Make QgsCoordinateTransform implicitly shared, no longer a QObject

There was no code in core using the signals/slots associated with QgsCoordinateTransform, and little reason to keep the class a QObject. Making it not a QObject simplifies code and allows QgsCoordinateTransform objects to be easily copied and passed around without complication.
qgis · Jul 16, 2016 · 736aab1 · 736aab1
1 parent 6fefbea
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diff --git a/doc/api_break.dox b/doc/api_break.dox
@@ -21,6 +21,8 @@ This page tries to maintain a list with incompatible changes that happened in pr
 \subsection qgis_api_break_3_0_QgsCoordinateTransform QgsCoordinateTransform
 
 <ul>
+<li>QgsCoordinateTransform is no longer a QObject. readXml, writeXml and initialise are all normal public members now,
+not slots. The invalidTransformInput() signal has been removed.</li>
 <li>sourceCrs() and destCrs() now return a copy instead of a reference to the CRS. This has no effect on PyQGIS code, but c++
 plugins calling these methods will need to be updated.</li>
 </ul>

diff --git a/python/core/qgscoordinatetransform.sip b/python/core/qgscoordinatetransform.sip
@@ -7,19 +7,29 @@
 * layer's coordinate system and the coordinate system of the map canvas, although
 * it can be used in a more general sense to transform coordinates.
 *
-* All references to source and destination coordinate systems refer to
-* layer and map canvas respectively. All operations are from the perspective
-* of the layer. For example, a forward transformation transforms coordinates from the
-* layers coordinate system to the map canvas.
+* When used to transform between a layer and the map canvas, all references to source
+* and destination coordinate systems refer to layer and map canvas respectively. All
+* operations are from the perspective of the layer. For example, a forward transformation
+* transforms coordinates from the layer's coordinate system to the map canvas.
+* \note Since QGIS 3.0 QgsCoordinateReferenceSystem objects are implicitly shared.
 */
-class QgsCoordinateTransform : QObject
+
+class QgsCoordinateTransform
 {
 %TypeHeaderCode
 #include <qgscoordinatetransform.h>
 %End
 
   public:
-    /** Default constructor. Make sure you use initialized() manually if you use this one! */
+
+    //! Enum used to indicate the direction (forward or inverse) of the transform
+    enum TransformDirection
+    {
+      ForwardTransform,     /*!< Transform from source to destination CRS. */
+      ReverseTransform      /*!< Transform from destination to source CRS. */
+    };
+
+    /** Default constructor, creates an invalid QgsCoordinateTransform. */
     QgsCoordinateTransform();
 
     /** Constructs a QgsCoordinateTransform using QgsCoordinateReferenceSystem objects.
@@ -56,13 +66,6 @@ class QgsCoordinateTransform : QObject
 
     QgsCoordinateTransform* clone() const /Factory/;
 
-    //! Enum used to indicate the direction (forward or inverse) of the transform
-    enum TransformDirection
-    {
-      ForwardTransform,     /*!< Transform from source to destination CRS. */
-      ReverseTransform      /*!< Transform from destination to source CRS. */
-    };
-
     /*!
      * Set the source (layer) QgsCoordinateReferenceSystem
      * @param theCRS QgsCoordinateReferenceSystem representation of the layer's coordinate system
@@ -196,24 +199,20 @@ class QgsCoordinateTransform : QObject
     int destinationDatumTransform() const;
     void setDestinationDatumTransform( int dt );
 
-  public slots:
     //!initialize is used to actually create the Transformer instance
     void initialise();
 
     /** Restores state from the given Dom node.
      * @param theNode The node from which state will be restored
      * @return bool True on success, False on failure
      */
-    bool readXML( QDomNode & theNode );
+    bool readXML( const QDomNode & theNode );
 
     /** Stores state to the given Dom node in the given document
      * @param theNode The node in which state will be restored
      * @param theDoc The document in which state will be stored
      * @return bool True on success, False on failure
      */
-    bool writeXML( QDomNode & theNode, QDomDocument & theDoc );
+    bool writeXML( QDomNode & theNode, QDomDocument & theDoc ) const;
 
-  signals:
-    /** Signal when an invalid pj_transform() has occurred */
-    void  invalidTransformInput() const;
 };
diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
@@ -454,7 +454,6 @@ SET(QGIS_CORE_MOC_HDRS
   qgsapplication.h
   qgsbrowsermodel.h
   qgscontexthelp.h
-  qgscoordinatetransform.h
   qgscredentials.h
   qgsdataitem.h
   qgsdataprovider.h
@@ -620,6 +619,8 @@ SET(QGIS_CORE_HDRS
   qgsconditionalstyle.h
   qgscoordinatereferencesystem.h  
   qgscoordinatereferencesystem_p.h
+  qgscoordinatetransform.h
+  qgscoordinatetransform_p.h
   qgscoordinateutils.h
   qgscrscache.h
   qgscsexception.h