Accessibility in Flutter Treemap (SfTreemap)

28 Jul 20254 minutes to read

Screen reader

The SfTreemap can be accessed by the screen readers by wrapping the SfTreemap widget to the Semantics widget.

late List<PopulationModel> _source;
  late String _semanticLabel = 'Asia is the most populated continent and Australia is the least populated continent';

  @override
  void initState() {
    _source = const <PopulationModel>[
        PopulationModel('Asia', 456.07),
        PopulationModel('Africa', 121.61),
        PopulationModel('Europe', 74.64),
        PopulationModel('North America', 57.9),
        PopulationModel('South America', 42.25),
        PopulationModel('Australia', 2.54),
    ];
    super.initState();
  }

  @override
  void dispose() {
    _source.clear();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Semantics(
          label: 'Syncfusion Flutter Treemap',
          value: _semanticLabel,
          child: Column(
            children: [
              Expanded(
                child: SfTreemap(
                  dataCount: _source.length,
                  weightValueMapper: (int index) {
                    return _source[index].populationInCrores;
                  },
                  levels: [
                    TreemapLevel(
                      groupMapper: (int index) {
                        return _source[index].continent;
                      },
                    ),
                  ],
                ),
              ),
            ],
          ),
        ),
    );
  }

class PopulationModel {
  const PopulationModel(this.continent, this.populationInCrores);

  final String continent;
  final double populationInCrores;
}

Sufficient contrast

You can customize the color of the SfTreemap elements using the following APIs for the sufficient contrast.

Large fonts

The font size of the SfTreemap will be automatically scaled based on the device settings. Additionally, you can change the font size of the SfTreemap elements using the following APIs:

Easier touch targets

The SfTreemap has touch target as 48 * 48 for all elements, following standard accessibility guidelines.