Provide operators for QMargins.

Provide addition/subtraction for QMargins as well as
multiplication and division for int/qreal similar
to QPoint. Add unary minus.

Change-Id: If4eb831cfd610b34b5ca361619b1636031811d0a
Reviewed-by: Oliver Wolff <oliver.wolff@digia.com>
Reviewed-by: Mitch Curtis <mitch.curtis@digia.com>

4 files changed, 314 insertions, 0 deletions

diff --git a/dist/changes-5.1.0 b/dist/changes-5.1.0
index 1124c9b9c5..4aa06cf342 100644
--- a/dist/changes-5.1.0
+++ b/dist/changes-5.1.0
@@ -50,6 +50,9 @@ QtCore
    * Added marginsAdded(), marginsRemoved() and operators +, -, +=, -=
      taking a QMargins object allowing for conveniently adding or removing
      margins.
+ - QMargins:
+   * Added operators for adding and subtracting QMargins objects,
+     multiplication and division for int/qreal and unary minus.
 
  -
 
diff --git a/src/corelib/tools/qmargins.cpp b/src/corelib/tools/qmargins.cpp
index 214466194a..e30675dc63 100644
--- a/src/corelib/tools/qmargins.cpp
+++ b/src/corelib/tools/qmargins.cpp
@@ -216,6 +216,181 @@ QT_BEGIN_NAMESPACE
     \since 5.1
 */
 
+/*!
+    \fn const QMargins operator+(const QMargins &m1, const QMargins &m2)
+    \relates QMargins
+
+    Returns a QMargins object that is the sum of the given margins, \a m1
+    and \a m2; each component is added separately.
+
+    \sa QMargins::operator+=(), QMargins::operator-=()
+
+    \since 5.1
+*/
+
+/*!
+    \fn const QMargins operator-(const QMargins &m1, const QMargins &m2)
+    \relates QMargins
+
+    Returns a QMargins object that is formed by subtracting \a m2 from
+    \a m1; each component is subtracted separately.
+
+    \sa QMargins::operator+=(), QMargins::operator-=()
+
+    \since 5.1
+*/
+
+/*!
+    \fn const QMargins operator*(const QMargins &margins, int factor)
+    \relates QMargins
+
+    Returns a QMargins object that is formed by multiplying each component
+    of the given \a margins by \a factor.
+
+    \sa QMargins::operator*=(), QMargins::operator/=()
+
+    \since 5.1
+*/
+
+/*!
+    \fn const QMargins operator*(int factor, const QMargins &margins)
+    \relates QMargins
+    \overload
+
+    Returns a QMargins object that is formed by multiplying each component
+    of the given \a margins by \a factor.
+
+    \sa QMargins::operator*=(), QMargins::operator/=()
+
+    \since 5.1
+*/
+
+/*!
+    \fn const QMargins operator*(const QMargins &margins, qreal factor)
+    \relates QMargins
+    \overload
+
+    Returns a QMargins object that is formed by multiplying each component
+    of the given \a margins by \a factor.
+
+    \sa QMargins::operator*=(), QMargins::operator/=()
+
+    \since 5.1
+*/
+
+/*!
+    \fn const QMargins operator*(qreal factor, const QMargins &margins)
+    \relates QMargins
+    \overload
+
+    Returns a QMargins object that is formed by multiplying each component
+    of the given \a margins by \a factor.
+
+    \sa QMargins::operator*=(), QMargins::operator/=()
+
+    \since 5.1
+*/
+
+/*!
+    \fn const QMargins operator/(const QMargins &margins, int divisor)
+    \relates QMargins
+
+    Returns a QMargins object that is formed by dividing the components of
+    the given \a margins by the given \a divisor.
+
+    \sa QMargins::operator*=(), QMargins::operator/=()
+
+    \since 5.1
+*/
+
+/*!
+    \fn const QMargins operator/(const QMargins &, qreal)
+    \relates QMargins
+    \overload
+
+    Returns a QMargins object that is formed by dividing the components of
+    the given \a margins by the given \a divisor.
+
+    \sa QMargins::operator*=(), QMargins::operator/=()
+
+    \since 5.1
+*/
+
+/*!
+    \fn QMargins operator-(const QMargins &margins)
+    \relates QMargins
+
+    Returns a QMargin object that is formed by negating all components of \a margins.
+
+    \since 5.1
+*/
+
+/*!
+    \fn QMargins &operator+=(const QMargins &margins)
+
+    Add each component of \a margins to the respective component of this object
+    and returns a reference to it.
+
+    \sa operator-=()
+
+    \since 5.1
+*/
+
+/*!
+    \fn QMargins &operator-=(const QMargins &margins)
+
+    Subtract each component of \a margins from the respective component of this object
+    and returns a reference to it.
+
+    \sa operator+=()
+
+    \since 5.1
+*/
+
+/*!
+    \fn QMargins &operator*=(int factor)
+
+    Multiplies each component of this object by \a factor
+    and returns a reference to it.
+
+    \sa operator/=()
+
+    \since 5.1
+*/
+
+/*!
+    \fn QMargins &operator*=(qreal factor)
+    \overload
+
+    Multiplies each component of this object by \a factor
+    and returns a reference to it.
+
+    \sa operator/=()
+
+    \since 5.1
+*/
+
+/*!
+    \fn QMargins &operator/=(int divisor)
+
+    Divides each component of this object by \a divisor
+    and returns a reference to it.
+
+    \sa operator*=()
+
+    \since 5.1
+*/
+
+/*!
+    \fn QMargins &operator/=(qreal divisor)
+
+    \overload
+
+    \sa operator*=()
+
+    \since 5.1
+*/
+
 /*****************************************************************************
   QMargins stream functions
  *****************************************************************************/
diff --git a/src/corelib/tools/qmargins.h b/src/corelib/tools/qmargins.h
index a933a60fed..dd6fb0261a 100644
--- a/src/corelib/tools/qmargins.h
+++ b/src/corelib/tools/qmargins.h
@@ -67,6 +67,15 @@ public:
     void setRight(int right);
     void setBottom(int bottom);
 
