De-uglify a tiny bit the NURBS code

2 files changed, 122 insertions, 158 deletions

diff --git a/src/lib/VSDContentCollector.cpp b/src/lib/VSDContentCollector.cpp
index 4edffb3..2b0b29a 100644
--- a/src/lib/VSDContentCollector.cpp
+++ b/src/lib/VSDContentCollector.cpp
@@ -1311,192 +1311,155 @@ void libvisio::VSDContentCollector::collectArcTo(unsigned /* id */, unsigned lev
   }
 }
 
-void libvisio::VSDContentCollector::_generateCubicBeziersFromNURBS(const std::vector<std::pair<double, double> > &controlPoints,
-    const std::vector<double> &knotVector)
+
+void libvisio::VSDContentCollector::_outputCubicBezierSegment(const std::vector<std::pair<double, double> > &points)
 {
-  if (controlPoints.empty() || knotVector.empty())
+  if (points.size() < 4)
     return;
-
   WPXPropertyList node;
+  node.insert("libwpg:path-action", "C");
+  double x = points[1].first;
+  double y = points[1].second;
+  transformPoint(x, y);
+  node.insert("svg:x1", m_scale*x);
+  node.insert("svg:y1", m_scale*y);
+  x = points[2].first;
+  y = points[2].second;
+  transformPoint(x, y);
+  node.insert("svg:x2", m_scale*x);
+  node.insert("svg:y2", m_scale*y);
+  x = points[3].first;
+  y = points[3].second;
+  transformPoint(x, y);
+  node.insert("svg:x", m_scale*x);
+  node.insert("svg:y", m_scale*y);
 
-  /* Decomposition of a spline of 3rd degree into Bezier segments
-   * adapted from the algorithm DecomposeCurve (Les Piegl, Wayne Tiller:
-   * The NURBS Book, 2nd Edition, 1997
-   */
-
-  unsigned m = controlPoints.size() + 4;
-  unsigned a = 3;
-  unsigned b = 4;
-  std::vector< std::pair<double, double> > Qw(4), NextQw(4);
-  unsigned i = 0;
-  for (; i <= 3; i++)
-    Qw[i] = controlPoints[i];
-  while (b < m)
-  {
-    i = b;
-    while (b < m && knotVector[b+1] == knotVector[b])
-      b++;
-    unsigned mult = b - i + 1;
-    if (mult < 3)
-    {
-      double numer = (double)(knotVector[b] - knotVector[a]);
-      unsigned j = 3;
-      std::map<unsigned, double> alphas;
-      for (; j >mult; j--)
-        alphas[j-mult-1] = numer/double(knotVector[a+j]-knotVector[a]);
-      unsigned r = 3 - mult;
-      for (j=1; j<=r; j++)
-      {
-        unsigned save = r - j;
-        unsigned s = mult+j;
-        for (unsigned k = 3; k>=s; k--)
-        {
-          double alpha = alphas[k-s];
-          Qw[k].first = alpha*Qw[k].first + (1.0-alpha)*Qw[k-1].first;
-          Qw[k].second = alpha*Qw[k].second + (1.0-alpha)*Qw[k-1].second;
-        }
-        if (b < m)
-        {
-          NextQw[save].first = Qw[3].first;
-          NextQw[save].second = Qw[3].second;
-        }
-      }
-    }
-    // Pass the segment to the path
+  if (!m_noFill && !m_noShow)
+    m_currentFillGeometry.push_back(node);
+  if (!m_noLine && !m_noShow)
+    m_currentLineGeometry.push_back(node);
+}
 
