Fixed rounding errors in QtQuick1 to int conversions

qRound introduced errors when qreal is single precision. Added
double signature for qround so that string and int don't lose precision
in conversion.

Task-number: QTBUG-33625

Change-Id: I58582f57d5cd68fcad3fe9efb5fea5935f61b9e3
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

2 files changed, 15 insertions, 4 deletions

diff --git a/src/declarative/qml/qdeclarativeobjectscriptclass.cpp b/src/declarative/qml/qdeclarativeobjectscriptclass.cpp
index 99d34b4..8cfdad2 100644
--- a/src/declarative/qml/qdeclarativeobjectscriptclass.cpp
+++ b/src/declarative/qml/qdeclarativeobjectscriptclass.cpp
@@ -328,7 +328,12 @@ void QDeclarativeObjectScriptClass::setProperty(Object *object,
 {
     return setProperty(toQObject(object), name, value, context());
 }
-
+namespace {
+int qRoundDouble(double d)
+{
+    return d >= double(0.0) ? int(d + double(0.5)) : int(d - int(d-1) + double(0.5)) + int(d-1);
+}
+}
 void QDeclarativeObjectScriptClass::setProperty(QObject *obj,
                                                 const Identifier &name,
                                                 const QScriptValue &value,
@@ -405,7 +410,7 @@ void QDeclarativeObjectScriptClass::setProperty(QObject *obj,
     } else {
         //### expand optimization for other known types
         if (lastData->propType == QMetaType::Int && value.isNumber()) {
-            int rawValue = qRound(value.toNumber());
+            int rawValue = qRoundDouble(value.toNumber());
             int status = -1;
             int flags = 0;
             void *a[] = { (void *)&rawValue, 0, &status, &flags };
diff --git a/src/declarative/qml/qdeclarativestringconverters.cpp b/src/declarative/qml/qdeclarativestringconverters.cpp
index bb5eacb..738619d 100644
--- a/src/declarative/qml/qdeclarativestringconverters.cpp
+++ b/src/declarative/qml/qdeclarativestringconverters.cpp
@@ -97,13 +97,19 @@ QVariant QDeclarativeStringConverters::variantFromString(const QString &s)
     return QVariant(s);
 }
 
+namespace {
+int qRoundDouble(double d)
+{
+    return d >= double(0.0) ? int(d + double(0.5)) : int(d - int(d-1) + double(0.5)) + int(d-1);
+}
+}
 QVariant QDeclarativeStringConverters::variantFromString(const QString &s, int preferredType, bool *ok)
 {
     switch (preferredType) {
     case QMetaType::Int:
-        return QVariant(int(qRound(s.toDouble(ok))));
+        return QVariant(int(qRoundDouble(s.toDouble(ok))));
     case QMetaType::UInt:
-        return QVariant(uint(qRound(s.toDouble(ok))));
+        return QVariant(uint(qRoundDouble(s.toDouble(ok))));
     case QMetaType::QColor:
         return QVariant::fromValue(colorFromString(s, ok));
 #ifndef QT_NO_DATESTRING