C

DelegatingLabelStyle
abstract

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A foundational abstract implementation of ILabelStyle that delegates its behavior to pre-configured style instances.

Remarks

This class supports three primary use cases:

  • Wrapping another style with a customized API. This is ideal for providing a simpler or domain-specific API by mapping properties from a subclass to the corresponding values of the delegated style. Subclasses typically return the preconfigured instance from getStyle and modify it in the constructor or through custom property setters.
  • Dynamically reconfiguring a style based on the target label. In this scenario, the implementation keeps one or more style instances as fields and switches between them in getStyle, depending on attributes of the label, such as its tag property. This approach may also involve dynamically reconfiguring the style instance for specific label instances. When appropriate, implementations may override clone to simply return this.
  • Replacing one part of the implementation of another style. Instead of subclassing another style, the implementation delegates to all but a subset of the various aspects to an existing implementation and provides its own implementation, otherwise, via overriding specific methods of the base LabelStyleBase<TVisual> class.

Subclasses must implement getStyle and should ensure that it executes quickly and without allocations.

See Also

Developer's Guide

API

getStyle

Members

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Constructors

DelegatingLabelStyle

()
protected
Creates a new instance of this style.

Properties

renderer

: ILabelStyleRenderer
readonly
Gets the renderer implementation for this instance.
The private implementation will delegate all API calls back to this instance.
readonlyfinal

Methods

clone

(): Object
Returns a memberwise clone.
Note that stateless subclasses that implement the flyweight pattern and do not carry any state can override this method and return this, instead, as the base implementation is completely stateless.

Return Value

Object
A clone of this instance.

createVisual

(context: IRenderContext, label: ILabel): Visual
protected
Creates the visual with the style from getStyle and the label from getLabel.
protected

Parameters

context: IRenderContext
The render context.
label: ILabel
The label to which this style instance is assigned.

Return Value

Visual
The visual as required by the createVisual interface.

See Also

API
updateVisual

getBounds

(context: ICanvasContext, label: ILabel): Rect
protected
Gets the bounds with the style from getStyle and the label from getLabel.
protected

Parameters

context: ICanvasContext
The canvas context.
label: ILabel
The label to which this style instance is assigned.

Return Value

Rect
The visual bounds of the visual representation.

getLabel

(label: ILabel): ILabel
protected
Returns the label used for rendering.
Overriding this method allows for advanced customizations such as using a SimpleLabel with modified layoutParameter and use it for rendering while preserving the original label's structure.
protected

Parameters

label: ILabel
The original label to be rendered.

Return Value

ILabel
The label used for rendering. By default, this method returns the provided label. Subclasses can override this method to return a different label, such as a SimpleLabel, to customize rendering behavior.

getPreferredSize

(label: ILabel): Size
protected
Gets the preferred size of the label from getLabel with the style from getStyle.
protected

Parameters

label: ILabel
The label.

Return Value

Size
The size.

getStyle

(label: ILabel): ILabelStyle
protectedabstract
Provides the core implementation of this style, returning the instance to delegate rendering logic.
This method should ideally return the same instance for identical items to ensure optimal performance. It should avoid performing expensive operations as it will be invoked frequently during rendering and other operations like hit-testing. Ideally, it should be implemented allocation-free.
protectedabstract

Parameters

label: ILabel
The label for which the style instance should be returned and applied.

Return Value

ILabelStyle
The ILabelStyle instance responsible for handling all related requests.

isHit

(
context: IInputModeContext
location: Point
label: ILabel
): boolean
protected
Determines with the style from getStyle whether the visualization of the label from getLabel is hit at the given location.
protected

Parameters

context: IInputModeContext
The input mode context.
location: Point
The point to test.
label: ILabel
The label to which this style instance is assigned.

Return Value

boolean
true if the specified label is hit; false otherwise.

isInBox

(
context: IInputModeContext
rectangle: Rect
label: ILabel
): boolean
protected
Determines with the style from getStyle whether the visualization of the label from getLabel is included in the marquee selection.
protected

Parameters

context: IInputModeContext
The input mode context.
rectangle: Rect
The marquee selection box.
label: ILabel
The label to which this style instance is assigned.

Return Value

boolean
true if the specified label is visible and selected by the marquee rectangle; false otherwise.

isInPath

(
context: IInputModeContext
path: GeneralPath
label: ILabel
): boolean
protected
Determines with the style from getStyle whether the visualization of the label from getLabel is included in the lasso selection.
protected

Parameters

context: IInputModeContext
The input mode context.
path: GeneralPath
The lasso selection path.
label: ILabel
The label to which this style instance is assigned.

Return Value

boolean
true if the specified label is visible and selected by the lasso path; false otherwise.

isVisible

(
context: ICanvasContext
rectangle: Rect
label: ILabel
): boolean
protected
Determines with the style from getStyle whether the visualization of the label from getLabel is visible.
protected

Parameters

context: ICanvasContext
The canvas context.
rectangle: Rect
The clipping rectangle.
label: ILabel
The label to which this style instance is assigned.

Return Value

boolean
true if the specified label is visible in the clipping rectangle; false otherwise.

lookup

(label: ILabel, type: Constructor): any
protected
Performs the lookup operation with the style from getStyle and the label from getLabel.
protected

Parameters

label: ILabel
The label to use for the context lookup.
type: Constructor
The type to query.

Return Value

any
An implementation of the type or null.

updateVisual

(
context: IRenderContext
oldVisual: Visual
label: ILabel
): Visual
protected
Updates the visual with the style from getStyle and the label from getLabel.
protected

Parameters

context: IRenderContext
The render context.
oldVisual: Visual
The visual that has been created in the call to createVisual.
label: ILabel
The label to which this style instance is assigned.

Return Value

Visual
The visual as required by the createVisual interface.

See Also

API
createVisual