Add QGraphicsView::isTransformed(), and use it to avoid view transforms.

Ensure that we don't ask for or multiply with the view transform if the
view is not transformed.

1 files changed, 12 insertions, 0 deletions

diff --git a/src/gui/graphicsview/qgraphicsview.cpp b/src/gui/graphicsview/qgraphicsview.cpp
index e9a432e..c91e0d1 100644
--- a/src/gui/graphicsview/qgraphicsview.cpp
+++ b/src/gui/graphicsview/qgraphicsview.cpp
@@ -3555,6 +3555,18 @@ QTransform QGraphicsView::viewportTransform() const
 }
 
 /*!
+    Returns true if the view is transformed (i.e., a non-identity transform
+    has been assigned, or the scrollbars are adjusted).
+
+    \sa setTransform(), horizontalScrollBar(), verticalScrollBar()
+*/
+bool QGraphicsView::isTransformed() const
+{
+    Q_D(const QGraphicsView);
+    return !d->identityMatrix || d->horizontalScroll() || d->verticalScroll();
+}
+
+/*!
     Sets the view's current transformation matrix to \a matrix.
 
     If \a combine is true, then \a matrix is combined with the current matrix;