EditLabelHelper

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An IEditLabelHelper implementation which provides a number of methods that can be overridden to change the default behavior.

Inheritance Hierarchy

EditLabelHelper

Implemented Interfaces

IEditLabelHelper

Remarks

This implementation exhibits the default behavior which is modeled after the behavior used by GraphEditorInputMode's startLabelAddition and startLabelEditing. It can be customized by overriding its various factory methods.

Examples

It is recommended to use the various protected methods to customize the wanted behavior while keeping the overall functionality unchanged.

Modifying the initial properties of a new edge label

class CustomEditLabelHelper extends BaseClass(EditLabelHelper) {
  protected onLabelAdding(
    context: IInputModeContext,
    evt: LabelEditingEventArgs,
  ): void {
    // let the base implementation do the work
    super.onLabelAdding(context, evt)
    // for new edge labels: use a custom parameter
    if (evt.owner instanceof IEdge) {
      evt.layoutParameter =
        new EdgeSegmentLabelModel().createParameterFromCenter()
    }
  }
}

The new implementation can be conveniently set using the GraphDecorator:

Setting a new EditLabelHelper for edges

graph.decorator.edges.editLabelHelper.addConstant(
  new CustomEditLabelHelper(),
)

Type Details

yFiles module: view

Properties

graph

: IGraph?

Gets or sets the graph instance to retrieve the default values from.

Remarks

If this instance is not set, the implementation will try to retrieve the graph from the IInputModeContext's ILookup.

Property Value

The graph instance.

Methods

addLabel

(context: IInputModeContext, evt: LabelEditingEventArgs) : ILabel

Handles adding the label upon finish.

Remarks

This implementation uses addLabel to add the label to the graph. The graph is tried to retrieve from graph first. If graph is null, the context is asked for a graph implementation. If no graph is retrieved, null is returned.

Parameters

options - Object
A map of options to pass to the method.

context - IInputModeContext: The valid input mode context for this action.
evt - LabelEditingEventArgs: A template to get all properties to create the label from. Note that the preferredSize can be null. In this case it will be determined automatically.

Returns

↪ILabel?: The newly created label, or null if no graph is available.

cancel

(context: IInputModeContext, evt: LabelEditingEventArgs)

Invoked if the label editing action has been canceled.

Remarks

Implementations which maintain a state have to clean up here.

Parameters

options - Object
A map of options to pass to the method.

context - IInputModeContext: The current input mode context.
evt - LabelEditingEventArgs: Additional information about the label or label owner and whether the editing operation has been canceled programmatically.

Implements

IEditLabelHelper

finish

(context: IInputModeContext, evt: LabelEditingEventArgs, action: LabelEditingAction) : ILabel

Invoked after the label editing gesture has successfully finished.

Remarks

Completes the gesture by applying the changes, according to action.

Depending on action, this method delegates to addLabel, setLabelText, removeLabel, and labelDropped.

Parameters

options - Object
A map of options to pass to the method.

context - IInputModeContext: The input mode context from the input mode which invoked that method.
evt - LabelEditingEventArgs: The LabelEditingEventArgs which provide the information for the label to be added or edited. In particular, the owner for newly added labels or the label to edit or remove, and the text to set
action - LabelEditingAction: Whether to ADD a new label or EDIT or REMOVE an existing label.

Returns

↪ILabel?: The added, edited, or removed label if the action has been completed successfully. null, otherwise.

Implements

IEditLabelHelper

getDefaults

(context: IInputModeContext, owner: ILabelOwner) : ILabelDefaults

Obtains the defaults for the label owner.

Remarks

This implementation tries to get the defaults from the graph. If no graph is set, it tries to get a graph from the context and, if one is returned, to get the defaults from that graph.

Parameters

options - Object
A map of options to pass to the method.

context - IInputModeContext: The input mode context
owner - ILabelOwner: The owner to get the label defaults for

Returns

↪ILabelDefaults?: The label defaults.

getLabelParameter

(context: IInputModeContext, owner: ILabelOwner) : ILabelModelParameter

Determines the label model parameter to use for the label, depending on the owner.

Remarks

This method will obtain the default parameter instances from getDefaults considering the type of the current owner.

Parameters

options - Object
A map of options to pass to the method.

context - IInputModeContext: The input mode context.
owner - ILabelOwner: The label's owner.

Returns

↪ILabelModelParameter?: The layout parameter to use or null.

getLabelStyle

(context: IInputModeContext, owner: ILabelOwner) : ILabelStyle

Determines the style to use for the label, depending on the owner.

Remarks

This method will obtain the default style instances from getDefaults considering the type of the current owner.

Parameters

options - Object
A map of options to pass to the method.

context - IInputModeContext: The input mode context.
owner - ILabelOwner: The label's owner.

Returns

↪ILabelStyle?: The style to use or null.

getPreferredSize

(context: IInputModeContext, label: ILabel) : Size

Gets the preferred size for the label.

Remarks

This implementation yields null to indicate that the preferred size should be calculated after the text has been entered.

