Tabulator scrolling to top all the time

Wijnko · May 23, 2023, 3:28pm

I have a question on the Tabulator model in panel. I have created a Bug issue some time ago (Tabulator scrolls to top when other element on the page changes · Issue #4451 · holoviz/panel · GitHub), about the Table scrolling to the top all the time when something on the page is updated. I think this is solved in Panel 1.0, I assume by the DOM Shadow roots isolation somehow.

I do however still have the issue of scrolling to Row 0 after setting or patching the data. Looking into the source code, I found that on every patch, the element.scrollTop is set to this._lastVerticalScrollbarTopPosition. However, as far as I can see, this variable is initialised to 0, but never set to any other value. As such the scroll position is manually set to 0 on every patch.

github.com

holoviz/panel/blob/main/panel/models/tabulator.ts#L352

      
        
                  this.setPage()
              })
              this.connect(p.max_page.change, () => this.setMaxPage())
              this.connect(p.frozen_rows.change, () => this.setFrozen())
              this.connect(p.sorters.change, () => this.setSorters())
              this.connect(this.model.source.properties.data.change, () => this.setData())
              this.connect(this.model.source.streaming, () => this.addData())
              this.connect(this.model.source.patching, () => {
                const inds = this.model.source.selected.indices
                this.updateOrAddData();
                this.tabulator.rowManager.element.scrollTop = this._lastVerticalScrollbarTopPosition;
                // Restore indices since updating data may have reset checkbox column
                this.model.source.selected.indices = inds;
              })
              this.connect(this.model.source.selected.change, () => this.setSelection())
              this.connect(this.model.source.selected.properties.indices.change, () => this.setSelection())
            }
            
            
get groupBy(): boolean | ((data: any) => string) {
              const groupby = (data: any) => {
                const groups = []

Did I perhaps miss the point where the _lastVerticalScrollbarTopPosition is set, or is there a valid reason to always have the scroll position set it to 0?

I am not sure if the javascript tabulator object can patch without scroll position effects. In my usecase I patch a cell onclick, and ideally the cell would not move on patch. Could removing this scrollpos line perhaps achieve that?

Thanks and regards,
Wijnko

Wijnko · May 24, 2023, 8:45am

I have found a commit where the last line setting the _lastVerticalScrollbarTopPosition variable was deleted. Was the code still using this variable perhaps forgotten here? (@maximlt )