-    node.clear();
-    node.insert("libwpg:path-action", "C");
-    double x = Qw[1].first;
-    double y = Qw[1].second;
-    transformPoint(x, y);
-    node.insert("svg:x1", m_scale*x);
-    node.insert("svg:y1", m_scale*y);
-    x = Qw[2].first;
-    y = Qw[2].second;
-    transformPoint(x, y);
-    node.insert("svg:x2", m_scale*x);
-    node.insert("svg:y2", m_scale*y);
-    x = Qw[3].first;
-    y = Qw[3].second;
-    transformPoint(x, y);
-    node.insert("svg:x", m_scale*x);
-    node.insert("svg:y", m_scale*y);
+void libvisio::VSDContentCollector::_outputQuadraticBezierSegment(const std::vector<std::pair<double, double> > &points)
+{
+  if (points.size() < 3)
+    return;
+  WPXPropertyList node;
+  node.insert("libwpg:path-action", "Q");
+  double x = points[1].first;
+  double y = points[1].second;
+  transformPoint(x, y);
+  node.insert("svg:x1", m_scale*x);
+  node.insert("svg:y1", m_scale*y);
+  x = points[2].first;
+  y = points[2].second;
+  transformPoint(x, y);
+  node.insert("svg:x", m_scale*x);
+  node.insert("svg:y", m_scale*y);
 
-    if (!m_noFill && !m_noShow)
-      m_currentFillGeometry.push_back(node);
-    if (!m_noLine && !m_noShow)
-      m_currentLineGeometry.push_back(node);
+  if (!m_noFill && !m_noShow)
+    m_currentFillGeometry.push_back(node);
+  if (!m_noLine && !m_noShow)
+    m_currentLineGeometry.push_back(node);
+}
 
-    std::swap(Qw, NextQw);
+void libvisio::VSDContentCollector::_outputLinearBezierSegment(const std::vector<std::pair<double, double> > &points)
+{
+  if (points.size() < 2)
+    return;
+  WPXPropertyList node;
+  node.insert("libwpg:path-action", "L");
+  double x = points[1].first;
+  double y = points[1].second;
+  transformPoint(x, y);
+  node.insert("svg:x", m_scale*x);
+  node.insert("svg:y", m_scale*y);
 
-    if (b < m)
-    {
-      for (i=3-mult; i <= 3; i++)
-      {
-        Qw[i].first = controlPoints[b-3+i].first;
-        Qw[i].second = controlPoints[b-3+i].second;
-      }
-      a = b;
-      b++;
-    }
-  }
-  m_originalX = controlPoints.back().first;
-  m_originalY = controlPoints.back().second;
-  m_x = controlPoints.back().first;
-  m_y = controlPoints.back().second;
-  transformPoint(m_x, m_y);
+  if (!m_noFill && !m_noShow)
+    m_currentFillGeometry.push_back(node);
+  if (!m_noLine && !m_noShow)
+    m_currentLineGeometry.push_back(node);
 }
 
-
-void libvisio::VSDContentCollector::_generateQuadraticBeziersFromNURBS(const std::vector<std::pair<double, double> > &controlPoints,
-    const std::vector<double> &knotVector)
+void libvisio::VSDContentCollector::_generateBezierSegmentsFromNURBS(unsigned degree,
+    const std::vector<std::pair<double, double> > &controlPoints, const std::vector<double> &knotVector)
 {
-  if (controlPoints.empty() || knotVector.empty())
+  if (controlPoints.empty() || knotVector.empty() || !degree)
     return;
 
-  WPXPropertyList node;
-
-  /* Decomposition of a spline of 2nd degree into Bezier segments
+  /* Decomposition of a uniform spline of a given degree into Bezier segments
    * adapted from the algorithm DecomposeCurve (Les Piegl, Wayne Tiller:
    * The NURBS Book, 2nd Edition, 1997
    */
 
