Cache summed up area for curve geometry classes

nyalldawson · nyalldawson · commit 1c05421486d7 · 2022-09-28T15:58:22.000+10:00
Avoids recalculation when area is retrieved multiple times
diff --git a/python/core/auto_generated/geometry/qgscurve.sip.in b/python/core/auto_generated/geometry/qgscurve.sip.in
@@ -323,6 +323,7 @@ Scrolls the curve vertices so that they start with the vertex at the given index
 
 
 
+
 };
 
 /************************************************************************
diff --git a/src/core/geometry/qgscircularstring.cpp b/src/core/geometry/qgscircularstring.cpp
@@ -1347,8 +1347,14 @@ bool QgsCircularString::pointAt( int node, QgsPoint &point, Qgis::VertexType &ty
 
 void QgsCircularString::sumUpArea( double &sum ) const
 {
-  int maxIndex = numPoints() - 2;
+  if ( mHasCachedSummedUpArea )
+  {
+    sum += mSummedUpArea;
+    return;
+  }
 
+  int maxIndex = numPoints() - 2;
+  mSummedUpArea = 0;
   for ( int i = 0; i < maxIndex; i += 2 )
   {
     QgsPoint p1( mX[i], mY[i] );
@@ -1359,11 +1365,11 @@ void QgsCircularString::sumUpArea( double &sum ) const
     if ( p1 == p3 )
     {
       double r2 = QgsGeometryUtils::sqrDistance2D( p1, p2 ) / 4.0;
-      sum += M_PI * r2;
+      mSummedUpArea += M_PI * r2;
       continue;
     }
 
-    sum += 0.5 * ( mX[i] * mY[i + 2] - mY[i] * mX[i + 2] );
+    mSummedUpArea += 0.5 * ( mX[i] * mY[i + 2] - mY[i] * mX[i + 2] );
 
     //calculate area between circle and chord, then sum / subtract from total area
     double midPointX = ( p1.x() + p3.x() ) / 2.0;
@@ -1397,13 +1403,16 @@ void QgsCircularString::sumUpArea( double &sum ) const
 
     if ( !circlePointLeftOfLine )
     {
-      sum += circleChordArea;
+      mSummedUpArea += circleChordArea;
     }
     else
     {
-      sum -= circleChordArea;
+      mSummedUpArea -= circleChordArea;
     }
   }
+
+  mHasCachedSummedUpArea = true;
+  sum += mSummedUpArea;
 }
 
 bool QgsCircularString::hasCurvedSegments() const
diff --git a/src/core/geometry/qgscompoundcurve.cpp b/src/core/geometry/qgscompoundcurve.cpp
@@ -1148,10 +1148,19 @@ std::tuple<std::unique_ptr<QgsCurve>, std::unique_ptr<QgsCurve> > QgsCompoundCur
 
 void QgsCompoundCurve::sumUpArea( double &sum ) const
 {
+  if ( mHasCachedSummedUpArea )
+  {
+    sum += mSummedUpArea;
+    return;
+  }
+
+  mSummedUpArea = 0;
   for ( const QgsCurve *curve : mCurves )
   {
-    curve->sumUpArea( sum );
+    curve->sumUpArea( mSummedUpArea );
   }
+  mHasCachedSummedUpArea = true;
+  sum += mSummedUpArea;
 }
 
 void QgsCompoundCurve::close()
diff --git a/src/core/geometry/qgscurve.cpp b/src/core/geometry/qgscurve.cpp
@@ -295,6 +295,7 @@ void QgsCurve::clearCache() const
   mBoundingBox = QgsRectangle();
   mHasCachedValidity = false;
   mValidityFailureReason.clear();
+  mHasCachedSummedUpArea = false;
   QgsAbstractGeometry::clearCache();
 }
 
diff --git a/src/core/geometry/qgscurve.h b/src/core/geometry/qgscurve.h
@@ -341,6 +341,9 @@ class CORE_EXPORT QgsCurve: public QgsAbstractGeometry SIP_ABSTRACT
      */
     mutable QgsRectangle mBoundingBox;
 
+    mutable bool mHasCachedSummedUpArea = false;
+    mutable double mSummedUpArea = 0;
+
   private:
 
     mutable bool mHasCachedValidity = false;
diff --git a/src/core/geometry/qgslinestring.cpp b/src/core/geometry/qgslinestring.cpp
@@ -1936,6 +1936,13 @@ QgsPoint QgsLineString::centroid() const
 
 void QgsLineString::sumUpArea( double &sum ) const
 {
+  if ( mHasCachedSummedUpArea )
+  {
+    sum += mSummedUpArea;
+    return;
+  }
+
+  mSummedUpArea = 0;
   const int maxIndex = mX.size();
   if ( maxIndex == 0 )
     return;
@@ -1946,10 +1953,13 @@ void QgsLineString::sumUpArea( double &sum ) const
   double prevY = *y++;
   for ( int i = 1; i < maxIndex; ++i )
   {
-    sum += 0.5 * ( prevX * ( *y ) - prevY * ( *x ) );
+    mSummedUpArea += 0.5 * ( prevX * ( *y ) - prevY * ( *x ) );
     prevX = *x++;
     prevY = *y++;
   }
+
+  mHasCachedSummedUpArea = true;
+  sum += mSummedUpArea;
 }
 
 void QgsLineString::importVerticesFromWkb( const QgsConstWkbPtr &wkb )

