[Cuis-dev] Strange issue with layout

[Juan Vuletich]

Hi Hilaire,

Your code is perfectly fine.

The origin of the problem is that VectorEngine draws pixels differently 
from BitBlt.. In particular, if a morph that #requiresVectorCanvas like 
your DecoratedPane is made submorph of another that doesn't 
#requiresVectorCanvas (and uses BitBlt by default), then we can't 
guarantee that they fill exactly the same pixels, even if they request 
to fill the same rectangle. The whole problem disappears if the whole 
morph uses only VectorCanvas. You can try this by slightly zooming it. 
Still, using BitBlt when possible has a significant performance 
advantage, so we need another solution.

The easiest solution I see, if acceptable to you, is to remove the call 
to super in DecoratedPane>>#drawOn:. Then you'll need to adjust the 
color of the owner LayoutMorph.

If you absolutely need the LayoutMorph to be gray, then what would be 
required is to add anothe morph between them, to draw the box using 
BitBlt. It could make layout a bit more complicated, so I think my 
previous suggestion is better.

Hope this helps.

On 7/2/2023 2:56 PM, Hilaire Fernandes via Cuis-dev wrote:
>
> Hi,
>
> In my bread crump morph below you can observe the views under the 
> button nav bar are shifted one pixel to the right and the bottom 
> directions:
>
> ...
>
>
> I need to explain a bit the logic of the GUI tool. The data can be 
> viewed or edited. In the screenshot it is in edit mode, to got back to 
> view mode, click on the button 'Foron', it is the named of the edited 
> object (a School instance).
>
> When the tool is in editor mode, the decorated morph are layout with a 
> one pixel gap as I explained above. Between the 4 decorated morphs 
> (Information, Time slots, etc.) there is also this unexpected 1 pixel 
> gap. It produces glitch in the background when the whole morph is 
> dragged around. When in viewer mode, although the same kind of 
> decorated morphs are used, there is no such visual artifact.
>
> For me code seems all good.
>
> In case one want to take a look I have an image:
>
> https://www.dropbox.com/scl/fi/islj0kloljw040wvbr3f2/dynabook.zip?rlkey=kuoxfzjobr3jesjdngd6k1ype&dl=0
>
> Thanks
>
> Hilaire
>
> -- 
> GNU Dr. Geo
> http://drgeo.eu
> http://blog.drgeo.eu


-- 
Juan Vuletich
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