Use C++ <cmath> instead of <math.h>

Including math.h can pollute the default namespace, and break
some compilers if cmath versions of the method are declared as using.

Switching to C++ math functions also greatly simplifies handling of
float qreal as C++ automatically chooses the right method.

[ChangeLog][QtCore][QtMath] qmath.h no longer includes math.h, so any
sources depending on that indirect inclusion may fail to build.

Change-Id: I4d0e331dafba354ec05dc5052e61ef4ff8d387fe
Reviewed-by: Rafael Roquetto <rafael.roquetto@kdab.com>

3 files changed, 12 insertions, 10 deletions

diff --git a/examples/widgets/graphicsview/boxes/qtbox.cpp b/examples/widgets/graphicsview/boxes/qtbox.cpp
index e368ddb307..5e142832e0 100644
--- a/examples/widgets/graphicsview/boxes/qtbox.cpp
+++ b/examples/widgets/graphicsview/boxes/qtbox.cpp
@@ -242,7 +242,7 @@ void ItemBase::keyPressEvent(QKeyEvent *event)
 void ItemBase::wheelEvent(QGraphicsSceneWheelEvent *event)
 {
     prepareGeometryChange();
-    m_size = int(m_size * exp(-event->delta() / 600.0));
+    m_size = int(m_size * qExp(-event->delta() / 600.0));
     if (m_size > MAX_ITEM_SIZE)
         m_size = MAX_ITEM_SIZE;
     else if (m_size < MIN_ITEM_SIZE)
@@ -404,10 +404,10 @@ void CircleItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option
 {
     int dt = m_startTime.msecsTo(QTime::currentTime());
 
-    qreal r0 = 0.5 * m_size * (1.0 - exp(-0.001 * ((dt + 3800) % 4000)));
-    qreal r1 = 0.5 * m_size * (1.0 - exp(-0.001 * ((dt + 0) % 4000)));
-    qreal r2 = 0.5 * m_size * (1.0 - exp(-0.001 * ((dt + 1800) % 4000)));
-    qreal r3 = 0.5 * m_size * (1.0 - exp(-0.001 * ((dt + 2000) % 4000)));
+    qreal r0 = 0.5 * m_size * (1.0 - qExp(-0.001 * ((dt + 3800) % 4000)));
+    qreal r1 = 0.5 * m_size * (1.0 - qExp(-0.001 * ((dt + 0) % 4000)));
+    qreal r2 = 0.5 * m_size * (1.0 - qExp(-0.001 * ((dt + 1800) % 4000)));
+    qreal r3 = 0.5 * m_size * (1.0 - qExp(-0.001 * ((dt + 2000) % 4000)));
 
     if (r0 > r1)
         r0 = 0.0;
diff --git a/examples/widgets/graphicsview/boxes/scene.cpp b/examples/widgets/graphicsview/boxes/scene.cpp
index 2ca061a43a..48bdcb9d93 100644
--- a/examples/widgets/graphicsview/boxes/scene.cpp
+++ b/examples/widgets/graphicsview/boxes/scene.cpp
@@ -35,6 +35,7 @@
 #include "scene.h"
 #include <QtGui/qmatrix4x4.h>
 #include <QtGui/qvector3d.h>
+#include <cmath>
 
 #include "3rdparty/fbm.h"
 
@@ -856,7 +857,7 @@ void Scene::renderCubemaps()
 
         float angle = 2.0f * PI * i / m_cubemaps.size();
 
-        center = m_trackBalls[1].rotation().rotatedVector(QVector3D(cos(angle), sin(angle), 0.0f));
+        center = m_trackBalls[1].rotation().rotatedVector(QVector3D(std::cos(angle), std::sin(angle), 0.0f));
 
         for (int face = 0; face < 6; ++face) {
             m_cubemaps[i]->begin(face);
@@ -910,7 +911,7 @@ void Scene::drawBackground(QPainter *painter, const QRectF &)
 
     QMatrix4x4 view;
     view.rotate(m_trackBalls[2].rotation());
-    view(2, 3) -= 2.0f * exp(m_distExp / 1200.0f);
+    view(2, 3) -= 2.0f * std::exp(m_distExp / 1200.0f);
     renderBoxes(view);
 
     defaultStates();
diff --git a/examples/widgets/graphicsview/boxes/trackball.cpp b/examples/widgets/graphicsview/boxes/trackball.cpp
index 2267636fa4..b1159b4989 100644
--- a/examples/widgets/graphicsview/boxes/trackball.cpp
+++ b/examples/widgets/graphicsview/boxes/trackball.cpp
@@ -33,6 +33,7 @@
 
 #include "trackball.h"
 #include "scene.h"
+#include <cmath>
 
 //============================================================================//
 //                                  TrackBall                                 //
@@ -94,19 +95,19 @@ void TrackBall::move(const QPointF& p, const QQuaternion &transformation)
             QVector3D lastPos3D = QVector3D(m_lastPos.x(), m_lastPos.y(), 0.0f);
             float sqrZ = 1 - QVector3D::dotProduct(lastPos3D, lastPos3D);
             if (sqrZ > 0)
-                lastPos3D.setZ(sqrt(sqrZ));
+                lastPos3D.setZ(std::sqrt(sqrZ));
             else
                 lastPos3D.normalize();
 
             QVector3D currentPos3D = QVector3D(p.x(), p.y(), 0.0f);
             sqrZ = 1 - QVector3D::dotProduct(currentPos3D, currentPos3D);
             if (sqrZ > 0)
-                currentPos3D.setZ(sqrt(sqrZ));
+                currentPos3D.setZ(std::sqrt(sqrZ));
             else
                 currentPos3D.normalize();
 
             m_axis = QVector3D::crossProduct(lastPos3D, currentPos3D);
-            float angle = 180 / PI * asin(sqrt(QVector3D::dotProduct(m_axis, m_axis)));
+            float angle = 180 / PI * std::asin(std::sqrt(QVector3D::dotProduct(m_axis, m_axis)));
 
             m_angularVelocity = angle / msecs;
             m_axis.normalize();