move QgsCadUtils::lineCircleIntersection to QgsGeometryUtils

also add a test
qgis · Jan 24, 2018 · 6a2a626 · 6a2a626
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diff --git a/python/core/geometry/qgsgeometryutils.sip.in b/python/core/geometry/qgsgeometryutils.sip.in
@@ -138,6 +138,19 @@ Returns the squared distance between a point and a line.
        # (True, 'Point (0 0)', True)
 %End
 
+    static bool lineCircleIntersection( const QgsPointXY &center, const double radius,
+                                        const QgsPointXY &linePoint1, const QgsPointXY &linePoint2,
+                                        QgsPointXY &intersection /In,Out/ );
+%Docstring
+ lineCircleIntersection returns the closest intersection of a line and a circle
+@param center the center of the circle
+@param radius the radius of the circle
+@param linePoint1 a first point on the line
+@param linePoint2 a second point on the line
+@param intersection the initial point and the returned intersection point
+@return true if an intersection has been found
+%End
+
     static QgsPoint projPointOnSegment( const QgsPoint &p, const QgsPoint &s1, const QgsPoint &s2 );
 %Docstring
  Project the point on a segment

diff --git a/src/core/geometry/qgsgeometryutils.cpp b/src/core/geometry/qgsgeometryutils.cpp
@@ -310,6 +310,56 @@ bool QgsGeometryUtils::segmentIntersection( const QgsPoint &p1, const QgsPoint &
   return !( lambdaw < 0. + tolerance || lambdaw >= wl - tolerance );
 }
 
+bool QgsGeometryUtils::lineCircleIntersection( const QgsPointXY &center, const double radius,
+    const QgsPointXY &linePoint1, const QgsPointXY &linePoint2,
+    QgsPointXY &intersection )
+{
+  // formula taken from http://mathworld.wolfram.com/Circle-LineIntersection.html
+
+  const double x1 = linePoint1.x() - center.x();
+  const double y1 = linePoint1.y() - center.y();
+  const double x2 = linePoint2.x() - center.x();
+  const double y2 = linePoint2.y() - center.y();
+  const double dx = x2 - x1;
+  const double dy = y2 - y1;
+
+  const double dr = std::sqrt( std::pow( dx, 2 ) + std::pow( dy, 2 ) );
+  const double d = x1 * y2 - x2 * y1;
+
+  const double disc = std::pow( radius, 2 ) * std::pow( dr, 2 ) - std::pow( d, 2 );
+
+  if ( disc < 0 )
+  {
+    //no intersection or tangent
+    return false;
+  }
+  else
+  {
+    // two solutions
+    const int sgnDy = dy < 0 ? -1 : 1;
+
+    const double ax = center.x() + ( d * dy + sgnDy * dx * std::sqrt( std::pow( radius, 2 ) * std::pow( dr, 2 ) - std::pow( d, 2 ) ) ) / ( std::pow( dr, 2 ) );
+    const double ay = center.y() + ( -d * dx + std::fabs( dy ) * std::sqrt( std::pow( radius, 2 ) * std::pow( dr, 2 ) - std::pow( d, 2 ) ) ) / ( std::pow( dr, 2 ) );
+    const QgsPointXY p1( ax, ay );
+
+    const double bx = center.x() + ( d * dy - sgnDy * dx * std::sqrt( std::pow( radius, 2 ) * std::pow( dr, 2 ) - std::pow( d, 2 ) ) ) / ( std::pow( dr, 2 ) );
+    const double by = center.y() + ( -d * dx - std::fabs( dy ) * std::sqrt( std::pow( radius, 2 ) * std::pow( dr, 2 ) - std::pow( d, 2 ) ) ) / ( std::pow( dr, 2 ) );
+    const QgsPointXY p2( bx, by );
+
+    // snap to nearest intersection
+
+    if ( intersection.sqrDist( p1 ) < intersection.sqrDist( p2 ) )
+    {
+      intersection.set( p1.x(), p1.y() );
+    }
+    else
+    {
+      intersection.set( p2.x(), p2.y() );
+    }
+    return true;
+  }
+}
+
 QVector<QgsGeometryUtils::SelfIntersection> QgsGeometryUtils::getSelfIntersections( const QgsAbstractGeometry *geom, int part, int ring, double tolerance )
 {
   QVector<SelfIntersection> intersections;

