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/****************************************************************************
**
** Qt adaptation of geosimplify-js
** Copyright (C) 2017 Daniel Patterson
** See 3rdParty/geosimplify.js for the original license.
**
** Copyright (C) 2020 Paolo Angelelli <paolo.angelelli@gmail.com>
** Copyright (C) 2020 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the QtLocation module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL3$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see http://www.qt.io/terms-conditions. For further
** information use the contact form at http://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPLv3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or later as published by the Free
** Software Foundation and appearing in the file LICENSE.GPL included in
** the packaging of this file. Please review the following information to
** ensure the GNU General Public License version 2.0 requirements will be
** met: http://www.gnu.org/licenses/gpl-2.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include "qgeosimplify_p.h"
#include <QtPositioning/private/qlocationutils_p.h>
QT_BEGIN_NAMESPACE
double QGeoSimplify::getDist(const QGeoCoordinate &p1, const QGeoCoordinate &p2)
{
return p1.distanceTo(p2);
}
QDoubleVector2D QGeoSimplify::closestPoint(const QDoubleVector2D &p, const QDoubleVector2D &a, const QDoubleVector2D &b)
{
if (a == b)
return a;
const double u = ((p.x() - a.x()) * (b.x() - a.x()) + (p.y() - a.y()) * (b.y() - a.y()) ) / (b - a).lengthSquared();
const QDoubleVector2D intersection(a.x() + u * (b.x() - a.x()) , a.y() + u * (b.y() - a.y()) );
QDoubleVector2D candidate = ( (p-a).length() < (p-b).length() ) ? a : b;
if (u > 0 && u < 1
&& (p-intersection).length() < (p-candidate).length() ) // And it falls in the segment
candidate = intersection;
return candidate;
}
QGeoCoordinate QGeoSimplify::closestPoint(const QGeoCoordinate &pc, const QGeoCoordinate &ac, const QGeoCoordinate &bc, const double &leftBound)
{
QDoubleVector2D p = QWebMercator::coordToMercator(pc);
if (p.x() < leftBound)
p.setX(p.x() + leftBound); // unwrap X
QDoubleVector2D a = QWebMercator::coordToMercator(ac);
if (a.x() < leftBound)
a.setX(a.x() + leftBound); // unwrap X
QDoubleVector2D b = QWebMercator::coordToMercator(bc);
if (b.x() < leftBound)
b.setX(b.x() + leftBound); // unwrap X
QDoubleVector2D intersection = closestPoint(p, a, b);
if (intersection.x() > 1.0)
intersection.setX(intersection.x() - leftBound); // wrap X
const QGeoCoordinate closest = QWebMercator::mercatorToCoord(intersection);
return closest;
}
double QGeoSimplify::getSegDist(const QGeoCoordinate &pc, const QGeoCoordinate &ac, const QGeoCoordinate &bc, const double &leftBound)
{
const QGeoCoordinate closest = closestPoint(pc, ac, bc, leftBound);
const double distanceMeters = pc.distanceTo(closest);
return distanceMeters;
}
double QGeoSimplify::getSegDist(const QDoubleVector2D &p, const QDoubleVector2D &a, const QDoubleVector2D &b, const double &leftBound)
{
QDoubleVector2D intersection = closestPoint(p, a, b);
return getDist(intersection, p, leftBound);
}
void QGeoSimplify::simplifyDPStep(const QList<QGeoCoordinate> &points, const double &leftBound, int first, int last, double offsetTolerance, QList<QGeoCoordinate> &simplified)
{
double maxDistanceFound = offsetTolerance;
int index = 0;
for (int i = first + 1; i < last; i++) {
const double distance = getSegDist(points.at(i),
points.at(first),
points.at(last),
leftBound);
if (distance > maxDistanceFound) {
index = i;
maxDistanceFound = distance;
}
}
if (index > 0) {
if (index - first > 1)
simplifyDPStep(points,
leftBound,
first,
index,
offsetTolerance,
simplified);
simplified.append(points.at(index));
if (last - index > 1)
simplifyDPStep(points,
leftBound,
index,
last,
offsetTolerance,
simplified);
}
}
double QGeoSimplify::getDist(QDoubleVector2D a, QDoubleVector2D b, const double &leftBound)
{
if (a.x() > 1.0)
a.setX(a.x() - leftBound); // wrap X
if (b.x() > 1.0)
b.setX(b.x() - leftBound); // wrap X
return QWebMercator::mercatorToCoord(a).distanceTo(
