LevelOfDetailNodeStyle.java

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package complete.orgchart;

import com.yworks.yfiles.view.GraphComponent;
import com.yworks.yfiles.view.IVisual;
import com.yworks.yfiles.view.IRenderContext;
import com.yworks.yfiles.graph.styles.AbstractNodeStyle;
import com.yworks.yfiles.geometry.IRectangle;
import com.yworks.yfiles.graph.INode;
import com.yworks.yfiles.view.input.GraphViewerInputMode;
import com.yworks.yfiles.view.input.ItemHoverInputMode;

/**
 * An {@link com.yworks.yfiles.graph.styles.AbstractNodeStyle} implementation that returns either an
 * DetailVisual, IntermediateVisual or OverviewVisual for the given INode dependent on the current
 * zoom value of the GraphComponent.
 */
public class LevelOfDetailNodeStyle extends AbstractNodeStyle {

  // thresholds for the zoom level to choose the correct level of detail.
  private static final double DETAIL_THRESHOLD = 0.7;
  private static final double INTERMEDIATE_THRESHOLD = 0.4;

  /**
   * Default constructor for subclasses of AbstractNodeStyle that in our case calls the superclass constructor with
   * the type that indicates the return value and parameter type for the methods #createVisual and #updateVisual.
   * In this case this is the {@link OrgChartVisual} class because this is the common superclass of the three possible return values
   * DetailVisual, IntermediateVisual and OverviewVisual.
   */
  public LevelOfDetailNodeStyle() {
    super();
  }

  @Override
  protected OrgChartVisual createVisual(IRenderContext context, INode node) {
    double zoom = context.getZoom();
    GraphComponent component = (GraphComponent) context.getCanvasComponent();
    ItemHoverInputMode hoverInputMode = ((GraphViewerInputMode) component.getInputMode()).getItemHoverInputMode();

    Employee employee = (Employee) node.getTag();
    IRectangle nodeLayout = node.getLayout();
    boolean nodeIsFocused = component.getCurrentItem() == node;
    boolean nodeIsHovered = hoverInputMode.getCurrentHoverItem() == node;

    // build a visual that is appropriate for the given zoom level
    if (zoom >= DETAIL_THRESHOLD) {
      return new DetailVisual(employee, nodeLayout, nodeIsFocused, nodeIsHovered);
    } else if (zoom >= INTERMEDIATE_THRESHOLD) {
      return new IntermediateVisual(employee, nodeLayout, nodeIsFocused, nodeIsHovered);
    } else {
      return new OverviewVisual(employee, nodeLayout, nodeIsFocused, nodeIsHovered);
    }
  }

  @Override
  protected IVisual updateVisual(IRenderContext context, IVisual oldVisual, INode node) {
    if (!(oldVisual instanceof OrgChartVisual)) {
      return createVisual(context, node);
    }

    OrgChartVisual orgChartVisual = (OrgChartVisual) oldVisual;

    double zoom = context.getZoom();

    // find out if we can re-use the old visual or if we have to return a new one.
    // this is the case when the current zoom level doesn't match the current type of the old visual.
    if (   (orgChartVisual instanceof DetailVisual && zoom >= DETAIL_THRESHOLD)
        || (orgChartVisual instanceof IntermediateVisual && DETAIL_THRESHOLD >= zoom && zoom >= INTERMEDIATE_THRESHOLD)
        || (orgChartVisual instanceof OverviewVisual && zoom < INTERMEDIATE_THRESHOLD)) {

      GraphComponent component = (GraphComponent) context.getCanvasComponent();
      ItemHoverInputMode hoverInputMode = ((GraphViewerInputMode) component.getInputMode()).getItemHoverInputMode();

      IRectangle nodeLayout = node.getLayout();
      boolean nodeIsFocused = component.getCurrentItem() == node;
      boolean nodeIsHovered = hoverInputMode.getCurrentHoverItem() == node;

      orgChartVisual.setLayout(nodeLayout);
      orgChartVisual.setFocused(nodeIsFocused);
      orgChartVisual.setHovered(nodeIsHovered);
      return orgChartVisual;
    } else {
      // in this case we need another visual for the current zoom level, so simply delegate to the #createVisual method.
      return createVisual(context, node);
    }
  }

}