Hi Nicolas,


thanks for the insight. On my system, it is not rounded ... I have the latest trunk updates installed.

________________________________
Von: Squeak-dev <squeak-dev-bounces at lists.squeakfoundation.org> im Auftrag von Nicolas Cellier <nicolas.cellier.aka.nice at gmail.com>
Gesendet: Dienstag, 22. Oktober 2019 15:00:27
An: The general-purpose Squeak developers list
Betreff: Re: [squeak-dev] Fractional bounds and flickering (contains images that may be disturbing to some readers)

Hi Christoph,
I cannot reproduce. It seems like bounds soon get rounded in my image:

    (SystemWindow new openInWorld extent: (24214/31)@(11565/31)) bounds extent.
        781 at 373

Le mar. 22 oct. 2019 à 13:40, Thiede, Christoph <Christoph.Thiede at student.hpi.uni-potsdam.de<mailto:Christoph.Thiede at student.hpi.uni-potsdam.de>> a écrit :

Hi all,


In the latest days, I encountered flickering problems caused by non-integer bounds of system windows again. For me, the following fails reproducibly in different images:


SystemWindow new openInWorld extent: (24214/31)@(11565/31).


If I hover and unhover the window a few times, its contents are drawn badly and incompletely like this:


[cid:16df38cc226f456b1e51]


  *   As you can see, the issue also affects other morphs in the same region (in the screenshot I am hovering the implementors button of the background browser).
  *   The issue only occurs with very complex fractions, so the extent 500 @ 300 / 2 would not be a problem (at least in my image). I could not reproduce it using floats.
  *   The situation can be also reproduced by composing a few morphs manually, but the more submorphs there, the higher the flickering rate appears to be.
  *   [World imageForm] does not contain any abnormalities, maybe the problem is related to the damage recording?

I would like to solve this bug, but I'm not sure where the problem actually arises. In general, should morphs be allowed to have non-integer bounds? This could be useful e. g. for exact animations, but we already have some rounding that (unfortunately) rule out this use case:

  *   #position: appears to round the delta value for movement
  *   #extent: and #bounds: do no rounding at all.

Should we maybe apply some rounding or at least truncating there? Or just convert the arguments using #asFloat before?
Or do you have any idea how one could debug the problem?

(For relevancy: I often call Preferences >> #changeFontSize:, and each time all windows are drawn badly until I round their bounds. This can indeed be quite annoying:
[cid:16df38cc227f456b1e52])

Looking forward to your help!
Best,
Christoph

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