tests/auto/qpathclipper/tst_qpathclipper.cpp
changeset 0 1918ee327afb
child 4 3b1da2848fc7
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/auto/qpathclipper/tst_qpathclipper.cpp	Mon Jan 11 14:00:40 2010 +0000
@@ -0,0 +1,1423 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights.  These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+#include "private/qpathclipper_p.h"
+#include "paths.h"
+
+#include <QtTest/QtTest>
+
+#include <qpainterpath.h>
+#include <qpolygon.h>
+#include <qdebug.h>
+#include <qpainter.h>
+
+#include <math.h>
+
+class tst_QPathClipper : public QObject
+{
+    Q_OBJECT
+
+public:
+    tst_QPathClipper();
+    virtual ~tst_QPathClipper();
+
+private:
+    void clipTest(int subjectIndex, int clipIndex, QPathClipper::Operation op);
+
+    QList<QPainterPath> paths;
+
+public slots:
+    void initTestCase();
+
+private slots:
+    void testWingedEdge();
+
+    void testComparePaths();
+
+    void clip_data();
+    void clip();
+
+    void clip2();
+    void clip3();
+
+    void testIntersections();
+    void testIntersections2();
+    void testIntersections3();
+    void testIntersections4();
+    void testIntersections5();
+    void testIntersections6();
+    void testIntersections7();
+    void testIntersections8();
+    void testIntersections9();
+
+    void zeroDerivativeCurves();
+
+    void task204301_data();
+    void task204301();
+
+    void task209056();
+    void task251909();
+};
+
+Q_DECLARE_METATYPE(QPainterPath)
+Q_DECLARE_METATYPE(QPathClipper::Operation)
+
+tst_QPathClipper::tst_QPathClipper()
+{
+}
+
+tst_QPathClipper::~tst_QPathClipper()
+{
+}
+
+void tst_QPathClipper::initTestCase()
+{
+    paths << Paths::rect();
+    paths << Paths::heart();
+    paths << Paths::body();
+    paths << Paths::mailbox();
+    paths << Paths::deer();
+    paths << Paths::fire();
+
+    paths << Paths::random1();
+    paths << Paths::random2();
+
+    paths << Paths::heart2();
+    paths << Paths::rect2();
+    paths << Paths::rect3();
+    paths << Paths::rect4();
+    paths << Paths::rect5();
+    paths << Paths::rect6();
+
+    paths << Paths::frame1();
+    paths << Paths::frame2();
+    paths << Paths::frame3();
+    paths << Paths::frame4();
+
+    paths << Paths::triangle1();
+    paths << Paths::triangle2();
+
+    paths << Paths::node();
+    paths << Paths::interRect();
+
+    paths << Paths::simpleCurve();
+    paths << Paths::simpleCurve2();
+    paths << Paths::simpleCurve3();
+
+    paths << Paths::bezier1();
+    paths << Paths::bezier2();
+    paths << Paths::bezier3();
+    paths << Paths::bezier4();
+
+    paths << Paths::bezierFlower();
+    paths << Paths::lips();
+    paths << Paths::clover();
+    paths << Paths::ellipses();
+    paths << Paths::windingFill();
+    paths << Paths::oddEvenFill();
+    paths << Paths::squareWithHole();
+    paths << Paths::circleWithHole();
+    paths << Paths::bezierQuadrant();
+
+    // make sure all the bounding rects are centered at the origin
+    for (int i = 0; i < paths.size(); ++i) {
+        QRectF bounds = paths[i].boundingRect();
+
+        QMatrix m(1, 0,
+                  0, 1,
+                  -bounds.center().x(), -bounds.center().y());
+
+        paths[i] = m.map(paths[i]);
+    }
+}
+
+static QPainterPath samplePath1()
+{
+    QPainterPath path;
+    path.moveTo(QPointF(200, 246.64789));
+    path.lineTo(QPointF(200, 206.64789));
+    path.lineTo(QPointF(231.42858, 206.64789));
+    path.lineTo(QPointF(231.42858, 246.64789));
+    path.lineTo(QPointF(200, 246.64789));
+    return path;
+}
+
+static QPainterPath samplePath2()
+{
+    QPainterPath path;
+    path.moveTo(QPointF(200, 146.64789));
+    path.lineTo(QPointF(200, 106.64789));
+    path.lineTo(QPointF(231.42858, 106.64789));
+    path.lineTo(QPointF(231.42858, 146.64789));
+    path.lineTo(QPointF(200, 146.64789));
+    return path;
+}
+
+static QPainterPath samplePath3()
+{
+    QPainterPath path;
+    path.moveTo(QPointF(231.42858, 80.933609));
+    path.lineTo(QPointF(200, 80.933609));
+    path.lineTo(QPointF(200, 96.64788999999999));
+    path.lineTo(QPointF(231.42858, 96.64788999999999));
+    path.lineTo(QPointF(231.42858, 80.933609));
+    return path;
+}
+
+static QPainterPath samplePath4()
+{
+    QPainterPath path;
+    path.moveTo(QPointF(288.571434, 80.933609));
+    path.lineTo(QPointF(431.42858, 80.933609));
+    path.lineTo(QPointF(431.42858, 96.64788999999999));
+    path.lineTo(QPointF(288.571434, 96.64788999999999));
+    path.lineTo(QPointF(288.571434, 80.933609));
+    return path;
+}
+
+static QPainterPath samplePath5()
+{
+    QPainterPath path;
+    path.moveTo(QPointF(588.571434, 80.933609));
+    path.lineTo(QPointF(682.85715, 80.933609));
+    path.lineTo(QPointF(682.85715, 96.64788999999999));
+    path.lineTo(QPointF(588.571434, 96.64788999999999));
+    path.lineTo(QPointF(588.571434, 80.933609));
+    return path;
+}
+
+static QPainterPath samplePath6()
+{
+    QPainterPath path;
+    path.moveTo(QPointF(588.571434, 80.933609));
+    path.lineTo(QPointF(200, 80.933609));
+    path.lineTo(QPointF(200, 446.6479));
+    path.lineTo(QPointF(682.85715, 446.6479));
+    path.lineTo(QPointF(682.85715, 96.64788999999999));
