"

 COPYRIGHT (c) 1993 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.

"

Object subclass:#WindowGroup

	instanceVariableNames:'views topViews myProcess mySensor isModal previousGroup focusView

		focusSequence preEventHook postEventHook pointerView

		isForModalSubview'

	classVariableNames:'LastActiveGroup LastActiveProcess LeaveSignal

		WindowGroupQuerySignal LastEventQuerySignal'

	poolDictionaries:''

	category:'Interface-Support'

!

!WindowGroup class methodsFor:'documentation'!

copyright

"

 COPYRIGHT (c) 1993 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

"

    In Smalltalk/X, the known (ST-80) concept of a controller has been

    extended (split) into a WindowGroup which handles process related stuff, 

    and the Controller, which only handles events for a view and defines the user interaction.

    All interaction is via event queues - there is no polling in controllers (not even conceptionally).

    WindowGroups are responsible to wait for and forward events for a group of 

    windows. All views in a windowGroup share a single windowSensor which holds the

    event queue (therefore subviews all share the same input event queue).

    The event queues are filled with incoming events as arriving from the physical display.

    This is done by a separate process (so called event-dispatcher) which runs at a higher

    priority. The event dispatcher determines the queue into which an event has to be placed

    by the view for which the event is destined (via the views sensor).

    There may be multiple event dispatchers running (to support multiple displays);

    see the documentation/examples in DeviceWorkstation/XWorkstation on how this is done.

    Except for modal boxes, a separate process is created for each windowGroup 

    which waits for events to arrive and processes them, by sending corresponding

    event messages to the views controller or the view (*). 

    The controller is determined by asking the view (for which the event is destined);

    if the returned controller is nil, the event is sent directly to the view.

    This allows for simple views to work without a controller.

    (all of this is actually done in a WindowEvent method)

    Therefore, multiple applications run pseudo parallel.

    Even if some window performs a long time computation, events are still received

    and entered into the corresponding event queues (because the event dispatcher process

    runs at a higher priority). However, the actual processing of the event is only

    possibly if no other process is busy at the same or a higher priority.

    It is possible to change a windowProcesses priority in order to give other windows

    a chance to execute (some views do this while performing longtime actions).

    Modal boxes create an extra window group for the components of the modal

    box, but execute the event-processing loop for this new group in the original process - 

    therefore, the original windowgroup is blocked for the duration of the modal 

    interaction.

    However, the modal-event processing loop peeks into the original groups event queue

    from time to time, and handles expose events. Thus, even while blocked for user input,

    the original group continues to get update/redraw events.

    Normally, one windowgroup is associated to each topview (StandardSystemView)

    and all of its subviews. However, this is not strictly required; 

    it is possible to create extra windowgroups for subviews, which will let them

    run in parallel 

    On the other hand, multiple topviews can be placed into the same windowGroup;

    which allows for multiview applications, of which only one communicates with

    the user at a time.

    Multiple topviews within a windowGropup can be configured to behave like one 

    unit with respect to iconification, deiconification and termination.

    This is done by creating multiple topViews in one group, and setting up a master/slave

    or partner relation among them (see TopView>>beSlave and TopView>>bePartner).

    WindowGroups also support a focus window: this is the one that gets the

    keyboard input - even if the cursor is located in another subview.

    The sequence is defined by the topView or its model (typically an applicationModel).

    It should return an orderedCollection of subviews when asked via #focusSequence.

    For debugging, windowGroups allow hooks to be installed around the processing of

    events - preEventHook is sent a #procesEvent: message before an event is processed,

    postEventHook is informed after the event has been processed.

    The preEventHook should return true - if it returns true, the event is considered

    being already processed by the hook and ignored.

    This allows for event-tracing, timing or even filtering (if preEventHook returns true).

    (notice: there is also an eventHook facility available in the sensor class.)

    Finally, windowgroups are the perfect place for things like defining a

    cursor for all associated views, flushing all input, waiting for expose

    events etc.

    Dont get confused:

    [instance variables:]

    [class variables:]

    (*) 

    For more information, read 'introduction to view programming' in the

    doc/online directory.

    [author:]

    [see also:]

"

! !

!WindowGroup class methodsFor:'initialization'!

initialize

    LeaveSignal isNil ifTrue:[

    ].

    "WindowGroup initialize"

    "Modified: 9.11.1996 / 17:00:53 / cg"

! !

!WindowGroup class methodsFor:'instance creation'!

new

    "create and return a new WindowGroup object"

    ^ self basicNew initialize

! !

!WindowGroup class methodsFor:'Signal constants'!

lastEventQuerySignal

    "return the signal which is used to query for the last event"

    ^ LastEventQuerySignal

    "Created: 17.7.1996 / 20:36:04 / cg"

!

leaveSignal

    "return the signal which is used to exit a modal loop.

     This private signal, is always caught while a modalbox is active.

     Raising it will exit the modal loop and return from the views #openModal

     method."

