Use qRadiansToDegrees() and qDegreesToRadians() more widely

They document intent more clearly (and replace *two* local hand-rolled
versions of each).  Also kill an extraneous #include of <math.h>; and
switch to qmath.h as source for M_PI, replacing the M_PID value (and
friends) previously provided by (thankfully private)
qlocationutils_p.h (at more precision than even long double would
retain - qmath.h's M_PI is entirely sufficient even for long double,
as is the Linux <math.h> one).

Task-number: QTBUG-58083
Change-Id: I6fa4abd3c8ed9c826998f2cdc2aefc51681c19c1
Reviewed-by: Paolo Angelelli <paolo.angelelli@qt.io>

6 files changed, 25 insertions, 50 deletions

diff --git a/src/location/declarativemaps/qdeclarativecirclemapitem.cpp b/src/location/declarativemaps/qdeclarativecirclemapitem.cpp
index 89b139c8..a4eee272 100644
--- a/src/location/declarativemaps/qdeclarativecirclemapitem.cpp
+++ b/src/location/declarativemaps/qdeclarativecirclemapitem.cpp
@@ -40,7 +40,7 @@
 #include "qwebmercator_p.h"
 #include <QtLocation/private/qgeomap_p.h>
 
-#include <cmath>
+#include <qmath.h>
 #include <algorithm>
 
 #include <QtCore/QScopedValueRollback>
@@ -128,11 +128,6 @@ QT_BEGIN_NAMESPACE
     \image api-mapcircle.png
 */
 
-#ifdef M_PI
-#undef M_PI
-#endif
-#define M_PI 3.14159265358979323846264338327950288
-
 static const int CircleSamples = 128;
 
 struct Vertex
diff --git a/src/positioning/qdoublematrix4x4.cpp b/src/positioning/qdoublematrix4x4.cpp
index bca38075..76e1252b 100644
--- a/src/positioning/qdoublematrix4x4.cpp
+++ b/src/positioning/qdoublematrix4x4.cpp
@@ -508,7 +508,7 @@ void QDoubleMatrix4x4::rotate(double angle, double x, double y, double z)
         s = 0.0;
         c = -1.0;
     } else {
-        double a = angle * M_PI / 180.0;
+        double a = qDegreesToRadians(angle);
         c = std::cos(a);
         s = std::sin(a);
     }
@@ -614,7 +614,7 @@ void QDoubleMatrix4x4::projectedRotate(double angle, double x, double y, double
         s = 0.0;
         c = -1.0;
     } else {
-        double a = angle * M_PI / 180.0;
+        double a = qDegreesToRadians(angle);
         c = std::cos(a);
         s = std::sin(a);
     }
@@ -778,7 +778,7 @@ void QDoubleMatrix4x4::perspective(double verticalAngle, double aspectRatio, dou
 
     // Construct the projection.
     QDoubleMatrix4x4 m(1);
-    double radians = (verticalAngle / 2.0) * M_PI / 180.0;
+    double radians = qDegreesToRadians(verticalAngle / 2.0);
     double sine = std::sin(radians);
     if (sine == 0.0)
         return;
diff --git a/src/positioning/qgeocoordinate.cpp b/src/positioning/qgeocoordinate.cpp
index 8d39a62e..b0d9fc0f 100644
--- a/src/positioning/qgeocoordinate.cpp
+++ b/src/positioning/qgeocoordinate.cpp
@@ -45,26 +45,12 @@
 #include <QDataStream>
 #include <QDebug>
 #include <qnumeric.h>
-
-#include <math.h>
-
-#ifndef M_PI
-#define M_PI 3.14159265358979323846
-#endif
+#include <qmath.h>
 
 QT_BEGIN_NAMESPACE
 
 static const double qgeocoordinate_EARTH_MEAN_RADIUS = 6371.0072;
 
-inline static double qgeocoordinate_degToRad(double deg)
-{
-    return deg * M_PI / 180;
-}
-inline static double qgeocoordinate_radToDeg(double rad)
-{
-    return rad * 180 / M_PI;
-}
-
 
 QGeoCoordinatePrivate::QGeoCoordinatePrivate():
     lat(qQNaN()),
@@ -430,15 +416,15 @@ qreal QGeoCoordinate::distanceTo(const QGeoCoordinate &other) const
     }
 
     // Haversine formula
-    double dlat = qgeocoordinate_degToRad(other.d->lat - d->lat);
-    double dlon = qgeocoordinate_degToRad(other.d->lng - d->lng);
+    double dlat = qDegreesToRadians(other.d->lat - d->lat);
+    double dlon = qDegreesToRadians(other.d->lng - d->lng);
     double haversine_dlat = sin(dlat / 2.0);
     haversine_dlat *= haversine_dlat;
     double haversine_dlon = sin(dlon / 2.0);
     haversine_dlon *= haversine_dlon;
     double y = haversine_dlat
-             + cos(qgeocoordinate_degToRad(d->lat))
-             * cos(qgeocoordinate_degToRad(other.d->lat))
+             + cos(qDegreesToRadians(d->lat))
+             * cos(qDegreesToRadians(other.d->lat))
              * haversine_dlon;
     double x = 2 * asin(sqrt(y));
     return qreal(x * qgeocoordinate_EARTH_MEAN_RADIUS * 1000);
@@ -462,14 +448,14 @@ qreal QGeoCoordinate::azimuthTo(const QGeoCoordinate &other) const
         return 0;
     }
 