+    path.lineTo(QPointF(731.42858, 96.64788999999999));
+    path.lineTo(QPointF(731.42858, 56.64788999999999));
+    path.lineTo(QPointF(588.571434, 56.64788999999999));
+    path.lineTo(QPointF(588.571434, 80.933609));
+    return path;
+}
+
+static QPainterPath samplePath7()
+{
+    QPainterPath path;
+    path.moveTo(QPointF(682.85715, 206.64789));
+    path.lineTo(QPointF(682.85715, 246.64789));
+    path.lineTo(QPointF(588.571434, 246.64789));
+    path.lineTo(QPointF(588.571434, 206.64789));
+    path.lineTo(QPointF(682.85715, 206.64789));
+    return path;
+}
+
+static QPainterPath samplePath8()
+{
+    QPainterPath path;
+    path.moveTo(QPointF(682.85715, 406.64789));
+    path.lineTo(QPointF(682.85715, 446.64789));
+    path.lineTo(QPointF(588.571434, 446.64789));
+    path.lineTo(QPointF(588.571434, 406.64789));
+    path.lineTo(QPointF(682.85715, 406.64789));
+    return path;
+}
+
+static QPainterPath samplePath9()
+{
+    QPainterPath path;
+    path.moveTo(QPointF(682.85715, 426.64789));
+    path.lineTo(QPointF(682.85715, 446.6479));
+    path.lineTo(QPointF(568.571434, 446.6479));
+    path.lineTo(QPointF(568.571434, 426.64789));
+    path.lineTo(QPointF(682.85715, 426.64789));
+    return path;
+}
+
+static QPainterPath samplePath10()
+{
+    QPainterPath path;
+    path.moveTo(QPointF(511.42858, 446.6479));
+    path.lineTo(QPointF(368.571434, 446.6479));
+    path.lineTo(QPointF(368.571434, 426.64789));
+    path.lineTo(QPointF(511.42858, 426.64789));
+    path.lineTo(QPointF(511.42858, 446.6479));
+    return path;
+}
+
+static QPainterPath samplePath11()
+{
+    QPainterPath path;
+    path.moveTo(QPointF(165.71429, 338.79076));
+    path.lineTo(QPointF(227.74288, 338.79076));
+    path.cubicTo(QPointF(232.95048, 338.79076),
+                 QPointF(237.14288, 342.88102),
+                 QPointF(237.14288, 347.96176));
+    path.lineTo(QPointF(237.14288, 366.76261));
+    path.cubicTo(QPointF(237.14288, 371.84335),
+                 QPointF(232.95048, 375.93361),
+                 QPointF(227.74288, 375.93361));
+    path.lineTo(QPointF(165.7142905131896, 375.93361));
+    path.lineTo(QPointF(165.71429, 338.79076));
+    return path;
+}
+static QPainterPath samplePath12()
+{
+    QPainterPath path;
+    path.moveTo(QPointF(333.297085225735, 61.53486494396167));
+    path.cubicTo(QPointF(339.851755668807, 65.26555884471786),
+                 QPointF(346.7164458828328, 69.04482864715078),
+                 QPointF(353.4159970843586, 72.56059416636147));
+    path.cubicTo(QPointF(353.4166971116034, 72.56155590850551),
+                 QPointF(353.4173961086004, 72.56251809989483),
+                 QPointF(353.4180950127331, 72.56348028832946));
+    path.cubicTo(QPointF(342.4340366381152, 76.42344228577481),
+                 QPointF(317.0596805768079, 94.67086588954379),
+                 QPointF(309.78055, 101.00195));
+    path.cubicTo(QPointF(286.0370715501102, 121.6530659984711),
+                 QPointF(272.7748256344584, 134.1525788344904),
+                 QPointF(250.7436468364447, 150.4434491585085));
+    path.lineTo(QPointF(247.03629, 146.56585));
+    path.lineTo(QPointF(240.71086, 91.501867));
+    path.cubicTo(QPointF(240.71086, 91.501867),
+                 QPointF(305.6382515924416, 62.21715375368672),
+                 QPointF(333.297085225735, 61.53486494396167));
+    return path;
+}
+
+static QPainterPath samplePath13()
+{
+    QPainterPath path;
+    path.moveTo(QPointF(160, 200));
+    path.lineTo(QPointF(100, 200));
+    path.lineTo(QPointF(100, 130));
+    path.lineTo(QPointF(160, 130));
+    path.lineTo(QPointF(160, 200));
+    return path;
+}
+
+static QPainterPath samplePath14()
+{
+    QPainterPath path;
+    path.moveTo(QPointF(100, 180));
+    path.lineTo(QPointF(100, 80));
+    path.lineTo(QPointF(120, 80));
+    path.lineTo(QPointF(120, 100));
+    path.lineTo(QPointF(160, 100));
+    path.lineTo(QPointF(160, 180));
+    path.lineTo(QPointF(100, 180));
+    return path;
+}
+
+void tst_QPathClipper::clip_data()
+{
+    //create the testtable instance and define the elements
+    QTest::addColumn<QPainterPath>("subject");
+    QTest::addColumn<QPainterPath>("clip");
+    QTest::addColumn<QPathClipper::Operation>("op");
+    QTest::addColumn<QPainterPath>("result");
+
+    //next we fill it with data
+    QTest::newRow( "simple1" )  << Paths::frame3()
+                                << Paths::frame4()
+                                << QPathClipper::BoolAnd
+                                << samplePath1();
+
+    QTest::newRow( "simple2" )  << Paths::frame3()
+                                << Paths::frame4() * QTransform().translate(0, -100)
+                                << QPathClipper::BoolAnd
+                                << samplePath2();
+
+    QTest::newRow( "simple3" )  << Paths::frame3()
+                                << Paths::frame4() * QTransform().translate(0, -150)
+                                << QPathClipper::BoolAnd
+                                << samplePath3();
+
+    QTest::newRow( "simple4" )  << Paths::frame3()
+                                << Paths::frame4() * QTransform().translate(200, -150)
