Use qRadiansToDegrees() and qDegreesToRadians() more widely

Especially in examples, where we should show off our convenience
functions, prefer calling these functions over doing arithmetic with
M_PI (or approximations thereto) and 180 (give or take simple
factors).  This incidentally documents what's going on, just by the
name of the function used (and reveals at least one place where
variables were misnamed; the return from atan is in radians, *not*
degrees).

Task-number: QTBUG-58083
Change-Id: I6e5d66721cafab423378f970af525400423e971e
Reviewed-by: Jüri Valdmann <juri.valdmann@qt.io>
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

3 files changed, 5 insertions, 9 deletions

diff --git a/tests/auto/gui/math3d/qmatrixnxn/tst_qmatrixnxn.cpp b/tests/auto/gui/math3d/qmatrixnxn/tst_qmatrixnxn.cpp
index c2c04b69c5..96d983c8f7 100644
--- a/tests/auto/gui/math3d/qmatrixnxn/tst_qmatrixnxn.cpp
+++ b/tests/auto/gui/math3d/qmatrixnxn/tst_qmatrixnxn.cpp
@@ -2278,8 +2278,8 @@ void tst_QMatrixNxN::rotate4x4_data()
     float y = 2.0f;
     float z = -6.0f;
     float angle = -45.0f;
-    float c = std::cos(angle * M_PI / 180.0f);
-    float s = std::sin(angle * M_PI / 180.0f);
+    float c = std::cos(qDegreesToRadians(angle));
+    float s = std::sin(qDegreesToRadians(angle));
     float len = std::sqrt(x * x + y * y + z * z);
     float xu = x / len;
     float yu = y / len;
diff --git a/tests/auto/gui/math3d/qquaternion/tst_qquaternion.cpp b/tests/auto/gui/math3d/qquaternion/tst_qquaternion.cpp
index 53af65e010..097dd111d3 100644
--- a/tests/auto/gui/math3d/qquaternion/tst_qquaternion.cpp
+++ b/tests/auto/gui/math3d/qquaternion/tst_qquaternion.cpp
@@ -815,7 +815,7 @@ void tst_QQuaternion::fromAxisAndAngle()
     // http://www.j3d.org/matrix_faq/matrfaq_latest.html#Q56
     // to calculate the answer we expect to get.
     QVector3D vector = QVector3D(x1, y1, z1).normalized();
-    const float a = (angle * M_PI / 180.0) / 2.0;
+    const float a = qDegreesToRadians(angle) / 2.0;
     const float sin_a = std::sin(a);
     const float cos_a = std::cos(a);
     QQuaternion result(cos_a,
diff --git a/tests/auto/gui/painting/qwmatrix/tst_qwmatrix.cpp b/tests/auto/gui/painting/qwmatrix/tst_qwmatrix.cpp
index 46420b49c5..da88a868f3 100644
--- a/tests/auto/gui/painting/qwmatrix/tst_qwmatrix.cpp
+++ b/tests/auto/gui/painting/qwmatrix/tst_qwmatrix.cpp
@@ -114,12 +114,8 @@ void tst_QWMatrix::mapping_data()
                                 << QRect( 0, 0, 30, 40 )
                                 << QPolygon( QRect( -300, -400, 300, 400 ) );
 
-#if defined(Q_OS_WIN) && !defined(M_PI)
-#define M_PI 3.14159265897932384626433832795f
-#endif
-
     const auto rotate = [](qreal degrees) {
-        const qreal rad = M_PI * degrees / 180.;
+        const qreal rad = qDegreesToRadians(degrees);
         return QMatrix(std::cos(rad), -std::sin(rad),
                        std::sin(rad),  std::cos(rad), 0, 0);
     };
@@ -140,7 +136,7 @@ void tst_QWMatrix::mapping_data()
 
 #if 0
     const auto rotScale = [](qreal degrees, qreal scale) {
-        const qreal rad = M_PI * degrees / 180.;
+        const qreal rad = qDegreesToRadians(degrees);
         return QMatrix(scale * std::cos(rad), -scale * std::sin(rad),
                        scale * std::sin(rad),  scale * std::cos(rad), 0, 0);
     };