aspectSymbol

    "ST-80 compatibility: set model and aspect

     messages - needs a view which uses these"