Spreadsheet's scrolling gets confused when loading a scrolled document with frozen rows/columns

[thevaadinman]

Description

Spreadsheet fails to load a document correctly when

• the sheet has frozen rows or columns and
• the sheet is scrolled before being saved

It then gets confused about what content should be scrolled where, resulting in a state where you cannot scroll to the beginning of the document, the freeze panes are not sized correctly and elements on screen look garbled as a result.

Expected outcome

The expected outcome is a reproduction of the document in the state it was saved in, which displays all the necessary data and can be scrolled to show the entirety of its contents.

Minimal reproducible example

Load up the attached test file in the Spreadsheet Demo UI.

Freeze_and_scroll_test.xlsx

Steps to reproduce

• Open up Excel or LibreOffice Calc.
• Create a document with some content.
• Freeze the first few rows.
• Scroll horizontally until the first few columns are not visible.
• Save as XLSX.
• Load up the file in Spreadsheet.

Environment

Vaadin version(s): 25.0-SNAPSHOT
OS: n/a

Browsers

Issue is not browser related

[thevaadinman]

This was reported as a bug by a customer as a bugfix priority.
I am working on a preliminary fix to act as a starting point for the Components team.

Additional information by the reporter:

In Excel's file format, and therefore in POI, "no split" is indicated by 0, but Vaadin is setting both splits to file split location + view shift without first checking that the sheet PaneInformation position is > 0.

[thevaadinman]

This appears tangentially related to #8094