ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/viewport/ViewportLayer.java - gerrit/statet/org.eclipse.statet-commons - Git at Google

 /*=============================================================================#
  # 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
  #     Stephan Wahlbrink <sw@wahlbrink.eu> - dim-based implementation
  #=============================================================================*/

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

 import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
 import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;

 import org.eclipse.swt.widgets.Display;

 import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
 import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
 import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
 import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
 import org.eclipse.statet.ecommons.waltable.grid.ClientAreaResizeCommand;
 import org.eclipse.statet.ecommons.waltable.layer.ILayer;
 import org.eclipse.statet.ecommons.waltable.layer.TransformLayer;
 import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
 import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEvent;
 import org.eclipse.statet.ecommons.waltable.layer.event.IStructuralChangeEvent;
 import org.eclipse.statet.ecommons.waltable.print.PrintEntireGridCommand;
 import org.eclipse.statet.ecommons.waltable.print.TurnViewportOffCommand;
 import org.eclipse.statet.ecommons.waltable.print.TurnViewportOnCommand;
 import org.eclipse.statet.ecommons.waltable.selection.CellSelectionEvent;
 import org.eclipse.statet.ecommons.waltable.selection.ColumnSelectionEvent;
 import org.eclipse.statet.ecommons.waltable.selection.RowSelectionEvent;
 import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
 import org.eclipse.statet.ecommons.waltable.swt.SWTUtil;


 /**
  * Viewport - the visible area of NatTable
  *
  * Places a 'viewport' over the table. Introduces scroll bars over the table and
  * keeps them in sync with the data being displayed. This is typically placed over the
  * {@link SelectionLayer}.
  */
 public class ViewportLayer extends TransformLayer {

 	static final int EDGE_HOVER_REGION_SIZE= 16;

 	static final int PAGE_INTERSECTION_SIZE= EDGE_HOVER_REGION_SIZE;


 	private final ILayer scrollableLayer;

 	// The viewport current origin
 	private boolean viewportOff= false;
 	private final long[] savedOriginPixel= new long[2];

 	// Edge hover scrolling
 	private MoveViewportRunnable edgeHoverRunnable;


 	/**
 	 * Creates a new viewport layer.
 	 *
 	 * @param underlyingLayer the underlying scrollable layer
 	 */
 	public ViewportLayer(/*@NonNull*/ final ILayer underlyingLayer) {
 		super(underlyingLayer);
 		this.scrollableLayer= underlyingLayer;

 		registerCommandHandlers();

 		initDims();
 	}


 	@Override
 	public void dispose() {
 		super.dispose();

 		for (final Orientation orientation : Orientation.values()) {
 			disposeDim(orientation);
 		}

 		cancelEdgeHoverScroll();
 	}


 	public boolean isViewportOff() {
 		return this.viewportOff;
 	}


 	@Override
 	protected void initDims() {
 		final ILayer scrollable= getScrollableLayer();
 		if (scrollable == null) {
 			return;
 		}
 		for (final Orientation orientation : Orientation.values()) {
 			disposeDim(orientation);
 			setDim(new ViewportLayerDim(this, scrollable.getDim(orientation)));
 		}
 	}

 	protected void disposeDim(final Orientation orientation) {
 		final ViewportLayerDim dim= get(orientation);
 		if (dim != null) {
 			dim.dispose();
 		}
 	}

 	@Override
 	public IViewportDim getDim(final Orientation orientation) {
 		return (IViewportDim) super.getDim(orientation);
 	}

 	final ViewportLayerDim get(final Orientation orientation) {
 		return (ViewportLayerDim) super.getDim(orientation);
 	}

 	// Configuration

 	@Override
 	protected void registerCommandHandlers() {
 		registerCommandHandler(new RecalculateScrollBarsCommandHandler(this));
 		registerCommandHandler(new ShowCellInViewportCommandHandler(this));
 		registerCommandHandler(new ShowPositionInViewportCommandHandler());
 		registerCommandHandler(new ViewportSelectDimPositionsCommandHandler(this));
 		registerCommandHandler(new ViewportDragCommandHandler(this));
 		registerCommandHandler(new SelectRelativePageCommandHandler(this));
 		registerCommandHandler(new ScrollStepCommandHandler(this));
 		registerCommandHandler(new ScrollPageCommandHandler(this));
 	}


