Add some more line segment methods

nyalldawson · nyalldawson · commit 70b67c6150bd · 2018-04-24T10:07:51.000+12:00
diff --git a/python/core/geometry/qgslinesegment.sip.in b/python/core/geometry/qgslinesegment.sip.in
@@ -7,6 +7,7 @@
  ************************************************************************/
 
 
+
 class QgsLineSegment2D
 {
 %Docstring
@@ -24,6 +25,12 @@ Represents a single 2D line segment, consisting of a 2D start and end vertex onl
 %Docstring
 Constructor for a QgsLineSegment2D from the specified ``start`` point to
 the ``end`` point.
+%End
+
+    QgsLineSegment2D( double x1, double y1, double x2, double y2 );
+%Docstring
+Constructor for a QgsLineSegment2D from the point (``x1``, ``y2``) to
+(``x2``, ``y2``).
 %End
 
     double length() const;
diff --git a/python/core/geometry/qgslinestring.sip.in b/python/core/geometry/qgslinestring.sip.in
@@ -12,6 +12,7 @@
 
 
 
+
 class QgsLineString: QgsCurve
 {
 %Docstring
@@ -62,6 +63,13 @@ This constructor is more efficient then calling setPoints()
 or repeatedly calling addVertex()
 
 .. versionadded:: 3.0
+%End
+
+    explicit QgsLineString( const QgsLineSegment2D &segment );
+%Docstring
+Construct a linestring from a single 2d line segment.
+
+.. versionadded:: 3.2
 %End
 
     virtual bool equals( const QgsCurve &other ) const;
diff --git a/src/core/geometry/qgslinesegment.h b/src/core/geometry/qgslinesegment.h
@@ -11,6 +11,8 @@
 #include "qgis_core.h"
 #include "qgspointxy.h"
 
+class QgsLineString;
+
 /**
  * \ingroup core
  * Represents a single 2D line segment, consisting of a 2D start and end vertex only.
@@ -30,6 +32,15 @@ class CORE_EXPORT QgsLineSegment2D
       , mEnd( end )
     {}
 
+    /**
+     * Constructor for a QgsLineSegment2D from the point (\a x1, \a y2) to
+     * (\a x2, \a y2).
+     */
+    QgsLineSegment2D( double x1, double y1, double x2, double y2 )
+      : mStart( QgsPointXY( x1, y1 ) )
+      , mEnd( QgsPointXY( x2, y2 ) )
+    {}
+
     /**
      * Returns the length of the segment.
      * \see lengthSquared()
diff --git a/src/core/geometry/qgslinestring.cpp b/src/core/geometry/qgslinestring.cpp
@@ -22,6 +22,7 @@
 #include "qgsgeometryutils.h"
 #include "qgsmaptopixel.h"
 #include "qgswkbptr.h"
+#include "qgslinesegment.h"
 
 #include <cmath>
 #include <memory>
@@ -161,6 +162,17 @@ QgsLineString::QgsLineString( const QVector<QgsPointXY> &points )
   }
 }
 
+QgsLineString::QgsLineString( const QgsLineSegment2D &segment )
+{
+  mWkbType = QgsWkbTypes::LineString;
+  mX.resize( 2 );
+  mY.resize( 2 );
+  mX[0] = segment.startX();
+  mX[1] = segment.endX();
+  mY[0] = segment.startY();
+  mY[1] = segment.endY();
+}
+
 bool QgsLineString::equals( const QgsCurve &other ) const
 {
   const QgsLineString *otherLine = qgsgeometry_cast< const QgsLineString * >( &other );
diff --git a/src/core/geometry/qgslinestring.h b/src/core/geometry/qgslinestring.h
@@ -26,6 +26,8 @@
 #include "qgscurve.h"
 #include "qgscompoundcurve.h"
 
+class QgsLineSegment2D;
+
 /***************************************************************************
  * This class is considered CRITICAL and any change MUST be accompanied with
  * full unit tests in testqgsgeometry.cpp.
@@ -77,6 +79,12 @@ class CORE_EXPORT QgsLineString: public QgsCurve
      */
     QgsLineString( const QVector<QgsPointXY> &points );
 
+    /**
+     * Construct a linestring from a single 2d line segment.
+     * \since QGIS 3.2
+     */
+    explicit QgsLineString( const QgsLineSegment2D &segment );
+
     bool equals( const QgsCurve &other ) const override;
 
     /**
diff --git a/tests/src/core/testqgsgeometry.cpp b/tests/src/core/testqgsgeometry.cpp
@@ -50,6 +50,7 @@
 #include "qgsgeometryfactory.h"
 #include "qgscurvepolygon.h"
 #include "qgsproject.h"
+#include "qgslinesegment.h"
 
 //qgs unit test utility class
 #include "qgsrenderchecker.h"
@@ -2849,6 +2850,15 @@ void TestQgsGeometry::lineString()
   QCOMPARE( from2Pts.zAt( 1 ), 23.0 );
   QCOMPARE( from2Pts.mAt( 1 ), 24.0 );
 
+  // from lineSegment
+  QgsLineString fromSegment( QgsLineSegment2D( QgsPointXY( 1, 2 ), QgsPointXY( 3, 4 ) ) );
+  QCOMPARE( fromSegment.wkbType(), QgsWkbTypes::LineString );
+  QCOMPARE( fromSegment.numPoints(), 2 );
+  QCOMPARE( fromSegment.xAt( 0 ), 1.0 );
+  QCOMPARE( fromSegment.yAt( 0 ), 2.0 );
+  QCOMPARE( fromSegment.xAt( 1 ), 3.0 );
+  QCOMPARE( fromSegment.yAt( 1 ), 4.0 );
+
   //addVertex
   QgsLineString l2;
   l2.addVertex( QgsPoint( 1.0, 2.0 ) );
diff --git a/tests/src/python/test_qgslinesegment.py b/tests/src/python/test_qgslinesegment.py
@@ -27,6 +27,9 @@ def testConstruct(self):
         segment = QgsLineSegment2D(QgsPointXY(1, 2), QgsPointXY(3, 4))
         self.assertEqual(segment.start(), QgsPointXY(1, 2))
         self.assertEqual(segment.end(), QgsPointXY(3, 4))
+        segment = QgsLineSegment2D(1, 2, 3, 4)
+        self.assertEqual(segment.start(), QgsPointXY(1, 2))
+        self.assertEqual(segment.end(), QgsPointXY(3, 4))
 
     def testGettersSetters(self):
         segment = QgsLineSegment2D(QgsPointXY(1, 2), QgsPointXY(3, 4))