+                                << QPathClipper::BoolAnd
+                                << samplePath4();
+
+    QTest::newRow( "simple5" )  << Paths::frame3()
+                                << Paths::frame4() * QTransform().translate(500, -150)
+                                << QPathClipper::BoolAnd
+                                << samplePath5();
+
+    QTest::newRow( "simple6" )  << Paths::frame3()
+                                << Paths::frame4() * QTransform().translate(500, -150)
+                                << QPathClipper::BoolOr
+                                << samplePath6();
+
+    QTest::newRow( "simple7" )  << Paths::frame3()
+                                << Paths::frame4() * QTransform().translate(500, 0)
+                                << QPathClipper::BoolAnd
+                                << samplePath7();
+
+    QTest::newRow( "simple8" )  << Paths::frame3()
+                                << Paths::frame4() * QTransform().translate(500, 200)
+                                << QPathClipper::BoolAnd
+                                << samplePath8();
+
+    QTest::newRow( "simple9" )  << Paths::frame3()
+                                << Paths::frame4() * QTransform().translate(480, 220)
+                                << QPathClipper::BoolAnd
+                                << samplePath9();
+
+    QTest::newRow( "simple10" )  << Paths::frame3()
+                                 << Paths::frame4() * QTransform().translate(280, 220)
+                                 << QPathClipper::BoolAnd
+                                 << samplePath10();
+
+    QTest::newRow( "simple11" )  << Paths::frame2()*QTransform().translate(40, 235)
+                                 << Paths::frame1()
+                                 << QPathClipper::BoolAnd
+                                 << samplePath11();
+
+    QTest::newRow( "intersection_at_edge" )  << Paths::lips()
+                                             << Paths::mailbox()*QTransform().translate(-85, 34)
+                                             << QPathClipper::BoolAnd
+                                             << samplePath12();
+
+    QTest::newRow( "simple_move_to1" )  << Paths::rect4()
+                                       << Paths::rect2() * QTransform().translate(-20, 50)
+                                       << QPathClipper::BoolAnd
+                                       << samplePath13();
+
+    QTest::newRow( "simple_move_to2" )  << Paths::rect4()
+                                        << Paths::rect2() * QTransform().translate(-20, 0)
+                                        << QPathClipper::BoolAnd
+                                        << samplePath14();
+}
+
+static const int precision = 8;
+static const qreal epsilon = pow(0.1, precision);
+
+static inline bool fuzzyIsZero(qreal x, qreal relative)
+{
+    if (qAbs(relative) < epsilon)
+        return qAbs(x) < epsilon;
+    else
+        return qAbs(x / relative) < epsilon;
+}
+
+static bool fuzzyCompare(const QPointF &a, const QPointF &b)
+{
+    const QPointF delta = a - b;
+
+    const qreal x = qMax(qAbs(a.x()), qAbs(b.x()));
+    const qreal y = qMax(qAbs(a.y()), qAbs(b.y()));
+
+    return fuzzyIsZero(delta.x(), x) && fuzzyIsZero(delta.y(), y);
+}
+
+static bool isClosed(const QPainterPath &path)
+{
+    if (path.elementCount() == 0)
+        return false;
+
+    QPointF first = path.elementAt(0);
+    QPointF last = path.elementAt(path.elementCount() - 1);
+
+    return fuzzyCompare(first, last);
+}
+
+// rotation and direction independent path comparison
+// allows paths to be shifted or reversed relative to each other
+static bool comparePaths(const QPainterPath &actual, const QPainterPath &expected)
+{
+    const int endActual = isClosed(actual) ? actual.elementCount() - 1 : actual.elementCount();
+    const int endExpected = isClosed(expected) ? expected.elementCount() - 1 : expected.elementCount();
+
+    if (endActual != endExpected)
+        return false;
+
+    for (int i = 0; i < endActual; ++i) {
+        int k = 0;
+        for (k = 0; k < endActual; ++k) {
+            int i1 = k;
+            int i2 = (i + k) % endActual;
+
+            QPointF a = actual.elementAt(i1);
+            QPointF b = expected.elementAt(i2);
+
+            if (!fuzzyCompare(a, b))
+                break;
+        }
+
+        if (k == endActual)
+            return true;
+
+        for (k = 0; k < endActual; ++k) {
+            int i1 = k;
+            int i2 = (i + endActual - k) % endActual;
+
+            QPointF a = actual.elementAt(i1);
+            QPointF b = expected.elementAt(i2);
+
+            if (!fuzzyCompare(a, b))
+                break;
+        }
+
+        if (k == endActual)
+            return true;
+    }
+
+    return false;
+}
+
+// sanity check to make sure comparePaths declared above works
+void tst_QPathClipper::testComparePaths()
+{
+    QPainterPath a;
+    QPainterPath b;
+
+    a.addRect(0, 0, 10, 10);
+    b.addRect(0, 0, 10.00001, 10.00001);
+
+    QVERIFY(!comparePaths(a, b));
+
+    b = QPainterPath();
+    b.addRect(0, 0, 10.00000000001, 10.00000000001);
+
+    QVERIFY(comparePaths(a, b));
+
