RFR: 8218745: TableView: visual glitch at borders on horizontal scrolling [v6]

[Marius Hanl]

> 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...

Marius Hanl has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains six commits:

 - Merge branch 'master' of https://github.com/openjdk/jfx into 8218745-tableview-glitch-clipping-fix
   
   # Conflicts:
   #	modules/javafx.controls/src/test/java/test/javafx/scene/control/TableViewTest.java
   #	modules/javafx.controls/src/test/java/test/javafx/scene/control/TreeTableViewTest.java
 - Merge branch 'master' of https://github.com/openjdk/jfx into 8218745-tableview-glitch-clipping-fix
   
   # Conflicts:
   #	modules/javafx.controls/src/test/java/test/javafx/scene/control/TableViewTest.java
   #	modules/javafx.controls/src/test/java/test/javafx/scene/control/TreeTableViewTest.java
   #	modules/javafx.controls/src/test/java/test/javafx/scene/control/skin/VirtualFlowTest.java
   #	modules/javafx.graphics/src/test/java/test/com/sun/javafx/sg/prism/NGNodeTest.java
 - Merge branch 'master' of https://github.com/openjdk/jfx into 8218745-tableview-glitch-clipping-fix
   
   # Conflicts:
   #	modules/javafx.controls/src/test/java/test/javafx/scene/control/TableViewTest.java
   #	modules/javafx.controls/src/test/java/test/javafx/scene/control/TreeTableViewTest.java
 - Merge branch 'master' of https://github.com/openjdk/jfx into 8218745-tableview-glitch-clipping-fix
   
   # Conflicts:
   #	modules/javafx.graphics/src/main/java/com/sun/javafx/sg/prism/NGNode.java
 - Improve test
 - 8218745: TableView: visual glitch at borders on horizontal scrolling

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

Changes: https://git.openjdk.org/jfx/pull/1462/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1462&range=05
  Stats: 239 lines in 11 files changed: 163 ins; 56 del; 20 mod
  Patch: https://git.openjdk.org/jfx/pull/1462.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1462/head:pull/1462

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