C

LabelDropInputMode

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An ItemDropInputMode<T> specialized to the drag and drop of ILabels.

Remarks

This input mode can visualize a preview of the draggedItem during the drag operation, and supports snapping via the snapContext and highlighting of the dropTarget via a HighlightIndicatorManager<T>.

Examples

Typically the LabelDropInputMode is installed as child mode of a GraphEditorInputMode and can be retrieved from the labelDropInputMode property.
Getting the LabelDropInputMode from its parent input mode
const labelDropInputMode = mode.labelDropInputMode

See Also

Developer's Guide

Members

Show:

Constructors

LabelDropInputMode

(transferType: string)
Initializes a new instance of the LabelDropInputMode class for the given data type.

This instance fires events only if a drag operation carries DragDropItem of the given type.

When no transferType is provided, it defaults to DEFAULT_TRANSFER_TYPE so it fires only for DragDropItem carrying this data type. For example, startDrag initiates such a drag operation.

Parameters

transferType: string
A list of types for which this input mode is registered.

Properties

autoEditLabel

: boolean
Gets or sets a value indicating whether the EDIT_LABEL command is automatically raised after a label has been created.
The default value is false.
final

capturePointerInputDuringDrag

: boolean
Gets or sets a value indicating whether to capture pointer input during drag operations.
The default is true and thus prevents pointer events from being processed by visuals in the canvas.
final

Property Value

true if pointer input should be captured during the drag; false otherwise.

controller

: ConcurrencyController
protectedreadonly
Gets the installed controller.
protectedreadonlyfinal

disableSnappingRecognizer

: function(EventArgs, unknown): boolean
Gets or sets the event recognizer that determines whether to disable snapping temporarily.
final

Property Value

The disable snapping recognizer. The default recognizer checks for a pressed using CONTROL_KEY.

dragDropEffect

: DragDropEffects
Gets or sets the DragDropEffects that will be used for drags on the canvas.
conversionfinal

draggedItem

: ILabel
protectedreadonly
Gets the currently dragged IModelItem instance.

This implementation simply tries to cast the dropData to ILabel.

If native drag and drop is used, the value of this property is always null. This is because the protected mode prevents access to the actual data during dragover.

protectedreadonly

dropData

: any
readonly
Gets the data carried by a drag operation.
This is only valid, if a drag entered the CanvasComponent first.
readonly

dropLocation

: Point
readonly
Gets the pointer position after dropping an item.
The position is returned in world coordinates according to the CanvasComponent into which this input mode is installed.
readonlyfinal

dropTarget

: IModelItem
Gets the drop target at snappedPointerPosition
final

See Also

API
highlightDropTarget

enabled

: boolean
Gets or sets the enabled state of this input mode.
Clients can use this property to disable or reenable this instance. This will set the enabled property of the installed controller so a disabled instance should never try to acquire the input mutex.

Examples

Disabling the NodeDropInputMode on its parent input mode
mode.nodeDropInputMode.enabled = false

exclusive

: boolean
Gets or sets a value indicating whether this mode will be the only one running when it has the mutex.

The value of this property will be delegated to the exclusive property of the controller.

If this mode is marked as exclusive and has the mutex, all other modes added to the same MultiplexingInputMode will be deactivated. Otherwise, it will always run concurrently with all other modes.

final

highlightDropTarget

: boolean
Gets or sets whether the drop target is highlighted.
final

See Also

Developer's Guide

isDragging

: boolean
readonly
Gets a value indicating whether a drag operation is currently in progress.
readonlyfinal

isValidLabelOwnerPredicate

: function(ILabelOwner, ILabel): boolean
Gets or sets the predicate for testing whether an existing label owner in the graph can be used as owner for the currently dragged label.

The default implementation checks whether a valid label model parameter could be found for the combination of label owner and dragged label, and whether the label has an IEditLabelHelper that forbids adding new labels.

Note that during native drag and drop, draggedItem is always null and cannot be used for this check.

final

itemCreator

: function(IInputModeContext, IGraph, any, IModelItem, Point): ILabel
Gets or sets the callback for item creation.
Called by method onDragDropped.
final

See Also

Developer's Guide

lastDragEventArgs

: DragEventArgs
readonly
Gets the last processed drag event argument.
readonlyfinal

parentInputModeContext

: IInputModeContext
protectedreadonly
Retrieves the IInputModeContext this mode has been installed in.
The value will be null if this mode is currently not installed. Use createInputModeContext to obtain a context that has this IInputMode as the inputMode.
protectedreadonlyfinal

pointerPosition

: IPoint
readonly
Gets the current pointer position during drag operations.
The position is returned in world coordinates according to the CanvasComponent into which this input mode is installed.
readonlyfinal

previewGraph

: IGraph
protectedreadonly
Gets the graph displayed as item preview.
protectedreadonlyfinal

Property Value

The preview graph or null if no preview is displayed at the moment.