+    b = QPainterPath();
+    b.moveTo(10, 0);
+    b.lineTo(0, 0);
+    b.lineTo(0, 10);
+    b.lineTo(10, 10);
+
+    QVERIFY(comparePaths(a, b));
+    b.lineTo(10, 0);
+    QVERIFY(comparePaths(a, b));
+
+    b = QPainterPath();
+    b.moveTo(10, 0);
+    b.lineTo(0, 10);
+    b.lineTo(0, 0);
+    b.lineTo(10, 10);
+
+    QVERIFY(!comparePaths(a, b));
+}
+
+void tst_QPathClipper::clip()
+{
+    if (sizeof(double) != sizeof(qreal)) {
+        QSKIP("This test only works for qreal=double, otherwise ends in rounding errors", SkipAll);
+    }
+    QFETCH( QPainterPath, subject );
+    QFETCH( QPainterPath, clip );
+    QFETCH( QPathClipper::Operation, op );
+    QFETCH( QPainterPath,  result);
+    QPathClipper clipper(subject, clip);
+    QPainterPath x = clipper.clip(op);
+
+    QVERIFY(comparePaths(x, result));
+}
+
+static inline QPointF randomPointInRect(const QRectF &rect)
+{
+    qreal rx = qrand() / (RAND_MAX + 1.);
+    qreal ry = qrand() / (RAND_MAX + 1.);
+
+    return QPointF(rect.left() + rx * rect.width(),
+                   rect.top() + ry * rect.height());
+}
+
+void tst_QPathClipper::clipTest(int subjectIndex, int clipIndex, QPathClipper::Operation op)
+{
+    const QPainterPath &subject = paths[subjectIndex];
+    const QPainterPath &clip = paths[clipIndex];
+    const int count = 40;
+
+    QRectF bounds = subject.boundingRect().united(clip.boundingRect());
+
+    const qreal adjustX = bounds.width() * 0.01;
+    const qreal adjustY = bounds.height() * 0.01;
+
+    // make sure we test some points that are outside both paths as well
+    bounds = bounds.adjusted(-adjustX, -adjustY, adjustX, adjustY);
+
+    const int dim = 256;
+    const qreal scale = qMin(dim / bounds.width(), dim / bounds.height());
+
+    QPathClipper clipper(subject, clip);
+    QPainterPath result = clipper.clip(op);
+
+    // using the image here is a bit of a hacky way to make sure we don't test points that
+    // are too close to the path edges to avoid test fails that are due to numerical errors
+    QImage img(dim, dim, QImage::Format_ARGB32_Premultiplied);
+    img.fill(0x0);
+    QPainter p(&img);
+    p.setRenderHint(QPainter::Antialiasing);
+    p.scale(scale, scale);
+    p.translate(-bounds.topLeft());
+    p.setPen(Qt::black);
+    p.drawPath(subject);
+    p.setPen(Qt::red);
+    p.drawPath(clip);
+    p.end();
+
+    for (int i = 0; i < count; ++i) {
+        QPointF point;
+        QRgb pixel;
+        do {
+            point = randomPointInRect(bounds);
+            const QPointF imagePoint = (point - bounds.topLeft()) * scale;
+
+            pixel = img.pixel(int(imagePoint.x()), int(imagePoint.y()));
+        } while (qAlpha(pixel) > 0);
+
+        const bool inSubject = subject.contains(point);
+        const bool inClip = clip.contains(point);
+
+        const bool inResult = result.contains(point);
+
+        bool expected = false;
+        switch (op) {
+        case QPathClipper::BoolAnd:
+            expected = inSubject && inClip;
+            break;
+        case QPathClipper::BoolOr:
+            expected = inSubject || inClip;
+            break;
+        case QPathClipper::BoolSub:
+            expected = inSubject && !inClip;
+            break;
+        default:
+            break;
+        }
+
+        if (expected != inResult) {
+            char str[256];
+            const char *opStr =
+                 op == QPathClipper::BoolAnd ? "and" :
+                 op == QPathClipper::BoolOr ? "or" : "sub";
+            sprintf(str, "Expected: %d, actual: %d, subject: %d, clip: %d, op: %s\n",
+                     int(expected), int(inResult), subjectIndex, clipIndex, opStr);
+
+            // debugging
+#if 0
+            QRect rect = bounds.toAlignedRect();
+
+            QPainter p(&img);
+            p.scale(scale, scale);
+            p.translate(-bounds.topLeft());
+
+            p.setPen(Qt::NoPen);
+            p.setBrush(QColor(0x700ff00));
+            p.drawPath(result);
+
+            p.setPen(Qt::blue);
+            p.drawPoint(point);
+            p.end();
+
+            char str2[256];
+            sprintf(str2, "fail-%d-%d-%s.png", subjectIndex, clipIndex, opStr);
+            img.save(str2);
+#endif
+            QFAIL(str);
+        }
+    }
+}
+
+void tst_QPathClipper::clip2()
+{
+    if (sizeof(double) != sizeof(qreal))
+        QSKIP("This test only works for qreal=double, otherwise ends in rounding errors", SkipAll);
+
+    int operation = 0;
+
+    for (int i = 0; i < paths.size(); ++i) {
+        for (int j = 0; j <= i; ++j) {
+            QPathClipper::Operation op = QPathClipper::Operation((operation++) % 3);
+            clipTest(i, j, op);
+        }
+    }
+}
+
+void tst_QPathClipper::clip3()
+{
+    int operation = 0;
+
+    // this subset should work correctly for qreal = float
+    for (int i = 0; i < 20; ++i) {
+        for (int j = 0; j <= i; ++j) {
+            QPathClipper::Operation op = QPathClipper::Operation((operation++) % 3);
+            clipTest(i, j, op);
+        }
+    }
+}
+
+void tst_QPathClipper::testIntersections()
+{
+    QPainterPath path1;
+    QPainterPath path2;
+
+    path1.addRect(0, 0, 100, 100);
+    path2.addRect(20, 20, 20, 20);
