Monday, March 27, 2017

Pivot charts in LibreOffice: Part 2

This time I'll present some necessary changes to make pivot charts actually useful and one unique feature that pivot charts have and normal charts don't - field buttons.

Pivot chart creation

If you watched the first video, you should notice that I showed the pivot chart was already created from the start. The reason for this was that the functionality to create a new pivot chart from the pivot table wasn't implemented yet. I have fixed this, so it is now possible to create a new pivot chart if you position the cursor on the pivot table, and select from the menu to create a new chart. The chart creation code will detect the pivot table and create a pivot chart instead of a normal chart.

Pivot chart wizard

When we want to create a new chart, we first get the chart creation wizard, where we can select the chart type, define the ranges for labels and data, define data series ranges, and add some additional chart elements like title, subtitle,...

For the pivot chart we get a similar wizard now, where we can select the chart type and additional data. The wizard step to add data ranges and the step to define the data series is however disabled as these steps are not needed when we get the data from the pivot table.

Pivot chart creation wizard

Pivot chart buttons

This time the biggest change are the pivot chart buttons, which are unique to pivot charts (normal charts don't have them). The purpose of the buttons is to show the layout of the pivot table, so it shows the pivot table fields. On the top it shows the buttons that represent the page fields (if present) and the data fields of the pivot table. At the bottom it shows buttons for row fields next to each other, and in the legend it show the buttons from column fields stacked.

Field buttons in a pivot chart

As they are buttons, there is an action performed when clicking on them, but this is not implemented yet and I'll described this next time in more detail.

From the implementation point of view, the most challenging thing with the buttons was to position them correctly inside the chart as they are part of the chart structure, and to position everything else accordingly (and not breaking the normal charts in the process).


This is an updated video of the current state of pivot charts:

You can find the video on YouTube at the following URL:


Again, many thanks to Nantes Métropole and Ville de Nantes for making this work possible.

Read more about Nantes deployment here.

To be continued...

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