QtCore: add constexpr to geometric classes

This turns code like QPoint(12, 12) into a compile-time
expression, under a C++11 compiler, and allows to define
arrays of these types that end up in read-only memory,
just like PODs would.

Some constructors and QLine::pointAt() needed to be
adjusted to fit into the empty-body/only-return-expression
requirement for constexpr constructors/functions.

Change-Id: Id11ee2752c948930c3e40a91d1f6d7c97db7a373
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 70 insertions, 72 deletions

diff --git a/src/corelib/tools/qline.h b/src/corelib/tools/qline.h
index 58ef0316ad..92ea4ea426 100644
--- a/src/corelib/tools/qline.h
+++ b/src/corelib/tools/qline.h
@@ -56,37 +56,37 @@ QT_BEGIN_NAMESPACE
 class Q_CORE_EXPORT QLine
 {
 public:
-    inline QLine();
-    inline QLine(const QPoint &pt1, const QPoint &pt2);
-    inline QLine(int x1, int y1, int x2, int y2);
+    Q_DECL_CONSTEXPR inline QLine();
+    Q_DECL_CONSTEXPR inline QLine(const QPoint &pt1, const QPoint &pt2);
+    Q_DECL_CONSTEXPR inline QLine(int x1, int y1, int x2, int y2);
 
-    inline bool isNull() const;
+    Q_DECL_CONSTEXPR inline bool isNull() const;
 
-    inline QPoint p1() const;
-    inline QPoint p2() const;
+    Q_DECL_CONSTEXPR inline QPoint p1() const;
+    Q_DECL_CONSTEXPR inline QPoint p2() const;
 
-    inline int x1() const;
-    inline int y1() const;
+    Q_DECL_CONSTEXPR inline int x1() const;
+    Q_DECL_CONSTEXPR inline int y1() const;
 
-    inline int x2() const;
-    inline int y2() const;
+    Q_DECL_CONSTEXPR inline int x2() const;
+    Q_DECL_CONSTEXPR inline int y2() const;
 
-    inline int dx() const;
-    inline int dy() const;
+    Q_DECL_CONSTEXPR inline int dx() const;
+    Q_DECL_CONSTEXPR inline int dy() const;
 
     inline void translate(const QPoint &p);
     inline void translate(int dx, int dy);
 
-    inline QLine translated(const QPoint &p) const;
-    inline QLine translated(int dx, int dy) const;
+    Q_DECL_CONSTEXPR inline QLine translated(const QPoint &p) const;
+    Q_DECL_CONSTEXPR inline QLine translated(int dx, int dy) const;
 
     inline void setP1(const QPoint &p1);
     inline void setP2(const QPoint &p2);
     inline void setPoints(const QPoint &p1, const QPoint &p2);
     inline void setLine(int x1, int y1, int x2, int y2);
 
-    inline bool operator==(const QLine &d) const;
-    inline bool operator!=(const QLine &d) const { return !(*this == d); }
+    Q_DECL_CONSTEXPR inline bool operator==(const QLine &d) const;
+    Q_DECL_CONSTEXPR inline bool operator!=(const QLine &d) const { return !(*this == d); }
 
 private:
     QPoint pt1, pt2;
@@ -97,53 +97,53 @@ Q_DECLARE_TYPEINFO(QLine, Q_MOVABLE_TYPE);
  * class QLine inline members
  *******************************************************************************/
 
-inline QLine::QLine() { }
+Q_DECL_CONSTEXPR inline QLine::QLine() { }
 
-inline QLine::QLine(const QPoint &pt1_, const QPoint &pt2_) : pt1(pt1_), pt2(pt2_) { }
+Q_DECL_CONSTEXPR inline QLine::QLine(const QPoint &pt1_, const QPoint &pt2_) : pt1(pt1_), pt2(pt2_) { }
 
-inline QLine::QLine(int x1pos, int y1pos, int x2pos, int y2pos) : pt1(QPoint(x1pos, y1pos)), pt2(QPoint(x2pos, y2pos)) { }
+Q_DECL_CONSTEXPR inline QLine::QLine(int x1pos, int y1pos, int x2pos, int y2pos) : pt1(QPoint(x1pos, y1pos)), pt2(QPoint(x2pos, y2pos)) { }
 
-inline bool QLine::isNull() const
+Q_DECL_CONSTEXPR inline bool QLine::isNull() const
 {
     return pt1 == pt2;
 }
 
-inline int QLine::x1() const
+Q_DECL_CONSTEXPR inline int QLine::x1() const
 {
     return pt1.x();
 }
 
-inline int QLine::y1() const
+Q_DECL_CONSTEXPR inline int QLine::y1() const
 {
     return pt1.y();
 }
 
-inline int QLine::x2() const
+Q_DECL_CONSTEXPR inline int QLine::x2() const
 {
     return pt2.x();
 }
 
-inline int QLine::y2() const
+Q_DECL_CONSTEXPR inline int QLine::y2() const
 {
     return pt2.y();
 }
 
