QPainterPath: detach and reset before streaming in

Otherwise we end up appending and modifying the shared object.

Pick-to: 5.15 6.5 6.6 6.7
Task-number: QTBUG-122704
Change-Id: I01ec3c774d9943adb903fffd17b692c2e6d53e97
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

2 files changed, 21 insertions, 8 deletions

diff --git a/src/gui/painting/qpainterpath.cpp b/src/gui/painting/qpainterpath.cpp
index 536318b3a8..8d23d167b0 100644
--- a/src/gui/painting/qpainterpath.cpp
+++ b/src/gui/painting/qpainterpath.cpp
@@ -2442,14 +2442,14 @@ QDataStream &operator>>(QDataStream &s, QPainterPath &p)
     int size;
     s >> size;
 
-    if (size == 0)
+    if (size == 0) {
+        p = {};
         return s;
+    }
 
     p.ensureData(); // in case if p.d_func() == 0
-    if (p.d_func()->elements.size() == 1) {
-        Q_ASSERT(p.d_func()->elements.at(0).type == QPainterPath::MoveToElement);
-        p.d_func()->elements.clear();
-    }
+    p.detach();
+    p.d_func()->elements.clear();
     for (int i=0; i<size; ++i) {
         int type;
         double x, y;
@@ -2472,9 +2472,7 @@ QDataStream &operator>>(QDataStream &s, QPainterPath &p)
     s >> fillRule;
     Q_ASSERT(fillRule == Qt::OddEvenFill || fillRule == Qt::WindingFill);
     p.d_func()->fillRule = Qt::FillRule(fillRule);
-    p.d_func()->dirtyBounds = true;
-    p.d_func()->dirtyControlBounds = true;
-    if (errorDetected)
+    if (errorDetected || p.d_func()->elements.isEmpty())
         p = QPainterPath();  // Better than to return path with possibly corrupt datastructure, which would likely cause crash
     return s;
 }
diff --git a/tests/auto/gui/painting/qpainterpath/tst_qpainterpath.cpp b/tests/auto/gui/painting/qpainterpath/tst_qpainterpath.cpp
index 89631a7f28..c00dc3a78a 100644
--- a/tests/auto/gui/painting/qpainterpath/tst_qpainterpath.cpp
+++ b/tests/auto/gui/painting/qpainterpath/tst_qpainterpath.cpp
@@ -765,6 +765,21 @@ void tst_QPainterPath::testOperatorDatastream()
     }
 
     QCOMPARE(other, path);
+
+    // Check reset & detach
+    QPainterPath p3;
+    p3.lineTo(1, 1);
+    QCOMPARE(p3.elementCount(), 2);
+    QPainterPath p4 = p3;
+    QCOMPARE(p4.elementCount(), 2);
+    {
+        QFile data(tempDir.path() + "/data");
+        QVERIFY(data.open(QFile::ReadOnly));
+        QDataStream stream(&data);
+        stream >> p3;
+    }
+    QCOMPARE(p3.elementCount(), path.elementCount());
+    QCOMPARE(p4.elementCount(), 2);
 }
 
 void tst_QPainterPath::closing()