Add some static methods for creating QgsCoordinateReferenceSystem

This avoids the need for

  QgsCoordinateReferenceSystem crs;
  crs.createFromSrsId(...)

and instead can be replaced with

  QgsCoordinateReferenceSystem crs = QgsCoordinateReferenceSystem::fromSrsId(...)

python/core/qgscoordinatereferencesystem.sip

@@ -190,6 +190,47 @@ class QgsCoordinateReferenceSystem
     // TODO QGIS 3: remove theType and always use EPSG code
     QgsCoordinateReferenceSystem( const long theId, CrsType theType = PostgisCrsId );
 
+    // static creators
+
+    /** Creates a CRS from a given OGC WMS-format Coordinate Reference System string.
+     * @param ogcCrs OGR compliant CRS definition, eg "EPSG:4326"
+     * @returns matching CRS, or an invalid CRS if string could not be matched
+     * @note added in QGIS 3.0
+     * @see createFromOgcWmsCrs()
+    */
+    static QgsCoordinateReferenceSystem fromOgcWmsCrs( const QString& ogcCrs );
+
+    /** Creates a CRS from a given EPSG ID.
+     * @param epsg epsg CRS ID
+     * @returns matching CRS, or an invalid CRS if string could not be matched
+     * @note added in QGIS 3.0
+    */
+    static QgsCoordinateReferenceSystem fromEpsgId( long epsg );
+
+    /** Creates a CRS from a proj4 style formatted string.
+     * @param proj4 proj4 format string
+     * @returns matching CRS, or an invalid CRS if string could not be matched
+     * @note added in QGIS 3.0
+     * @see createFromProj4()
+    */
+    static QgsCoordinateReferenceSystem fromProj4( const QString& proj4 );
+
+    /** Creates a CRS from a WKT spatial ref sys definition string.
+     * @param wkt WKT for the desired spatial reference system.
+     * @returns matching CRS, or an invalid CRS if string could not be matched
+     * @note added in QGIS 3.0
+     * @see createFromWkt()
+    */
+    static QgsCoordinateReferenceSystem fromWkt( const QString& wkt );
+
+    /** Creates a CRS from a specified QGIS SRS ID.
+     * @param srsId internal QGIS SRS ID
+     * @returns matching CRS, or an invalid CRS if ID could not be found
+     * @note added in QGIS 3.0
+     * @see createFromSrsId()
+    */
+    static QgsCoordinateReferenceSystem fromSrsId( long srsId );
+
     // Misc helper functions -----------------------
 
     /**

src/core/qgscoordinatereferencesystem.cpp

@@ -78,6 +78,39 @@ QgsCoordinateReferenceSystem& QgsCoordinateReferenceSystem::operator=( const Qgs
   return *this;
 }
 
+QgsCoordinateReferenceSystem QgsCoordinateReferenceSystem::fromOgcWmsCrs( const QString& ogcCrs )
+{
+  QgsCoordinateReferenceSystem crs;
+  crs.createFromOgcWmsCrs( ogcCrs );
+  return crs;
+}
+
+QgsCoordinateReferenceSystem QgsCoordinateReferenceSystem::fromEpsgId( long epsg )
+{
+  return fromOgcWmsCrs( "EPSG:" + QString::number( epsg ) );
+}
+
+QgsCoordinateReferenceSystem QgsCoordinateReferenceSystem::fromProj4( const QString& proj4 )
+{
+  QgsCoordinateReferenceSystem crs;
+  crs.createFromProj4( proj4 );
+  return crs;
+}
+
+QgsCoordinateReferenceSystem QgsCoordinateReferenceSystem::fromWkt( const QString& wkt )
+{
+  QgsCoordinateReferenceSystem crs;
+  crs.createFromWkt( wkt );
+  return crs;
+}
+
+QgsCoordinateReferenceSystem QgsCoordinateReferenceSystem::fromSrsId( long srsId )
+{
+  QgsCoordinateReferenceSystem crs;
+  crs.createFromSrsId( srsId );
+  return crs;
+}
+
 QgsCoordinateReferenceSystem::~QgsCoordinateReferenceSystem()
 {
 }

src/core/qgscoordinatereferencesystem.h

@@ -237,6 +237,47 @@ class CORE_EXPORT QgsCoordinateReferenceSystem
     //! Assignment operator
     QgsCoordinateReferenceSystem& operator=( const QgsCoordinateReferenceSystem& srs );
 