 	// Cell features

 	@Override
 	public ILayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
 		return super.getCellByPosition(columnPosition, rowPosition);
 	}

 	protected void fireScrollEvent() {
 		fireLayerEvent(new ScrollEvent(this));
 	}

 	@Override
 	public boolean doCommand(final ILayerCommand command) {
 		if (command instanceof ClientAreaResizeCommand) {
 			final ClientAreaResizeCommand clientAreaResizeCommand= (ClientAreaResizeCommand) command.cloneCommand();
 			if (clientAreaResizeCommand.convertToTargetLayer(this)) {
 				//remember the difference from client area to body region area
 				//needed because the scrollbar will be removed and therefore the client area will become bigger
 				final long widthDiff= clientAreaResizeCommand.getScrollable().getClientArea().width - clientAreaResizeCommand.getCalcArea().width;
 				final long heightDiff= clientAreaResizeCommand.getScrollable().getClientArea().height - clientAreaResizeCommand.getCalcArea().height;

 				get(HORIZONTAL).checkScrollBar(clientAreaResizeCommand.getScrollable());
 				get(VERTICAL).checkScrollBar(clientAreaResizeCommand.getScrollable());

 				get(HORIZONTAL).handleResize();
 				get(VERTICAL).handleResize();

 				//after handling the scrollbars recalculate the area to use for percentage calculation
 				final LRectangle possibleArea= SWTUtil.toNatTable(clientAreaResizeCommand.getScrollable().getClientArea());
 				possibleArea.width-= widthDiff;
 				possibleArea.height-= heightDiff;
 				clientAreaResizeCommand.setCalcArea(possibleArea);
 				//we don't return true here because the ClientAreaResizeCommand needs to be handled
 				//by the DataLayer in case percentage sizing is enabled
 				//if we would return true, the DataLayer wouldn't be able to calculate the column/row
 				//sizes regarding the client area
 				return super.doCommand(clientAreaResizeCommand);
 			}
 		}
 		else if (command instanceof TurnViewportOffCommand) {
 			if (!isViewportOff()) {
 				for (final Orientation orientation : Orientation.values()) {
 					this.savedOriginPixel[orientation.ordinal()]= get(orientation).getOriginPixel();
 				}
 				this.viewportOff= true;
 				fireScrollEvent();
 			}
 			return true;
 		}
 		else if (command instanceof TurnViewportOnCommand) {
 			if (isViewportOff()) {
 				this.viewportOff= false;
 				for (final Orientation orientation : Orientation.values()) {
 					get(orientation).doSetOriginPixel(this.savedOriginPixel[orientation.ordinal()]);
 				}
 				fireScrollEvent();
 			}
 			return true;
 		}
 		else if (command instanceof PrintEntireGridCommand) {
 			get(HORIZONTAL).movePositionIntoViewport(0);
 			get(VERTICAL).movePositionIntoViewport(0);
 		}
 		return super.doCommand(command);
 	}

 	/**
 	 * Recalculate scrollbar characteristics.
 	 */
 	public void recalculateScrollBars() {
 		get(HORIZONTAL).handleResize();
 		get(VERTICAL).handleResize();
 	}

 	// Event handling

 	@Override
 	public void handleLayerEvent(final ILayerEvent event) {
 		if (event instanceof IStructuralChangeEvent) {
 			final IStructuralChangeEvent structuralChangeEvent= (IStructuralChangeEvent) event;
 			if (structuralChangeEvent.isHorizontalStructureChanged()) {
 				get(HORIZONTAL).handleStructuralChange(structuralChangeEvent.getColumnDiffs());
 			}
 			if (structuralChangeEvent.isVerticalStructureChanged()) {
 				get(VERTICAL).handleStructuralChange(structuralChangeEvent.getRowDiffs());
 			}
 		}

 		if (event instanceof CellSelectionEvent) {
 			processSelection((CellSelectionEvent) event);
 		} else if (event instanceof ColumnSelectionEvent) {
 			processColumnSelection((ColumnSelectionEvent) event);
 		} else if (event instanceof RowSelectionEvent) {
 			processRowSelection((RowSelectionEvent) event);
 		}

 		super.handleLayerEvent(event);
 	}

 	/**
 	 * Handle {@link CellSelectionEvent}
 	 * @param selectionEvent
 	 */
 	private void processSelection(final CellSelectionEvent selectionEvent) {
 		if (selectionEvent.getRevealCell()) {
 			get(HORIZONTAL).movePositionIntoViewport(selectionEvent.getColumnPosition());
 			get(VERTICAL).movePositionIntoViewport(selectionEvent.getRowPosition());
 		}
 	}