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+    QVERIFY(path1.contains(path2));
+    QVERIFY(!path2.contains(path1));
+
+    path1 = QPainterPath();
+    path2 = QPainterPath();
+    path1.addEllipse(0, 0, 100, 100);
+    path2.addEllipse(200, 200, 100, 100);
+    QVERIFY(!path1.intersects(path2));
+    QVERIFY(!path2.intersects(path1));
+    QVERIFY(!path1.contains(path2));
+    QVERIFY(!path2.contains(path1));
+
+    path1 = QPainterPath();
+    path2 = QPainterPath();
+    path1.addEllipse(0, 0, 100, 100);
+    path2.addEllipse(50, 50, 100, 100);
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+    QVERIFY(!path1.contains(path2));
+    QVERIFY(!path2.contains(path1));
+
+    path1 = QPainterPath();
+    path2 = QPainterPath();
+    path1.addRect(100, 100, 100, 100);
+    path2.addRect(50, 100, 100, 20);
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+    QVERIFY(!path1.contains(path2));
+    QVERIFY(!path2.contains(path1));
+
+    path1 = QPainterPath();
+    path2 = QPainterPath();
+    path1.addRect(100, 100, 100, 100);
+    path2.addRect(110, 201, 100, 20);
+    QVERIFY(!path1.intersects(path2));
+    QVERIFY(!path2.intersects(path1));
+    QVERIFY(!path1.contains(path2));
+    QVERIFY(!path2.contains(path1));
+
+    path1 = QPainterPath();
+    path2 = QPainterPath();
+    path1.addRect(0, 0, 100, 100);
+    path2.addRect(20, 20, 20, 20);
+    path2.addRect(25, 25, 5, 5);
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+    QVERIFY(path1.contains(path2));
+    QVERIFY(!path2.contains(path1));
+}
+
+void tst_QPathClipper::testIntersections2()
+{
+    QPainterPath path1;
+    QPainterPath path2;
+
+    path1 = QPainterPath();
+    path2 = QPainterPath();
+
+    path1.moveTo(-8,-8);
+    path1.lineTo(107,-8);
+    path1.lineTo(107,107);
+    path1.lineTo(-8,107);
+
+    path2.moveTo(0,0);
+    path2.lineTo(100,0);
+    path2.lineTo(100,100);
+    path2.lineTo(0,100);
+    path2.lineTo(0,0);
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+    QVERIFY(path1.contains(path2));
+    QVERIFY(!path2.contains(path1));
+
+    path1.closeSubpath();
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+    QVERIFY(path1.contains(path2));
+    QVERIFY(!path2.contains(path1));
+}
+
+void tst_QPathClipper::testIntersections3()
+{
+    QPainterPath path1 = Paths::node();
+    QPainterPath path2 = Paths::interRect();
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+}
+
+void tst_QPathClipper::testIntersections4()
+{
+    QPainterPath path1;
+    QPainterPath path2;
+
+    path1.moveTo(-5, 0);
+    path1.lineTo(5, 0);
+
+    path2.moveTo(0, -5);
+    path2.lineTo(0, 5);
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+}
+
+void tst_QPathClipper::testIntersections5()
+{
+    QPainterPath path1;
+    QPainterPath path2;
+
+    path1.addRect(0, 0, 4, 4);
+    path1.addRect(2, 1, 1, 1);
+    path2.addRect(0.5, 2, 1, 1);
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+}
+
+void tst_QPathClipper::testIntersections6()
+{
+    QPainterPath path1;
+    QPainterPath path2;
+
+    path1.moveTo(QPointF(-115.567, -98.3254));
+    path1.lineTo(QPointF(-45.9007, -98.3254));
+    path1.lineTo(QPointF(-45.9007, -28.6588));
+    path1.lineTo(QPointF(-115.567, -28.6588));
+
+    path2.moveTo(QPointF(-110, -110));
+    path2.lineTo(QPointF(110, -110));
+    path2.lineTo(QPointF(110, 110));
+    path2.lineTo(QPointF(-110, 110));
+    path2.lineTo(QPointF(-110, -110));
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+}
+
+
+void tst_QPathClipper::testIntersections7()
+{
+    QPainterPath path1;
+    QPainterPath path2;
+
+    path1.addRect(0, 0, 10, 10);
+    path2.addRect(5, 0, 10, 10);
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+
+    path1 = QPainterPath();
+    path2 = QPainterPath();
+    path1.addRect(0, 0, 10, 10);
+    path2.addRect(0, 5, 10, 10);
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+
+    path1 = QPainterPath();
+    path2 = QPainterPath();
+    path1.addRect(0, 0, 10, 10);
+    path2.addRect(0, 0, 10, 10);
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+
+    ///
+    path1 = QPainterPath();
+    path2 = QPainterPath();
+    path1.addRect(1, 1, 10, 10);
+    path2.addRect(5, 1, 10, 10);
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+
+    path1 = QPainterPath();
+    path2 = QPainterPath();
+    path1.addRect(1, 1, 10, 10);
+    path2.addRect(1, 5, 10, 10);
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+
+    path1 = QPainterPath();
+    path2 = QPainterPath();
+    path1.addRect(1, 1, 10, 10);
+    path2.addRect(1, 1, 10, 10);
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+
+    path1 = QPainterPath();
+    path2 = QPainterPath();
+    path1.addRect(1, 1, 10, 10);
+    path2.addRect(5, 5, 10, 10);
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+
+    path1 = QPainterPath();
+    path2 = QPainterPath();
+    path1.addRect(1, 1, 10, 10);
+    path2.addRect(9, 9, 10, 10);
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+
+    path1 = QPainterPath();
+    path2 = QPainterPath();
+    path1.addRect(1, 1, 10, 10);
+    path2.addRect(10, 10, 10, 10);
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+
