Android Open Source - getback_gps Coordinate Rotation

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License

The source code is released under:

GNU General Public License

Java Source Code

/**
 * Coordinate converter class rotating a set of coordinates.
 *//from  w  ww .  ja  va 2s. c o  m
 * Copyright (C) 2012-2015 Dieter Adriaenssens
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @package com.github.ruleant.getback_gps.lib
 * @author  Dieter Adriaenssens <ruleant@users.sourceforge.net>
 */
package com.github.ruleant.getback_gps.lib;

/**
 * Coordinate converter class rotating a set of coordinates.
 *
 * @author Dieter Adriaenssens <ruleant@users.sourceforge.net>
 */
public class CoordinateRotation  implements CoordinateConverterInterface {
    /**
     * Rotation angle in radians (0-2*PI).
     */
    private double mAngle;

    /**
     * Rotation center.
     */
    private Coordinate mCenter;

    /**
     * Radius scale ratio.
     */
    private double mScaleRadius;

    /**
     * Constructor.
     *
     * @param center Rotation center coordinate
     * @param angle Rotation angle to apply to coordinate (0-360)
     * @param scaleRadius Radius scale ratio
     */
    public CoordinateRotation(final Coordinate center, final double angle,
                              final double scaleRadius) {
        setRotationCenter(center);
        setRotationAngle(angle);
        setScaleRadius(scaleRadius);
    }

    /**
     * Sets rotation angle.
     *
     * @param angle Rotation angle to apply to coordinate (0-360)
     */
    public final void setRotationAngle(final double angle) {
        mAngle = Math.toRadians(FormatUtils.normalizeAngle(angle));
    }

    /**
     * Sets rotation center.
     *
     * @param center Rotation center coordinate
     */
    public final void setRotationCenter(final Coordinate center) {
        if (center == null) {
            throw new IllegalArgumentException(
                    "Parameter center should not be null");
        }

        mCenter = center;
    }

    /**
     * Sets radius scale ratio.
     * Possible values :
     * - value > 1 : scale up
     * - value = 1 : no scaling
     * - 0 < value < 1 : scale down
     * - value = 0 : no radius (converted coordinate = rotation center)
     * - -1 < value < 0 : inverse angle + scale down
     * - value = -1 : inverse angle + no scaling
     * - value < -1 : inverse angle + scale up
     *
     * @param scaleRadius Radius scale ratio
     */
    public final void setScaleRadius(final double scaleRadius) {
        mScaleRadius = scaleRadius;
    }

    /**
     * Rotate coordinates with an angle, around a center.
     *
     * A couple of transformations are applied to convert the coordinates :
     * - to clockwise : a => -a
     * - rotate 90 counter-clockwise : -a => PI/2 - a
     * X = cos(PI/2 - a) = sin(a)
     * Y = sin(PI/2 - a) = cos(a)
     * - flip Y coordinate
     * Y = -cos(a)
     *
     * @param coordinate Unconverted coordinate
     * @return Converted coordinate
     */
    public final Coordinate getConvertedCoordinate(
            final Coordinate coordinate) {
        double angle = Math.toRadians(coordinate.getPolarAngle()) + mAngle;
        double radius = coordinate.getPolarRadius() * mScaleRadius;

        // Transform angle and convert to Cartesian
        return new Coordinate(
                mCenter.getCartesianX() + Math.round(Math.sin(angle) * radius),
                mCenter.getCartesianY() - Math.round(Math.cos(angle) * radius));
    }
}

Java Source Code List

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