ChartLegend class

A tappable legend for a chart.

Each item renders a color swatch plus its label. Tapping an item calls onToggle with that item's color so the caller can flip visibility. Items whose color is in hidden are rendered with reduced opacity and a strike-through label to signal that the series is currently hidden.

The widget is purely presentational — it does not own visibility state. Combine with ChartLegendScope for an end-to-end toggle experience, or manage the hidden set yourself if you need custom behavior.

Example

ChartLegend(
  items: const [
    ChartLegendItem(color: Colors.indigo, label: 'Sales'),
    ChartLegendItem(color: Colors.green, label: 'Revenue'),
  ],
  hidden: hiddenColors,
  onToggle: (color) => setState(() {
    hiddenColors.toggle(color);
  }),
)

Inheritance

• Object
• DiagnosticableTree
• Widget
• StatelessWidget
• ChartLegend

Constructors

ChartLegend({Key? key, required List<ChartLegendItem> items, Set<Color> hidden = const <Color>{}, ValueChanged<Color>? onToggle, ChartTheme? theme, Axis direction = Axis.horizontal, double runSpacing = 8.0, double spacing = 16.0, EdgeInsets padding = const EdgeInsets.symmetric(horizontal: 8, vertical: 6), double swatchSize = 12.0, TextStyle? labelStyle})

const

ChartLegend.fromDataSets(List<ChartDataSet> dataSets, {Key? key, Set<Color> hidden = const <Color>{}, ValueChanged<Color>? onToggle, ChartTheme? theme, Axis direction = Axis.horizontal, String seriesLabelFor(Color color, List<ChartDataSet> group)?})

Construct a legend from a list of ChartDataSets, grouped by color.

factory

Properties

direction → Axis

Whether items are laid out in a row (horizontal) or column (vertical). The horizontal variant wraps onto multiple lines when space runs out.

final

hashCode → int

The hash code for this object.

no setter, inherited

hidden → Set<Color>

Colors whose series are currently hidden (rendered dimmed).

final

items → List<ChartLegendItem>

The rows/columns to show.

final

key → Key?

Controls how one widget replaces another widget in the tree.

final, inherited

labelStyle → TextStyle?

Optional label text style override.

final

onToggle → ValueChanged<Color>?

Called when a legend entry is tapped. Omit to render a non-interactive legend.

final

padding → EdgeInsets

Padding around each tappable row.

final

runSpacing → double

Vertical gap between wrapped rows (horizontal) or between items (vertical).

final

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

spacing → double

Horizontal gap between items when laid out horizontally.

final

swatchSize → double

Diameter of the color swatch circle.

final

theme → ChartTheme?

Theme used for label colors. Falls back to the ambient Material theme.

final

Methods

build(BuildContext context) → Widget

Describes the part of the user interface represented by this widget.

override

createElement() → StatelessElement

Creates a StatelessElement to manage this widget's location in the tree.

inherited

debugDescribeChildren() → List<DiagnosticsNode>

Returns a list of DiagnosticsNode objects describing this node's children.

inherited

debugFillProperties(DiagnosticPropertiesBuilder properties) → void

Add additional properties associated with the node.

inherited

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) → DiagnosticsNode

Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.

inherited

toString({DiagnosticLevel minLevel = DiagnosticLevel.info}) → String

A string representation of this object.

inherited

toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug, int wrapWidth = 65}) → String

Returns a string representation of this node and its descendants.

inherited

toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String

Returns a one-line detailed description of the object.

inherited

toStringShort() → String

A short, textual description of this widget.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited