Fixed bugs in QPainterPath::united().

Change from a relative to an absolute fuzzy compare as was the case
pre-4.4. With a relative fuzzy compare points that have an x or y
coordinate of 0 will never be merged with points that are very close to
0, for example (1e-15, 0).

Task-number: 251909
Reviewed-by: Trond

2 files changed, 62 insertions, 27 deletions

diff --git a/src/gui/painting/qpathclipper.cpp b/src/gui/painting/qpathclipper.cpp
index 544b838..d4c92cc 100644
--- a/src/gui/painting/qpathclipper.cpp
+++ b/src/gui/painting/qpathclipper.cpp
@@ -45,9 +45,6 @@
 #include <private/qdatabuffer_p.h>
 #include <qmath.h>
 
-#include <QImage>
-#include <QPainter>
-
 /**
   The algorithm is as follows:
 
@@ -68,6 +65,20 @@
 
 QT_BEGIN_NAMESPACE
 
+static inline bool fuzzyIsNull(qreal d)
+{
+    if (sizeof(qreal) == sizeof(double))
+        return qAbs(d) <= 1e-12;
+    else
+        return qAbs(d) <= 1e-5f;
+}
+
+static inline bool comparePoints(const QPointF &a, const QPointF &b)
+{
+    return fuzzyIsNull(a.x() - b.x())
+           && fuzzyIsNull(a.y() - b.y());
+}
+
 //#define QDEBUG_CLIPPER
 static qreal dot(const QPointF &a, const QPointF &b)
 {
@@ -105,8 +116,10 @@ private:
 
 bool QIntersectionFinder::beziersIntersect(const QBezier &one, const QBezier &two) const
 {
-    return (one.pt1() == two.pt1() && one.pt2() == two.pt2() && one.pt3() == two.pt3() && one.pt4() == two.pt4())
-           || (one.pt1() == two.pt4() && one.pt2() == two.pt3() && one.pt3() == two.pt2() && one.pt4() == two.pt1())
+    return (comparePoints(one.pt1(), two.pt1()) && comparePoints(one.pt2(), two.pt2())
+            && comparePoints(one.pt3(), two.pt3()) && comparePoints(one.pt4(), two.pt4()))
+           || (comparePoints(one.pt1(), two.pt4()) && comparePoints(one.pt2(), two.pt3())
+               && comparePoints(one.pt3(), two.pt2()) && comparePoints(one.pt4(), two.pt1()))
            || QBezier::findIntersections(one, two, 0);
 }
 
@@ -118,17 +131,17 @@ bool QIntersectionFinder::linesIntersect(const QLineF &a, const QLineF &b) const
     const QPointF q1 = b.p1();
     const QPointF q2 = b.p2();
 
-    if (p1 == p2 || q1 == q2)
+    if (comparePoints(p1, p2) || comparePoints(q1, q2))
         return false;
 
-    const bool p1_equals_q1 = (p1 == q1);
-    const bool p2_equals_q2 = (p2 == q2);
+    const bool p1_equals_q1 = comparePoints(p1, q1);
+    const bool p2_equals_q2 = comparePoints(p2, q2);
 
     if (p1_equals_q1 && p2_equals_q2)
         return true;
 
-    const bool p1_equals_q2 = (p1 == q2);
-    const bool p2_equals_q1 = (p2 == q1);
+    const bool p1_equals_q2 = comparePoints(p1, q2);
+    const bool p2_equals_q1 = comparePoints(p2, q1);
 
     if (p1_equals_q2 && p2_equals_q1)
         return true;
@@ -184,8 +197,10 @@ bool QIntersectionFinder::linesIntersect(const QLineF &a, const QLineF &b) const
 
 void QIntersectionFinder::intersectBeziers(const QBezier &one, const QBezier &two, QVector<QPair<qreal, qreal> > &t, QDataBuffer<QIntersection> &intersections)
 {
-    if ((one.pt1() == two.pt1() && one.pt2() == two.pt2() && one.pt3() == two.pt3() && one.pt4() == two.pt4())
-        || (one.pt1() == two.pt4() && one.pt2() == two.pt3() && one.pt3() == two.pt2() && one.pt4() == two.pt1())) {
+    if ((comparePoints(one.pt1(), two.pt1()) && comparePoints(one.pt2(), two.pt2())
+         && comparePoints(one.pt3(), two.pt3()) && comparePoints(one.pt4(), two.pt4()))
+        || (comparePoints(one.pt1(), two.pt4()) && comparePoints(one.pt2(), two.pt3())
+            && comparePoints(one.pt3(), two.pt2()) && comparePoints(one.pt4(), two.pt1()))) {
 
         return;
     }
@@ -230,17 +245,17 @@ void QIntersectionFinder::intersectLines(const QLineF &a, const QLineF &b, QData
     const QPointF q1 = b.p1();
     const QPointF q2 = b.p2();
 
-    if (p1 == p2 || q1 == q2)
+    if (comparePoints(p1, p2) || comparePoints(q1, q2))
         return;
 
-    const bool p1_equals_q1 = (p1 == q1);
-    const bool p2_equals_q2 = (p2 == q2);
+    const bool p1_equals_q1 = comparePoints(p1, q1);
+    const bool p2_equals_q2 = comparePoints(p2, q2);
 
     if (p1_equals_q1 && p2_equals_q2)
         return;
 
-    const bool p1_equals_q2 = (p1 == q2);
-    const bool p2_equals_q1 = (p2 == q1);
+    const bool p1_equals_q2 = comparePoints(p1, q2);
+    const bool p2_equals_q1 = comparePoints(p2, q1);
 
     if (p1_equals_q2 && p2_equals_q1)
         return;
@@ -624,11 +639,11 @@ public:
         const qreal pivot = pivotComponents[depth & 1];
         const qreal value = pointComponents[depth & 1];
 
-        if (qFuzzyCompare(pivot, value)) {
+        if (fuzzyIsNull(pivot - value)) {
             const qreal pivot2 = pivotComponents[(depth + 1) & 1];
             const qreal value2 = pointComponents[(depth + 1) & 1];
 
-            if (qFuzzyCompare(pivot2, value2)) {
+            if (fuzzyIsNull(pivot2 - value2)) {
                 if (node.id < 0)
                     node.id = m_tree->nextId();
 
@@ -802,15 +817,15 @@ QWingedEdge::TraversalStatus QWingedEdge::next(const QWingedEdge::TraversalStatu
 
 static bool isLine(const QBezier &bezier)
 {
-    const bool equal_1_2 = bezier.pt1() == bezier.pt2();
-    const bool equal_2_3 = bezier.pt2() == bezier.pt3();
-    const bool equal_3_4 = bezier.pt3() == bezier.pt4();
+    const bool equal_1_2 = comparePoints(bezier.pt1(), bezier.pt2());
+    const bool equal_2_3 = comparePoints(bezier.pt2(), bezier.pt3());
+    const bool equal_3_4 = comparePoints(bezier.pt3(), bezier.pt4());
 
     // point?
     if (equal_1_2 && equal_2_3 && equal_3_4)
         return true;
 
-    if (bezier.pt1() == bezier.pt4())
+    if (comparePoints(bezier.pt1(), bezier.pt4()))
         return equal_1_2 || equal_3_4;
 
     return (equal_1_2 && equal_3_4) || (equal_1_2 && equal_2_3) || (equal_2_3 && equal_3_4);
@@ -844,14 +859,14 @@ void QPathSegments::addPath(const QPainterPath &path)
         else
             currentPoint = path.elementAt(i);
 
-        if (i > 0 && m_points.at(lastMoveTo) == currentPoint)
+        if (i > 0 && comparePoints(m_points.at(lastMoveTo), currentPoint))
             current = lastMoveTo;
         else
             m_points << currentPoint;
 
         switch (path.elementAt(i).type) {
         case QPainterPath::MoveToElement:
-            if (hasMoveTo && last != lastMoveTo && m_points.at(last) != m_points.at(lastMoveTo))
+            if (hasMoveTo && last != lastMoveTo && !comparePoints(m_points.at(last), m_points.at(lastMoveTo)))
                 m_segments << Segment(m_pathId, last, lastMoveTo);
             hasMoveTo = true;
             last = lastMoveTo = current;
@@ -879,7 +894,7 @@ void QPathSegments::addPath(const QPainterPath &path)
         }
     }
 
-    if (hasMoveTo && last != lastMoveTo && m_points.at(last) != m_points.at(lastMoveTo))
+    if (hasMoveTo && last != lastMoveTo && !comparePoints(m_points.at(last), m_points.at(lastMoveTo)))
         m_segments << Segment(m_pathId, last, lastMoveTo);
 
     for (int i = firstSegment; i < m_segments.size(); ++i) {
@@ -1357,7 +1372,7 @@ void QWingedEdge::addBezierEdge(const QBezier *bezier, const QPointF &a, const Q
     if (qFuzzyCompare(alphaA, alphaB))
         return;
 
-    if (a == b) {
+    if (comparePoints(a, b)) {
         int v = insert(a);
 
         addBezierEdge(bezier, v, v, alphaA, alphaB, path);
diff --git a/tests/auto/qpathclipper/tst_qpathclipper.cpp b/tests/auto/qpathclipper/tst_qpathclipper.cpp
index f3077ee..6e6b632 100644
--- a/tests/auto/qpathclipper/tst_qpathclipper.cpp
+++ b/tests/auto/qpathclipper/tst_qpathclipper.cpp
@@ -93,6 +93,7 @@ private slots:
     void task204301();
 
     void task209056();
+    void task251909();
 };
 
 Q_DECLARE_METATYPE(QPainterPath)
@@ -1397,6 +1398,25 @@ void tst_QPathClipper::task209056()
     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)