Authoring fundamentals
Accessibility
Combine Power BI report accessibility with Vega ARIA descriptions, clear visual encodings, and keyboard-aware interaction design.
Accessibility has two layers
| Layer | Controls |
|---|---|
| Power BI report | Visual title, alternative text, report tab order, focus mode, Show data, report theme, sharing context, and surrounding report navigation. |
| Vega specification | ARIA descriptions for SVG marks, text labels, color and contrast, mark size, interaction states, event behavior, and the information encoded by the visual. |
Power BI visual title and alternative text
Power BI reads the report visual's title and alternative text when assistive technology reaches the visual container. These properties describe the analytical purpose of the complete visual, while Vega descriptions can describe the rendered structure and individual data marks.
Vega ARIA descriptions in SVG
Vega supports ARIA properties when rendering SVG. A mark definition can expose an accessible group description, and a description encoding can generate a label for each data-backed mark item.
Vega mark
{
"type": "rect",
"name": "categoryBars",
"aria": true,
"description": "Bars showing total value by category",
"from": { "data": "chartData" },
"encode": {
"update": {
"description": {
"signal": "datum.Category + ': ' + format(datum.Amount, ',.2f')"
}
}
}
}Accessible visual encoding
- Give the Power BI visual a concise title that states the subject and measure.
- Add alternative text that explains the visual's analytical purpose rather than repeating the title.
- Use visible text, shape, position, or pattern alongside color when a state or category must remain distinguishable.
- Maintain readable foreground and background contrast for marks, labels, axes, legends, and interaction states.
- Keep important information available without relying exclusively on hover.
- Provide meaningful text labels or ARIA descriptions for the principal data marks in SVG output.
- Validate keyboard focus order and the Power BI Show data experience on the finished report canvas.