1 files changed, 32 insertions, 0 deletions
diff --git a/src/gui/painting/qbezier.cpp b/src/gui/painting/qbezier.cpp
index 9d204f9a39..bdba3f21ef 100644
--- a/src/gui/painting/qbezier.cpp
+++ b/src/gui/painting/qbezier.cpp
@@ -220,6 +220,38 @@ void QBezier::addToPolygon(QPolygonF *polygon, qreal bezier_flattening_threshold
     }
 }
 
+void QBezier::addToPolygon(QDataBuffer<QPointF> &polygon, qreal bezier_flattening_threshold) const
+{
+    QBezier beziers[32];
+    beziers[0] = *this;
+    QBezier *b = beziers;
+
+    while (b >= beziers) {
+        // check if we can pop the top bezier curve from the stack
+        qreal y4y1 = b->y4 - b->y1;
+        qreal x4x1 = b->x4 - b->x1;
+        qreal l = qAbs(x4x1) + qAbs(y4y1);
+        qreal d;
+        if (l > 1.) {
+            d = qAbs( (x4x1)*(b->y1 - b->y2) - (y4y1)*(b->x1 - b->x2) )
+                + qAbs( (x4x1)*(b->y1 - b->y3) - (y4y1)*(b->x1 - b->x3) );
+        } else {
+            d = qAbs(b->x1 - b->x2) + qAbs(b->y1 - b->y2) +
+                qAbs(b->x1 - b->x3) + qAbs(b->y1 - b->y3);
+            l = 1.;
+        }
+        if (d < bezier_flattening_threshold*l || b == beziers + 31) {
+            // good enough, we pop it off and add the endpoint
+            polygon.add(QPointF(b->x4, b->y4));
+            --b;
+        } else {
+            // split, second half of the polygon goes lower into the stack
+            b->split(b+1, b);
+            ++b;
+        }
+    }
+}
+
 QRectF QBezier::bounds() const
 {
     qreal xmin = x1;