+    // static creators
+
+    /** Creates a CRS from a given OGC WMS-format Coordinate Reference System string.
+     * @param ogcCrs OGR compliant CRS definition, eg "EPSG:4326"
+     * @returns matching CRS, or an invalid CRS if string could not be matched
+     * @note added in QGIS 3.0
+     * @see createFromOgcWmsCrs()
+    */
+    static QgsCoordinateReferenceSystem fromOgcWmsCrs( const QString& ogcCrs );
+
+    /** Creates a CRS from a given EPSG ID.
+     * @param epsg epsg CRS ID
+     * @returns matching CRS, or an invalid CRS if string could not be matched
+     * @note added in QGIS 3.0
+    */
+    static QgsCoordinateReferenceSystem fromEpsgId( long epsg );
+
+    /** Creates a CRS from a proj4 style formatted string.
+     * @param proj4 proj4 format string
+     * @returns matching CRS, or an invalid CRS if string could not be matched
+     * @note added in QGIS 3.0
+     * @see createFromProj4()
+    */
+    static QgsCoordinateReferenceSystem fromProj4( const QString& proj4 );
+
+    /** Creates a CRS from a WKT spatial ref sys definition string.
+     * @param wkt WKT for the desired spatial reference system.
+     * @returns matching CRS, or an invalid CRS if string could not be matched
+     * @note added in QGIS 3.0
+     * @see createFromWkt()
+    */
+    static QgsCoordinateReferenceSystem fromWkt( const QString& wkt );
+
+    /** Creates a CRS from a specified QGIS SRS ID.
+     * @param srsId internal QGIS SRS ID
+     * @returns matching CRS, or an invalid CRS if ID could not be found
+     * @note added in QGIS 3.0
+     * @see createFromSrsId()
+    */
+    static QgsCoordinateReferenceSystem fromSrsId( long srsId );
+
     // Misc helper functions -----------------------
 
     /**
@@ -256,6 +297,7 @@ class CORE_EXPORT QgsCoordinateReferenceSystem
      * and refer to QGIS internal CRS IDs.
      * @note this method is expensive. Consider using QgsCRSCache::crsByOgcWmsCrs() instead.
      * @return True on success else false
+     * @see fromOgcWmsCrs()
      */
     // TODO QGIS 3: remove "QGIS" and "CUSTOM", only support "USER" (also returned by authid())
     bool createFromOgcWmsCrs( const QString& theCrs );
@@ -277,6 +319,7 @@ class CORE_EXPORT QgsCoordinateReferenceSystem
      * @note this method is expensive. Consider using QgsCRSCache::crsByWkt() instead.
      * @param theWkt The WKT for the desired spatial reference system.
      * @return True on success else false
+     * @see fromWkt()
      */
     bool createFromWkt( const QString &theWkt );
 
@@ -287,6 +330,7 @@ class CORE_EXPORT QgsCoordinateReferenceSystem
      * @note this method is expensive. Consider using QgsCRSCache::crsBySrsId() instead.
      * @param theSrsId The internal QGIS CRS ID for the desired spatial reference system.
      * @return True on success else false
+     * @see fromSrsId()
      */
     bool createFromSrsId( const long theSrsId );
 
@@ -310,6 +354,7 @@ class CORE_EXPORT QgsCoordinateReferenceSystem
      * @note this method is expensive. Consider using QgsCRSCache::crsByProj4() instead.
      * @param theProjString A proj4 format string
      * @return True on success else false
+     * @see fromProj4()
      */
     bool createFromProj4( const QString &theProjString );
 

