🚀 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.

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:
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