On Sat, Jan 28, 2023 at 8:58 PM <commits at source.squeak.org> wrote:

> Christoph Thiede uploaded a new version of Morphic to project The Inbox:
> http://source.squeak.org/inbox/Morphic-ct.2082.mcz
>
> ==================== Summary ====================
>
> Name: Morphic-ct.2082
> Author: ct
> Time: 28 January 2023, 8:57:55.639628 pm
> UUID: dfcaa928-8758-5a42-a55b-2d89712a2a86
> Ancestors: Morphic-mt.2081
>
> To review: Fixes flickering in multi-column lists by ensuring sufficiently
> stable computation in #maxWidth.
>
> This is likely to have a small but noticable negative impact on the
> performance for large lists, but I think this is inevitable if we want to
> avoid flickering. Otherwise, we could only consider computing the layout
> completely lazily during drawing.
>

One of the  best ways to test speed impact on huge lists is to explore bits
in a Form.
It takes a while to process a million elements :-D
[bits explore]timeToRun 89621
Best,
Karl

[image: image.png]



>
> For instance, the original bug can be reproduced by loading the
> SimulationMethodFinder from SimulationStudio, doing Morph new
> exploreProtocol and scrolling down until methodCommentAsBalloonHelp comes
> into view.
>
> =============== Diff against Morphic-mt.2081 ===============
>
> Item was changed:
>   ----- Method: LazyListMorph>>maxWidth (in category 'layout') -----
>   maxWidth
> +       "Approximate the maximum width of this lazy list. Take all visible
> items as a sample.
> +
> +       NOTE that we MUST compute the width for all items in view!!
> Otherwise, maxWidth might be instable and be increased again during drawing
> in #item:, causing the receiver to flicker after each #layoutChanged (e.g.,
> from PluggableMultiColumnListMorph>>#updateColumns)."
> -       "Approximate the maximum width of this lazy list. Take first n
> items as a sample."
>
> +       | listSize visibleBounds topRow bottomRow |
> +       maxWidth ifNotNil: [^maxWidth].
> +
> -       | threshold listSize |
> -       maxWidth ifNotNil:[^maxWidth].
> -
> -       threshold := 30.
>         listSize := self getListSize.
>
> +       visibleBounds := self bounds: self owner bounds from: self owner.
> +       topRow := self rowAtLocation: visibleBounds topLeft.
> +       bottomRow := self rowAtLocation: visibleBounds bottomLeft.
> +
>         maxWidth := 0.
> +       topRow to: bottomRow do: [:index |
> -       1 to: (threshold min: listSize) do: [:index |
>                 maxWidth := maxWidth max: (self widthToDisplayItem: (self
> getListItem: index))].
> +
> +       ^ maxWidth!
> -
> -       ^ maxWidth
> - !
>
>
>
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