Document the difference between +0.0 and -0.0 for QPointF and QSizeF.

Reviewed-by: Robert Griebl

2 files changed, 10 insertions, 2 deletions

diff --git a/src/corelib/tools/qpoint.cpp b/src/corelib/tools/qpoint.cpp
index 66f06e9..c297709 100644
--- a/src/corelib/tools/qpoint.cpp
+++ b/src/corelib/tools/qpoint.cpp
@@ -438,8 +438,12 @@ QDebug operator<<(QDebug d, const QPointF &p)
 /*!
     \fn bool QPointF::isNull() const
 
-    Returns true if both the x and y coordinates are set to 0.0,
+    Returns true if both the x and y coordinates are set to +0.0;
     otherwise returns false.
+
+    \note Since this function treats +0.0 and -0.0 differently, points
+    with zero-valued coordinates where either or both values have a
+    negative sign are not defined to be null points.
 */
 
 
diff --git a/src/corelib/tools/qsize.cpp b/src/corelib/tools/qsize.cpp
index 20ac344..12287ab 100644
--- a/src/corelib/tools/qsize.cpp
+++ b/src/corelib/tools/qsize.cpp
@@ -492,9 +492,13 @@ QDebug operator<<(QDebug dbg, const QSize &s) {
 /*!
     \fn bool QSizeF::isNull() const
 
-    Returns true if both the width and height is 0; otherwise returns
+    Returns true if both the width and height are +0.0; otherwise returns
     false.
 
+    \note Since this function treats +0.0 and -0.0 differently, sizes with
+    zero width and height where either or both values have a negative
+    sign are not defined to be null sizes.
+
     \sa isValid(), isEmpty()
 */