RFR: JDK-8218745: TableView: visual glitch at borders on horizontal scrolling

[Kevin Rushforth]

On Wed, 10 Jan 2024 22:39:22 GMT, Andy Goryachev <angorya at openjdk.org> wrote:

>> This PR fixes the border glitch/gap as explained in both linked tickets.
>> 
>> I noted that the `ScrollPane` control does not suffer from this problem, although the code is mostly the same as in `VirtualFlow`. The `ScrollPane` snaps the content correctly, no matter which scale. I carefully checked the code and it seems that the container structure in `ScrollPane` was explicitly written to handle this perfectly. There was definitely some thought on that.
>> 
>> So to finally fix this issue, I rewrote the `VirtualFlow` container/scrolling code to be **exactly** the same as in `ScrollPane`(Skin).
>> And this also fixes the issue, while behaving the same as before.
>> 
>> In the future it may makes sense to try to somewhat unify the code from `ScrollPane` and `VirtualFlow`. I already have some ideas.
>> 
>> Unfortunately though, one more container is introduced to `VirtualFlow`, so the css needs to be changed since it is very strictly written in the first place:
>> Before: `.list-view:focused > .virtual-flow > .clipped-container > .sheet > .list-cell`
>> After: `.list-view:focused > .virtual-flow > .viewport > .clipped-container > .sheet > .list-cell`
>> 
>> To better understand this, the container structure (tree) is shown below:
>> 
>> - ScrollPane
>>   - viewRect ->  `setClip` -> clipRect (viewContent size)
>>     - viewContent -> `setLayoutX`
>>       - Content
>>   - vsb
>>   - hsb
>>   - corner
>> 
>> ---
>> - VirtualFlow
>>   - viewRect **(->NEW IN THIS PR<-)** -> `setClip` -> clipRect (clippedContainer size)
>>     - clippedContainer/clipView -> `setLayoutX` (when scrolling)
>>       - sheet
>>         - Cell
>>   - vsb
>>   - hsb
>>   - corner
>
> modules/javafx.controls/src/main/resources/com/sun/javafx/scene/control/skin/caspian/caspian.css line 1508:
> 
>> 1506: }
>> 1507: 
>> 1508: .list-view:focused > .virtual-flow > .viewport > .clipped-container > .sheet > .list-cell:focused {
> 
> This might require a CSR as it might break custom stylesheets that modify list/tree/table/views.

Yes, I think a CSR would be in order. Thanks for bringing this up @andy-goryachev-oracle

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PR Review Comment: https://git.openjdk.org/jfx/pull/1330#discussion_r1450407373