tests/src/core/testqgscoordinatereferencesystem.cpp

@@ -38,12 +38,16 @@ class TestQgsCoordinateReferenceSystem: public QObject
     void copyCtor();
     void assignmentCtor();
     void createFromId();
+    void fromEpsgId();
     void createFromOgcWmsCrs();
     void createFromSrid();
     void createFromWkt();
+    void fromWkt();
     void createFromESRIWkt();
-    void createFromSrsId();
+    void createFromSrId();
+    void fromSrsId();
     void createFromProj4();
+    void fromProj4();
     void isValid();
     void validate();
     void equality();
@@ -161,6 +165,16 @@ void TestQgsCoordinateReferenceSystem::createFromId()
                       QgsCoordinateReferenceSystem::EpsgCrsId );
   debugPrint( myCrs );
   QVERIFY( myCrs.isValid() );
+  QCOMPARE( myCrs.srsid(), GEOCRS_ID );
+}
+
+void TestQgsCoordinateReferenceSystem::fromEpsgId()
+{
+  QgsCoordinateReferenceSystem myCrs = QgsCoordinateReferenceSystem::fromEpsgId( GEO_EPSG_CRS_ID );
+  QVERIFY( myCrs.isValid() );
+  QCOMPARE( myCrs.srsid(), GEOCRS_ID );
+  myCrs = QgsCoordinateReferenceSystem::fromEpsgId( -999 );
+  QVERIFY( !myCrs.isValid() );
 }
 void TestQgsCoordinateReferenceSystem::createFromOgcWmsCrs()
 {
@@ -175,6 +189,7 @@ void TestQgsCoordinateReferenceSystem::createFromSrid()
   myCrs.createFromSrid( GEOSRID );
   debugPrint( myCrs );
   QVERIFY( myCrs.isValid() );
+  QCOMPARE( myCrs.srsid(), GEOCRS_ID );
 }
 void TestQgsCoordinateReferenceSystem::createFromWkt()
 {
@@ -182,6 +197,16 @@ void TestQgsCoordinateReferenceSystem::createFromWkt()
   myCrs.createFromWkt( GEOWKT );
   debugPrint( myCrs );
   QVERIFY( myCrs.isValid() );
+  QCOMPARE( myCrs.srsid(), GEOCRS_ID );
+}
+
+void TestQgsCoordinateReferenceSystem::fromWkt()
+{
+  QgsCoordinateReferenceSystem myCrs = QgsCoordinateReferenceSystem::fromWkt( GEOWKT );
+  QVERIFY( myCrs.isValid() );
+  QCOMPARE( myCrs.srsid(), GEOCRS_ID );
+  myCrs = QgsCoordinateReferenceSystem::fromWkt( "not wkt" );
+  QVERIFY( !myCrs.isValid() );
 }
 
 QString TestQgsCoordinateReferenceSystem::testESRIWkt( int i, QgsCoordinateReferenceSystem &myCrs )
@@ -297,17 +322,41 @@ void TestQgsCoordinateReferenceSystem::createFromESRIWkt()
 
   //  QVERIFY( bOK );
 }
-void TestQgsCoordinateReferenceSystem::createFromSrsId()
+void TestQgsCoordinateReferenceSystem::createFromSrId()
 {
   QgsCoordinateReferenceSystem myCrs;
   QVERIFY( myCrs.createFromSrid( GEOSRID ) );
   debugPrint( myCrs );
+  QVERIFY( myCrs.isValid() );
+  QCOMPARE( myCrs.srsid(), GEOCRS_ID );
+}
+
+void TestQgsCoordinateReferenceSystem::fromSrsId()
+{
+  QgsCoordinateReferenceSystem myCrs = QgsCoordinateReferenceSystem::fromSrsId( GEOCRS_ID );
+  debugPrint( myCrs );
+  QVERIFY( myCrs.isValid() );
+  QCOMPARE( myCrs.srsid(), GEOCRS_ID );
+  myCrs = QgsCoordinateReferenceSystem::fromSrsId( -9999 );
+  QVERIFY( !myCrs.isValid() );
 }
 void TestQgsCoordinateReferenceSystem::createFromProj4()
 {
   QgsCoordinateReferenceSystem myCrs;
   QVERIFY( myCrs.createFromProj4( GEOPROJ4 ) );
   debugPrint( myCrs );
+  QVERIFY( myCrs.isValid() );
+  QCOMPARE( myCrs.srsid(), GEOCRS_ID );
+}
+
+void TestQgsCoordinateReferenceSystem::fromProj4()
+{
+  QgsCoordinateReferenceSystem myCrs = QgsCoordinateReferenceSystem::fromProj4( GEOPROJ4 );
+  debugPrint( myCrs );
+  QVERIFY( myCrs.isValid() );
+  QCOMPARE( myCrs.srsid(), GEOCRS_ID );
+  myCrs = QgsCoordinateReferenceSystem::fromProj4( "" );
+  QVERIFY( !myCrs.isValid() );
 }
 void TestQgsCoordinateReferenceSystem::isValid()
 {
@@ -434,7 +483,7 @@ void TestQgsCoordinateReferenceSystem::isGeographic()
 
   QgsCoordinateReferenceSystem nonGeographic;
   nonGeographic.createFromId( 3857, QgsCoordinateReferenceSystem::EpsgCrsId );
-  QVERIFY( !geographic.nonGeographic() );
+  QVERIFY( !nonGeographic.isGeographic() );
 }
 void TestQgsCoordinateReferenceSystem::mapUnits()
 {