Parameters

options - Object
A map of options to pass to the method.

context - IInputModeContext: The input mode context.
label - ILabel: The label to get the preferred size from.

Returns

↪Size?: The size to use or null.

initialize

(context: IInputModeContext, evt: LabelEditingEventArgs, action: LabelEditingAction)

Invoked at the beginning of a label adding or label editing gesture.

Remarks

Delegates to onLabelAdding, onLabelEditing, onLabelDropping, and onLabelPasting depending on the action.

Parameters

options - Object
A map of options to pass to the method.

context - IInputModeContext: The input mode context from the input mode which invoked that method.
evt - LabelEditingEventArgs: A configuration object which supports customizing the label editing.
action - LabelEditingAction: Whether to ADD a new label, EDIT an existing label, or create a new label during DROP or PASTE.

Implements

IEditLabelHelper

labelDropped

(context: IInputModeContext, evt: LabelEditingEventArgs) : ILabel

Handles adding the label upon finish after the drop action of a drag and drop operation.

Remarks

This implementation uses addLabel to add the label to the given evt' owner. If this helper's graph is not null, said instance is used to add the label. If graph is null, this implementation tries to retrieve a graph from the given context. If the retrieved graph is not null, said instance is used to add the label. If the retrieved graph is null, this implementation returns null without adding a label.

Parameters

options - Object
A map of options to pass to the method.

context - IInputModeContext: The valid input mode context for this action.
evt - LabelEditingEventArgs: Provides the owner to add the label to and the label properties (such as style) for the new label. If evt' label properties are not set, the properties of evt' label are used instead.

Returns

↪ILabel?: The newly created label.

onLabelAdding

(context: IInputModeContext, evt: LabelEditingEventArgs)

Will be called from initialize to initialize the helper for ADDing labels.

Remarks

This method delegates to getLabelParameter, getLabelStyle, and getPreferredSize to set the appropriate properties on evt and sets the handled property to true. Label creation thus is always possible and will be handled by this instance.

Parameters

options - Object
A map of options to pass to the method.

context - IInputModeContext: The input mode context.
evt - LabelEditingEventArgs: The original event arguments.

onLabelDropping

(context: IInputModeContext, evt: LabelEditingEventArgs)

Invoked from initialize to initialize the helper for adding labels after the drop action of a drag and drop operation.

Remarks

Called by LabelDropInputMode when a label is dropped on the owner.

This implementation does nothing.

Parameters

options - Object
A map of options to pass to the method.

context - IInputModeContext: The input mode context.
evt - LabelEditingEventArgs: The original event arguments.

onLabelEditing

(context: IInputModeContext, evt: LabelEditingEventArgs)

Will be called from initialize to initialize the helper for EDITing labels.

Remarks

If label is set, this implementation does nothing which means that this label will be edited normally.

If label is null but owner is not null, this method sets the label of the given evt to the first of the labels that belong to said owner. If no label is found, this method sets the properties of the given evt to the values returned by getLabelParameter, getLabelStyle, and getPreferredSize to prepare defaults for label adding.

This method always sets the handled property of the given evt to true, so label editing is always possible and will be handled by this EditLabelHelper instance.

Parameters

options - Object
A map of options to pass to the method.

context - IInputModeContext: The input mode context.
evt - LabelEditingEventArgs: The original event arguments.

onLabelPasting

(context: IInputModeContext, evt: LabelEditingEventArgs, newOwner: ILabelOwner, originalLabel: ILabel)

Invoked from initialize to initialize the helper for adding labels during paste from the GraphClipboard.

Remarks

Called by GraphClipboard when a label is pasted.

This implementation uses getLabelParameter to provide a suitable layoutParameter if the item type of the model changed.

Parameters

options - Object
A map of options to pass to the method.

context - IInputModeContext: The input mode context.
evt - LabelEditingEventArgs: The original event arguments.
newOwner - ILabelOwner: The owner the new label will be pasted on.
originalLabel - ILabel: The original of the new label.

removeLabel

(context: IInputModeContext, label: ILabel) : boolean

Handles removing the label upon finish.

Remarks

This implementation uses remove to remove the label. The graph is tried to retrieve from graph first. If graph is null, the context is asked for a graph implementation. If no graph is retrieved, null is returned.

Parameters

options - Object
A map of options to pass to the method.

context - IInputModeContext: The IInputModeContext.
label - ILabel: The label to remove.

Returns

↪boolean: Whether a label was removed.

setLabelText

(context: IInputModeContext, label: ILabel, text: string) : boolean

Handles changing the label text upon finish.

Remarks

This implementation uses setLabelText to add the label to the graph. The graph is tried to retrieve from graph first. If graph is null, the context is asked for a graph implementation. If no graph is retrieved, null is returned.

If the label's text is not changed, null is returned.

Parameters

options - Object
A map of options to pass to the method.

context - IInputModeContext: The IInputModeContext.
label - ILabel: The label on which to set the text.
text - string: The text to set on the label.

Returns

↪boolean: Whether a new label text was set.