SwtNodeDropInputMode.java

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package integration.swt;

import com.yworks.yfiles.graph.INode;
import com.yworks.yfiles.view.CanvasControl;
import com.yworks.yfiles.view.input.NodeDropInputMode;
import javafx.scene.input.DragEvent;

/**
 * Handles drop events for node templates.
 * This mode assumes that drag and drop operations transfer name of an
 * {@link integration.swt.NodeTemplate} constant as plain text that
 * may be used for retrieving a INode instance.
 */
class SwtNodeDropInputMode extends NodeDropInputMode {
  // holds the name of the NodeTemplate that is currently dragged
  private Object dragData;

  /**
   * Sets the name of the NodeTemplate that is currently dragged.
   */
  void setDragData(Object dragData) {
    this.dragData = dragData;
  }

  /**
   * Accepts drag events if plain text is transferred that identifies
   * a node template.
   */
  @Override
  protected boolean acceptDrag(DragEvent e) {
    CanvasControl canvasControl = getInputModeContext().getCanvasControl();
    if (!isEnabled() || canvasControl == null) {
      return false;
    }
    return e.getDragboard().hasString() && getDraggedItem() != null;
  }

  /**
   * Retrieves the node template that is identified by the currently
   * transferred text.
   * @return an INode instance that determines the visual representation
   * of the new node created on drop or <code>null</code> if there is no
   * INode instance corresponding to the currently transferred text.
   */
  @Override
  protected INode getDraggedItem() {
    // get the text that has been transferred
    if (dragData instanceof String) {
      // determine the enum constant of NodeTemplate the text is representing
      NodeTemplate template = NodeTemplate.valueOf((String) dragData);
      // returns the node that applies the template
      return template.node();
    } else {
      return null;
    }
  }
}