+    QMargins &operator+=(const QMargins &margins);
+    QMargins &operator-=(const QMargins &margins);
+    QMargins &operator+=(int);
+    QMargins &operator-=(int);
+    QMargins &operator*=(int);
+    QMargins &operator/=(int);
+    QMargins &operator*=(qreal);
+    QMargins &operator/=(qreal);
+
 private:
     int m_left;
     int m_top;
@@ -177,6 +186,89 @@ inline QRect &QRect::operator-=(const QMargins &margins)
     return *this;
 }
 
+Q_DECL_CONSTEXPR inline QMargins operator+(const QMargins &m1, const QMargins &m2)
+{
+    return QMargins(m1.left() + m2.left(), m1.top() + m2.top(),
+                    m1.right() + m2.right(), m1.bottom() + m2.bottom());
+}
+
+Q_DECL_CONSTEXPR inline QMargins operator-(const QMargins &m1, const QMargins &m2)
+{
+    return QMargins(m1.left() - m2.left(), m1.top() - m2.top(),
+                    m1.right() - m2.right(), m1.bottom() - m2.bottom());
+}
+
+Q_DECL_CONSTEXPR inline QMargins operator*(const QMargins &margins, int factor)
+{
+    return QMargins(margins.left() * factor, margins.top() * factor,
+                    margins.right() * factor, margins.bottom() * factor);
+}
+
+Q_DECL_CONSTEXPR inline QMargins operator*(int factor, const QMargins &margins)
+{
+    return QMargins(margins.left() * factor, margins.top() * factor,
+                    margins.right() * factor, margins.bottom() * factor);
+}
+
+Q_DECL_CONSTEXPR inline QMargins operator*(const QMargins &margins, qreal factor)
+{
+    return QMargins(qRound(margins.left() * factor), qRound(margins.top() * factor),
+                    qRound(margins.right() * factor), qRound(margins.bottom() * factor));
+}
+
+Q_DECL_CONSTEXPR inline QMargins operator*(qreal factor, const QMargins &margins)
+{
+    return QMargins(qRound(margins.left() * factor), qRound(margins.top() * factor),
+                    qRound(margins.right() * factor), qRound(margins.bottom() * factor));
+}
+
+Q_DECL_CONSTEXPR inline QMargins operator/(const QMargins &margins, int divisor)
+{
+    return QMargins(margins.left() / divisor, margins.top() / divisor,
+                    margins.right() / divisor, margins.bottom() / divisor);
+}
+
+Q_DECL_CONSTEXPR inline QMargins operator/(const QMargins &margins, qreal divisor)
+{
+    return QMargins(qRound(margins.left() / divisor), qRound(margins.top() / divisor),
+                    qRound(margins.right() / divisor), qRound(margins.bottom() / divisor));
+}
+