 	/**
 	 * Handle {@link ColumnSelectionEvent}
 	 * @param selectionEvent
 	 */
 	private void processColumnSelection(final ColumnSelectionEvent selectionEvent) {
 		final long explicitePosition= selectionEvent.getColumnPositionToReveal();
 		if (explicitePosition >= 0) {
 			get(HORIZONTAL).movePositionIntoViewport(explicitePosition);
 		}
 	}

 	/**
 	 * Handle {@link RowSelectionEvent}
 	 * @param selectionEvent
 	 */
 	private void processRowSelection(final RowSelectionEvent selectionEvent) {
 		final long explicitePosition= selectionEvent.getRowPositionToReveal();
 		if (explicitePosition >= 0) {
 			get(VERTICAL).movePositionIntoViewport(explicitePosition);
 			return;
 		}
 	}

 	// Accessors

 	/**
 	 * @return The scrollable layer underlying the viewport.
 	 */
 	public ILayer getScrollableLayer() {
 		return this.scrollableLayer;
 	}

 	@Override
 	public String toString() {
 		return "Viewport Layer"; //$NON-NLS-1$
 	}

 	// Edge hover scrolling

 	/**
 	 * Used for edge hover scrolling. Called from the ViewportDragCommandHandler.
 	 * @param x
 	 * @param y
 	 */
 	public void drag(final long x, final long y) {
 		if (x < 0 && y < 0) {
 			cancelEdgeHoverScroll();
 			return;
 		}

 		MoveViewportRunnable move= this.edgeHoverRunnable;
 		if (move == null) {
 			move= new MoveViewportRunnable();
 		}

 		move.fast= true;
 		boolean requireSchedule= false;

 		final LRectangle clientArea= getClientAreaProvider().getClientArea();
 		for (final Orientation orientation : Orientation.values()) {
 			final LRange lRange= clientArea.getRange(orientation);
 			final long pixel= (orientation == HORIZONTAL) ? x : y;
 			int change= 0;
 			if (pixel >= lRange.start && pixel < lRange.start + EDGE_HOVER_REGION_SIZE) {
 				change= -1;
 				if (pixel >= lRange.start + EDGE_HOVER_REGION_SIZE/2) {
 					move.fast= false;
 				}
 			} else if (pixel >= lRange.end - EDGE_HOVER_REGION_SIZE && pixel < lRange.end) {
 				change= 1;
 				if (pixel < lRange.end - EDGE_HOVER_REGION_SIZE/2) {
 					move.fast= false;
 				}
 			}
 			move.change[orientation.ordinal()]= change;
 			requireSchedule |= (change != 0);
 		}

 		if (requireSchedule) {
 			move.schedule();
 		} else {
 			cancelEdgeHoverScroll();
 		}
 	}

 	/**
 	 * Cancels an edge hover scroll.
 	 */
 	private void cancelEdgeHoverScroll() {
 		this.edgeHoverRunnable= null;
 	}

 	/**
 	 * Runnable that incrementally scrolls the viewport when drag hovering over an edge.
 	 */
 	class MoveViewportRunnable implements Runnable {


 		private final int[] change= new int[2];
 		private boolean fast;

 		private final Display display= Display.getCurrent();


 		public MoveViewportRunnable() {
 		}


 		public void schedule() {
 			if (ViewportLayer.this.edgeHoverRunnable != this) {
 				ViewportLayer.this.edgeHoverRunnable= this;
 				this.display.timerExec(500, this);
 			}
 		}

 		@Override
 		public void run() {
 			if (ViewportLayer.this.edgeHoverRunnable != this) {
 				return;
 			}

 			for (final Orientation orientation : Orientation.values()) {
 				switch (this.change[orientation.ordinal()]) {
 				case -1:
 					get(orientation).scrollBackwardByPosition();
 					break;
 				case 1:
 					get(orientation).scrollForwardByPosition();
 					break;
 				}
 			}

 			this.display.timerExec(this.fast ? 100 : 500, this);
 		}

 	}

 }
	/*=============================================================================#
	# 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
	# Stephan Wahlbrink <sw@wahlbrink.eu> - dim-based implementation
	#=============================================================================*/

