GroupLayer class final
A container for other layers and group layers. It is used to represent datasets that are composed of multiple layers to be managed as a single layer with respect to display in a map or scene.
Group layers are designed for presentation of operational layers that are related by a theme. You can add several related operational child layers into a group layer so the layers can be displayed together. Suppose there are several feature layers that represent existing infrastructure projects (buildings, sidewalks, roads, and trees). You can add these feature layers into a single group layer called "Existing". Similarly assume there are also proposed infrastructure projects that are features in other layers. These layers can be added to a group layer called "Planned". You can manage the visibility of the existing or planned features as separate groups.
For the most part, group layers behave like any other layer in that:
- A group layer has visual properties (visibility, opacity) that can be applied to all layers in the group layer at once. This is helpful when controlling the visibility of the group.
- You can set a scale range on a group layer using the minimum and maximum scale properties. If a child layer has more restricted scale range, that scale range will be honored for that child layer.
- A group layer may be queried for the aggregate geographic extent of its child layers
- A group layer may be nested inside another group layer. There is no defined nesting level limit.
- Cloning a group layer will also clone its child layers
- A group layer does not have its own attribute values. The text from the child layers is displayed instead.
- A group layer is not time-aware, but may contain layers that are
- A group layer cannot be added to a basemap
The full extent of a group layer is derived asynchronously based on what information is available from the child layers. This means the full extent can change when child layers are added or removed. The full extent geometry will have the spatial reference of the first loaded child layer.
The visual opacity property of the group layer affects the opacity of the
child layers. The opacity of the child layers is a mathematical product of
the individual child layer's opacity and the group layer's opacity. Opacity
values range from 0.0 (transparent) to 1.0 (opaque). This means that setting
the opacity of the group layer to 0.0 will make all child layers transparent
[0 * AnyNumber = 0]. Likewise when the group layer opacity is 1.0, will set
the opacity of the child layers to their individual layer opacity 1 *
AnyNumber = AnyNumber.
Constructors
-
GroupLayer({List<
Layer> layers = const []}) -
Creates a group layer object with child layers.
factory
Properties
- attribution → String
-
The attribution text for the layer.
no setterinherited
- canChangeVisibility → bool
-
A flag indicating whether the layer content's visibility can be changed.
no setterinherited
- description ↔ String
-
The description for the layer.
getter/setter pairinherited
- fullExtent → Envelope?
-
The full extent of this layer, which is the extent where all layer data is
contained.
no setterinherited
- hashCode → int
-
The hash code for this object.
no setterinherited
- id ↔ String
-
The unique identifying string for the layer, as specified in a map or
scene.
getter/setter pairinherited
- isIdentifyEnabled → bool
-
True if the layer supports identify, false otherwise.
no setterinherited
- isVisible ↔ bool
-
The layer content's visibility.
getter/setter pairinherited
- item → Item?
-
The item the layer has been created from.
no setterinherited
-
layers
→ List<
Layer> -
The child layers associated with a group layer.
no setter
- loadError → ArcGISException?
-
The load error.
no setterinherited
- loadStatus → LoadStatus
-
The load status.
no setterinherited
- maxScale ↔ double
-
The maximum scale for the layer.
getter/setter pairinherited
- minScale ↔ double
-
The minimum scale for the layer.
getter/setter pairinherited
- name ↔ String
-
The layer content's name.
getter/setter pairinherited
-
onLoadStatusChanged
→ Stream<
LoadStatus> -
A stream that reports changes to the
LoadStatus.no setterinherited -
onSubLayerContentChanged
→ Stream<
List< LayerContent> > -
Callback invoked when the sublayer content of the layer content have
changed.
no setterinherited
-
onVisibilityChanged
→ Stream<
bool> -
Callback invoked when the visibility of the layer changes.
no setterinherited
- opacity ↔ double
-
The opacity for the layer.
getter/setter pairinherited
- runtimeType → Type
-
A representation of the runtime type of the object.
no setterinherited
- showChildrenInLegend ↔ bool
-
Determines if the child layers should be shown in the map legend.
getter/setter pair
- showInLegend ↔ bool
-
A flag indicating whether the layer content participates in the legend.
getter/setter pairinherited
- spatialReference → SpatialReference?
-
The spatial reference of the layer.
no setterinherited
-
subLayerContents
→ List<
LayerContent> -
The sub layer contents of a layer content.
no setterinherited
- visibilityMode ↔ GroupVisibilityMode
-
The visibility mode for the layers in a table of contents.
getter/setter pair
Methods
-
cancelLoad(
) → void -
Cancels loading metadata for the object.
inherited
-
clone(
) → Layer -
Clones this instance of the layer and its members.
inherited
-
fetchLegendInfos(
) → Future< List< LegendInfo> > -
Fetches the list of legend info.
inherited
-
isVisibleAtScale(
double scale) → bool -
Returns the layer content's effective visibility at the specified scale.
inherited
-
load(
) → Future< void> -
Loads the metadata for the object asynchronously.
inherited
-
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a nonexistent method or property is accessed.
inherited
-
retryLoad(
) → Future< void> -
Loads or retries loading metadata for the object asynchronously.
inherited
-
toString(
) → String -
A string representation of this object.
inherited
Operators
-
operator ==(
Object other) → bool -
The equality operator.
inherited