See Also

Developer's Guide

priority

: number
Gets the priority of this input mode.
The priority will influence the order in which the modes will be installed into the CanvasComponent. The lower the priority value, the earlier it will be installed. If two modes are using the same priority value, the first one to be registered will be installed earlier.
final

showPreview

: boolean
Gets or sets whether a preview of the dragged element is displayed during the drag.
final

See Also

Developer's Guide

snapContext

: GraphSnapContext
Gets or sets the GraphSnapContext which is used to snap the dragged element during the drag.
If set to null (the default), this input mode tries to obtain the GraphSnapContext from the IInputModeContext. To explicitly disable snapping, a GraphSnapContext implementation that is disabled needs to be set.
final

See Also

Developer's Guide

snappedPointerPosition

: Point
readonly
Gets the current snapped pointer position during drag operations.
The position is returned in world coordinates according to the CanvasComponent into which this input mode is installed. If snappingEnabled is false, this value corresponds with pointerPosition.
readonlyfinal

snappingEnabled

: boolean
Gets or sets whether dragged items are snapped.
final

See Also

Developer's Guide

useLocationForParameter

: boolean
Gets or sets a value indicating whether the default implementation of getNewLabelModelParameter should determine a parameter that best matches the location of the dropped label, or if it should directly use the parameter stored in the dropped item.
The default value is false, which means the parameter from the dropped label will be used directly.
final

validDropHitTestable

: IHitTestable
Gets or sets the IHitTestable that determines whether the given location is a valid drop location.
final

Property Value

The hit testable that yields true for valid drop locations.

See Also

Developer's Guide

Methods

adjustEffect

(evt: DragEventArgs): boolean
protected
Called to adjust the dropEffect accordingly.
protected

Parameters

evt: DragEventArgs
The event args of the drag event to adjust the effects for.

Return Value

boolean
true if the drag event is handled by this input mode.

cancel

()
Cleanly cancels this mode.

cleanUp

()
protected
Cleanup method that calls cleanUpSnapContext, cleanUpPreview and cleanUpDropTarget.
This method should be called for cleanup actions after a drag/drop gesture has been finished or canceled.
protected

cleanUpDropTarget

()
protected
Cleans up the drop target and its highlighting.
protected

cleanUpPreview

()
protected
Cleans up the item preview.
protected

cleanUpSnapContext

()
protected
Cleans up the snap context.
protected

collectSnapResults

(evt: CollectSnapResultsEventArgs, source: any)
protected
Callback registered on the SnapContext that collects SnapResults for the dragged element.
The default implementation doesn't collect any snap results.
protected

Parameters

evt: CollectSnapResultsEventArgs
The arguments describing the movement SnapResults shall be collected for.
source: any
The SnapContext this callback is registered at.

createInputModeContext

(): IInputModeContext
protected
Creates an implementation of IInputModeContext that is specific to this mode.

This is needed for events that are triggered by this InputMode to signalize where the event is coming from. A common usage for this is for example in isHit calls.

The result can be given to isHit or enumerateHits to let implementations of IHitTestable get access to the current IInputModeContext. This can be done by looking up IInputModeContext from the ICanvasContext's lookup method or simply downcasting.

protected

Return Value

IInputModeContext
A readily configured IInputModeContext.

createInputModeEventArgs

(): InputModeEventArgs
protected
Helper method that yields a suitably configured InputModeEventArgs for this input mode.
protected

Return Value

InputModeEventArgs
An input mode event argument that is configured for this instance.

createLabel

(
context: IInputModeContext
graph: IGraph
label: ILabel
dropTarget: ILabelOwner
parameter: ILabelModelParameter
): ILabel
protected
Creates the label in the graph after it's been dropped.

This method is called by the itemCreator that is set as default on this class.

It queries the dropTarget for an IEditLabelHelper. If one is found, it delegates to its finish method with action DROP to create the label. If none is found, the label is added using the graph's addLabel method.

protected

Parameters

context: IInputModeContext
The context for which the label should be created.
graph: IGraph
The Graph in which to create the label.
label: ILabel
The label that was dragged and should therefore be created.
dropTarget: ILabelOwner
The ILabelOwner on which the label is dropped.
parameter: ILabelModelParameter
The ILabelModelParameter of the new label.

Return Value

ILabel
a newly created label.

See Also

Developer's Guide

getDropTarget

(dragLocation: Point): IModelItem
protected
Looks for a valid label owner at the dragLocation.
protected

Parameters

dragLocation: Point
The location to return the drop target for.

Return Value

IModelItem
A label owner or null if no valid label owner was found at the drag location.

