TreemapLegend class

Shows legend for the data rendered in the treemap.

By default, legend will not be shown.

If SfTreemap.colorMappers is null, then the legend items' icon color and legend item's text will be applied based on the value of TreemapLevel.color and the values returned from the TreemapLevel.groupMapper callback of first TreemapLevel added in the SfTreemap.levels collection.

If SfTreemap.colorMappers is not null and TreemapColorMapper.value constructor is used, the legend item's icon color will be applied based on the TreemapColorMapper.color property and the legend text applied based on the TreemapColorMapper.value property.

And, when using TreemapColorMapper.range constructor, the legend item's icon color will be applied based on the TreemapColorMapper.color property and the legend text will be applied based on the TreemapColorMapper.name property. If the TreemapColorMapper.name property is null, then the text will be applied based on the TreemapColorMapper.from and TreemapColorMapper.to properties

The below code snippet represents how to setting default legend to the tree map.

late List<SocialMediaUsers> _source;

@override
void initState() {
  _source = <SocialMediaUsers>[
    SocialMediaUsers('India', 'Facebook', 280),
    SocialMediaUsers('India', 'Instagram', 88),
    SocialMediaUsers('USA', 'Facebook', 190),
    SocialMediaUsers('USA', 'Instagram', 120),
    SocialMediaUsers('Japan', 'Twitter', 48),
    SocialMediaUsers('Japan', 'Instagram', 31),
  ];
  super.initState();
}

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: SfTreemap(
      dataCount: _source.length,
      weightValueMapper: (int index) {
        return _source[index].usersInMillions;
      },
      levels: [
        TreemapLevel(
          groupMapper: (int index) {
            return _source[index].country;
          },
        ),
      ],
      legend: TreemapLegend(),
    ),
  );
}

class SocialMediaUsers {
  const SocialMediaUsers(
    this.country,
    this.socialMedia,
    this.usersInMillions,
  );
  final String country;
  final String socialMedia;
  final double usersInMillions;
}

The below code snippet represents how to setting bar legend to the tree map.

late List<SocialMediaUsers> _source;

@override
void initState() {
  _source = <SocialMediaUsers>[
    SocialMediaUsers('India', 'Facebook', 280),
    SocialMediaUsers('India', 'Instagram', 88),
    SocialMediaUsers('USA', 'Facebook', 190),
    SocialMediaUsers('USA', 'Instagram', 120),
    SocialMediaUsers('Japan', 'Twitter', 48),
    SocialMediaUsers('Japan', 'Instagram', 31),
  ];
  super.initState();
}

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: SfTreemap(
      dataCount: _source.length,
      weightValueMapper: (int index) {
        return _source[index].usersInMillions;
      },
      levels: [
        TreemapLevel(
          groupMapper: (int index) {
            return _source[index].country;
          },
        ),
      ],
      legend: TreemapLegend.bar(),
    ),
  );
}

class SocialMediaUsers {
  const SocialMediaUsers(
    this.country,
    this.socialMedia,
    this.usersInMillions,
  );
  final String country;
  final String socialMedia;
  final double usersInMillions;
}

See also:

• To render bar legend, refer TreemapLegend.bar constructor.

Inheritance

• Object
• DiagnosticableTree
• TreemapLegend

Annotations

• @immutable

Constructors

TreemapLegend({bool shouldAlwaysShowScrollbar = false, Widget? title, TreemapLegendPosition position = TreemapLegendPosition.top, Offset? offset, TreemapLegendOverflowMode overflowMode = TreemapLegendOverflowMode.wrap, Axis? direction, EdgeInsetsGeometry? padding = const EdgeInsets.all(10.0), double spacing = 10.0, TextStyle? textStyle, TreemapIconType iconType = TreemapIconType.circle, Size iconSize = const Size(8.0, 8.0)})

Provides additional information about the data rendered in the tree map by initializing the SfTreemap.legend property.

const

TreemapLegend.bar({bool shouldAlwaysShowScrollbar = false, Widget? title, TreemapLegendOverflowMode overflowMode = TreemapLegendOverflowMode.scroll, EdgeInsetsGeometry? padding = const EdgeInsets.all(10.0), TreemapLegendPosition position = TreemapLegendPosition.top, Offset? offset, double spacing = 2.0, TextStyle? textStyle, Axis? direction, Size? segmentSize, TreemapLegendLabelsPlacement? labelsPlacement, TreemapLegendEdgeLabelsPlacement edgeLabelsPlacement = TreemapLegendEdgeLabelsPlacement.inside, TreemapLabelOverflow labelOverflow = TreemapLabelOverflow.visible, TreemapLegendPaintingStyle segmentPaintingStyle = TreemapLegendPaintingStyle.solid, bool showPointerOnHover = false, TreemapLegendPointerBuilder? pointerBuilder, Color? pointerColor, Size pointerSize = const Size(16, 12)})

Creates a bar type legend for the tree map.

const

Properties

direction → Axis?

Arranges the legend items in either horizontal or vertical direction.

final

edgeLabelsPlacement → TreemapLegendEdgeLabelsPlacement

Place the edge labels either inside or outside of the bar legend.

final

hashCode → int

The hash code for this object.

no setter, override

iconSize → Size

Customizes the size of the icon.

final

iconType → TreemapIconType

Specifies the shape of the legend icon.

final

labelOverflow → TreemapLabelOverflow

Trims or removes the legend text when it is overflowed from the bar legend.

final

labelsPlacement → TreemapLegendLabelsPlacement?

Place the labels either between the segments or on the segments.

final

offset → Offset?

Places the legend in custom position.

final

overflowMode → TreemapLegendOverflowMode

Wraps or scrolls the legend items when it overflows.

final

padding → EdgeInsetsGeometry?

Sets the padding around the legend.

final

pointerBuilder → TreemapLegendPointerBuilder?

Returns a widget for the given value.

final

pointerColor → Color?

Customizes the color of the pointer.

final

pointerSize → Size

Customizes the size of the pointer.

final

position → TreemapLegendPosition

Positions the legend in the different directions.

final

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

segmentPaintingStyle → TreemapLegendPaintingStyle

Applies gradient or solid color for the bar segments.

final

segmentSize → Size?

Customizes the size of the bar segments.

final

shouldAlwaysShowScrollbar → bool

Toggles the scrollbar visibility.

final

showPointerOnHover → bool

Specifies whether the pointer should be shown while hovering on the TreemapLegend segments.

final

spacing → double

Specifies the space between the each legend items.

final

textStyle → TextStyle?

Customizes the legend item's text style.

final

title → Widget?

Enables a title for the legends to provide a small note about the legends.

final

Methods

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.

override

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}) → 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 brief description of this object, usually just the runtimeType and the hashCode.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

override