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

[henrykdz]

On Thu, 19 Dec 2024 16:03:02 GMT, Marius Hanl <mhanl at openjdk.org> wrote:

>> This PR fixes the horizontal virtualization performed in the `TableRowSkinBase`, which significantly improves performance with many columns (and thus many cells). Scrolling up and down as well as scrolling left and right feels much more snappy.
>> 
>> In order to do that, there are multiple things needed:
>> - the `isColumnPartiallyOrFullyVisible` needs to be fixed to take the `VirtualFlow` into account, not the `TableView`. Since rows are inside the `VirtualFlow`, we need to use the width from there
>>   - The wrong implementation right now leads to [JDK-8276326](https://bugs.openjdk.org/browse/JDK-8276326), where if you scroll to the right with many columns, cells on the left start to be empty (since they are removed when they shouldn't be)
>>   - It also does not help performance when scrolled to the left, as the right cells are not removed (only when scrolling to the right, cells on the left are removed)
>> - To improve performance, `isColumnPartiallyOrFullyVisible` was refactored to take in everything that is needed directly, without reiterating through all columns
>> - As before, the `TableRow` adds or removes cells that are visible or not. 
>> Note that this is only done when a fixed cell size is set. 
>> The reason for that is that we always know the row height. If not set, we need all cells so we can iterate over them to get the max height. I'm not sure if this can be improved, but this is not the goal of this PR and can be checked later
>> - The other issue mentioned in [JDK-8276326](https://bugs.openjdk.org/browse/JDK-8276326) happens only when a fixed cell size is set (empty rows). This is related and also fixed:
>>   - Cells start to be empty when scolling around a lot. This is because cells that are in the pile (ready to be reused) will not receive any layout requests (`requestLayout`) while all cells in the viewport will receive them. As soon as they are reused, they are visually outdated and not updated, leading to empty cells
>>   Fix is to request layout to those cells as well, and as soon as they are reused, they will layout themself
>>   - This has revealed another error: Cells that are not used anymore (added to the pile and invisible) are STILL inside the `VirtualFlow` sheet (as children). This will cause them to actually do the layout when requested, and especially when the height of the `TableView` changed drastically (e.g. from 50 visible cells to just 10), we have 40 cells laying around, receiving the layout request I added to fix [JDK-82763...
>
> Marius Hanl has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains four commits:
> 
>  - Merge branch 'master' of https://github.com/openjdk/jfx into 8185887-virtualization
>    
>    # Conflicts:
>    #	modules/javafx.controls/src/test/java/test/javafx/scene/control/skin/VirtualFlowTest.java
>  - Merge branch 'master' of https://github.com/openjdk/jfx into 8185887-virtualization
>    
>    # Conflicts:
>    #	modules/javafx.controls/src/main/java/javafx/scene/control/skin/TableRowSkinBase.java
>    #	modules/javafx.controls/src/main/java/javafx/scene/control/skin/TreeTableRowSkin.java
>    #	modules/javafx.controls/src/main/java/javafx/scene/control/skin/VirtualFlow.java
>  - 8185887: Reset disclosureNodeDirty in updateDisclosureNodeAndGraphic()
>  - 8185887: TableRowSkinBase fails to correctly virtualize cells in horizontal direction

https://github.com/user-attachments/assets/6a07c5f9-7ac3-4148-b1db-07957af06e7a



> @henrykdz : thank you for the bug report! I can help you to file a bug. Two questions:
> 
> 1. is the issue you describe still present when tested with the changes in this PR?  Or is it a separate issue?
> 2. can you create a simple SCCE (self-contained short example), see for instance https://github.com/andy-goryachev-oracle/Test/blob/main/src/goryachev/bugs/TreeView_RenderingFailure_8346824_8347357.java


https://github.com/user-attachments/assets/b0d65fa0-0556-4687-a80b-1168866324f7

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PR Comment: https://git.openjdk.org/jfx/pull/1644#issuecomment-2583064466