+    path1 = QPainterPath();
+    path2 = QPainterPath();
+    path1.addRect(1, 1, 9, 9);
+    path2.addRect(11, 11, 10, 10);
+
+    QVERIFY(!path1.intersects(path2));
+    QVERIFY(!path2.intersects(path1));
+
+    path1 = QPainterPath();
+    path2 = QPainterPath();
+    path1.addRect(1, 1, 10, 10);
+    path2.addRect(12, 12, 10, 10);
+
+    QVERIFY(!path1.intersects(path2));
+    QVERIFY(!path2.intersects(path1));
+
+    path1 = QPainterPath();
+    path2 = QPainterPath();
+    path1.addRect(11, 11, 10, 10);
+    path2.addRect(12, 12, 10, 10);
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+
+    path1 = QPainterPath();
+    path2 = QPainterPath();
+    path1.addRect(11, 11, 10, 10);
+    path2.addRect(10, 10, 10, 10);
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+}
+
+
+void tst_QPathClipper::testIntersections8()
+{
+    QPainterPath path1 = Paths::node() * QTransform().translate(100, 50);
+    QPainterPath path2 = Paths::node() * QTransform().translate(150, 50);;
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+
+    path1 = Paths::node();
+    path2 = Paths::node();
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+
+    path1 = Paths::node();
+    path2 = Paths::node() * QTransform().translate(0, 30);
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+
+    path1 = Paths::node();
+    path2 = Paths::node() * QTransform().translate(30, 0);
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+
+    path1 = Paths::node();
+    path2 = Paths::node() * QTransform().translate(30, 30);
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+
+    path1 = Paths::node();
+    path2 = Paths::node() * QTransform().translate(1, 1);
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+}
+
+
+void tst_QPathClipper::testIntersections9()
+{
+    QPainterPath path1;
+    QPainterPath path2;
+
+    path1.addRect(QRectF(-1,143, 146, 106));
+    path2.addRect(QRectF(-9,145, 150, 100));
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+
+    path1 = QPainterPath();;
+    path2 = QPainterPath();
+
+    path1.addRect(QRectF(-1,191, 136, 106));
+    path2.addRect(QRectF(-19,194, 150, 100));
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+
+    path1 = QPainterPath();;
+    path2 = QPainterPath();
+
+    path1.moveTo(-1 ,  143);
+    path1.lineTo(148 ,  143);
+    path1.lineTo(148 ,  250);
+    path1.lineTo(-1 ,  250);
+
+    path2.moveTo(-5 ,  146);
+    path2.lineTo(145 ,  146);
+    path2.lineTo(145 ,  246);
+    path2.lineTo(-5 ,  246);
+    path2.lineTo(-5 ,  146);
+
+    QVERIFY(path1.intersects(path2));
+    QVERIFY(path2.intersects(path1));
+}
+
+QPainterPath pathFromRect(qreal x, qreal y, qreal w, qreal h)
+{
+    QPainterPath path;
+    path.addRect(QRectF(x, y, w, h));
+    return path;
+}
+
+QPainterPath pathFromLine(qreal x1, qreal y1, qreal x2, qreal y2)
+{
+    QPainterPath path;
+    path.moveTo(x1, y1);
+    path.lineTo(x2, y2);
+    return path;
+}
+
+static int loopLength(const QWingedEdge &list, QWingedEdge::TraversalStatus status)
+{
+    int start = status.edge;
+
+    int length = 0;
+    do {
+        ++length;
+        status = list.next(status);
+    } while (status.edge != start);
+
+    return length;
+}
+
+void tst_QPathClipper::testWingedEdge()
+{
+    {
+        QWingedEdge list;
+        int e1 = list.addEdge(QPointF(0, 0), QPointF(10, 0));
+        int e2 = list.addEdge(QPointF(0, 0), QPointF(0, 10));
+        int e3 = list.addEdge(QPointF(0, 0), QPointF(-10, 0));
+        int e4 = list.addEdge(QPointF(0, 0), QPointF(0, -10));
+
+        QCOMPARE(list.edgeCount(), 4);
+        QCOMPARE(list.vertexCount(), 5);
+
+        QWingedEdge::TraversalStatus status = { e1, QPathEdge::RightTraversal, QPathEdge::Forward };
+
+        status = list.next(status);
+        QCOMPARE(status.direction, QPathEdge::Backward);
+        QCOMPARE(status.traversal, QPathEdge::LeftTraversal);
+        QCOMPARE(status.edge, e1);
+
+        status = list.next(status);
+        QCOMPARE(status.direction, QPathEdge::Forward);
+        QCOMPARE(status.traversal, QPathEdge::RightTraversal);
+        QCOMPARE(status.edge, e4);
+
+        status = list.next(status);
+        QCOMPARE(status.direction, QPathEdge::Backward);
+        QCOMPARE(status.traversal, QPathEdge::LeftTraversal);
+        QCOMPARE(status.edge, e4);
+
+        status = list.next(status);
+        QCOMPARE(status.direction, QPathEdge::Forward);
+        QCOMPARE(status.traversal, QPathEdge::RightTraversal);
+        QCOMPARE(status.edge, e3);
+
+        status = list.next(status);
+        QCOMPARE(status.direction, QPathEdge::Backward);
+        QCOMPARE(status.traversal, QPathEdge::LeftTraversal);
+        QCOMPARE(status.edge, e3);
+
+        status = list.next(status);
+        QCOMPARE(status.direction, QPathEdge::Forward);
+        QCOMPARE(status.traversal, QPathEdge::RightTraversal);
+        QCOMPARE(status.edge, e2);
+
+        status = list.next(status);
+        QCOMPARE(status.direction, QPathEdge::Backward);
+        QCOMPARE(status.traversal, QPathEdge::LeftTraversal);
+        QCOMPARE(status.edge, e2);
+
+        status = list.next(status);
+        QCOMPARE(status.direction, QPathEdge::Forward);