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

	import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.HORIZONTAL;
	import static org.eclipse.statet.ecommons.waltable.coordinate.Orientation.VERTICAL;

	import org.eclipse.swt.widgets.Display;

	import org.eclipse.statet.ecommons.waltable.command.ILayerCommand;
	import org.eclipse.statet.ecommons.waltable.coordinate.LRange;
	import org.eclipse.statet.ecommons.waltable.coordinate.LRectangle;
	import org.eclipse.statet.ecommons.waltable.coordinate.Orientation;
	import org.eclipse.statet.ecommons.waltable.grid.ClientAreaResizeCommand;
	import org.eclipse.statet.ecommons.waltable.layer.ILayer;
	import org.eclipse.statet.ecommons.waltable.layer.TransformLayer;
	import org.eclipse.statet.ecommons.waltable.layer.cell.ILayerCell;
	import org.eclipse.statet.ecommons.waltable.layer.event.ILayerEvent;
	import org.eclipse.statet.ecommons.waltable.layer.event.IStructuralChangeEvent;
	import org.eclipse.statet.ecommons.waltable.print.PrintEntireGridCommand;
	import org.eclipse.statet.ecommons.waltable.print.TurnViewportOffCommand;
	import org.eclipse.statet.ecommons.waltable.print.TurnViewportOnCommand;
	import org.eclipse.statet.ecommons.waltable.selection.CellSelectionEvent;
	import org.eclipse.statet.ecommons.waltable.selection.ColumnSelectionEvent;
	import org.eclipse.statet.ecommons.waltable.selection.RowSelectionEvent;
	import org.eclipse.statet.ecommons.waltable.selection.SelectionLayer;
	import org.eclipse.statet.ecommons.waltable.swt.SWTUtil;


	/**
	* Viewport - the visible area of NatTable
	*
	* Places a 'viewport' over the table. Introduces scroll bars over the table and
	* keeps them in sync with the data being displayed. This is typically placed over the
	* {@link SelectionLayer}.
	*/
	public class ViewportLayer extends TransformLayer {

	static final int EDGE_HOVER_REGION_SIZE= 16;

	static final int PAGE_INTERSECTION_SIZE= EDGE_HOVER_REGION_SIZE;


	private final ILayer scrollableLayer;

	// The viewport current origin
	private boolean viewportOff= false;
	private final long[] savedOriginPixel= new long[2];

	// Edge hover scrolling
	private MoveViewportRunnable edgeHoverRunnable;


	/**
	* Creates a new viewport layer.
	*
	* @param underlyingLayer the underlying scrollable layer
	*/
	public ViewportLayer(/@NonNull/ final ILayer underlyingLayer) {
	super(underlyingLayer);
	this.scrollableLayer= underlyingLayer;

	registerCommandHandlers();

	initDims();
	}


	@Override
	public void dispose() {
	super.dispose();

	for (final Orientation orientation : Orientation.values()) {
	disposeDim(orientation);
	}

	cancelEdgeHoverScroll();
	}


	public boolean isViewportOff() {
	return this.viewportOff;
	}


	@Override
	protected void initDims() {
	final ILayer scrollable= getScrollableLayer();
	if (scrollable == null) {
	return;
	}
	for (final Orientation orientation : Orientation.values()) {
	disposeDim(orientation);
	setDim(new ViewportLayerDim(this, scrollable.getDim(orientation)));
	}
	}

	protected void disposeDim(final Orientation orientation) {
	final ViewportLayerDim dim= get(orientation);
	if (dim != null) {
	dim.dispose();
	}
	}

	@Override
	public IViewportDim getDim(final Orientation orientation) {
	return (IViewportDim) super.getDim(orientation);
	}

	final ViewportLayerDim get(final Orientation orientation) {
	return (ViewportLayerDim) super.getDim(orientation);
	}