-  unsigned m = controlPoints.size() + 3;
-  unsigned a = 2;
-  unsigned b = 3;
-  std::vector< std::pair<double, double> > Qw(3), NextQw(3);
+  unsigned m = controlPoints.size() + degree + 1;
+  unsigned a = degree;
+  unsigned b = degree + 1;
+  std::vector< std::pair<double, double> > points(degree + 1), nextPoints(degree + 1);
   unsigned i = 0;
-  for (; i <= 2; i++)
-    Qw[i] = controlPoints[i];
+  for (; i <= degree; i++)
+    points[i] = controlPoints[i];
   while (b < m)
   {
     i = b;
     while (b < m && knotVector[b+1] == knotVector[b])
       b++;
     unsigned mult = b - i + 1;
-    if (mult < 2)
+    if (mult < degree)
     {
       double numer = (double)(knotVector[b] - knotVector[a]);
-      unsigned j = 2;
+      unsigned j = degree;
       std::map<unsigned, double> alphas;
       for (; j >mult; j--)
         alphas[j-mult-1] = numer/double(knotVector[a+j]-knotVector[a]);
-      unsigned r = 2 - mult;
+      unsigned r = degree - mult;
       for (j=1; j<=r; j++)
       {
         unsigned save = r - j;
         unsigned s = mult+j;
-        for (unsigned k = 2; k>=s; k--)
+        for (unsigned k = degree; k>=s; k--)
         {
           double alpha = alphas[k-s];
-          Qw[k].first = alpha*Qw[k].first + (1.0-alpha)*Qw[k-1].first;
-          Qw[k].second = alpha*Qw[k].second + (1.0-alpha)*Qw[k-1].second;
+          points[k].first = alpha*points[k].first + (1.0-alpha)*points[k-1].first;
+          points[k].second = alpha*points[k].second + (1.0-alpha)*points[k-1].second;
         }
         if (b < m)
         {
-          NextQw[save].first = Qw[2].first;
-          NextQw[save].second = Qw[2].second;
+          nextPoints[save].first = points[degree].first;
+          nextPoints[save].second = points[degree].second;
         }
       }
     }
     // Pass the segment to the path
 
-    node.clear();
-    node.insert("libwpg:path-action", "Q");
-    double x = Qw[1].first;
-    double y = Qw[1].second;
-    transformPoint(x, y);
-    node.insert("svg:x1", m_scale*x);
-    node.insert("svg:y1", m_scale*y);
-    x = Qw[2].first;
-    y = Qw[2].second;
-    transformPoint(x, y);
-    node.insert("svg:x", m_scale*x);
-    node.insert("svg:y", m_scale*y);
-
-    if (!m_noFill && !m_noShow)
-      m_currentFillGeometry.push_back(node);
-    if (!m_noLine && !m_noShow)
-      m_currentLineGeometry.push_back(node);
+    switch (degree)
+    {
+    case 1:
+      _outputLinearBezierSegment(points);
+      break;
+    case 2:
+      _outputQuadraticBezierSegment(points);
+      break;
+    case 3:
+      _outputCubicBezierSegment(points);
+      break;
+    default:
+      break;
+    }
 
-    std::swap(Qw, NextQw);
+    std::swap(points, nextPoints);
 
     if (b < m)
     {
-      for (i=2-mult; i <= 2; i++)
+      for (i=degree-mult; i <= degree; i++)
       {
-        Qw[i].first = controlPoints[b-2+i].first;
-        Qw[i].second = controlPoints[b-2+i].second;
+        points[i].first = controlPoints[b-degree+i].first;
+        points[i].second = controlPoints[b-degree+i].second;
       }
       a = b;
       b++;
     }
   }
-  m_originalX = controlPoints.back().first;
-  m_originalY = controlPoints.back().second;
-  m_x = controlPoints.back().first;
-  m_y = controlPoints.back().second;
-  transformPoint(m_x, m_y);
 }
 
 #define VSD_NUM_POLYLINES_PER_NURBS 200
@@ -1534,22 +1497,20 @@ void libvisio::VSDContentCollector::_generatePolylineFromNURBS(unsigned degree,
       m_currentLineGeometry.push_back(node);
   }
 
-  m_originalX = controlPoints.back().first;
-  m_originalY = controlPoints.back().second;
-  m_x = controlPoints.back().first;
-  m_y = controlPoints.back().second;
-  transformPoint(m_x, m_y);
+  double x = controlPoints.back().first;
+  double y = controlPoints.back().second;
+  transformPoint(x, y);
   node.clear();
   node.insert("libwpg:path-action", "L");
-  node.insert("svg:x", m_scale*m_x);
-  node.insert("svg:y", m_scale*m_y);
+  node.insert("svg:x", m_scale*x);
+  node.insert("svg:y", m_scale*y);
   if (!m_noFill && !m_noShow)
     m_currentFillGeometry.push_back(node);
   if (!m_noLine && !m_noShow)
     m_currentLineGeometry.push_back(node);
 }
 
