From b615be69f06a97aff3694065e97541133647d877 Mon Sep 17 00:00:00 2001
From: Lars Knoll <lars.knoll@nokia.com>
Date: Tue, 2 Jun 2009 21:02:42 +0200
Subject: implement equality operator in a more sane way
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Using qFuzzyCompare for checking whether two transformations
are equal doesn't give us too much and is inconsistent with
our other matrix classes. Using simple floating point
equality is a lot faster as well.

Added qFuzzyCompare overloads for QMatrix and QTransform to still
allow for fuzzy comparisons.

Reviewed-By: Samuel Rødal
---
 src/gui/painting/qmatrix.cpp             | 11 +++++++++++
 src/gui/painting/qmatrix.h               | 11 +++++++++++
 src/gui/painting/qtransform.cpp          | 25 ++++++++++++++++++++-----
 src/gui/painting/qtransform.h            | 14 ++++++++++++++
 tests/auto/qtransform/tst_qtransform.cpp |  2 +-
 5 files changed, 57 insertions(+), 6 deletions(-)

diff --git a/src/gui/painting/qmatrix.cpp b/src/gui/painting/qmatrix.cpp
index 030415d..7e26a99 100644
--- a/src/gui/painting/qmatrix.cpp
+++ b/src/gui/painting/qmatrix.cpp
@@ -1194,4 +1194,15 @@ QDebug operator<<(QDebug dbg, const QMatrix &m)
     Use the mapRect() function instead.
 */
 
+
+/*!
+    \fn bool qFuzzyCompare(const QMatrix& m1, const QMatrix& m2)
+
+    \relates QMatrix
+    \since 4.6
+
+    Returns true if \a m1 and \a m2 are equal, allowing for a small
+    fuzziness factor for floating-point comparisons; false otherwise.
+*/
+
 QT_END_NAMESPACE
diff --git a/src/gui/painting/qmatrix.h b/src/gui/painting/qmatrix.h
index 1df2395..4a4e91f 100644
--- a/src/gui/painting/qmatrix.h
+++ b/src/gui/painting/qmatrix.h
@@ -165,6 +165,17 @@ inline bool QMatrix::isIdentity() const
            && qFuzzyIsNull(_m21) && qFuzzyIsNull(_dx) && qFuzzyIsNull(_dy);
 }
 
+inline bool qFuzzyCompare(const QMatrix& m1, const QMatrix& m2)
+{
+    return qFuzzyCompare(m1.m11(), m2.m11())
+        && qFuzzyCompare(m1.m12(), m2.m12())
+        && qFuzzyCompare(m1.m21(), m2.m21())
+        && qFuzzyCompare(m1.m22(), m2.m22())
+        && qFuzzyCompare(m1.dx(), m2.dx())
+        && qFuzzyCompare(m1.dy(), m2.dy());
+}
+
+
 /*****************************************************************************
  QMatrix stream functions
  *****************************************************************************/
diff --git a/src/gui/painting/qtransform.cpp b/src/gui/painting/qtransform.cpp
index 4bc20f6..385fde1 100644
--- a/src/gui/painting/qtransform.cpp
+++ b/src/gui/painting/qtransform.cpp
@@ -708,11 +708,15 @@ QTransform & QTransform::rotateRadians(qreal a, Qt::Axis axis)
 */
 bool QTransform::operator==(const QTransform &o) const
 {
-#define qFZ qFuzzyCompare
-    return qFZ(affine._m11, o.affine._m11) &&  qFZ(affine._m12, o.affine._m12) &&  qFZ(m_13, o.m_13)
-        && qFZ(affine._m21, o.affine._m21) &&  qFZ(affine._m22, o.affine._m22) &&  qFZ(m_23, o.m_23)
-        && qFZ(affine._dx, o.affine._dx) &&  qFZ(affine._dy, o.affine._dy) &&  qFZ(m_33, o.m_33);
-#undef qFZ
+    return affine._m11 == o.affine._m11 &&
+           affine._m12 == o.affine._m12 &&
+           affine._m21 == o.affine._m21 &&
+           affine._m22 == o.affine._m22 &&
+           affine._dx == o.affine._dx &&
+           affine._dy == o.affine._dy &&
+           m_13 == o.m_13 &&
+           m_23 == o.m_23 &&
+           m_33 == o.m_33;
 }
 
 /*!
@@ -2178,6 +2182,17 @@ QTransform::operator QVariant() const
     \sa reset()
 */
 
+/*!
+    \fn bool qFuzzyCompare(const QTransform& t1, const QTransform& t2)
+
+    \relates QTransform
+    \since 4.6
+
+    Returns true if \a t1 and \a t2 are equal, allowing for a small
+    fuzziness factor for floating-point comparisons; false otherwise.
+*/
+
+
 // returns true if the transform is uniformly scaling
 // (same scale in x and y direction)
 // scale is set to the max of x and y scaling factors
diff --git a/src/gui/painting/qtransform.h b/src/gui/painting/qtransform.h
index a5002ca..57ec826 100644
--- a/src/gui/painting/qtransform.h
+++ b/src/gui/painting/qtransform.h
@@ -331,6 +331,20 @@ inline QTransform &QTransform::operator-=(qreal num)
     return *this;
 }
 
+inline bool qFuzzyCompare(const QTransform& t1, const QTransform& t2)
+{
+    return qFuzzyCompare(t1.m11(), t2.m11())
+        && qFuzzyCompare(t1.m12(), t2.m12())
+        && qFuzzyCompare(t1.m13(), t2.m13())
+        && qFuzzyCompare(t1.m21(), t2.m21())
+        && qFuzzyCompare(t1.m22(), t2.m22())
+        && qFuzzyCompare(t1.m23(), t2.m23())
+        && qFuzzyCompare(t1.m31(), t2.m31())
+        && qFuzzyCompare(t1.m32(), t2.m32())
+        && qFuzzyCompare(t1.m33(), t2.m33());
+}
+
+
 /****** stream functions *******************/
 #ifndef QT_NO_DATASTREAM
 Q_GUI_EXPORT QDataStream &operator<<(QDataStream &, const QTransform &);
diff --git a/tests/auto/qtransform/tst_qtransform.cpp b/tests/auto/qtransform/tst_qtransform.cpp
index 3b13a41..99a449a 100644
--- a/tests/auto/qtransform/tst_qtransform.cpp
+++ b/tests/auto/qtransform/tst_qtransform.cpp
@@ -654,7 +654,7 @@ void tst_QTransform::transform()
     d.rotate(30);
     e.shear(0.5, 0.5);
 
-    QCOMPARE(t, e * d * c * b * a);
+    QVERIFY(qFuzzyCompare(t, e * d * c * b * a));
 }
 
 void tst_QTransform::mapEmptyPath()
-- 
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