Overview for Screen Reader Users

By default, Olli renders an accessible visualization as a tree view based on the W3C Navigation TreeView Example.

Each element of the tree view contains a textual description, with high level descriptions at the top of the tree and detailed data values at the bottom. The top of each chart contains a description of the chart type and data fields. The next level contains descriptions of the chart encodings (e.g. axes, legends). After that, the data is broken down by category for discrete encodings, and interval for continuous encodings. At any location in the tree, press 't' to open a table view of the data.

Olli controls

Press o to jump to the Olli structure.

When Olli has focus, the following keyboard commands are available:

  • Up / Down arrow — move up or down a level in the tree view
  • Left / Right arrow — move to previous or next item in a level
  • Home / End — move to first or last item in a level
  • x — jump to x-axis of current chart
  • y — jump to y-axis of current chart
  • l — jump to legend of current chart
  • o — jump to top level of current tree
  • Shift + Left / Right arrow — when chart has facets or layers, move to the corresponding item in the previous or next facet or layer
  • t — open the table view for the current location
  • f — open the filter menu to add or remove data filters

When there is more than one Olli instance on the page:

  • o — jump to the last visited Olli tree (or the first one on the page if none have been visited)

When focused on the top level of the current Olli tree:

  • o — jump to the next Olli tree on the page
  • shift + o — jump to the previous Olli tree

Example

Vega-Lite Visualization:

Olli output: