RFR: 8299753: Tree/TableView: Column Resizing With Fractional Scale [v2]

[Andy Goryachev]

On Sun, 2 Jul 2023 12:53:05 GMT, John Hendrikx <jhendrikx at openjdk.org> wrote:

> My observation is that this algorithm seems unable to provide a proper user resizing experience as it seems to discard important information it would need to do so.

please elaborate, or point to a specific problem.  It is entirely possible that a better algorithm might exist, but it might be out of scope *at the moment*, as this is a follow-up for a specific issue. 



> The `ResizeHelper` is short-lived, and created/recreated many times during a resize operation. I'm not even sure why it is being instantiated at all (it literally is created and discarded in a single method). 

convenience - it does have some data, and it's easier to keep code along with the data.


> The `SMALL_DELTA` constant that changes behavior on how large a "drag" was registered is a red flag; this shouldn't matter. The sizes should always be based on what they were initially (at the start of the drag), and where the cursor is currently, regardless of what path the cursor took to get there (ie. there should be no memory effects, the algorithm should only need the initial sizes + current position).

This is not my experience.  Specifically, the difference in behavior between small changes (when the users resizes the columns slowly and we get small deltas of 1 pixel) and large changes (e.g. when initially resizing the table, or the user moves the mouse quickly) are significant. 

For example, I tried to use your  SpaceDistributor from #1111 and it suffered from the same problem as bypassing the small delta path (by setting SMALL_DELTA=0) - when the user resizes the columns slowly, the same column gets the pixel and grows wider than the rest.

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PR Comment: https://git.openjdk.org/jfx/pull/1156#issuecomment-1622127738