-inline QPoint QLine::p1() const
+Q_DECL_CONSTEXPR inline QPoint QLine::p1() const
 {
     return pt1;
 }
 
-inline QPoint QLine::p2() const
+Q_DECL_CONSTEXPR inline QPoint QLine::p2() const
 {
     return pt2;
 }
 
-inline int QLine::dx() const
+Q_DECL_CONSTEXPR inline int QLine::dx() const
 {
     return pt2.x() - pt1.x();
 }
 
-inline int QLine::dy() const
+Q_DECL_CONSTEXPR inline int QLine::dy() const
 {
     return pt2.y() - pt1.y();
 }
@@ -159,12 +159,12 @@ inline void QLine::translate(int adx, int ady)
     this->translate(QPoint(adx, ady));
 }
 
-inline QLine QLine::translated(const QPoint &p) const
+Q_DECL_CONSTEXPR inline QLine QLine::translated(const QPoint &p) const
 {
     return QLine(pt1 + p, pt2 + p);
 }
 
-inline QLine QLine::translated(int adx, int ady) const
+Q_DECL_CONSTEXPR inline QLine QLine::translated(int adx, int ady) const
 {
     return translated(QPoint(adx, ady));
 }
@@ -191,7 +191,7 @@ inline void QLine::setLine(int aX1, int aY1, int aX2, int aY2)
     pt2 = QPoint(aX2, aY2);
 }
 
-inline bool QLine::operator==(const QLine &d) const
+Q_DECL_CONSTEXPR inline bool QLine::operator==(const QLine &d) const
 {
     return pt1 == d.pt1 && pt2 == d.pt2;
 }
@@ -213,26 +213,26 @@ public:
 
     enum IntersectType { NoIntersection, BoundedIntersection, UnboundedIntersection };
 
-    inline QLineF();
-    inline QLineF(const QPointF &pt1, const QPointF &pt2);
-    inline QLineF(qreal x1, qreal y1, qreal x2, qreal y2);
-    inline QLineF(const QLine &line) : pt1(line.p1()), pt2(line.p2()) { }
+    Q_DECL_CONSTEXPR inline QLineF();
+    Q_DECL_CONSTEXPR inline QLineF(const QPointF &pt1, const QPointF &pt2);
+    Q_DECL_CONSTEXPR inline QLineF(qreal x1, qreal y1, qreal x2, qreal y2);
+    Q_DECL_CONSTEXPR inline QLineF(const QLine &line) : pt1(line.p1()), pt2(line.p2()) { }
 
     static QLineF fromPolar(qreal length, qreal angle);
 
-    bool isNull() const;
+    Q_DECL_CONSTEXPR bool isNull() const;
 
-    inline QPointF p1() const;
-    inline QPointF p2() const;
+    Q_DECL_CONSTEXPR inline QPointF p1() const;
+    Q_DECL_CONSTEXPR inline QPointF p2() const;
 
-    inline qreal x1() const;
-    inline qreal y1() const;
+    Q_DECL_CONSTEXPR inline qreal x1() const;
+    Q_DECL_CONSTEXPR inline qreal y1() const;
 
-    inline qreal x2() const;
-    inline qreal y2() const;
+    Q_DECL_CONSTEXPR inline qreal x2() const;
+    Q_DECL_CONSTEXPR inline qreal y2() const;
 
-    inline qreal dx() const;
-    inline qreal dy() const;
+    Q_DECL_CONSTEXPR inline qreal dx() const;
+    Q_DECL_CONSTEXPR inline qreal dy() const;
 
     qreal length() const;
     void setLength(qreal len);
@@ -243,29 +243,29 @@ public:
     qreal angleTo(const QLineF &l) const;
 
     QLineF unitVector() const;
-    QLineF normalVector() const;
+    Q_DECL_CONSTEXPR inline QLineF normalVector() const;
 
     // ### Qt 5: rename intersects() or intersection() and rename IntersectType IntersectionType
     IntersectType intersect(const QLineF &l, QPointF *intersectionPoint) const;
 
     qreal angle(const QLineF &l) const;
 
-    QPointF pointAt(qreal t) const;
+    Q_DECL_CONSTEXPR inline QPointF pointAt(qreal t) const;
     inline void translate(const QPointF &p);
     inline void translate(qreal dx, qreal dy);
 
-    inline QLineF translated(const QPointF &p) const;
-    inline QLineF translated(qreal dx, qreal dy) const;
+    Q_DECL_CONSTEXPR inline QLineF translated(const QPointF &p) const;
+    Q_DECL_CONSTEXPR inline QLineF translated(qreal dx, qreal dy) const;
 
     inline void setP1(const QPointF &p1);
     inline void setP2(const QPointF &p2);
     inline void setPoints(const QPointF &p1, const QPointF &p2);
     inline void setLine(qreal x1, qreal y1, qreal x2, qreal y2);
 
-    inline bool operator==(const QLineF &d) const;
-    inline bool operator!=(const QLineF &d) const { return !(*this == d); }
+    Q_DECL_CONSTEXPR inline bool operator==(const QLineF &d) const;
+    Q_DECL_CONSTEXPR inline bool operator!=(const QLineF &d) const { return !(*this == d); }
 