+        QCOMPARE(status.traversal, QPathEdge::RightTraversal);
+        QCOMPARE(status.edge, e1);
+    }
+    {
+        QWingedEdge list;
+        int e1 = list.addEdge(QPointF(5, 0), QPointF(5, 10));
+        int e2 = list.addEdge(QPointF(5, 0), QPointF(10, 5));
+        int e3 = list.addEdge(QPointF(10, 5), QPointF(5, 10));
+        int e4 = list.addEdge(QPointF(5, 0), QPointF(0, 5));
+        int e5 = list.addEdge(QPointF(0, 5), QPointF(5, 10));
+
+        QCOMPARE(list.edgeCount(), 5);
+        QCOMPARE(list.vertexCount(), 4);
+
+        QWingedEdge::TraversalStatus status = { e1, QPathEdge::RightTraversal, QPathEdge::Forward };
+
+        status = list.next(status);
+        QCOMPARE(status.direction, QPathEdge::Backward);
+        QCOMPARE(status.traversal, QPathEdge::LeftTraversal);
+        QCOMPARE(status.edge, e5);
+
+        status = list.next(status);
+        QCOMPARE(status.direction, QPathEdge::Backward);
+        QCOMPARE(status.traversal, QPathEdge::LeftTraversal);
+        QCOMPARE(status.edge, e4);
+
+        status = list.next(status);
+        QCOMPARE(status.direction, QPathEdge::Forward);
+        QCOMPARE(status.traversal, QPathEdge::RightTraversal);
+        QCOMPARE(status.edge, e1);
+
+        QCOMPARE(loopLength(list, status), 3);
+
+        status.flip();
+        QCOMPARE(status.direction, QPathEdge::Backward);
+        QCOMPARE(status.traversal, QPathEdge::LeftTraversal);
+        QCOMPARE(loopLength(list, status), 3);
+
+        status = list.next(status);
+        QCOMPARE(status.direction, QPathEdge::Forward);
+        QCOMPARE(status.traversal, QPathEdge::RightTraversal);
+        QCOMPARE(status.edge, e2);
+
+        status = list.next(status);
+        QCOMPARE(status.direction, QPathEdge::Forward);
+        QCOMPARE(status.traversal, QPathEdge::RightTraversal);
+        QCOMPARE(status.edge, e3);
+
+        status = list.next(status);
+        QCOMPARE(status.direction, QPathEdge::Backward);
+        QCOMPARE(status.traversal, QPathEdge::LeftTraversal);
+        QCOMPARE(status.edge, e1);
+
+        status = list.next(status);
+        status.flip();
+        QCOMPARE(status.direction, QPathEdge::Backward);
+        QCOMPARE(status.traversal, QPathEdge::LeftTraversal);
+        QCOMPARE(status.edge, e2);
+        QCOMPARE(loopLength(list, status), 4);
+
+        status = list.next(status);
+        QCOMPARE(status.direction, QPathEdge::Forward);
+        QCOMPARE(status.traversal, QPathEdge::RightTraversal);
+        QCOMPARE(status.edge, e4);
+
+        status = list.next(status);
+        QCOMPARE(status.direction, QPathEdge::Forward);
+        QCOMPARE(status.traversal, QPathEdge::RightTraversal);
+        QCOMPARE(status.edge, e5);
+
+        status = list.next(status);
+        QCOMPARE(status.direction, QPathEdge::Backward);
+        QCOMPARE(status.traversal, QPathEdge::LeftTraversal);
+        QCOMPARE(status.edge, e3);
+
+        status = list.next(status);
+        QCOMPARE(status.direction, QPathEdge::Backward);
+        QCOMPARE(status.traversal, QPathEdge::LeftTraversal);
+        QCOMPARE(status.edge, e2);
+    }
+    {
+        QPainterPath path = pathFromRect(0, 0, 20, 20);
+        QWingedEdge list(path, QPainterPath());
+
+        QCOMPARE(list.edgeCount(), 4);
+        QCOMPARE(list.vertexCount(), 4);
+
+        QWingedEdge::TraversalStatus status = { 0, QPathEdge::RightTraversal, QPathEdge::Forward };
+
+        QPathEdge *edge = list.edge(status.edge);
+        QCOMPARE(QPointF(*list.vertex(edge->first)), QPointF(0, 0));
+        QCOMPARE(QPointF(*list.vertex(edge->second)), QPointF(20, 0));
+
+        status = list.next(status);
+        QCOMPARE(status.edge, 1);
+
+        status = list.next(status);
+        QCOMPARE(status.edge, 2);
+
+        status = list.next(status);
+        QCOMPARE(status.edge, 3);
+
+        status = list.next(status);
+        QCOMPARE(status.edge, 0);
+
+        status.flipDirection();
+        status = list.next(status);
+        QCOMPARE(status.edge, 3);
+
+        status = list.next(status);
+        QCOMPARE(status.edge, 2);
+
+        status = list.next(status);
+        QCOMPARE(status.edge, 1);
+
+        status = list.next(status);
+        QCOMPARE(status.edge, 0);
+
+        QWingedEdge list2(path, pathFromRect(10, 5, 20, 10));
+
+        QCOMPARE(list2.edgeCount(), 12);
+        QCOMPARE(list2.vertexCount(), 10);
+
+        status.flipDirection();
+        QCOMPARE(loopLength(list2, status), 8);
+
+        status = list2.next(status);
+        edge = list2.edge(status.edge);
+        QCOMPARE(QPointF(*list2.vertex(edge->first)), QPointF(20, 0));
+        QCOMPARE(QPointF(*list2.vertex(edge->second)), QPointF(20, 5));
+
+        status = list2.next(status);
+        status.flipTraversal();
+
+        edge = list2.edge(status.edge);
+        QCOMPARE(QPointF(*list2.vertex(edge->first)), QPointF(10, 5));
+        QCOMPARE(QPointF(*list2.vertex(edge->second)), QPointF(20, 5));
+
+        QCOMPARE(loopLength(list2, status), 4);
+
+        status.flipDirection();
+        status = list2.next(status);
+        status.flipTraversal();
+
+        edge = list2.edge(status.edge);