QWebMercator::mercatorToCoord(b));
}
void QGeoSimplify::simplifyDPStep(const QList<QDoubleVector2D> &points,
const double &leftBound,
int first,
int last,
double offsetTolerance,
QList<QDoubleVector2D> &simplified)
{
double maxDistanceFound = offsetTolerance;
int index = 0;
for (int i = first + 1; i < last; i++) {
const double distance = getSegDist(points.at(i),
points.at(first),
points.at(last),
leftBound);
if (distance > maxDistanceFound) {
index = i;
maxDistanceFound = distance;
}
}
if (index > 0) {
if (index - first > 1)
simplifyDPStep(points,
leftBound,
first,
index,
offsetTolerance,
simplified);
simplified.append(points.at(index));
if (last - index > 1)
simplifyDPStep(points,
leftBound,
index,
last,
offsetTolerance,
simplified);
}
}
static double pixelDistanceAtZoomAndLatitude(int zoom, double latitude)
{
const double den = double((1 << (zoom + 8)));
const double pixelDist = (QLocationUtils::earthMeanCircumference() *
std::cos(QLocationUtils::radians(latitude))) / den;
return pixelDist;
}
static QGeoCoordinate unwrappedToGeo(QDoubleVector2D p, double leftBound)
{
if (p.x() > 1.0)
p.setX(p.x() - leftBound);
return QWebMercator::mercatorToCoord(p);
}
void QGeoSimplify::simplifyDPStepZL(const QList<QDoubleVector2D> &points,
const double &leftBound,
int first,
int last,
int zoomLevel,
QList<QDoubleVector2D> &simplified)
{
const QGeoCoordinate firstC = unwrappedToGeo(points.at(first), leftBound);
const QGeoCoordinate lastC = unwrappedToGeo(points.at(last), leftBound);
double maxDistanceFound = (pixelDistanceAtZoomAndLatitude(zoomLevel, firstC.latitude())
+ pixelDistanceAtZoomAndLatitude(zoomLevel, lastC.latitude())) * 0.5;
int index = 0;
for (int i = first + 1; i < last; i++) {
const double distance = getSegDist(points.at(i),
points.at(first),
points.at(last),
leftBound);
if (distance > maxDistanceFound) {
index = i;
maxDistanceFound = distance;
}
}
if (index > 0) {
if (index - first > 1)
simplifyDPStepZL(points,
leftBound,
first,
index,
zoomLevel,
simplified);
simplified.append(points.at(index));
if (last - index > 1)
simplifyDPStepZL(points,
leftBound,
index,
last,
zoomLevel,
simplified);
}
}
QList<QGeoCoordinate> QGeoSimplify::simplifyDouglasPeucker(const QList<QGeoCoordinate> &points,
const double &leftBound,
double offsetTolerance) {
const int last = points.size() - 1;
QList<QGeoCoordinate> simplified { points.first() };
simplifyDPStep(points, leftBound, 0, last, offsetTolerance, simplified);
simplified.append(points.at(last));
return simplified;
}
QList<QDoubleVector2D> QGeoSimplify::simplifyDouglasPeucker(const QList<QDoubleVector2D> &points,
const double &leftBound,
double offsetTolerance) {
const int last = points.size() - 1;
QList<QDoubleVector2D> simplified { points.first() };
simplifyDPStep(points, leftBound, 0, last, offsetTolerance, simplified);
simplified.append(points.at(last));
return simplified;
}
QList<QDoubleVector2D> QGeoSimplify::simplifyDouglasPeuckerZL(const QList<QDoubleVector2D> &points,
const double &leftBound,
int zoomLevel)
{
const int last = points.size() - 1;
QList<QDoubleVector2D> simplified { points.first() };
simplifyDPStepZL(points, leftBound, 0, last, zoomLevel, simplified);
simplified.append(points.at(last));
return simplified;
}
QList<QGeoCoordinate> QGeoSimplify::geoSimplify(const QList<QGeoCoordinate> &points,
const double &leftBound,
double offsetTolerance) // also in meters
{
if (points.size() <= 2)
return points;
return simplifyDouglasPeucker(points,
leftBound,
offsetTolerance);
}
QList<QDoubleVector2D> QGeoSimplify::geoSimplify(const QList<QDoubleVector2D> &points,
const double &leftBound,
double offsetTolerance) // also in meters
{
if (points.size() <= 2)
return points;
return simplifyDouglasPeucker(points,
leftBound,
offsetTolerance);
}
QList<QDoubleVector2D> QGeoSimplify::geoSimplifyZL(const QList<QDoubleVector2D> &points,
const double &leftBound,
int zoomLevel)
{
if (points.size() <= 2)
return points;
return simplifyDouglasPeuckerZL(points,
leftBound,
zoomLevel);
}
QT_END_NAMESPACE
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