On Thu, 23 May 2024 21:51:55 GMT, Marius Hanl <mh...@openjdk.org> wrote:

> Alternative PR to https://github.com/openjdk/jfx/pull/1330 which does not 
> modify the layout of `VirtualFlow`.
> 
> This PR fixes the glitching by removing the code in `NGNode.renderRectClip`, 
> which made many calculations leading to floating point errors.
> Interestingly I found out, that `getClippedBounds(..)` is already returning 
> the correct bounds that just need to be intersected with the clip of the 
> `Graphics` object.
> 
> So the following code is effectively doing the same:
> 
> Old:
> 
> BaseBounds newClip = clipNode.getShape().getBounds();
> if (!clipNode.getTransform().isIdentity()) {
>     newClip = clipNode.getTransform().transform(newClip, newClip);
> }
> final BaseTransform curXform = g.getTransformNoClone();
> final Rectangle curClip = g.getClipRectNoClone();
> newClip = curXform.transform(newClip, newClip); // <- The value of newClip 
> after the transform is what getClippedBounds(..) is returning
> newClip.intersectWith(PrEffectHelper.getGraphicsClipNoClone(g));
> Rectangle clipRect = new Rectangle(newClip)
> 
> 
> New:
> 
> BaseTransform curXform = g.getTransformNoClone();
> BaseBounds clipBounds = getClippedBounds(new RectBounds(), curXform);
> Rectangle clipRect = new Rectangle(clipBounds);
> clipRect.intersectWith(PrEffectHelper.getGraphicsClipNoClone(g));
> 
> 
> As you can see, there are very similar, but `getClippedBounds` does a much 
> better job in calculating the bounds.
> I also wrote a tests proving the bug. I took 100% of the setup and values 
> from a debugging session I did when reproducing this bug.
> 
> I checked several scenarios and code and could not find any regressions.
> Still, since this is change affects all nodes with rectangular clips, we 
> should be careful.
> Performance wise I could not spot any difference, I do not expect any 
> difference.
> **So I would like to have at least 2 reviewers.**
> Note that I will do more testing as well soon on all JavaFX applications I 
> have access to. -> DONE: Could not spot any problem or difference.
> 
> ---
> 
> As written in the other PR, I have some interesting findings on this 
> particular problem.
> 
> Copy&Paste from the other PR:
> --
> 
> Ok, so I found out the following:
> When a Rectangle is used as clip without any effect or opacity modification, 
> the rendering goes another (probably faster) route with rendering the clip. 
> That's why setting the `opacity` to `0.99` fixes the issue - another route 
> will be used for the rendering.
> This happens at the low level (`NGNode`) side of JavaFX.
> ...
> I could track it down to be a typical floating point problem
> ...
> The bug always appear...

This pull request has now been integrated.

Changeset: ec8c032e
Author:    Marius Hanl <mh...@openjdk.org>
URL:       
https://git.openjdk.org/jfx/commit/ec8c032e95f376d154978af4b7e92bfd5fd48ea6
Stats:     238 lines in 11 files changed: 163 ins; 56 del; 19 mod

8218745: TableView: visual glitch at borders on horizontal scrolling

Reviewed-by: angorya, arapte

-------------

PR: https://git.openjdk.org/jfx/pull/1462

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