| /******************************************************************************* |
| * Copyright (c) 2010 itemis AG and others. |
| * All rights reserved. This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License v1.0 |
| * which accompanies this distribution, and is available at |
| * http://www.eclipse.org/legal/epl-v10.html |
| * |
| * Contributors: |
| * Alexander Nyßen (itemis AG) - initial API and implementation |
| *******************************************************************************/ |
| |
| package org.eclipse.draw2d.geometry; |
| |
| import java.math.BigDecimal; |
| |
| /** |
| * A Utilities class for precise geometry calculations. |
| * |
| * @author Alexander Nyssen |
| * @since 3.7 |
| */ |
| public class PrecisionGeometry { |
| |
| /* |
| * Precise calculations on doubles are performed based on BigDecimals, |
| * converting to 16 digits scale, so there are no undesired rounding |
| * effects. |
| */ |
| private static final int ROUNDING = BigDecimal.ROUND_HALF_EVEN; |
| private static final int SCALE = 16; |
| |
| protected static final double preciseAdd(double d1, double d2) { |
| return doubleToBigDecimal(d1).add(doubleToBigDecimal(d2)) |
| .setScale(SCALE, ROUNDING).doubleValue(); |
| } |
| |
| protected static final double preciseSubtract(double d1, double d2) { |
| return doubleToBigDecimal(d1).subtract(doubleToBigDecimal(d2)) |
| .setScale(SCALE, ROUNDING).doubleValue(); |
| } |
| |
| protected static final double preciseMultiply(double d1, double d2) { |
| return doubleToBigDecimal(d1).multiply(doubleToBigDecimal(d2)) |
| .setScale(SCALE, ROUNDING).doubleValue(); |
| } |
| |
| protected static final double preciseDivide(double d1, double d2) { |
| return doubleToBigDecimal(d1).divide(doubleToBigDecimal(d2), SCALE, |
| ROUNDING).doubleValue(); |
| } |
| |
| protected static final double preciseNegate(double d) { |
| return doubleToBigDecimal(d).negate().setScale(SCALE, ROUNDING) |
| .doubleValue(); |
| } |
| |
| protected static final double preciseAbs(double d) { |
| return doubleToBigDecimal(d).abs().setScale(SCALE, ROUNDING) |
| .doubleValue(); |
| } |
| |
| protected static final BigDecimal doubleToBigDecimal(double d) { |
| // may not use BigDecimal.valueOf due to J2SE-1.4 backwards |
| // compatibility |
| return new BigDecimal(Double.toString(d)); |
| } |
| |
| /** |
| * Converts a double value into an integer value, avoiding rounding effects. |
| * |
| * @param doubleValue |
| * the double value to convert |
| * @return the integer value for the double. |
| */ |
| protected static final int doubleToInteger(double doubleValue) { |
| return (int) Math.floor(doubleValue + 0.000000001); |
| } |
| } |