com.yworks.yfiles.view

Interface IDisposeVisualCallback

public interface IDisposeVisualCallback

A callback which will be called to free the resources which are occupied by the given removedVisual when the visual will be removed.

Clients have to register this callback in a IVisualCreator.createVisual(IRenderContext) method using method IRenderContext.setDisposeCallback(Node, IDisposeVisualCallback) if the visual occupies resources which have to be cleaned up after the visual is no longer needed.

The method will be called when the removedVisual is removed to free the resources which are allocated by that visual.

This callback can also be used to support caching for temporarily removed visuals. A visual is removed temporarily when it is moved out of the viewport and re-added when it is moved back into the viewport.

If the visual should be cached the callback has to return the visual. When it is re-added IVisualCreator.updateVisual(IRenderContext, Node) is called for the visual. Note that it is possible that the visual will not be cached or discarded without furhter notice. Thus, this callback has to free its resources (if necessary) for temporarily removed visuals, too. As a concequence, for cached visuals the IVisualCreator.updateVisual(IRenderContext, Node) method has to be able to re-allocate the necessary resources.

See Also:

IRenderContext.setDisposeCallback(Node, IDisposeVisualCallback)

Method Summary

Modifier and Type	Method and Description
Node	dispose(IRenderContext context, Node removedVisual, boolean dispose) A callback which will be called to free the resources which are occupied by the given removedVisual when the visual will be removed.

Method Detail

dispose

Node dispose(IRenderContext context,
             Node removedVisual,
             boolean dispose)

A callback which will be called to free the resources which are occupied by the given removedVisual when the visual will be removed.

Clients have to register this callback in a IVisualCreator.createVisual(IRenderContext) method using method IRenderContext.setDisposeCallback(Node, IDisposeVisualCallback) if the visual occupies resources which have to be cleaned up after the visual is no longer needed.

The method will be called when the removedVisual is removed to free the resources which are allocated by that visual.

This callback can also be used to support caching for temporarily removed visuals. A visual is removed temporarily when it is moved out of the viewport and re-added when it is moved back into the viewport.

If the visual should be cached the callback has to return the visual. When it is re-added IVisualCreator.updateVisual(IRenderContext, Node) is called for the visual. Note that it is possible that the visual will not be cached or discarded without furhter notice. Thus, this callback has to free its resources (if necessary) for temporarily removed visuals, too. As a concequence, for cached visuals the IVisualCreator.updateVisual(IRenderContext, Node) method has to be able to re-allocate the necessary resources.

Parameters:

context - A valid render context.

removedVisual - The visual whose resources need to be freed.

dispose - Indicates that the visual is not going to be used again in any case and can be disposed for good. In the case that this parameter is set to true clients should take this as a signal to free the resources used by the removedVisual. If this parameter is set to false, the visual is eventually made visible in the scene graph of the CanvasControl again and may therefore be reused. Note that there is no guarantee that the visual is not garbage collected anyways if VisualCaching is set to VisualCachingPolicy.WEAK.

Returns:

The removed visual if it should be cached, null otherwise.

See Also:

IRenderContext.setDisposeCallback(Node, IDisposeVisualCallback)