	// Configuration

	@Override
	protected void registerCommandHandlers() {
	registerCommandHandler(new RecalculateScrollBarsCommandHandler(this));
	registerCommandHandler(new ShowCellInViewportCommandHandler(this));
	registerCommandHandler(new ShowPositionInViewportCommandHandler());
	registerCommandHandler(new ViewportSelectDimPositionsCommandHandler(this));
	registerCommandHandler(new ViewportDragCommandHandler(this));
	registerCommandHandler(new SelectRelativePageCommandHandler(this));
	registerCommandHandler(new ScrollStepCommandHandler(this));
	registerCommandHandler(new ScrollPageCommandHandler(this));
	}


	// Cell features

	@Override
	public ILayerCell getCellByPosition(final long columnPosition, final long rowPosition) {
	return super.getCellByPosition(columnPosition, rowPosition);
	}

	protected void fireScrollEvent() {
	fireLayerEvent(new ScrollEvent(this));
	}

	@Override
	public boolean doCommand(final ILayerCommand command) {
	if (command instanceof ClientAreaResizeCommand) {
	final ClientAreaResizeCommand clientAreaResizeCommand= (ClientAreaResizeCommand) command.cloneCommand();
	if (clientAreaResizeCommand.convertToTargetLayer(this)) {
	//remember the difference from client area to body region area
	//needed because the scrollbar will be removed and therefore the client area will become bigger
	final long widthDiff= clientAreaResizeCommand.getScrollable().getClientArea().width - clientAreaResizeCommand.getCalcArea().width;
	final long heightDiff= clientAreaResizeCommand.getScrollable().getClientArea().height - clientAreaResizeCommand.getCalcArea().height;

	get(HORIZONTAL).checkScrollBar(clientAreaResizeCommand.getScrollable());
	get(VERTICAL).checkScrollBar(clientAreaResizeCommand.getScrollable());

	get(HORIZONTAL).handleResize();
	get(VERTICAL).handleResize();

	//after handling the scrollbars recalculate the area to use for percentage calculation
	final LRectangle possibleArea= SWTUtil.toNatTable(clientAreaResizeCommand.getScrollable().getClientArea());
	possibleArea.width-= widthDiff;
	possibleArea.height-= heightDiff;
	clientAreaResizeCommand.setCalcArea(possibleArea);
	//we don't return true here because the ClientAreaResizeCommand needs to be handled
	//by the DataLayer in case percentage sizing is enabled
	//if we would return true, the DataLayer wouldn't be able to calculate the column/row
	//sizes regarding the client area
	return super.doCommand(clientAreaResizeCommand);
	}
	}
	else if (command instanceof TurnViewportOffCommand) {
	if (!isViewportOff()) {
	for (final Orientation orientation : Orientation.values()) {
	this.savedOriginPixel[orientation.ordinal()]= get(orientation).getOriginPixel();
	}
	this.viewportOff= true;
	fireScrollEvent();
	}
	return true;
	}
	else if (command instanceof TurnViewportOnCommand) {
	if (isViewportOff()) {
	this.viewportOff= false;
	for (final Orientation orientation : Orientation.values()) {
	get(orientation).doSetOriginPixel(this.savedOriginPixel[orientation.ordinal()]);
	}
	fireScrollEvent();
	}
	return true;
	}
	else if (command instanceof PrintEntireGridCommand) {
	get(HORIZONTAL).movePositionIntoViewport(0);
	get(VERTICAL).movePositionIntoViewport(0);
	}
	return super.doCommand(command);
	}

	/**
	* Recalculate scrollbar characteristics.
	*/
	public void recalculateScrollBars() {
	get(HORIZONTAL).handleResize();
	get(VERTICAL).handleResize();
	}

	// Event handling

	@Override
	public void handleLayerEvent(final ILayerEvent event) {
	if (event instanceof IStructuralChangeEvent) {
	final IStructuralChangeEvent structuralChangeEvent= (IStructuralChangeEvent) event;
	if (structuralChangeEvent.isHorizontalStructureChanged()) {
	get(HORIZONTAL).handleStructuralChange(structuralChangeEvent.getColumnDiffs());
	}
	if (structuralChangeEvent.isVerticalStructureChanged()) {
	get(VERTICAL).handleStructuralChange(structuralChangeEvent.getRowDiffs());
	}
	}

	if (event instanceof CellSelectionEvent) {
	processSelection((CellSelectionEvent) event);
	} else if (event instanceof ColumnSelectionEvent) {
	processColumnSelection((ColumnSelectionEvent) event);
	} else if (event instanceof RowSelectionEvent) {
	processRowSelection((RowSelectionEvent) event);
	}

	super.handleLayerEvent(event);
	}

	/**
	* Handle {@link CellSelectionEvent}
	* @param selectionEvent
	*/
	private void processSelection(final CellSelectionEvent selectionEvent) {
	if (selectionEvent.getRevealCell()) {
	get(HORIZONTAL).movePositionIntoViewport(selectionEvent.getColumnPosition());
	get(VERTICAL).movePositionIntoViewport(selectionEvent.getRowPosition());
	}
	}