Original file line number	Diff line number	Diff line change
`@@ -323,6 +323,7 @@ Scrolls the curve vertices so that they start with the vertex at the given index`
`323`	`323`
`324`	`324`
`325`	`325`
	`326`	`+`
`326`	`327`	`};`
`327`	`328`
`328`	`329`	`/************************************************************************`
Original file line number	Diff line number	Diff line change
`@@ -1347,8 +1347,14 @@ bool QgsCircularString::pointAt( int node, QgsPoint &point, Qgis::VertexType &ty`
`1347`	`1347`
`1348`	`1348`	`void QgsCircularString::sumUpArea( double &sum ) const`
`1349`	`1349`	`{`
`1350`		`- int maxIndex = numPoints() - 2;`
	`1350`	`+ if ( mHasCachedSummedUpArea )`
	`1351`	`+ {`
	`1352`	`+ sum += mSummedUpArea;`
	`1353`	`+ return;`
	`1354`	`+ }`
`1351`	`1355`
	`1356`	`+ int maxIndex = numPoints() - 2;`
	`1357`	`+ mSummedUpArea = 0;`
`1352`	`1358`	`for ( int i = 0; i < maxIndex; i += 2 )`
`1353`	`1359`	`{`
`1354`	`1360`	`QgsPoint p1( mX[i], mY[i] );`
`@@ -1359,11 +1365,11 @@ void QgsCircularString::sumUpArea( double &sum ) const`
`1359`	`1365`	`if ( p1 == p3 )`
`1360`	`1366`	`{`
`1361`	`1367`	`double r2 = QgsGeometryUtils::sqrDistance2D( p1, p2 ) / 4.0;`
`1362`		`- sum += M_PI * r2;`
	`1368`	`+ mSummedUpArea += M_PI * r2;`
`1363`	`1369`	`continue;`
`1364`	`1370`	`}`
`1365`	`1371`
`1366`		`- sum += 0.5 * ( mX[i] * mY[i + 2] - mY[i] * mX[i + 2] );`
	`1372`	`+ mSummedUpArea += 0.5 * ( mX[i] * mY[i + 2] - mY[i] * mX[i + 2] );`
`1367`	`1373`
`1368`	`1374`	`//calculate area between circle and chord, then sum / subtract from total area`
`1369`	`1375`	`double midPointX = ( p1.x() + p3.x() ) / 2.0;`
`@@ -1397,13 +1403,16 @@ void QgsCircularString::sumUpArea( double &sum ) const`
`1397`	`1403`
`1398`	`1404`	`if ( !circlePointLeftOfLine )`
`1399`	`1405`	`{`
`1400`		`- sum += circleChordArea;`
	`1406`	`+ mSummedUpArea += circleChordArea;`
`1401`	`1407`	`}`
`1402`	`1408`	`else`
`1403`	`1409`	`{`
`1404`		`- sum -= circleChordArea;`
	`1410`	`+ mSummedUpArea -= circleChordArea;`
`1405`	`1411`	`}`
`1406`	`1412`	`}`
	`1413`	`+`
	`1414`	`+ mHasCachedSummedUpArea = true;`
	`1415`	`+ sum += mSummedUpArea;`
`1407`	`1416`	`}`
`1408`	`1417`
`1409`	`1418`	`bool QgsCircularString::hasCurvedSegments() const`
Original file line number	Diff line number	Diff line change
`@@ -1148,10 +1148,19 @@ std::tuple<std::unique_ptr<QgsCurve>, std::unique_ptr<QgsCurve> > QgsCompoundCur`
`1148`	`1148`
`1149`	`1149`	`void QgsCompoundCurve::sumUpArea( double &sum ) const`
`1150`	`1150`	`{`
	`1151`	`+ if ( mHasCachedSummedUpArea )`
	`1152`	`+ {`
	`1153`	`+ sum += mSummedUpArea;`
	`1154`	`+ return;`
	`1155`	`+ }`
	`1156`	`+`
	`1157`	`+ mSummedUpArea = 0;`
`1151`	`1158`	`for ( const QgsCurve *curve : mCurves )`
`1152`	`1159`	`{`
`1153`		`- curve->sumUpArea( sum );`
	`1160`	`+ curve->sumUpArea( mSummedUpArea );`
`1154`	`1161`	`}`
	`1162`	`+ mHasCachedSummedUpArea = true;`
	`1163`	`+ sum += mSummedUpArea;`
`1155`	`1164`	`}`
`1156`	`1165`
`1157`	`1166`	`void QgsCompoundCurve::close()`
Original file line number	Diff line number	Diff line change
`@@ -295,6 +295,7 @@ void QgsCurve::clearCache() const`
`295`	`295`	`mBoundingBox = QgsRectangle();`
`296`	`296`	`mHasCachedValidity = false;`
`297`	`297`	`mValidityFailureReason.clear();`
	`298`	`+ mHasCachedSummedUpArea = false;`
`298`	`299`	`QgsAbstractGeometry::clearCache();`
`299`	`300`	`}`
`300`	`301`