diff --git a/src/core/geometry/qgsgeometryutils.h b/src/core/geometry/qgsgeometryutils.h
@@ -136,6 +136,19 @@ class CORE_EXPORT QgsGeometryUtils
      */
     static bool segmentIntersection( const QgsPoint &p1, const QgsPoint &p2, const QgsPoint &q1, const QgsPoint &q2, QgsPoint &intersectionPoint SIP_OUT, bool &isIntersection SIP_OUT, const double tolerance = 1e-8, bool acceptImproperIntersection = false );
 
+    /**
+     * @brief lineCircleIntersection returns the closest intersection of a line and a circle
+     * @param center the center of the circle
+     * @param radius the radius of the circle
+     * @param linePoint1 a first point on the line
+     * @param linePoint2 a second point on the line
+     * @param intersection the initial point and the returned intersection point
+     * @return true if an intersection has been found
+     */
+    static bool lineCircleIntersection( const QgsPointXY &center, const double radius,
+                                        const QgsPointXY &linePoint1, const QgsPointXY &linePoint2,
+                                        QgsPointXY &intersection SIP_INOUT );
+
     /**
      * \brief Project the point on a segment
      * \param p The point

diff --git a/src/core/qgscadutils.cpp b/src/core/qgscadutils.cpp
@@ -18,6 +18,7 @@
 
 #include "qgslogger.h"
 #include "qgssnappingutils.h"
+#include "qgsgeometryutils.h"
 
 // tolerances for soft constraints (last values, and common angles)
 // for angles, both tolerance in pixels and degrees are used for better performance
@@ -33,57 +34,6 @@ struct EdgesOnlyFilter : public QgsPointLocator::MatchFilter
 /// @endcond
 