	/**
	* Handle {@link ColumnSelectionEvent}
	* @param selectionEvent
	*/
	private void processColumnSelection(final ColumnSelectionEvent selectionEvent) {
	final long explicitePosition= selectionEvent.getColumnPositionToReveal();
	if (explicitePosition >= 0) {
	get(HORIZONTAL).movePositionIntoViewport(explicitePosition);
	}
	}

	/**
	* Handle {@link RowSelectionEvent}
	* @param selectionEvent
	*/
	private void processRowSelection(final RowSelectionEvent selectionEvent) {
	final long explicitePosition= selectionEvent.getRowPositionToReveal();
	if (explicitePosition >= 0) {
	get(VERTICAL).movePositionIntoViewport(explicitePosition);
	return;
	}
	}

	// Accessors

	/**
	* @return The scrollable layer underlying the viewport.
	*/
	public ILayer getScrollableLayer() {
	return this.scrollableLayer;
	}

	@Override
	public String toString() {
	return "Viewport Layer"; //$NON-NLS-1$
	}

	// Edge hover scrolling

	/**
	* Used for edge hover scrolling. Called from the ViewportDragCommandHandler.
	* @param x
	* @param y
	*/
	public void drag(final long x, final long y) {
	if (x < 0 && y < 0) {
	cancelEdgeHoverScroll();
	return;
	}

	MoveViewportRunnable move= this.edgeHoverRunnable;
	if (move == null) {
	move= new MoveViewportRunnable();
	}

	move.fast= true;
	boolean requireSchedule= false;

	final LRectangle clientArea= getClientAreaProvider().getClientArea();
	for (final Orientation orientation : Orientation.values()) {
	final LRange lRange= clientArea.getRange(orientation);
	final long pixel= (orientation == HORIZONTAL) ? x : y;
	int change= 0;
	if (pixel >= lRange.start && pixel < lRange.start + EDGE_HOVER_REGION_SIZE) {
	change= -1;
	if (pixel >= lRange.start + EDGE_HOVER_REGION_SIZE/2) {
	move.fast= false;
	}
	} else if (pixel >= lRange.end - EDGE_HOVER_REGION_SIZE && pixel < lRange.end) {
	change= 1;
	if (pixel < lRange.end - EDGE_HOVER_REGION_SIZE/2) {
	move.fast= false;
	}
	}
	move.change[orientation.ordinal()]= change;
	requireSchedule \|= (change != 0);
	}

	if (requireSchedule) {
	move.schedule();
	} else {
	cancelEdgeHoverScroll();
	}
	}

	/**
	* Cancels an edge hover scroll.
	*/
	private void cancelEdgeHoverScroll() {
	this.edgeHoverRunnable= null;
	}

	/**
	* Runnable that incrementally scrolls the viewport when drag hovering over an edge.
	*/
	class MoveViewportRunnable implements Runnable {


	private final int[] change= new int[2];
	private boolean fast;

	private final Display display= Display.getCurrent();


	public MoveViewportRunnable() {
	}


	public void schedule() {
	if (ViewportLayer.this.edgeHoverRunnable != this) {
	ViewportLayer.this.edgeHoverRunnable= this;
	this.display.timerExec(500, this);
	}
	}

	@Override
	public void run() {
	if (ViewportLayer.this.edgeHoverRunnable != this) {
	return;
	}

	for (final Orientation orientation : Orientation.values()) {
	switch (this.change[orientation.ordinal()]) {
	case -1:
	get(orientation).scrollBackwardByPosition();
	break;
	case 1:
	get(orientation).scrollForwardByPosition();
	break;
	}
	}

	this.display.timerExec(this.fast ? 100 : 500, this);
	}

	}

	}