1 files changed, 32 insertions, 12 deletions
diff --git a/src/gui/styles/qstyleoption.cpp b/src/gui/styles/qstyleoption.cpp
index ce053ae..5b1bc61 100644
--- a/src/gui/styles/qstyleoption.cpp
+++ b/src/gui/styles/qstyleoption.cpp
@@ -48,6 +48,7 @@
 #ifndef QT_NO_DEBUG
 #include <qdebug.h>
 #endif
+#include <QtCore/qmath.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -4998,6 +4999,34 @@ QStyleOptionGraphicsItem::QStyleOptionGraphicsItem(int version)
 }
 
 /*!
+    \since 4.6
+
+    Returns the level of detail from the \a worldTransform.
+
+    Its value represents the maximum value of the height and
+    width of a unity rectangle, mapped using the \a worldTransform
+    of the painter used to draw the item. By default, if no
+    transformations are applied, its value is 1. If zoomed out 1:2, the level
+    of detail will be 0.5, and if zoomed in 2:1, its value is 2.
+
+    For more advanced level-of-detail metrics, use
+    QStyleOptionGraphicsItem::matrix directly.
+
+    \sa QStyleOptionGraphicsItem::matrix
+*/
+qreal QStyleOptionGraphicsItem::levelOfDetailFromTransform(const QTransform &worldTransform)
+{
+    if (worldTransform.type() <= QTransform::TxTranslate)
+        return 1; // Translation only? The LOD is 1.
+
+    // Two unit vectors.
+    QLineF v1(0, 0, 1, 0);
+    QLineF v2(0, 0, 0, 1);
+    // LOD is the transformed area of a 1x1 rectangle.
+    return qSqrt(worldTransform.map(v1).length() * worldTransform.map(v2).length());
+}
+
+/*!
     \fn QStyleOptionGraphicsItem::QStyleOptionGraphicsItem(const QStyleOptionGraphicsItem &other)
 
     Constructs a copy of \a other.
@@ -5029,19 +5058,10 @@ QStyleOptionGraphicsItem::QStyleOptionGraphicsItem(int version)
 
 /*!
     \variable QStyleOptionGraphicsItem::levelOfDetail
-    \brief a simple metric for determining an item's level of detail
-
-    This simple metric provides an easy way to determine the level of detail
-    for an item. Its value represents the maximum value of the height and
-    width of a unity rectangle, mapped using the complete transformation
-    matrix of the painter used to draw the item. By default, if no
-    transformations are applied, its value is 1. If zoomed out 1:2, the level
-    of detail will be 0.5, and if zoomed in 2:1, its value is 2.
-
-    For more advanced level-of-detail metrics, use
-    QStyleOptionGraphicsItem::matrix directly.
+    \obsolete
 
-    \sa QStyleOptionGraphicsItem::matrix
+    Use QStyleOptionGraphicsItem::levelOfDetailFromTransform
+    together with QPainter::worldTransform() instead.
 */
 
 /*!