New test. Check if epsilon value in method GetParmT() is enough for calculation.

--HG--
branch : develop

src/libs/vgeometry/vabstractcubicbezier.cpp

@@ -83,17 +83,7 @@ QPointF VAbstractCubicBezier::CutSpline(qreal length, QPointF &spl1p2, QPointF &
         length = GetLength()*0.98;
     }
 
-    const qreal eps = 0.001 * qAbs(length);
+    const qreal parT = GetParmT(length);
-    qreal parT = 0.5;
-    qreal step = parT;
-    qreal splLength = LengthT(parT);
-
-    while (qAbs(splLength - length) > eps)
-    {
-        step = step/2.0;
-        splLength > length ? parT -= step : parT += step;
-        splLength = LengthT(parT);
-    }
 
     QLineF seg1_2 ( GetP1 ().toQPointF(), GetControlPoint1 () );
     seg1_2.setLength(seg1_2.length () * parT);
@@ -137,6 +127,32 @@ QString VAbstractCubicBezier::NameForHistory(const QString &toolName) const
     return name;
 }
 
+//---------------------------------------------------------------------------------------------------------------------
+qreal VAbstractCubicBezier::GetParmT(qreal length) const
+{
+    if (length < 0)
+    {
+        return 0;
+    }
+    else if (length > GetLength())
+    {
+        length = GetLength();
+    }
+
+    const qreal eps = 0.001 * length;
+    qreal parT = 0.5;
+    qreal step = parT;
+    qreal splLength = LengthT(parT);
+
+    while (qAbs(splLength - length) > eps)
+    {
+        step /= 2.0;
+        splLength > length ? parT -= step : parT += step;
+        splLength = LengthT(parT);
+    }
+    return parT;
+}
+
 //---------------------------------------------------------------------------------------------------------------------
 void VAbstractCubicBezier::CreateName()
 {

src/libs/vgeometry/vabstractcubicbezier.h

@@ -48,6 +48,9 @@ public:
 
     virtual QString NameForHistory(const QString &toolName) const Q_DECL_OVERRIDE;
 
+    qreal GetParmT(qreal length) const;
+    qreal LengthT(qreal t) const;
+
 protected:
     virtual void CreateName() Q_DECL_OVERRIDE;
 
@@ -60,9 +63,6 @@ protected:
 
     virtual QPointF GetControlPoint1() const =0;
     virtual QPointF GetControlPoint2() const =0;
-
-private:
-    qreal LengthT(qreal t) const;
 };
 
 #endif // VABSTRACTCUBICBEZIER_H

src/test/ValentinaTest/tst_vspline.cpp

@@ -293,6 +293,20 @@ void TST_VSpline::CompareThreeWays()
     CompareSplines(spl3, spl1);
 }
 
+//---------------------------------------------------------------------------------------------------------------------
+void TST_VSpline::TestParametrT()
+{
+    VPointF p1(1168.8582803149607, 39.999874015748034, "p1", 5.0000125984251973, 9.9999874015748045);
+    VPointF p4(681.33729132409951, 1815.7969526662778, "p4", 5.0000125984251973, 9.9999874015748045);
+
+    VSpline spl(p1, p4, 229.381, 41.6325, 0.96294100000000005, 1.00054, 1);
+
+    const qreal halfLength = spl.GetLength()/2.0;
+    const qreal resLength = spl.LengthT(spl.GetParmT(halfLength));
+
+    QVERIFY(qAbs(halfLength - resLength) < UnitConvertor(0.5, Unit::Mm, Unit::Px));
+}
+
 //---------------------------------------------------------------------------------------------------------------------
 void TST_VSpline::CompareSplines(const VSpline &spl1, const VSpline &spl2) const
 {

src/test/ValentinaTest/tst_vspline.h

@@ -47,6 +47,7 @@ private slots:
     void GetSegmentPoints_TestPuzzle();
     void GetSegmentPoints_NullSegment();
     void CompareThreeWays();
+    void TestParametrT();
 
 private:
     Q_DISABLE_COPY(TST_VSpline)