RFR: 8185887: TableRowSkinBase fails to correctly virtualize cells in horizontal direction [v4]

[yosbits]

On Wed, 9 Sep 2020 02:46:37 GMT, yosbits <github.com+7517141+yososs at openjdk.org> wrote:

>> @yososs Per [this message](https://mail.openjdk.java.net/pipermail/openjfx-dev/2020-September/027534.html) on the
>> openjfx-dev mailing list, I have closed [JDK-8185886](https://bugs.openjdk.java.net/browse/JDK-8185886) as a duplicate,
>> and suggested another existing JBS issue for this PR to use. Please change the title to:  8185887: TableRowSkinBase
>> fails to correctly virtualize cells in horizontal direction
>
> Below are the answers to JBS's suggestions.
> 
>> The patch below resolves the issue, but it is not likely the correct solution (we are trying to determine the table
>> width, but we are getting the width and padding on the underlying virtualflow (the width is fine, the padding should
>> really come from tableview directly):
> 
> You probably mention this part,
> At least padding refers to Skinnable(TableRow or TreeTableRow). This is the same as before (L683). The width of
> VirtualFlow is determined by the header of Table.
> modules/javafx.controls/src/main/java/javafx/scene/control/skin/TableRowSkinBase.java#L360-L365
>  Java
>  final VirtualFlow<?> virtualFlow = getVirtualFlow();
>  final double scrollX = virtualFlow == null ? 0.0 : virtualFlow.getHbar().getValue();
>  final Insets padding = getSkinnable().getPadding();
>  final double vfWidth = virtualFlow == null ? 0.0:virtualFlow.getWidth();
>  final double headerWidth = vfWidth - (padding.getLeft() + padding.getRight());
> 
> For example, can you assume a case that does not work properly?

This is the answer to JBS's comment.

The BigTreeTableViewTest.java attached to this PR commentary is a modified version of the JDK-8166956 test code. The
original test code is good for reproducing the problem, but I have decided that it cannot be used as a test code
because the cell values are random and the cell values change randomly with the close / expand operation.

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PR: https://git.openjdk.java.net/jfx/pull/125