From 43d5b0c8b3e000bd7b09d132fceba431779ce2dd Mon Sep 17 00:00:00 2001
From: Nyall Dawson <nyall.dawson@gmail.com>
Date: Wed, 10 Mar 2021 14:20:21 +1000
Subject: [PATCH] Optimise two heavily used methods in QgsLineString

---
 src/core/geometry/qgslinestring.cpp | 36 ++++++++++++++++-------------
 src/core/geometry/qgslinestring.h   |  1 +
 2 files changed, 21 insertions(+), 16 deletions(-)

diff --git a/src/core/geometry/qgslinestring.cpp b/src/core/geometry/qgslinestring.cpp
index f3581eab7cc6..e5a2af5d2fb6 100644
--- a/src/core/geometry/qgslinestring.cpp
+++ b/src/core/geometry/qgslinestring.cpp
@@ -375,6 +375,18 @@ bool QgsLineString::removeDuplicateNodes( double epsilon, bool useZValues )
   return result;
 }
 
+bool QgsLineString::isClosed() const
+{
+  if ( mX.empty() )
+    return false;
+
+  bool closed = qgsDoubleNear( mX.first(), mX.last() ) &&
+                qgsDoubleNear( mY.first(), mY.last() );
+  if ( is3D() && closed )
+    closed &= qgsDoubleNear( mZ.first(), mZ.last() ) || ( std::isnan( mZ.first() ) && std::isnan( mZ.last() ) );
+  return closed;
+}
+
 QVector< QgsVertexId > QgsLineString::collectDuplicateNodes( double epsilon, bool useZValues ) const
 {
   QVector< QgsVertexId > res;
@@ -448,23 +460,15 @@ bool QgsLineString::fromWkb( QgsConstWkbPtr &wkbPtr )
 
 QgsRectangle QgsLineString::calculateBoundingBox() const
 {
-  double xmin = std::numeric_limits<double>::max();
-  double ymin = std::numeric_limits<double>::max();
-  double xmax = -std::numeric_limits<double>::max();
-  double ymax = -std::numeric_limits<double>::max();
+  if ( mX.empty() )
+    return QgsRectangle();
 
-  const int nb = mX.size();
-  const double *x = mX.constData();
-  const double *y = mY.constData();
-  for ( int i = 0; i < nb; ++i )
-  {
-    const double px = *x++;
-    xmin = std::min( xmin, px );
-    xmax = std::max( xmax, px );
-    const double py = *y++;
-    ymin = std::min( ymin, py );
-    ymax = std::max( ymax, py );
-  }
+  auto result = std::minmax_element( mX.begin(), mX.end() );
+  const double xmin = *result.first;
+  const double xmax = *result.second;
+  result = std::minmax_element( mY.begin(), mY.end() );
+  const double ymin = *result.first;
+  const double ymax = *result.second;
   return QgsRectangle( xmin, ymin, xmax, ymax, false );
 }
 
diff --git a/src/core/geometry/qgslinestring.h b/src/core/geometry/qgslinestring.h
index 7975b8e1b9de..d04bd3767700 100644
--- a/src/core/geometry/qgslinestring.h
+++ b/src/core/geometry/qgslinestring.h
@@ -590,6 +590,7 @@ class CORE_EXPORT QgsLineString: public QgsCurve
     bool isValid( QString &error SIP_OUT, int flags = 0 ) const override;
     QgsLineString *snappedToGrid( double hSpacing, double vSpacing, double dSpacing = 0, double mSpacing = 0 ) const override SIP_FACTORY;
     bool removeDuplicateNodes( double epsilon = 4 * std::numeric_limits<double>::epsilon(), bool useZValues = false ) override;
+    bool isClosed() const override SIP_HOLDGIL;
 
     /**
      * Returns a list of any duplicate nodes contained in the geometry, within the specified tolerance.