See Also

Developer's Guide

getLabelLayout

(dragLocation: Point, draggedLabel: ILabel): IOrientedRectangle
protected
Get the layout the dragged label currently has.
protected

Parameters

dragLocation: Point
The current drag location
draggedLabel: ILabel
The dragged label.

Return Value

IOrientedRectangle
The layout for the dragged label

getNewLabelModelParameter

(
owner: ILabelOwner
draggedLabel: ILabel
dragLocation: Point
): ILabelModelParameter
protected
Determines the ILabelModelParameter the label should have if it was dropped at dragLocation over owner.

If useLocationForParameter is false (the default), this implementation returns the layoutParameter of the draggedLabel if it is applicable to owner. If it is not applicable, the method returns null. In this case, the dragLocation is ignored.

If useLocationForParameter is true, this implementation will use the model of the draggedLabel (if compatible with owner) and calls findBestParameter to determine the parameter that best matches the current dragLocation.

protected

Parameters

owner: ILabelOwner
The label owner where the label would be created. May be null.
draggedLabel: ILabel
The label that is currently dragged.
dragLocation: Point
The current drag location.

Return Value

ILabelModelParameter
A ILabelModelParameter for draggedLabel, or null.

See Also

Developer's Guide

initializeDropTarget

()
protected
Initializes the drop target.
protected

initializePreview

()
protected
Initializes the item preview.
This method is called by onDragEntered. If a preview shall be displayed, the previewGraph is initialized and populatePreviewGraph is called.
protected

See Also

Developer's Guide

initializeSnapContext

()
protected
Initializes the snapping context.
This method is called by onDragEntered
protected

install

(context: IInputModeContext, controller: ConcurrencyController)
Installs this mode into the given canvas.
Clients should not call this method as this is handled by the framework.

Parameters

context: IInputModeContext
the context to install this mode into
controller: ConcurrencyController
The controller for this mode.

See Also

API
CanvasComponent

isValidLabelOwner

(owner: ILabelOwner, draggedLabel: ILabel): boolean
protected
Determines whether the specified label can be added to the given label owner.

This method validates whether the model of the draggedLabel can be added to the specified owner. The validation is successful if the model of the draggedLabel is of type FreeLabelModel. Alternatively, it is valid if the type of the draggedLabel's owner matches the type of the owner, such as when both are nodes, edges, or ports.

Additionally, the method checks whether the owner has an associated IEditLabelHelper that might prohibit adding new labels.

This method is used as the default implementation for the isValidLabelOwnerPredicate.

protected

Parameters

owner: ILabelOwner
The label owner to which the label is being added. This parameter cannot be null.
draggedLabel: ILabel
The label being dragged and potentially added to the owner.

Return Value

boolean
true if the draggedLabel can be added to the specified owner; otherwise, false.

onCanceled

()
protected
Called after cancel has been called.

Can be overridden in subclasses to perform additional actions after the mode has been canceled.

This implementation does nothing.

protected

onConcurrencyControllerActivated

()
protected
Called after the active property of the installed ConcurrencyController has been set to true.

Can be overridden in subclasses to perform additional actions after the mode has been activated.

Overriding implementations should call the base implementation.

protected

onConcurrencyControllerDeactivated

()
protected
Called after the active property of the installed ConcurrencyController has been set to false.

Can be overridden in subclasses to perform additional actions after the mode has been deactivated.

Overriding implementations should call the base implementation.

protected

onDragDropped

(evt: InputModeEventArgs)
protected
Called once a drag has been dropped on the canvas.
protected

Parameters

evt: InputModeEventArgs
The event argument that contains context information.

onDragEntered

(evt: InputModeEventArgs)
protected
Called once a drag has entered the canvas.
protected

Parameters

evt: InputModeEventArgs
The event argument that contains context information.

onDraggedOver

(evt: InputModeEventArgs)
protected
Called whenever a drag is over the canvas.
protected

Parameters

evt: InputModeEventArgs
The event argument that contains context information.

onDragLeft

(evt: InputModeEventArgs)
protected
Called once a drag has left the canvas.
protected

Parameters

evt: InputModeEventArgs
The event argument that contains context information.

onItemCreated

(evt: InputModeItemEventArgs<ILabel>)
protected
Called whenever a new item is created.
protected

Parameters

evt: InputModeItemEventArgs<ILabel>
The InputModeItemEventArgs<TModelItem> containing the new item.

onStopped

()
protected
Called after tryStop has been called.

Can be overridden in subclasses to perform additional actions after the mode has been stopped.

This implementation does nothing.

protected

populatePreviewGraph

(previewGraph: IGraph)
protected
Subclasses shall fill the specified graph that is used to preview the dragged item.
protected

Parameters

previewGraph: IGraph
The preview graph to fill.

setDragLocation

(location: Point)
protected
Sets the drag location and calls updatePreview to update the layout of item preview based on the pointer coordinates and the results of the snapContext.
protected

Parameters

location: Point
The current location of the pointer in world coordinates.

tryStop

(): boolean
Overridden to only return true if this instance does not currently have the input mutex.

