ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/selection/SelectionLayerStructuralChangeEventHandler.java

/*=============================================================================#
 # Copyright (c) 2012, 2021 Original NatTable authors and others.
 # 
 # This program and the accompanying materials are made available under the
 # terms of the Eclipse Public License 2.0 which is available at
 # https://www.eclipse.org/legal/epl-2.0.
 # 
 # SPDX-License-Identifier: EPL-2.0
 # 
 # Contributors:
 #     Original NatTable authors and others - initial API and implementation
 #=============================================================================*/

package org.eclipse.statet.ecommons.waltable.selection;

import java.util.Collection;
import java.util.List;

import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEventHandler;
import org.eclipse.statet.ecommons.waltable.layer.event.IStructuralChangeEvent;
import org.eclipse.statet.ecommons.waltable.layer.event.StructuralDiff;
import org.eclipse.statet.ecommons.waltable.layer.event.StructuralDiff.DiffTypeEnum;


public class SelectionLayerStructuralChangeEventHandler implements ILayerEventHandler<IStructuralChangeEvent> {

	private final ISelectionModel selectionModel;
	private final SelectionLayer selectionLayer;
	
	public SelectionLayerStructuralChangeEventHandler(final SelectionLayer selectionLayer, final ISelectionModel selectionModel) {
		this.selectionLayer= selectionLayer;
		this.selectionModel= selectionModel;
	}

	@Override
	public Class<IStructuralChangeEvent> getLayerEventClass() {
		return IStructuralChangeEvent.class;
	}

	@Override
	public void handleLayerEvent(final IStructuralChangeEvent event) {
		if (event.isHorizontalStructureChanged()) {
			// TODO handle column deletion
			this.selectionLayer.clear();
			return;
		}
		
		if (event.isVerticalStructureChanged()) {
			//if there are no row diffs, it seems to be a complete refresh
			if (event.getRowDiffs() == null) {
				final Collection<LRectangle> lRectangles= event.getChangedPositionRectangles();
				for (final LRectangle lRectangle : lRectangles) {
					final LRange changedRange= new LRange(lRectangle.y, lRectangle.y + lRectangle.height);
					if (selectedRowModified(changedRange)) {
						if (this.selectionLayer.getRowCount() > 0) {
							long columnPosition= this.selectionLayer.getSelectionAnchor().columnPosition;
							if (columnPosition == SelectionLayer.NO_SELECTION) {
								columnPosition= 0;
							}
							this.selectionLayer.setSelectionToCell(columnPosition, 0, false);
						}
						else {
							this.selectionLayer.clear();
						}
						return;
					}
				}
			}
			else {
				//there are row diffs so we try to determine the diffs to process
				for (final StructuralDiff diff : event.getRowDiffs()) {
					//DiffTypeEnum.CHANGE is used for resizing and shouldn't result in clearing the selection
					if (diff.getDiffType() != DiffTypeEnum.CHANGE) {
						if (selectedRowModified(diff.getBeforePositionRange())) {
							this.selectionLayer.clear();
							return;
						}
					}
				}
			}
		}
	}
	
	private boolean selectedRowModified(final LRange changedRange){
		final List<LRange> selectedRows= this.selectionModel.getSelectedRowPositions();
		for (final LRange rowRange : selectedRows) {
			if (rowRange.overlap(changedRange)){
				return true;
			}
		}
		return false;
	}

}