+        QCOMPARE(QPointF(*list2.vertex(edge->first)), QPointF(20, 5));
+        QCOMPARE(QPointF(*list2.vertex(edge->second)), QPointF(20, 15));
+
+        QCOMPARE(loopLength(list2, status), 4);
+        status = list2.next(status);
+        status = list2.next(status);
+
+        edge = list2.edge(status.edge);
+        QCOMPARE(QPointF(*list2.vertex(edge->first)), QPointF(30, 5));
+        QCOMPARE(QPointF(*list2.vertex(edge->second)), QPointF(30, 15));
+    }
+}
+
+void tst_QPathClipper::zeroDerivativeCurves()
+{
+    // zero derivative at end
+    {
+        QPainterPath a;
+        a.cubicTo(100, 0, 100, 100, 100, 100);
+        a.lineTo(100, 200);
+        a.lineTo(0, 200);
+
+        QPainterPath b;
+        b.moveTo(50, 100);
+        b.lineTo(150, 100);
+        b.lineTo(150, 150);
+        b.lineTo(50, 150);
+
+        QPainterPath c = a.united(b);
+        QVERIFY(c.contains(QPointF(25, 125)));
+        QVERIFY(c.contains(QPointF(75, 125)));
+        QVERIFY(c.contains(QPointF(125, 125)));
+    }
+
+    // zero derivative at start
+    {
+        QPainterPath a;
+        a.cubicTo(100, 0, 100, 100, 100, 100);
+        a.lineTo(100, 200);
+        a.lineTo(0, 200);
+
+        QPainterPath b;
+        b.moveTo(50, 100);
+        b.lineTo(150, 100);
+        b.lineTo(150, 150);
+        b.lineTo(50, 150);
+
+        QPainterPath c = a.united(b);
+        QVERIFY(c.contains(QPointF(25, 125)));
+        QVERIFY(c.contains(QPointF(75, 125)));
+        QVERIFY(c.contains(QPointF(125, 125)));
+    }
+}
+
+static bool strictContains(const QPainterPath &a, const QPainterPath &b)
+{
+    return b.subtracted(a) == QPainterPath();
+}
+
+Q_DECLARE_METATYPE(QPolygonF)
+
+void tst_QPathClipper::task204301_data()
+{
+    QTest::addColumn<QPolygonF>("points");
+
+    {
+        QPointF a(51.09013255685567855835, 31.30814891308546066284);
+        QPointF b(98.39898971840739250183, 11.02079074829816818237);
+        QPointF c(91.23911846894770860672, 45.86981737054884433746);
+        QPointF d(66.58616356085985898972, 63.10526528395712375641);
+        QPointF e(82.08219456479714892794, 94.90238165489137145414);
+        QPointF f(16.09013040543221251255, 105.66263409332729850121);
+        QPointF g(10.62811442650854587555, 65.09154842235147953033);
+        QPointF h(5.16609844751656055450, 24.52046275138854980469);
+        QPolygonF v;
+        v << a << b << c << d << e << f << g << h;
+        QTest::newRow("failed_on_linux") << v;
+    }
+
+    {
+        QPointF a(50.014648437500000, 24.392089843750000);
+        QPointF b(92.836303710937500, 5.548706054687500);
+        QPointF c(92.145690917968750, 54.390258789062500);
+        QPointF d(65.402221679687500, 74.345092773437500);
+        QPointF e(80.789794921787347, 124.298095703129690);
+        QPointF f(34.961242675812954, 87.621459960852135);
+        QPointF g(18.305969238281250, 57.426757812500000);
+        QPointF h(1.650695800781250, 27.232055664062500);
+        QPolygonF v;
+        v << a << b << c << d << e << f << g << h;
+        QTest::newRow("failed_on_windows") << v;
+    }
+}
+
+void tst_QPathClipper::task204301()
+{
+    QFETCH(QPolygonF, points);
+
+    QPointF a = points[0];
+    QPointF b = points[1];
+    QPointF c = points[2];
+    QPointF d = points[3];
+    QPointF e = points[4];
+    QPointF f = points[5];
+    QPointF g = points[6];
+    QPointF h = points[7];
+
+    QPainterPath subA;
+    subA.addPolygon(QPolygonF() << a << b << c << d);
+    subA.closeSubpath();
+
+    QPainterPath subB;
+    subB.addPolygon(QPolygonF() << f << e << d << g);
+    subB.closeSubpath();
+
+    QPainterPath subC;
+    subC.addPolygon(QPolygonF() << h << a << d << g);
+    subC.closeSubpath();
+
+    QPainterPath path;
+    path.addPath(subA);
+    path.addPath(subB);
+    path.addPath(subC);
+
+    QPainterPath simplified = path.simplified();
+
+    QVERIFY(strictContains(simplified, subA));
+    QVERIFY(strictContains(simplified, subB));
+    QVERIFY(strictContains(simplified, subC));
+}
+
+void tst_QPathClipper::task209056()
+{
+    QPainterPath p1;
+    p1.moveTo( QPointF(188.506, 287.793) );
+    p1.lineTo( QPointF(288.506, 287.793) );
+    p1.lineTo( QPointF(288.506, 387.793) );
+    p1.lineTo( QPointF(188.506, 387.793) );
+    p1.lineTo( QPointF(188.506, 287.793) );
+
+    QPainterPath p2;
+    p2.moveTo( QPointF(419.447, 164.383) );
+    p2.cubicTo( QPointF(419.447, 69.5486), QPointF(419.447, 259.218),QPointF(419.447, 164.383) );
+
+    p2.cubicTo( QPointF(48.9378, 259.218), QPointF(131.879, 336.097),QPointF(234.192, 336.097) );
+    p2.cubicTo( QPointF(336.506, 336.097), QPointF(419.447, 259.218),QPointF(419.447, 164.383) );
+
+    QPainterPath p3 = p1.intersected(p2);
+
+    QVERIFY(p3 != QPainterPath());
+}
+
+void tst_QPathClipper::task251909()
+{
+    QPainterPath p1;
+    p1.moveTo(0, -10);
+    p1.lineTo(10, -10);
+    p1.lineTo(10, 0);
+    p1.lineTo(0, 0);
+
+    QPainterPath p2;
+    p2.moveTo(0, 8e-14);
+    p2.lineTo(10, -8e-14);
+    p2.lineTo(10, 10);
+    p2.lineTo(0, 10);
+
+    QPainterPath result = p1.united(p2);
+
+    QVERIFY(result.elementCount() <= 5);
+}
+
+QTEST_APPLESS_MAIN(tst_QPathClipper)
+
+
+#include "tst_qpathclipper.moc"