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Conference bulova::decw_jan-89_to_nov-90

Title:	DECWINDOWS 26-JAN-89 to 29-NOV-90
Notice:	See 1639.0 for VMS V5.3 kit; 2043.0 for 5.4 IFT kit
Moderator:	STAR::VATNE

Created:	Mon Oct 30 1989
Last Modified:	Mon Dec 31 1990
Last Successful Update:	Fri Jun 06 1997
Number of topics:	3726
Total number of notes:	19516

1138.0. "Vanishing Windows" by SMAC10::NOBLE (Quick! back in the fish!) Wed Jul 19 1989 08:33

    I have a customer who is looking to replicate some VWS functionality
    under Decwindows. Under UIS he is able to use a call to make a window
    invisible whilst, say, outputting junk to it. He then calls up the
    window as needed later. 
    
    He says that he can't find a way to do this in DECwindows. I'm sure
    that there is but frankly, as you can probably guess by the tone
    of this note, my experience is limited. Can anyone help?
                                                                  
    
    Thanks,
    
    Steev

T.R	Title	User	Personal Name	Date	Lines
1138.1		VWSENG::KLEINSORGE	Toys 'R' Us	`Wed Jul 19 1989 10:10`	19
	Yes and no. You can do it, but differently... Under VWS, window contents are always valid. If you move the window offscreen (make it invisible) it still exists and is updated in offscreen memory, as is any part of the window that is onscreen but obscured. Moving it back onscreen just puts those pixels into the visible display. Under X11, if it ain't visible anything written to it go to the big bit-bucket in the sky. Except PIXMAP's. A PIXMAP is a offscreen bitmap of some arbitrary depth (i.e. planes). You can write to this just like it was a window (except you can't use the CLEAR type functions which are window-only). If he does all his drawing to a PIXMAP, then when he wants it onscreen, he can simply create a window and do a copy area from the PIXMAP to the window. This also solves the problem of handling window damage (fixing areas of a window that were obscured and then exposed).
1138.2	Map/Unmap	PROTO2::FISHER	Burns Fisher 381-1466, ZKO3-4/W23	`Wed Jul 19 1989 11:54`	11
	You can also create the window ahead of time and just not map it till you are ready for it. You can also unmap the window, which will make it disappear from the screen, but not totally go away. What Fred said about window contents is still true, however. If you unmap the window, you can't count on the contents sticking around. In fact, you can't count on the contents sticking around anytime...you must always be prepared to refresh any rectangle that you get from an expose event. Burns
1138.3	Another answer	CALL::SWEENEY	Honey, I iconified the kids	`Wed Jul 19 1989 21:46`	10
	Folks, we've got to take a step back before we can go two steps forward: Steev, do you understand the issues around programming to Xlib versus programming to the toolkit? Do you understand what is meant by "expose event"? Basically, by programming to the toolkit (as I hope 99% of all customers do) "XtSetValues" will change the "junk" and "XtManageChild" "XtUnmanageChild" will make the window "visible" and "invisible" with the current values.
1138.4	XtUnmanageCompletelyInexperienced	BRILLO::NOBLE	Deliberate errer	`Thu Jul 20 1989 04:20`	15
	Thanks for the answers so far; re. .3 - No I don't really understand the language here, I'm sort of hoping to repeat this stuff verbatim... However, I do have enough programming experience to hve some idea of what's going on, plus looking at the examples further back in the notesfile has helped a lot. I shall put what's been received here to my customer and see what he makes of it. Thanks! (Damn - another breach of notes etiquette...) Steev
1138.5		VWSENG::KLEINSORGE	XUIS or DIE.	`Thu Jul 20 1989 15:39`	6
	Pat, unless you are doing nothing but menus, it's hard not to use Xlib.