 
-// TODO: move to geometry utils (if not already there)
-static bool lineCircleIntersection( const QgsPointXY &center, const double radius, const QgsPointXY &edgePt0, const QgsPointXY &edgePt1, QgsPointXY &intersection )
-{
-  // formula taken from http://mathworld.wolfram.com/Circle-LineIntersection.html
-
-  const double x1 = edgePt0.x() - center.x();
-  const double y1 = edgePt0.y() - center.y();
-  const double x2 = edgePt1.x() - center.x();
-  const double y2 = edgePt1.y() - center.y();
-  const double dx = x2 - x1;
-  const double dy = y2 - y1;
-
-  const double dr = std::sqrt( std::pow( dx, 2 ) + std::pow( dy, 2 ) );
-  const double d = x1 * y2 - x2 * y1;
-
-  const double disc = std::pow( radius, 2 ) * std::pow( dr, 2 ) - std::pow( d, 2 );
-
-  if ( disc < 0 )
-  {
-    //no intersection or tangent
-    return false;
-  }
-  else
-  {
-    // two solutions
-    const int sgnDy = dy < 0 ? -1 : 1;
-
-    const double ax = center.x() + ( d * dy + sgnDy * dx * std::sqrt( std::pow( radius, 2 ) * std::pow( dr, 2 ) - std::pow( d, 2 ) ) ) / ( std::pow( dr, 2 ) );
-    const double ay = center.y() + ( -d * dx + std::fabs( dy ) * std::sqrt( std::pow( radius, 2 ) * std::pow( dr, 2 ) - std::pow( d, 2 ) ) ) / ( std::pow( dr, 2 ) );
-    const QgsPointXY p1( ax, ay );
-
-    const double bx = center.x() + ( d * dy - sgnDy * dx * std::sqrt( std::pow( radius, 2 ) * std::pow( dr, 2 ) - std::pow( d, 2 ) ) ) / ( std::pow( dr, 2 ) );
-    const double by = center.y() + ( -d * dx - std::fabs( dy ) * std::sqrt( std::pow( radius, 2 ) * std::pow( dr, 2 ) - std::pow( d, 2 ) ) ) / ( std::pow( dr, 2 ) );
-    const QgsPointXY p2( bx, by );
-
-    // snap to nearest intersection
-
-    if ( intersection.sqrDist( p1 ) < intersection.sqrDist( p2 ) )
-    {
-      intersection.set( p1.x(), p1.y() );
-    }
-    else
-    {
-      intersection.set( p2.x(), p2.y() );
-    }
-    return true;
-  }
-}
-
-
-
 QgsCadUtils::AlignMapPointOutput QgsCadUtils::alignMapPoint( const QgsPointXY &originalMapPoint, const QgsCadUtils::AlignMapPointContext &ctx )
 {
   QgsCadUtils::AlignMapPointOutput res;
@@ -312,13 +262,13 @@ QgsCadUtils::AlignMapPointOutput QgsCadUtils::alignMapPoint( const QgsPointXY &o
       {
         QgsPointXY verticalPt0( ctx.xConstraint.value, point.y() );
         QgsPointXY verticalPt1( ctx.xConstraint.value, point.y() + 1 );
-        res.valid &= lineCircleIntersection( previousPt, ctx.distanceConstraint.value, verticalPt0, verticalPt1, point );
+        res.valid &= QgsGeometryUtils::lineCircleIntersection( previousPt, ctx.distanceConstraint.value, verticalPt0, verticalPt1, point );
       }
       if ( ctx.yConstraint.locked )
       {
         QgsPointXY horizontalPt0( point.x(), ctx.yConstraint.value );
         QgsPointXY horizontalPt1( point.x() + 1, ctx.yConstraint.value );
-        res.valid &= lineCircleIntersection( previousPt, ctx.distanceConstraint.value, horizontalPt0, horizontalPt1, point );
+        res.valid &= QgsGeometryUtils::lineCircleIntersection( previousPt, ctx.distanceConstraint.value, horizontalPt0, horizontalPt1, point );
       }
     }
     else
@@ -340,7 +290,7 @@ QgsCadUtils::AlignMapPointOutput QgsCadUtils::alignMapPoint( const QgsPointXY &o
       if ( edgeMatch.hasEdge() && !ctx.angleConstraint.locked )
       {
         // we will magnietize to the intersection of that segment and the lockedDistance !
-        res.valid &= lineCircleIntersection( previousPt, ctx.distanceConstraint.value, edgePt0, edgePt1, point );
+        res.valid &= QgsGeometryUtils::lineCircleIntersection( previousPt, ctx.distanceConstraint.value, edgePt0, edgePt1, point );
       }
     }
   }

diff --git a/tests/src/core/testqgsgeometryutils.cpp b/tests/src/core/testqgsgeometryutils.cpp
@@ -55,6 +55,7 @@ class TestQgsGeometryUtils: public QObject
     void testPerpendicularSegment();
     void testClosestPoint();
     void testSegmentIntersection();
+    void testLineCircleIntersection();
 };
 
 
@@ -797,5 +798,22 @@ void TestQgsGeometryUtils::testSegmentIntersection()
   QVERIFY( inter == QgsPoint( 0, 0 ) );
 }
 
+void TestQgsGeometryUtils::testLineCircleIntersection()
+{
+  QgsPointXY center = QgsPoint( 2, 2 );
+  double radius = 2.0;
+  QgsPointXY linePoint1 = QgsPoint( 0, 2 );
+  QgsPointXY linePoint2 = QgsPoint( 2, 2 );
+  QgsPointXY intersection = QgsPoint( 3, 3 );
+  bool isIntersection = QgsGeometryUtils::lineCircleIntersection( center, radius, linePoint1, linePoint2, intersection );
+  QVERIFY( isIntersection );
+  QVERIFY( intersection == QgsPointXY( 4, 2 ) );
+
+  linePoint1 = QgsPoint( 5, 0 );
+  linePoint2 = QgsPoint( 5, 2 );
+  isIntersection = QgsGeometryUtils::lineCircleIntersection( center, radius, linePoint1, linePoint2, intersection );
+  QVERIFY( !isIntersection );
+}
+
 QGSTEST_MAIN( TestQgsGeometryUtils )
 #include "testqgsgeometryutils.moc"