🚀 go-pugleaf

<SMARTIN@ESOC.BITNET> writes:

>I am writing an application that requires a number of text icons to be
>updated fairly regularly (frequency definable by the user). Currently, I
>am using the SWI SetIconState with zero arguments to force an update, but
>if the update frequency is more than a few frames per second, the flicker
>is quite intolerable with or without icon borders. I have also tried the
>SWIs ForceRedrawWindow and UpdateWindow (names may be slightly wrong), but
>this does not improve things. My question is, is it possible to use the old
>GCOL type tricks by EORing text into the Icon? If so, how is this done ?
>If not, will updating the Icon as a Sprite help ?

>Any other hints on how I could rid myself of this annoying flicker would be
>greatly appreciated.

You could try waiting for the vertical sync before updating. In Basic
this is done by WAIT, but there is an Os_Byte call (I don't recall the
number) that has the same effect.

	Torben Mogensen (torbenm@diku.dk)

In article <1992Sep28.140636.11131@odin.diku.dk> torbenm@diku.dk (Torben AEgidius Mogensen) writes:
>You could try waiting for the vertical sync before updating. In Basic
>this is done by WAIT, but there is an Os_Byte call (I don't recall the
>number) that has the same effect.

   It is an OsByte 19 that waits for Vsync. The only problem I have found with 
this is that having the window up near the top of the screen still causes
flickers. The simple answer I think is that you can't avoid flicker entirely
in the Wimp, merely lessen it's noticability...

   Philip


-- 
 Philip R. Banks  pbanks@comp.vuw.ac.nz (An Arc owner with a mission)  @@@@@/|
    (Quite what mission I am not too sure yet. But I do have one!)     @@@@/#|
 "There may be an om in moment,but there's very few folk in focus!"    @@@/--|
	--'Hallowed be thy Name' by Emerson,Lake & Palmer.             @@/###|

SMARTIN@ESOC.BITNET writes:

>I am writing an application that requires a number of text icons to be
>updated fairly regularly (frequency definable by the user). Currently, I
>am using the SWI SetIconState with zero arguments to force an update, but
>if the update frequency is more than a few frames per second, the flicker
>is quite intolerable with or without icon borders.

Well, as others have said, you can call Os-Byte 19 / *FX19 / WAIT just before
causing update. THis works well, except near the top of the screen, and aslo
has the drawback of slowing things down a lot if you update many times a
second (especially if other programs are also WAITing... An ARM-3 machine
can do up to around 260,000 instructions in the time it takes to do a WAIT!)

Another trick that can reduce flicker substantially is to draw your info
into a sprite, and then SetIconState,0,0 the icon containing the sprite.
This should be near flicker-free without a WAIT, but a WAIT as well should
make it very good.

Minimising the area of the screen can help a lot too. If you have something
like "Reading file: 10%", all you really need to update is the percentage,
and so you can stop the flicker of the text "Reading file" completely.
As you are drawing less (2 characters only now), the redraw is faster, so
the flicker on the updated number is also reduced.

The last trick is to think about what info you are updating - does it need
to be updated so frequently? You could read the time when you update the
icon (SWI "OS_ReadMonotonicTime" TO timenow) and refuse to update the icon
until the new time is > 25 centiseconds or so, giving a maximum speed of
update of 4 updates a second... When doing a lot of stuff you can end up
continuously redrawing the icon and doing very little processing, and this
can stop that type of problem from happening.
-- 
_________________  "I'd like to answer this question in two ways:
  /____ _ _/_ __       First in my normal voice, and then
 // / //_//_ /_/       in a silly, high-pitched whine." (Monty Python)

In article <1992Sep28.140636.11131@odin.diku.dk> torbenm@diku.dk (Torben AEgidius Mogensen) writes:
>You could try waiting for the vertical sync before updating. In Basic
>this is done by WAIT, but there is an Os_Byte call (I don't recall the
>number) that has the same effect.

It's OS_Byte 19

>	Torben Mogensen (torbenm@diku.dk)

mad@bike

My other bike's a recumbent :)

In article <92272.103620SMARTIN@ESOC.BITNET> SMARTIN@ESOC.BITNET writes:
>I am writing an application that requires a number of text icons to be
>updated fairly regularly (frequency definable by the user). Currently, I
>am using the SWI SetIconState with zero arguments to force an update, but
>if the update frequency is more than a few frames per second, the flicker
>is quite intolerable with or without icon borders. I have also tried the
>SWIs ForceRedrawWindow and UpdateWindow (names may be slightly wrong), but
>this does not improve things. My question is, is it possible to use the old
>GCOL type tricks by EORing text into the Icon? If so, how is this done ?
>If not, will updating the Icon as a Sprite help ?

I already replied by mail, but, unless you need the extra functions
of icons (detecting clicks, etc), I would suggest ditching them and
doing text update manually by your program. The main programming effort lies
in working out where to plot the updates, from the window work area and the 
scroll offsets, but once this is done, it is fairly easy to make your 
redraw routine. The speed difference between this and using
icons is large.

	- Graham

gta@st-andrews.ac.uk
allan@mnhep8.hep.umn.edu