Fixed performance regression in curve stroking.

Change c46688b8a88da made us use m_curve_threshold for both
QBezier::shifted and QBezier::toPolygon, and adjusted the threshold
dynamically based on the painter scale. Since the threshold in shifted
was already relative to the pen width, it is independent from the
painter scale. Instead, we need to set a separate threshold for dashing.

Also, in several places we were calling setCurveThresholdForTransform
with the painter matrix even though we were transforming the points into
device coordinate space before stroking.

Task-number: QTBUG-13894
Reviewed-by: Gunnar Sletta

1 files changed, 2 insertions, 1 deletions

diff --git a/src/gui/painting/qstroker_p.h b/src/gui/painting/qstroker_p.h
index d646135..5607a8e 100644
--- a/src/gui/painting/qstroker_p.h
+++ b/src/gui/painting/qstroker_p.h
@@ -168,7 +168,7 @@ public:
     {
         qreal scale;
         qt_scaleForTransform(transform, &scale);
-        setCurveThreshold(scale == 0 ? qreal(0.5) : (qreal(0.5) / scale));
+        m_dashThreshold = scale == 0 ? qreal(0.5) : (qreal(0.5) / scale);
     }
 
     void setCurveThreshold(qfixed threshold) { m_curveThreshold = threshold; }
@@ -184,6 +184,7 @@ protected:
 
     QRectF m_clip_rect;
     qfixed m_curveThreshold;
+    qfixed m_dashThreshold;
 
     void *m_customData;
     qStrokerMoveToHook m_moveTo;