+inline QMargins &QMargins::operator+=(const QMargins &margins)
+{
+    return *this = *this + margins;
+}
+
+inline QMargins &QMargins::operator-=(const QMargins &margins)
+{
+    return *this = *this - margins;
+}
+
+inline QMargins &QMargins::operator*=(int factor)
+{
+    return *this = *this * factor;
+}
+
+inline QMargins &QMargins::operator/=(int divisor)
+{
+    return *this = *this / divisor;
+}
+
+inline QMargins &QMargins::operator*=(qreal factor)
+{
+    return *this = *this * factor;
+}
+
+inline QMargins &QMargins::operator/=(qreal divisor)
+{
+    return *this = *this / divisor;
+}
+
+Q_DECL_CONSTEXPR inline QMargins operator-(const QMargins &margins)
+{
+    return QMargins(-margins.left(), -margins.top(), -margins.right(), -margins.bottom());
+}
+
 #ifndef QT_NO_DEBUG_STREAM
 Q_CORE_EXPORT QDebug operator<<(QDebug, const QMargins &);
 #endif
diff --git a/tests/auto/corelib/tools/qmargins/tst_qmargins.cpp b/tests/auto/corelib/tools/qmargins/tst_qmargins.cpp
index 5e3b3d221e..b74fc53ed0 100644
--- a/tests/auto/corelib/tools/qmargins/tst_qmargins.cpp
+++ b/tests/auto/corelib/tools/qmargins/tst_qmargins.cpp
@@ -50,6 +50,7 @@ class tst_QMargins : public QObject
 private slots:
     void getSetCheck();
     void dataStreamCheck();
+    void operators();
 };
 
 // Testing get/set functions
@@ -75,6 +76,49 @@ void tst_QMargins::getSetCheck()
     QCOMPARE(margins, QMargins(5, 0, 5, 0));
 } 
 
+void tst_QMargins::operators()
+{
+    const QMargins m1(12, 14, 16, 18);
+    const QMargins m2(2, 3, 4, 5);
+
+    const QMargins added = m1 + m2;
+    QCOMPARE(added, QMargins(14, 17, 20, 23));
+    QMargins a = m1;
+    a += m2;
+    QCOMPARE(a, added);
+
+    const QMargins subtracted = m1 - m2;
+    QCOMPARE(subtracted, QMargins(10, 11, 12, 13));
+    a = m1;
+    a -= m2;
+    QCOMPARE(a, subtracted);
+
+    const QMargins doubled = m1 * 2;
+    QCOMPARE(doubled, QMargins(24, 28, 32, 36));
+    QCOMPARE(2 * m1, doubled);
+    QCOMPARE(qreal(2) * m1, doubled);
+    QCOMPARE(m1 * qreal(2), doubled);
+
+    a = m1;
+    a *= 2;
+    QCOMPARE(a, doubled);
+    a = m1;
+    a *= qreal(2);
+    QCOMPARE(a, doubled);
+
+    const QMargins halved = m1 / 2;
+    QCOMPARE(halved, QMargins(6, 7, 8, 9));
+
+    a = m1;
+    a /= 2;
+    QCOMPARE(a, halved);
+    a = m1;
+    a /= qreal(2);
+    QCOMPARE(a, halved);
+
+    QCOMPARE(m1 + (-m1), QMargins());
+}
+
 // Testing QDataStream operators
 void tst_QMargins::dataStreamCheck()
 {