Pie Chart¶
Displays proportional data as circular slices, with each slice size representing the relative value of data categories.
Chart components · element type pie-chart · binds through a data source
Related: Generic Chart · ECharts · Legend Entry
Examples¶
Alt text for the chart
Share of revenue by region in {$params.year}Set as Alt text, so the chart is described in the exported PDF.
Options¶
Configure the component with these main sections:
| Option | Description |
|---|---|
| Data Source | Required data source for chart data |
| Name Field | Field containing slice labels/categories |
| Value Field | Field containing numerical values for slice sizes |
| Alt text | Describe what the chart shows, for screen readers and the PDF tag tree |
Accessibility¶
Alt text, in the Accessibility section, is the description a screen reader reads out and the one that travels into the exported PDF's tag tree. It supports text templates, so it can name the measure and the breakdown — Share of revenue by region in {$params.year}.
Left empty, the chart is still described — as simply "Chart" — so an export never contains an undescribed graphic. That keeps the document valid; it does not make it useful, so write a real description for any chart that carries meaning.
Legend swatches need no description of their own. The coloured shape repeats what the legend text beside it already says, so it is marked as decoration and skipped.
Control chart positioning and appearance through pie configuration options:
| Option | Description |
|---|---|
| Chart Offset | Position chart within container (top, left, right, bottom spacing) |
| Pie Chart Size | Overall diameter of the pie chart (slider control) |
| Start Angle | Starting position for first slice (0-360 degrees) |
| Slice Offset | Spacing between individual slices |
| Gap between slices in pixels | Spacing between chart segments |
| Border Radius | Rounded corners for slice edges |
| Inner Pie Radius | Inner edge of the ring. Raise it above zero to produce a donut |
| Outer Pie Radius | Outer edge of the ring |
| Clockwise | Direction of slice arrangement |
| Legend Entry Template | Template for each legend label, so legend text can differ from the slice name |
Customize slice labeling with label options:
| Option | Description |
|---|---|
| Value Template | Format for slice labels using text templates |
| Max Label Width | Maximum width for label text |
| Lead Length | Length of label leader lines |
| Inner and Outer Point Radius | Control label positioning relative to slices |
Colour handling lives in the Styling section:
| Option | Default | Description |
|---|---|---|
| Use Specific Color Map | Off | Draws from a named colour map instead of the theme's default sequence |
| Color Map Name | Empty | Which map to use, when the above is on. Match this across charts so the same category keeps its colour |
| Use Distant Colors | Off | Spreads colours further apart in the palette, which helps when slices are few |
| Legend Items | From theme | Styling for the chart's own legend entries |
Styling includes color maps, individual color control, and legend configuration with positioning and formatting options.
Notes¶
- Ensure data source contains both name and value fields for proper chart generation
- Use Start Angle to position the most important slice at the top
- Apply Slice Offset to highlight specific slices by separating them
- Configure Inner Pie Radius to create donut charts for additional visual interest
- Use color maps for consistent theming across multiple charts in reports