Simplify calculation of center point and scale for PinchRecongizer

Constructing a QLineF to get at the centerPoint is not precise and can be done simpler.
The scale factor can be assigned directly to d->scaleFactor instead of creating a temporary
scaleFactor variable.

Reviewed-by: Zeno Albisser

1 files changed, 8 insertions, 11 deletions

diff --git a/src/gui/kernel/qstandardgestures.cpp b/src/gui/kernel/qstandardgestures.cpp
index 893ba2b..1821c3d 100644
--- a/src/gui/kernel/qstandardgestures.cpp
+++ b/src/gui/kernel/qstandardgestures.cpp
@@ -198,25 +198,22 @@ QGestureRecognizer::Result QPinchGestureRecognizer::recognize(QGesture *state,
                 d->startPosition[0] = p1.screenPos();
                 d->startPosition[1] = p2.screenPos();
             }
-            QLineF line(p1.screenPos(), p2.screenPos());
-            QLineF lastLine(p1.lastScreenPos(),  p2.lastScreenPos());
-            QLineF tmp(line);
-            tmp.setLength(line.length() / 2.);
-            QPointF centerPoint = tmp.p2();
 
             d->lastCenterPoint = d->centerPoint;
-            d->centerPoint = centerPoint;
-            d->changeFlags |= QPinchGesture::CenterPointChanged;
+            d->centerPoint = (p1.screenPos() + p2.screenPos()) / 2.0;
 
-            const qreal scaleFactor = line.length() / lastLine.length();
+            d->changeFlags |= QPinchGesture::CenterPointChanged;
 
             if (d->isNewSequence) {
-                d->lastScaleFactor = scaleFactor;
+                d->scaleFactor = 1.0;
+                d->lastScaleFactor = 1.0;
             } else {
                 d->lastScaleFactor = d->scaleFactor;
+                QLineF line(p1.screenPos(), p2.screenPos());
+                QLineF lastLine(p1.lastScreenPos(),  p2.lastScreenPos());
+                d->scaleFactor = line.length() / lastLine.length();
             }
-            d->scaleFactor = scaleFactor;
-            d->totalScaleFactor = d->totalScaleFactor * scaleFactor;
+            d->totalScaleFactor = d->totalScaleFactor * d->scaleFactor;
             d->changeFlags |= QPinchGesture::ScaleFactorChanged;
 
             qreal angle = QLineF(p1.screenPos(), p2.screenPos()).angle();