Return Value

boolean
true iff this instance does not own the mutex.

uninstall

(context: IInputModeContext)
Uninstalls this mode from the canvas.
Clients should not call this method as this is handled by the framework.

Parameters

context: IInputModeContext
the context

updateDropTarget

(dragLocation: Point)
protected
Calls getDropTarget for snappedPointerPosition and sets the returned item as dropTarget.
If highlightDropTarget is enabled, the highlight is updated as well.
protected

Parameters

dragLocation: Point
The location to update the drop target for.

updatePreview

(previewGraph: IGraph, dragLocation: Point)
protected
Subclasses shall update the previewGraph so the dragged item is displayed at the specified dragLocation.
protected

Parameters

previewGraph: IGraph
The preview graph to update.
dragLocation: Point
The current drag location.

Events

'drag-dropped'

: InputModeEventArgs
Occurs when a drag operation is dropped onto the CanvasComponent into which this instance is installed.

No event is raised

  • if this instance is not enabled,
  • if another concurrent input mode is active or
  • the data from the drag operation does not conform to the expected type.

To get additional data for the event, clients should use the sender which is set to the sending DropInputMode. The EventArgs provide no useful data.

Properties of

InputModeEventArgs
context: IInputModeContext
Gets the context for the current event.

See Also

Developer's Guide

'drag-entered'

: InputModeEventArgs
Occurs when a drag operation enters the CanvasComponent into which this instance is installed.

No event is raised

  • if this instance is not enabled,
  • if another concurrent input mode is active or
  • the data from the drag operation does not conform to the expected type.

To get additional data for the event, clients should use the sender which is set to the sending DropInputMode. The EventArgs provide no useful data.

Properties of

InputModeEventArgs
context: IInputModeContext
Gets the context for the current event.

See Also

Developer's Guide

'drag-left'

: InputModeEventArgs
Occurs when a drag operation leaves the CanvasComponent into which this instance is installed.

No event is raised

  • if this instance is not enabled,
  • if another concurrent input mode is active or
  • the data from the drag operation does not conform to the expected type.

To get additional data for the event, clients should use the sender which is set to the sending DropInputMode. The EventArgs provide no useful data.

Properties of

InputModeEventArgs
context: IInputModeContext
Gets the context for the current event.

See Also

Developer's Guide

'drag-over'

: InputModeEventArgs
Occurs when a drag operation drags over the CanvasComponent into which this instance is installed.

No event is raised

  • if this instance is not enabled,
  • if another concurrent input mode is active or
  • the data from the drag operation does not conform to the expected type.

To get additional data for the event, clients should use the sender which is set to the sending DropInputMode. The EventArgs provide no useful data.

Properties of

InputModeEventArgs
context: IInputModeContext
Gets the context for the current event.

See Also

Developer's Guide

'item-created'

: InputModeItemEventArgs<ILabel>
Occurs when a new item gets created by this input mode.
context: IInputModeContext
Gets the context for the current event.
item: TModelItem
Gets the item which has been created or changed.

Constants

DEFAULT_TRANSFER_TYPE

: string
static
The transfer type to which the LabelDropInputMode and its startDrag method is configured by default.

Static Methods

startDrag

(
dragSource: any
label: ILabel
dragDropEffects?: DragDropEffects
useCssCursors?: boolean
dragPreview?: any
): DragSource
static
Starts a drag and drop operation for a ILabel.

This method creates a DragSource, and then invokes startDrag with a DragDropItem that contains the label and the corresponding type.

If useLocationForParameter is false, then the label needs a correct preferred size. Additionally, the label owner needs a correct size for label parameters which consider the owner's geometry (e.g. stretch label models).

If useCssCursors is enabled, the following CSS classes are assigned to elements hovered during a drag operation, depending on the allowed drag-drop operations for these elements:

  • yfiles-cursor-dragdrop-move
  • yfiles-cursor-dragdrop-link
  • yfiles-cursor-dragdrop-all
  • yfiles-cursor-dragdrop-no-drop
static

Parameters

dragSource: any
The source of the drag operation.
label: ILabel
The label to drag.
dragDropEffects?: DragDropEffects
The allowed drag drop effects.
useCssCursors?: boolean
Whether to adjust the classes of elements being hovered over during the drag. The default is true.
dragPreview?: any
Optional element that should be shown during dragging, e.g. outside of the GraphComponent. Note that this feature requires support for CSS pointer-events and should not be used in browsers that do not support it.

Return Value

DragSource
The new DragSource instance.

See Also

API
startDrag, DragDropItem