    ^ LeaveSignal

!

windowGroupQuerySignal

    "return the signal which is used to query for the windowGroup"

    ^ WindowGroupQuerySignal

    "Created: 17.7.1996 / 20:36:04 / cg"

! !

!WindowGroup class methodsFor:'accessing'!

activeGroup

    "return the currently active windowGroup.

     The returned value may not be fully correct, in case the current process

     handles multiple windowGroups simultaneously. In this case, 

     (usually) the first group is returned (prefering a modal if there is one). 

     (maybe we should return a collection of windowGroups here).

     This method is required to simulate the historic ST-80 single display

     behavior for Cursor>>show / Cursor>>showWhile and some others (raising the

     activeGroups topView when modalBoxes appear) on multiple display screens. 

     These methods should change the cursor for the currently 

     active windowGroup ONLY, instead of globally affecting the display or

     all views

     (since, depending on the priority, other views could be unaffacted by this 

      and an overall cursor change does not make sense.)"

    |activeProcess groups wg|

    Processor isNil ifTrue:[^ nil]. "/ only during very early init phase

    activeProcess := Processor activeProcess.

    " caching the last value ..."

    activeProcess == LastActiveProcess ifTrue:[

    ].

    wg := WindowGroupQuerySignal raise.

    wg isNil ifTrue:[

    ].

    wg notNil ifTrue:[

    ].

    ^ wg

    "

     WindowGroup activeGroup 

    "

    "Modified: 3.9.1995 / 14:49:53 / claus"

    "Modified: 29.1.1997 / 19:46:25 / cg"

!

scheduledWindowGroups

    "return a collection of all windowGroups (possibly for different

     display devices) which are scheduled (i.e. which have a process 

     running, handling events)."

    |set screens|

    screens := Screen allScreens.

    screens size == 0 ifTrue:[^ #()].

    set := IdentitySet new.

    screens do:[:aDevice |

    ].

    ^ set asArray

    "

     WindowGroup scheduledWindowGroups   

    "

    "Modified: 1.9.1995 / 13:43:09 / claus"

    "Modified: 18.8.1997 / 18:44:29 / cg"

!

setActiveGroup:aGroup

    "set the currently active windowGroup.

     Temporary; do not use this interface, it will vanish."

    LastActiveProcess := Processor activeProcess.

    LastActiveGroup := aGroup

! !

!WindowGroup methodsFor:'accessing'!

device

    "return the device, we receive our events from"

    self obsoleteMethodWarning:'use #graphicsDevice'.

    ^ self graphicsDevice

    "Modified: 5.7.1996 / 17:53:58 / cg"

!

graphicsDevice

    "return the device, we receive our events from"

    |dev|

    topViews notNil ifTrue:[

    ].

    views notNil ifTrue:[

    ].

    ^ nil

    "Modified: 7.2.1997 / 16:14:24 / cg"

!

isModal

    "return true, if the receiver is in a modal mode

     (i.e. for a modal box)"

    ^ isModal

    "Modified: 7.3.1996 / 14:29:46 / cg"

!

mainGroup

    "return the main windowgroup (for modal groups only) 

     that is the top one, which is not modal.

     NonModal groups return themSelf.

     There is one exception to this: the debugger (which is sort of modal)

     returns itself as mainGroup (not its debuggee)."

    |g prev|

    g := self.

    [g notNil and:[g isModal and:[(prev := g previousGroup) notNil]]] whileTrue:[

    ].

    ^ g

    "Modified: 3.9.1995 / 14:57:20 / claus"

    "Modified: 7.3.1996 / 14:29:28 / cg"

!

mainGroup:aWindowGroup

    "set the main windowgroup (for modal/autonomous groups only) 

     Exposeevents for that windowGroup will be handled by this group

     as well."

    previousGroup := aWindowGroup

    "Created: 20.8.1997 / 17:57:35 / cg"

!

previousGroup

    "return the windowgroup that started this group. (for modal groups only).

     This may be another modalGroup (for boxes opened by boxes).

     NonModal groups return nil."

    ^ previousGroup

    "Modified: 7.3.1996 / 14:28:46 / cg"

!

process 

    "return the windowGroups process"

    ^ myProcess

!

sensor

    "return the windowGroups sensor.

     All events for any of the groups views is handled by that sensor."

    ^ mySensor

    "Modified: 7.3.1996 / 14:30:21 / cg"

!

sensor:aSensor

    "set the windowGroups sensor"

    mySensor := aSensor

! !

!WindowGroup methodsFor:'accessing-hook'!

postEventHook 

    "return the postEventHook if any"

    ^ postEventHook

    "Created: 7.3.1996 / 14:42:46 / cg"

!

postEventHook:anObject 

    "set the postEventHook - this one will get all events

     passed after being processed here (via #processEvent:)."

    postEventHook := anObject

!

preEventHook 

    "return the preEventHook if any"

    ^ preEventHook

    "Created: 7.3.1996 / 14:42:42 / cg"

!

preEventHook:anObject 

    "set the preEventHook - this one will get all events

     passed before being processed here (via #processEvent:).

     If this returns true, the event is supposed to be already