-    QLine toLine() const;
+    Q_DECL_CONSTEXPR QLine toLine() const;
 
 private:
     QPointF pt1, pt2;
@@ -276,66 +276,66 @@ Q_DECLARE_TYPEINFO(QLineF, Q_MOVABLE_TYPE);
  * class QLineF inline members
  *******************************************************************************/
 
-inline QLineF::QLineF()
+Q_DECL_CONSTEXPR inline QLineF::QLineF()
 {
 }
 
-inline QLineF::QLineF(const QPointF &apt1, const QPointF &apt2)
+Q_DECL_CONSTEXPR inline QLineF::QLineF(const QPointF &apt1, const QPointF &apt2)
     : pt1(apt1), pt2(apt2)
 {
 }
 
-inline QLineF::QLineF(qreal x1pos, qreal y1pos, qreal x2pos, qreal y2pos)
+Q_DECL_CONSTEXPR inline QLineF::QLineF(qreal x1pos, qreal y1pos, qreal x2pos, qreal y2pos)
     : pt1(x1pos, y1pos), pt2(x2pos, y2pos)
 {
 }
 
-inline qreal QLineF::x1() const
+Q_DECL_CONSTEXPR inline qreal QLineF::x1() const
 {
     return pt1.x();
 }
 
-inline qreal QLineF::y1() const
+Q_DECL_CONSTEXPR inline qreal QLineF::y1() const
 {
     return pt1.y();
 }
 
-inline qreal QLineF::x2() const
+Q_DECL_CONSTEXPR inline qreal QLineF::x2() const
 {
     return pt2.x();
 }
 
-inline qreal QLineF::y2() const
+Q_DECL_CONSTEXPR inline qreal QLineF::y2() const
 {
     return pt2.y();
 }
 
-inline bool QLineF::isNull() const
+Q_DECL_CONSTEXPR inline bool QLineF::isNull() const
 {
     return qFuzzyCompare(pt1.x(), pt2.x()) && qFuzzyCompare(pt1.y(), pt2.y());
 }
 
-inline QPointF QLineF::p1() const
+Q_DECL_CONSTEXPR inline QPointF QLineF::p1() const
 {
     return pt1;
 }
 
-inline QPointF QLineF::p2() const
+Q_DECL_CONSTEXPR inline QPointF QLineF::p2() const
 {
     return pt2;
 }
 
-inline qreal QLineF::dx() const
+Q_DECL_CONSTEXPR inline qreal QLineF::dx() const
 {
     return pt2.x() - pt1.x();
 }
 
-inline qreal QLineF::dy() const
+Q_DECL_CONSTEXPR inline qreal QLineF::dy() const
 {
     return pt2.y() - pt1.y();
 }
 
-inline QLineF QLineF::normalVector() const
+Q_DECL_CONSTEXPR inline QLineF QLineF::normalVector() const
 {
     return QLineF(p1(), p1() + QPointF(dy(), -dx()));
 }
@@ -351,12 +351,12 @@ inline void QLineF::translate(qreal adx, qreal ady)
     this->translate(QPointF(adx, ady));
 }
 
-inline QLineF QLineF::translated(const QPointF &p) const
+Q_DECL_CONSTEXPR inline QLineF QLineF::translated(const QPointF &p) const
 {
     return QLineF(pt1 + p, pt2 + p);
 }
 
-inline QLineF QLineF::translated(qreal adx, qreal ady) const
+Q_DECL_CONSTEXPR inline QLineF QLineF::translated(qreal adx, qreal ady) const
 {
     return translated(QPointF(adx, ady));
 }
@@ -369,14 +369,12 @@ inline void QLineF::setLength(qreal len)
     pt2 = QPointF(pt1.x() + v.dx() * len, pt1.y() + v.dy() * len);
 }
 
-inline QPointF QLineF::pointAt(qreal t) const
+Q_DECL_CONSTEXPR inline QPointF QLineF::pointAt(qreal t) const
 {
-    qreal vx = pt2.x() - pt1.x();
-    qreal vy = pt2.y() - pt1.y();
-    return QPointF(pt1.x() + vx * t, pt1.y() + vy * t);
+    return QPointF(pt1.x() + (pt2.x() - pt1.x()) * t, pt1.y() + (pt2.y() - pt1.y()) * t);
 }
 
-inline QLine QLineF::toLine() const
+Q_DECL_CONSTEXPR inline QLine QLineF::toLine() const
 {
     return QLine(pt1.toPoint(), pt2.toPoint());
 }
@@ -405,7 +403,7 @@ inline void QLineF::setLine(qreal aX1, qreal aY1, qreal aX2, qreal aY2)
 }
 
 
-inline bool QLineF::operator==(const QLineF &d) const
+Q_DECL_CONSTEXPR inline bool QLineF::operator==(const QLineF &d) const
 {
     return pt1 == d.pt1 && pt2 == d.pt2;
 }