-bool libvisio::VSDContentCollector::_areWeightsUniform(const std::vector<double> weights) const
+bool libvisio::VSDContentCollector::_isUniform(const std::vector<double> weights) const
 {
   if (weights.empty())
     return true;
@@ -1574,13 +1535,6 @@ void libvisio::VSDContentCollector::collectNURBSTo(unsigned /* id */, unsigned l
     // Here, maybe we should just draw line to (x2,y2)
     return;
 
-  // Fill in end knots
-  while (knotVector.size() < (controlPoints.size() + degree + 3))
-  {
-    double tmpBack = knotVector.back();
-    knotVector.push_back(tmpBack);
-  }
-
   // Convert control points to static co-ordinates
   for (std::vector<std::pair<double, double> >::iterator it = controlPoints.begin();
        it != controlPoints.end(); ++it)
@@ -1595,15 +1549,23 @@ void libvisio::VSDContentCollector::collectNURBSTo(unsigned /* id */, unsigned l
   controlPoints.push_back(std::pair<double,double>(x2, y2));
   controlPoints.insert(controlPoints.begin(), std::pair<double, double>(m_originalX, m_originalY));
 
-  if ((degree == 2 || degree == 3) && _areWeightsUniform(weights))
+  // Fill in end knots
+  while (knotVector.size() < (controlPoints.size() + degree + 1))
   {
-    if (degree == 2)
-      _generateQuadraticBeziersFromNURBS(controlPoints, knotVector);
-    else
-      _generateCubicBeziersFromNURBS(controlPoints, knotVector);
+    double tmpBack = knotVector.back();
+    knotVector.push_back(tmpBack);
   }
+
+  if (degree <= 3 && _isUniform(weights))
+    _generateBezierSegmentsFromNURBS(degree, controlPoints, knotVector);
   else
     _generatePolylineFromNURBS(degree, controlPoints, knotVector, weights);
+
+  m_originalX = controlPoints.back().first;
+  m_originalY = controlPoints.back().second;
+  m_x = controlPoints.back().first;
+  m_y = controlPoints.back().second;
+  transformPoint(m_x, m_y);
 }
 
 double libvisio::VSDContentCollector::_NURBSBasis(unsigned knot, unsigned degree, double point, const std::vector<double> &knotVector)
diff --git a/src/lib/VSDContentCollector.h b/src/lib/VSDContentCollector.h
index 0d1fd27..59e6614 100644
--- a/src/lib/VSDContentCollector.h
+++ b/src/lib/VSDContentCollector.h
@@ -220,13 +220,15 @@ private:
   bool parseFormatId( const char *formatString, unsigned short &result );
   void _appendField(WPXString &text);
 
-  void _generateCubicBeziersFromNURBS(const std::vector<std::pair<double, double> > &controlPoints,
-                                      const std::vector<double> &knotVector);
-  void _generateQuadraticBeziersFromNURBS(const std::vector<std::pair<double, double> > &controlPoints,
-                                          const std::vector<double> &knotVector);
+  // NURBS processing functions
+  bool _isUniform(const std::vector<double> weights) const;
   void _generatePolylineFromNURBS(unsigned degree, const std::vector<std::pair<double, double> > &controlPoints,
                                   const std::vector<double> &knotVector, const std::vector<double> &weights);
-  bool _areWeightsUniform(const std::vector<double> weights) const;
+  void _generateBezierSegmentsFromNURBS(unsigned degree, const std::vector<std::pair<double, double> > &controlPoints,
+                                        const std::vector<double> &knotVector);
+  void _outputCubicBezierSegment(const std::vector<std::pair<double, double> > &points);
+  void _outputQuadraticBezierSegment(const std::vector<std::pair<double, double> > &points);
+  void _outputLinearBezierSegment(const std::vector<std::pair<double, double> > &points);
 
   bool m_isPageStarted;
   double m_pageWidth;