LabelHandleProvider.java

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package input.labelhandleprovider;

import com.yworks.yfiles.graph.ILabel;
import com.yworks.yfiles.graph.labelmodels.FreeEdgeLabelModel;
import com.yworks.yfiles.graph.labelmodels.FreeLabelModel;
import com.yworks.yfiles.graph.labelmodels.FreeNodeLabelModel;
import com.yworks.yfiles.graph.labelmodels.ILabelModel;
import com.yworks.yfiles.graph.labelmodels.InteriorStretchLabelModel;
import com.yworks.yfiles.view.input.IHandle;
import com.yworks.yfiles.view.input.IHandleProvider;
import com.yworks.yfiles.view.input.IInputModeContext;

import java.util.ArrayList;
import java.util.List;

/**
 * Factory class for label handles. Depending on the label model of the given
 * label, this class provides custom handle implementations of
 * type {@link LabelResizeHandle} and {@link LabelRotateHandle}.
 * @see IHandle
 * @see ILabel
 * @see ILabelModel
 */
public class LabelHandleProvider implements IHandleProvider {
  private final ILabel label;

  /**
   * Initializes a new {@code LabelHandleProvider} instance for the given label.
   */
  public LabelHandleProvider( ILabel label ) {
    this.label = label;
  }

  /**
   * Returns rotation and resize handles as appropriate for the provider's
   * associated label.
   */
  @Override
  public Iterable<IHandle> getHandles( IInputModeContext context ) {
    List<IHandle> handles = new ArrayList<>();

    ILabelModel labelModel = label.getLayoutParameter().getModel();
    if (labelModel instanceof InteriorStretchLabelModel) {
      // some label models are not resizable at all - don't provide any handles
    } else if (isRotatable(labelModel)) {
      // these models support resizing in one direction
      handles.add(new LabelResizeHandle(label, false));
      // and rotation as well
      handles.add(new LabelRotateHandle(label, context));
    } else {
      // for all other models, we assume the center needs to stay the same
      // this requires that the label must be resized symmetrically in both directions
      handles.add(new LabelResizeHandle(label, true));
    }

    return handles;
  }

  /**
   * Determines if the label model supports rotated labels.
   */
  private static boolean isRotatable( ILabelModel model ) {
    return model instanceof FreeEdgeLabelModel ||
           model instanceof FreeNodeLabelModel ||
           model instanceof FreeLabelModel;
  }
}