Class: View

• Inheritance
• Description
• Related information
• Class protocol
  • defaults
  • instance creation
• Instance protocol
  • accessing-bg & border
  • accessing-channels
  • accessing-menus
  • accessing-mvc
  • change & update
  • drawing
  • event handling
  • focus handling
  • initialization & release
  • printing & storing
• Examples

Inheritance:

   Object
   |
   +--GraphicsMedium
      |
      +--DisplaySurface
         |
         +--SimpleView
            |
            +--View
               |
               +--ActiveHelpView
               |
               +--ApplicationSubView
               |
               +--BarChartWidget
               |
               +--CharacterSetView
               |
               +--ChartDescription
               |
               +--CodeCompletionHelpView
               |
               +--ComboView
               |
               +--CompositeView
               |
               +--DSVColumnView
               |
               +--DigitalLedDisplay
               |
               +--DisplayObjectView
               |
               +--EventMonitor::EventMonitorView
               |
               +--ExtendedComboBox
               |
               +--HTMLDocumentFrame
               |
               +--ImageView
               |
               +--Label
               |
               +--LabelledEnterField
               |
               +--ListModelView
               |
               +--ListView
               |
               +--MemoryMonitorView
               |
               +--MenuPanel
               |
               +--MeterClackCounter
               |
               +--MeterWidget
               |
               +--NoteBookView
               |
               +--ObjectView
               |
               +--PieChartWidget
               |
               +--ProgressIndicator
               |
               +--PullDownMenu
               |
               +--Scroller
               |
               +--SimpleFunctionGraphView
               |
               +--ThumbWheel
               |
               +--TopView
               |
               +--TransparentBox
               |
               +--UpDownButton
               |
               +--V::GraphPane
               |
               +--VUMeter

Package:

stx:libview

Category:

Views-Basic

Version:

rev: 1.100 date: 2019/05/30 09:19:23

user: cg

file: View.st directory: libview

module: stx stc-classLibrary: libview

Author:

Claus Gittinger

Description:

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)

    

Related information:

    StandardSystemView
    TopView
    DialogBox
    WindowGroup
    Model
    ValueHolder
    [introduction to view programming]

Class protocol:

 defaultAspectMessage

subclasses which by default do NOT want to be informed about changed
models should redefine this to return nil

 defaultChangeMessage

subclasses which by default do NOT want to inform the model
should redefine this to return nil

 defaultMenuMessage

subclasses which by default do NOT want to send menu messages
should return nil

 on: aModel aspect: aspectMsg

st-80 style view creation: create a new view, set its model
and selectors for aspect

 on: aModel aspect: aspectMsg change: changeMsg

st-80 style view creation: create a new view, set its model
and selectors for aspect and change

 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

 on: aModel aspect: aspectMsg menu: menuMsg

st-80 style view creation: create a new view, set its model
and selectors for aspect and menu

Instance protocol:

 allViewBackground: something if: condition

set the viewBackground to something, a color, image or form,
in myself and recursively in all of my subviews.
However, if I have a backgroundChannel, don't change my own bg.

 backgroundChannel

return a valueHolder for background color

 backgroundChannel: aValueHolder

set the backgroundChannel - a valueHolder holding a color

 enableChannel

return a valueHolder for enable/disable

 enableChannel: aValueHolder

set the valueHolder, which holds the enable boolean value

 foregroundChannel

return a valueHolder for foreground color

 foregroundChannel: aValueHolder

set the foregroundChannel - a valueHolder holding a color

 defaultMenuPerformer

the stuff below tries to make for a reasonable
default, in case the menuPerformer was NOT set explicitely
(you should not depend on this in your application)

 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: anObject

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

 menuMessage

Return the symbol sent to the model to acquire the menu

 menuMessage: aSymbol

ST-80 style menus: If a view's 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.

 menuPerformer

who should perform the menu actions?
If no menuPerformer was defined, it is the model if I have one.
Otherwise it is the menuPerformer (if nonNil), or myself.
The menuPerformer gets messages from the menu

 menuPerformer: anObject

change the one that does the menu actions.
See the comment in SimpleView>>activateMenu on who gets the menu's
message.

 performer: anObject

same as #menuPerformer - ST80 compatibility

 addModelInterfaceTo: aDictionary

this adds entries for all messages sent to my model
to aDictionary

 aspect

Return the aspect used with changes from/to the model

 aspectMessage

Return the aspect used with changes from/to the model

 aspectMessage: aspectSymbol

ST-80 style updating: If a view's aspectSymbol is nonNil,
it will respond to changes of this aspect from the model.

 change: changeSymbol

ST-80 style change notification: If a view's changeSymbol is nonNil,
it will send it to its model when something changes.
Alias for changeMessage: for ST-80 compatibility.

 changeMessage

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

 changeMessage: aSymbol

ST-80 style change notification: If a view's 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.

 controller: aController

set the controller

 menu: menuSymbol

ST-80 style menus: If a view's 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.

 model

return the model, for non-MVC views,
this is nil or the receiver

 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)

 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 receiver will implement corresponding messages (with a colon)
to set the message symbol.

usage example(s):

Button new modelInterface Label new modelInterface

usage example(s):

does the view support setting the menuMessage ? SelectionInListView new modelInterface includesKey:#menuMessage

 on: aModel aspect: aspectSymbol

ST-80 compatibility: set model and aspect
messages - needs a view which uses these

 on: aModel aspect: aspectSymbol change: changeSymbol

ST-80 compatibility: set model, aspect and change
messages - needs a view which uses these

 on: aModel aspect: aspectSymbol change: changeSymbol menu: menuSymbol

ST-80 compatibility: set model, aspect, change and menu
messages - needs a view which uses these

 on: aModel aspect: aspectSymbol menu: menuSymbol

ST-80 compatibility: set model, aspect and menu
messages - needs a view which uses these

 sendChangeMessage: aSelector with: arg

tell the model about a change

 sendChangeMessageWith: arg

tell the model about a change

 update: something with: aParameter from: changedObject

(comment from inherited method)
an update request

 updateFromModel

to be redefined in subclasses

 redraw

redraw myself
if there is a model, this one shall redraw itself,
otherwise we cannot do much here - has to be redefined in subclasses

 backgroundColorChanged

called to update the background color

 enableStateChanged

called to update enable/disable state

 foregroundColorChanged

called to update the foreground color

 wantsFocusWithButtonPress

views which do not like to take the keyboard focus
with buttonPress can do so by redefining this
to return false

 initialize

must be called if redefined

 release

(comment from inherited method)
remove all dependencies from the receiver

 displayOn: aStreamOrGC

redefined to also give a hint of where I am

Examples:

    |top v|

    top := StandardSystemView new.
    v := View new.
    v origin:0.25 @ 0.25 corner:0.75 @ 0.75.
    top addSubView:v.
    top open

    |top v|

    top := StandardSystemView new.
    v := View origin:0.25 @ 0.25 corner:0.75 @ 0.75 in:top.
    top open

    |top mh|

    mh := (PopUpMenu itemList:#( ('foo' foo) (#'bar' bar)) resources:nil) asValue.

    top := StandardSystemView extent:200@200.
    top menuHolder:mh.
    top open

    |top mh|

    mh := (PopUpMenu itemList:#( ('foo' foo) (#'bar' bar)) resources:nil) asValue.
    [
        Delay waitForSeconds:5.
        mh value: (PopUpMenu itemList:#( ('waboo' foo) (#'baz' bar)) resources:nil)
    ] fork.

    top := StandardSystemView extent:200@200.
    top menuHolder:mh.
    top open