hughes@ux.acs.umn.edu (Steve Hughes) (05/02/91)
"All I want out of life is a simple way to turn the screen off
instantly, then bring it back on instantly and without flicker."
IUm using HyperCard 2.0 and the picture XCMD to present 256 level
grey scale photographs as visual stimuli in a series of right-
hemisphere testing neuropsychology experiments, and brother, I got
trouble.
In the good ol' days of early April, the Ph.D. candidate whose
dissertation is riding on this stuff was really happy with how
things were looking--just loved to see those grey scale photos
flash onto the computer screen (they appear in pairs, one after
the other).
Here is how I did it:
put "PictureA" into pic1
put "PictureB" into pic2
picture pic2,file,rect,false
picture pic1,file,rect,false
set the visible of window pic1 to true
wait for 30 ticks
set the visible of window pic1 to false
wait for 30 ticks
set the visible of window pic2 to true
wait for 30 ticks
set the visible of window pic2 to false
My problem: One week before subjects are to be run, she decides
that the pictures do not appear smoothly enough, too much flicker
when we set visible to true. The Ph.D. candidate screams, "THE
PRESENTATION OF STIMULI MUST BE INSTANTANIOUS! HOW COULD WE HAVE
MISSED THIS? IT'S A DISASTER!" Hmmm...seems all the prior
literature is based on instant presentation of stimuli (using a
fast iris called a "tachistascope" mounted on the front of a slide
projector lens--instant open, instant closed).
Here's what happens: when I set visible to true, the picture sort
of "rolls" into visibility--presentation is not in sync with the
vertical retrace of the monitor (or it can't do it fast enough to
make it in one blanking period). The pictures sure appear fast on
a IIci, but not without some noticeable flicker. Trouble.
Facing total ruin, I consider a new career cleaning out public
lavatories.
Then: Inspiration!
I don't need to make the picture XCMD faster--I can create exactly
the effect I want if I can shut off the whole screen while I set
the visible of the picture to true, then turn the screen back on
after I've made the picture visible. I'd do it like this:
screenOff <--- XCMD to dim screen to black instantly
set the visible of window pic1 to true
screenOn <--- XCMD to turn screen to white instantly
wait for 30 ticks
screenOff
set the visible of window pic1 to false
wait for 30 ticks
set the visible of window pic2 to true
screenOn
wait for 30 ticks
screenOff
(etc.)
Can this be done? I think so, screen savers do it all the time.
I've got AfterDark set to the "Face Away" module with 0 second dim
time and 0% intensity. "Blip!" screen off. "Blip!" screen on.
Pictures (and, of course, everything else) appear and disappear
INSTANTLY. just like I want them to. Different settings make it
fade slower or to a less dark final brightness. So it looks like I
CAN turn the screen off and on, instantly and with out flicker.
My other problem:
I have no idea how this is done! Looks like there must be some
(God willing, fairly easy) way to adjust the screen brightness
with software (note the Mac Classic's Brightness cdev).
Maybe a hardware location?
Maybe a toolbox call?
Well?
Does anybody know anything about this?
-Steve
P.S. Changing the odd and confusing bit depth parameter of the
picture XCMD does not speed it up (like it should?).
"I'm at the end of the road, my back's against the wall, I'm
outta' ammo, sweet God Almighty, does _somebody_ know the answer?"
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Steve Hughes
Pediatric Neuropsychology
University of Minnesota
hughes@ux.acs.umn.edu
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++mxmora@unix.SRI.COM (Matt Mora) (05/03/91)
In article <3848@ux.acs.umn.edu> hughes@ux.acs.umn.edu (Steve Hughes) writes: >Can this be done? I think so, screen savers do it all the time. >I've got AfterDark set to the "Face Away" module with 0 second dim >time and 0% intensity. "Blip!" screen off. "Blip!" screen on. >Pictures (and, of course, everything else) appear and disappear >INSTANTLY. just like I want them to. Different settings make it >fade slower or to a less dark final brightness. So it looks like I >CAN turn the screen off and on, instantly and with out flicker. Hmmm. I think the dimming is done with gamma color tables (or whatever they are called) and will only work on color machines. I guess that is not a problem for you since you are trying to display grayscale pictures. I seem to recall someone mentioning that the gamma stuff is a bitch. I look it up and let you know my findings. matt -- ___________________________________________________________ Matthew Mora | my Mac Matt_Mora@sri.com SRI International | my unix mxmora@unix.sri.com ___________________________________________________________
cad0410@ritvax.isc.rit.edu (DORN, CA) (05/04/91)
In article <3848@ux.acs.umn.edu>, hughes@ux.acs.umn.edu (Steve Hughes) writes... > >"All I want out of life is a simple way to turn the screen off >instantly, then bring it back on instantly and without flicker." > >IUm using HyperCard 2.0 and the picture XCMD to present 256 level >grey scale photographs as visual stimuli in a series of right- >hemisphere testing neuropsychology experiments, and brother, I got >trouble. > >In the good ol' days of early April, the Ph.D. candidate whose >dissertation is riding on this stuff was really happy with how >things were looking--just loved to see those grey scale photos >flash onto the computer screen (they appear in pairs, one after >the other). > >Here is how I did it: > > put "PictureA" into pic1 > put "PictureB" into pic2 > picture pic2,file,rect,false > picture pic1,file,rect,false > set the visible of window pic1 to true > wait for 30 ticks > set the visible of window pic1 to false > wait for 30 ticks > set the visible of window pic2 to true > wait for 30 ticks > set the visible of window pic2 to false > >My problem: One week before subjects are to be run, she decides >that the pictures do not appear smoothly enough, too much flicker >when we set visible to true. The Ph.D. candidate screams, "THE >PRESENTATION OF STIMULI MUST BE INSTANTANIOUS! HOW COULD WE HAVE >MISSED THIS? IT'S A DISASTER!" Hmmm...seems all the prior >literature is based on instant presentation of stimuli (using a >fast iris called a "tachistascope" mounted on the front of a slide >projector lens--instant open, instant closed). > >Here's what happens: when I set visible to true, the picture sort >of "rolls" into visibility--presentation is not in sync with the >vertical retrace of the monitor (or it can't do it fast enough to >make it in one blanking period). The pictures sure appear fast on >a IIci, but not without some noticeable flicker. Trouble. > >Facing total ruin, I consider a new career cleaning out public >lavatories. > > Then: Inspiration! >I don't need to make the picture XCMD faster--I can create exactly >the effect I want if I can shut off the whole screen while I set >the visible of the picture to true, then turn the screen back on >after I've made the picture visible. I'd do it like this: > > screenOff <--- XCMD to dim screen to black instantly > set the visible of window pic1 to true > screenOn <--- XCMD to turn screen to white instantly > wait for 30 ticks > screenOff > set the visible of window pic1 to false > wait for 30 ticks > set the visible of window pic2 to true > screenOn > wait for 30 ticks > screenOff > (etc.) > >Can this be done? I think so, screen savers do it all the time. >I've got AfterDark set to the "Face Away" module with 0 second dim >time and 0% intensity. "Blip!" screen off. "Blip!" screen on. >Pictures (and, of course, everything else) appear and disappear >INSTANTLY. just like I want them to. Different settings make it >fade slower or to a less dark final brightness. So it looks like I >CAN turn the screen off and on, instantly and with out flicker. > >My other problem: >I have no idea how this is done! Looks like there must be some >(God willing, fairly easy) way to adjust the screen brightness >with software (note the Mac Classic's Brightness cdev). > >Maybe a hardware location? > >Maybe a toolbox call? > >Well? > >Does anybody know anything about this? > >-Steve > >P.S. Changing the odd and confusing bit depth parameter of the >picture XCMD does not speed it up (like it should?). > > >"I'm at the end of the road, my back's against the wall, I'm >outta' ammo, sweet God Almighty, does _somebody_ know the answer?" > > put "PictureA" into pic1 > put "PictureB" into pic2 > picture pic2,file,rect,false > picture pic1,file,rect,false > set the visible of window pic1 to true > wait for 30 ticks > set the visible of window pic1 to false > wait for 30 ticks > set the visible of window pic2 to true > wait for 30 ticks > set the visible of window pic2 to false Well if I understand your problem correctly how about creating a button large enough to cover the whole picture area in which you want to display in. Hide the button and set the hilite of the button to true (this will make the screen look black when it is un-hidden). Use this button instead of your screenOff/screenOn idea like so. set the hilite of button "Cover" to true show button "Cover" <--- this will black out your screen set the visible of window pic1 to true hide button "Cover" <--- this will instantly uncover your picture wait for 30 ticks show button "Cover" set the visible of window pic1 to false wait for 30 ticks set the visible of window pic2 to true hide button "Cover" wait for 30 ticks show button "Cover" (etc.) Hope this helps, Cea
cad0410@ritvax.isc.rit.edu (DORN, CA) (05/04/91)
In article <3848@ux.acs.umn.edu>, hughes@ux.acs.umn.edu (Steve Hughes) writes... > >"All I want out of life is a simple way to turn the screen off >instantly, then bring it back on instantly and without flicker." > Oops, I also forgot to mention when you create the button, make it a rectangle (or opaque) and don't show its name. --Cea
man@cs.brown.edu (Mark H. Nodine) (05/08/91)
In article <1991May3.172724.13806@isc.rit.edu>, cad0410@ritvax.isc.rit.edu (DORN, CA) writes: |> In article <3848@ux.acs.umn.edu>, hughes@ux.acs.umn.edu (Steve Hughes) writes... |> > |> >"All I want out of life is a simple way to turn the screen off |> >instantly, then bring it back on instantly and without flicker." |> > |> >IUm using HyperCard 2.0 and the picture XCMD to present 256 level |> >grey scale photographs as visual stimuli in a series of right- |> >hemisphere testing neuropsychology experiments, and brother, I got |> >trouble. |> |> Well if I understand your problem correctly how about creating a |> button large enough to cover the whole picture area in which you |> want to display in. Hide the button and set the hilite of the |> button to true (this will make the screen look black when it |> is un-hidden). Use this button instead of your screenOff/screenOn |> idea like so. No dice on this one. The picture XCMD creates a window in the palette layer (it can be at the back of the palette layer if you use the right window styles), but your button goes in on the document layer. So it will neatly show up _behind_ the pictures you're trying to hide with it. If you're sure you're going to be running on a Classic or some other machine with software brightness control, then it should be easy to write an XCMD to set (and fetch for resetting) the brightness level. I don't know how to do it, though. --Mark