| /********************************************************************** |
| * Copyright (c) 2013, 2014 Ericsson, École Polytechnique de Montréal |
| * |
| * All rights reserved. This program and the accompanying materials are |
| * made available under the terms of the Eclipse Public License 2.0 which |
| * accompanies this distribution, and is available at |
| * https://www.eclipse.org/legal/epl-2.0/ |
| * |
| * SPDX-License-Identifier: EPL-2.0 |
| * |
| * Contributors: |
| * Bernd Hufmann - Initial API and implementation |
| * Geneviève Bastien - Moved some methods to ITmfTimeProvider |
| **********************************************************************/ |
| package org.eclipse.tracecompass.tmf.ui.viewers.xycharts; |
| |
| import org.eclipse.tracecompass.tmf.ui.viewers.ITmfTimeProvider; |
| |
| /** |
| * Interface adding some methods specific for SWT charts to the base time |
| * provider interface. Typically, the time will be shown on the x-axis. |
| * |
| * @author Bernd Hufmann |
| */ |
| public interface ITmfChartTimeProvider extends ITmfTimeProvider { |
| |
| /** |
| * Returns a constant time offset that is used to normalize the time values |
| * to a range of 0..53 bits to avoid loss of precision when converting long |
| * <-> double. |
| * |
| * Time values are stored in TMF as long values. The SWT chart library uses |
| * values of type double (on x and y axis). To avoid loss of precision when |
| * converting long <-> double the values need to fit within 53 bits. |
| * |
| * Subtract the offset when using time values provided externally for |
| * internal usage in SWT chart. Add the offset when using time values |
| * provided by SWT chart (e.g. for display purposes) and when broadcasting |
| * them externally (e.g. time synchronization signals). |
| * |
| * For example the offset can be calculated as the time of the first time |
| * value in the current time range to be displayed in the chart. Add +1 to |
| * avoid 0 when using logarithmic scale. |
| * |
| * t0=10000, t2=20000, tn=N -> timeOffset=t0-1 -> t0'=1, t1'=10001, |
| * tn'=N-timeOffset |
| * |
| * where t0 ... tn are times used externally and t0' ... tn' are times used |
| * internally by the SWT chart. |
| * |
| * @return the time offset |
| */ |
| long getTimeOffset(); |
| |
| } |