Hello everyone 👋

I had a great experience participating in this year’s Google Summer of Code (GSoC) with LibreOffice.
It’s a great experience to collaborate with people from all over the world, contribute to an open-source project, and learned a lot along the way.

Overview

This project is about creating a new dialog to edit Table Styles (actually autoformats, which are predefined templates). The dialog was based on the UX team’s proposal.

Current Limitations:

  • In both Writer and Calc, users could not edit an existing table style. The only option was to format a table manually and then save it as a new style, but that’s not very intuitive.
  • Even though the underlying data structure for autoformats is similar in Writer and Calc, each has its own implementation, including a separate “AutoFormat Dialog”.
  • Autoformats are stored in a binary file which was hard to maintain and not backwards compatible.
  • Applying autoformat did not follow the ODF(Open Document Format) specification.

Project Outcomes

AutoFormat Dialog: Now the dialog is shared between Writer and Calc. Nothing is changed visually except the addition of New Style and Edit Style buttons.

AutoFormat Dialog

Table Style Dialog:

  • Added inheritance feature to table styles, every style by default inherits from Default Style.
  • Users can customize styles for 16 elements (first-row, last-row, body, etc). The styles are applied according to ODF priority.

Table Styles Dialog

Adapting ODF specification: Table Styles are now applied according to element priority. For example:

  • The first row of a table is formatted by the style in first-row element.
  • If no background color is defined, it falls back to the odd-row style.
  • If that is also undefined, it falls back to the body style, and so on.

Styles Sidebar: We can edit/create table styles from the Styles Sidebar in Writer.

Writer Styles Sidebar

Technical Details

Although the project is about creating a dialog, the hardest part was unifying the autoformat code from Writer and Calc. Writer and Calc have SwTableAutoFormatTable and ScAutoFormat classes, respectively for handling autoformats, which are required for table styling. I created a new SvxAutoFormat class which combines the common functionality of Writer and Calc. Now this new class is inherited by both Writer and Calc classes.

SvxAutoFormat

Loading Table Styles: Becasue we wanted to replace the old binary file for loading/storing table styles, I created an XML file (‘tablestyles.xml’) based on existing table styles which are shipped with LibreOffice. I created SvxTableStylesImport class which is used to load styles to SvxAutoFormat and SvxTableStylesExport class to save the SvxAutoFormat to the XML file.

Other Improvements:

Related Patches:

What’s Left

  • Add UI tests to verify the workflow.

Limitations

  • Backward compatibility: Old .odt files open correctly, but since the internal structure of table styles has changed to follow ODF, when you interact with the table (inserting/deleting rows/columns), the style of the table changes.
  • Number formatting in the Table Styles dialog is not yet functional (planned fix).
  • Table Styles are currently shared across all documents. If you edit a style in one document, the change will persist in other documents.

Future Scope

  • Add WYSIWYG preview of table styles in the Writer styles sidebar.
  • In Impress, the Table styles panel has checkboxes to enable/disable certain element styles, I have already implemented the backend functionality, depending on the UX team’s approval, this can be added to the new dialog or sidebar.

Impress Table Styles

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I’m very grateful to the entire community. Special thanks to my mentors, Rafael Lima and Heiko Tietze, for their patience and support throughout the process. Looking forward to contributing more to the community!🚀