"

 COPYRIGHT (c) 1988 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.

"

DisplaySurface subclass:#DisplayRootView

	instanceVariableNames:''

	classVariableNames:''

	poolDictionaries:''

	category:'Views-Special'

!

copyright

"

 COPYRIGHT (c) 1988 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 describes Xs rootWindow (which is the background window and

    can be used for drawing outside of Views i.e. for dragging between Views).

    There is one global variable (RootView) which is the Displays rootview.

    (this is the default displays rootView; to access other devices' rootView,

     use someDisplay rootView),

    Instances of myself (i.e. these rootViews) are light-weight views; 

    they do not support events, models etc.

    They are pure drawing canvases and should be only used for special

    applications. There may be display systems in which rootViews are not

    supported/allowed implemented. So be VERY careful when using them.

    To draw in the (Displays) root window:

        RootView paint:(Color red).

        RootView fillRectangleX:10 y:10 width:100 height:100.

    of course, all stuff from View and its superclasses can be used:

        RootView paint:(Color red).

        RootView noClipByChildren.

        RootView fillRectangleX:10 y:10 width:100 height:100.

    you have to be careful with some window managers, since what you

    see on the screen is not always really the root window. Some Desktops

    add their own view in between (although the Xworkstation class does

    care for this, it seems not to work correctly on all systems).

    In general, you should never use the RootView for normal applications.

    [author:]

        Claus Gittinger

"

! !

initialize

    Display isNil ifTrue:[

	Workstation initialize

    ].

    super initialize

! !

on:aDisplay

    "since there is only one RootView - catch new and return

     the one and only rootView."

    aDisplay == Display ifTrue:[

	RootView notNil ifTrue:[^ RootView].

	RootView := super on:aDisplay.

	^ RootView

    ].

    ^ super on:aDisplay

! !

!DisplayRootView methodsFor:'accessing'!

controller

    "I have no controller"

    ^ nil

!

name

    ^ 'RootWindow'

!

sensor

    "I have no sensor"

    ^ nil

!

windowGroup

    "I have no windowGroup"

    ^ nil

! !

!DisplayRootView methodsFor:'destroying'!

destroy

    "catch destroy - some windowmanagers get confused if

     we destroy the rootWindow if its a virtual root window"

    ^ self

! !

!DisplayRootView methodsFor:'initialization'!

initialize

    super initialize.

    width := device width.

    height := device height.

    drawableId := device rootWindowFor:self.

    realized := true.

!

reinitialize

    "reinit after snapin"

    width := device width.

    height := device height.

    drawableId := device rootWindowFor:self.

    realized := true.

    gcId := nil.

! !

!DisplayRootView methodsFor:'queries'!

canDrop:anObjectOrCollection

    "return true, if anObjectOrCollection can be

     dropped in the receiver. This method should be

     redefined in views which can take objects"

    ^ false

!

isWindowManagerRunning

    "answer true, if a window manager is currently running.

     This is done by performing an action (enabling button events of

     root window), which will fail if a window manager is running."

    |errorOccured|

    errorOccured := false.

    device class deviceErrorSignal handle:[:ex |

	errorOccured := true.

	ex return

    ] do:[

	self enableButtonEvents.

	device flush.

    ].

    ^ errorOccured

    "

     DisplayRootView new

     RootView isWindowManagerRunning

    "

! !

version

! !

DisplayRootView initialize!