-    double dlon = qgeocoordinate_degToRad(other.d->lng - d->lng);
-    double lat1Rad = qgeocoordinate_degToRad(d->lat);
-    double lat2Rad = qgeocoordinate_degToRad(other.d->lat);
+    double dlon = qDegreesToRadians(other.d->lng - d->lng);
+    double lat1Rad = qDegreesToRadians(d->lat);
+    double lat2Rad = qDegreesToRadians(other.d->lat);
 
     double y = sin(dlon) * cos(lat2Rad);
     double x = cos(lat1Rad) * sin(lat2Rad) - sin(lat1Rad) * cos(lat2Rad) * cos(dlon);
 
-    double azimuth = qgeocoordinate_radToDeg(atan2(y, x)) + 360.0;
+    double azimuth = qRadiansToDegrees(atan2(y, x)) + 360.0;
     double whole;
     double fraction = modf(azimuth, &whole);
     return qreal((int(whole + 360) % 360) + fraction);
@@ -479,12 +465,12 @@ void QGeoCoordinatePrivate::atDistanceAndAzimuth(const QGeoCoordinate &coord,
                                                  qreal distance, qreal azimuth,
                                                  double *lon, double *lat)
 {
-    double latRad = qgeocoordinate_degToRad(coord.d->lat);
-    double lonRad = qgeocoordinate_degToRad(coord.d->lng);
+    double latRad = qDegreesToRadians(coord.d->lat);
+    double lonRad = qDegreesToRadians(coord.d->lng);
     double cosLatRad = cos(latRad);
     double sinLatRad = sin(latRad);
 
-    double azimuthRad = qgeocoordinate_degToRad(azimuth);
+    double azimuthRad = qDegreesToRadians(azimuth);
 
     double ratio = (distance / (qgeocoordinate_EARTH_MEAN_RADIUS * 1000.0));
     double cosRatio = cos(ratio);
@@ -495,8 +481,8 @@ void QGeoCoordinatePrivate::atDistanceAndAzimuth(const QGeoCoordinate &coord,
     double resultLonRad = lonRad + atan2(sin(azimuthRad) * sinRatio * cosLatRad,
                                    cosRatio - sinLatRad * sin(resultLatRad));
 
-    *lat = qgeocoordinate_radToDeg(resultLatRad);
-    *lon = qgeocoordinate_radToDeg(resultLonRad);
+    *lat = qRadiansToDegrees(resultLatRad);
+    *lon = qRadiansToDegrees(resultLonRad);
 }
 
 /*!
diff --git a/src/positioning/qlocationutils_p.h b/src/positioning/qlocationutils_p.h
index f66179e1..75c4b7f4 100644
--- a/src/positioning/qlocationutils_p.h
+++ b/src/positioning/qlocationutils_p.h
@@ -51,14 +51,10 @@
 //
 
 #include <QtCore/QtGlobal>
-#include <math.h>
+#include <math.h> // needed for non-std:: versions of functions
+#include <qmath.h>
 #include <QtPositioning/QGeoCoordinate>
 
-static const double M_PID     = 3.14159265358979323846264338327950288; // to get more precision than float
-static const double M_1_180D  = 0.0055555555555555555555555555555555555555556;
-static const double M_1_PID   = 1.0 / M_PID;
-static const double M_PI_180D = M_PID / 180.0; //0.0174532925199432954743716805978692718781530857086181640625;
-static const double M_180_PID = 180.0 / M_PID; // 57.29577951308232286464772187173366546630859375
 static const double offsetEpsilon = 0.0000000000001;
 static const double leftOffset = -180.0 + offsetEpsilon;
 static const double rightOffset = 180.0 - offsetEpsilon;
@@ -209,12 +205,12 @@ public:
 
     inline static double radians(double degrees)
     {
-        return degrees * M_PI_180D;
+        return qDegreesToRadians(degrees);
     }
 
     inline static double degrees(double radians)
     {
-        return radians * M_180_PID;
+        return qRadiansToDegrees(radians);
     }
 
     inline static double earthMeanRadius()
@@ -224,7 +220,7 @@ public:
 
     inline static double earthMeanDiameter()
     {
-        return earthMeanRadius() * 2.0 * M_PID;
+        return earthMeanRadius() * 2.0 * M_PI;
     }
 
     inline static double mercatorMaxLatitude()
diff --git a/src/positioning/qwebmercator.cpp b/src/positioning/qwebmercator.cpp
index da35c7d7..b8abac2b 100644
--- a/src/positioning/qwebmercator.cpp
+++ b/src/positioning/qwebmercator.cpp
@@ -41,8 +41,7 @@
 #include "qgeocoordinate.h"
 
 #include <qnumeric.h>
-
-#include <cmath>
+#include <qmath.h>
 
 #include "qdoublevector2d_p.h"
 #include "qdoublevector3d_p.h"
@@ -111,7 +110,7 @@ QGeoCoordinate QWebMercator::mercatorToCoordClamped(const QDoubleVector2D &merca
     else if (fy > 1.0)
         fy = 1.0;
 
-    double lat = (180.0 / M_PI) * (2.0 * std::atan(std::exp(M_PI * (1.0 - 2.0 * fy))) - (M_PI / 2.0));
+    double lat = qRadiansToDegrees(2.0 * std::atan(std::exp(M_PI * (1.0 - 2.0 * fy))) - (M_PI / 2.0));
 
     double lng;
     if (fx >= 0) {
diff --git a/src/positioning/qwebmercator_p.h b/src/positioning/qwebmercator_p.h
index 2b8e9564..52a5e040 100644
--- a/src/positioning/qwebmercator_p.h
+++ b/src/positioning/qwebmercator_p.h
@@ -52,7 +52,6 @@
 
 #include <qglobal.h>
 #include <QtCore/qvariant.h>
-#include <math.h>
 #include "qpositioningglobal_p.h"
 
 QT_BEGIN_NAMESPACE