[needs-docs] Append a local, user writable folder to proj 6 search paths

Now, proj will search in the current user profile "proj" folder (e.g. .local/share/QGIS/QGIS3/profiles/default/proj" on linux) for grid files and other proj helper files. This allows users (and plugins) to install grid files and make them available for use in QGIS without requiring administrator access to the system.
qgis · Jun 3, 2019 · a4e5e6a · a4e5e6a
1 parent 19933e0
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diff --git a/python/core/auto_generated/qgsprojutils.sip.in b/python/core/auto_generated/qgsprojutils.sip.in
@@ -29,6 +29,16 @@ Utility functions for working with the proj library.
 Returns the proj library major version number.
 %End
 
+    static QStringList searchPaths();
+%Docstring
+Returns the current list of Proj file search paths.
+
+.. note::
+
+   Only available on builds based on Proj >= 6.0. Builds based on
+   earlier Proj versions will always return an empty list.
+%End
+
 };
 
 /************************************************************************

diff --git a/src/core/qgsapplication.cpp b/src/core/qgsapplication.cpp
@@ -51,6 +51,7 @@
 #include "qgslayoutrendercontext.h"
 #include "qgssqliteutils.h"
 #include "qgsstyle.h"
+#include "qgsprojutils.h"
 #include "qgsvaliditycheckregistry.h"
 
 #include "gps/qgsgpsconnectionregistry.h"
@@ -91,6 +92,11 @@
 #include <cpl_conv.h> // for setting gdal options
 #include <sqlite3.h>
 
+#if PROJ_VERSION_MAJOR>=6
+#include <proj.h>
+#endif
+
+
 #define CONN_POOL_MAX_CONCURRENT_CONNS      4
 
 QObject *ABISYM( QgsApplication::mFileOpenEventReceiver );
@@ -295,6 +301,20 @@ void QgsApplication::init( QString profileFolder )
   }
   ABISYM( mSystemEnvVars ) = systemEnvVarMap;
 
+#if PROJ_VERSION_MAJOR>=6
+  // append local user-writable folder as a proj search path
+  QStringList currentProjSearchPaths = QgsProjUtils::searchPaths();
+  currentProjSearchPaths.append( qgisSettingsDirPath() + QStringLiteral( "proj" ) );
+  const char **newPaths = new const char *[currentProjSearchPaths.length()];
+  for ( int i = 0; i < currentProjSearchPaths.count(); ++i )
+  {
+    newPaths[i] = currentProjSearchPaths.at( i ).toUtf8().constData();
+  }
+  proj_context_set_search_paths( nullptr, currentProjSearchPaths.count(), newPaths );
+  delete [] newPaths;
+#endif
+
+
   // allow Qt to search for Qt plugins (e.g. sqldrivers) in our plugin directory
   QCoreApplication::addLibraryPath( pluginPath() );
 

diff --git a/src/core/qgsprojutils.cpp b/src/core/qgsprojutils.cpp
@@ -15,7 +15,9 @@
  *                                                                         *
  ***************************************************************************/
 #include "qgsprojutils.h"
+#include "qgis.h"
 #include <QString>
+#include <QSet>
 
 #if PROJ_VERSION_MAJOR>=6
 #include <proj.h>
@@ -215,3 +217,32 @@ QStringList QgsProjUtils::nonAvailableGrids( const QString &projDef )
 
 #endif
 
+QStringList QgsProjUtils::searchPaths()
+{
+#if PROJ_VERSION_MAJOR >= 6
+  const QString path( proj_info().searchpath );
+  QStringList paths;
+// #ifdef Q_OS_WIN
+#if 1 // -- see https://github.com/OSGeo/proj.4/pull/1497
+  paths = path.split( ';' );
+#else
+  paths = path.split( ':' );
+#endif
+
+  QSet<QString> existing;
+  // thin out duplicates from paths -- see https://github.com/OSGeo/proj.4/pull/1498
+  QStringList res;
+  res.reserve( paths.count() );
+  for ( const QString &p : qgis::as_const( paths ) )
+  {
+    if ( existing.contains( p ) )
+      continue;
+
+    existing.insert( p );
+    res << p;
+  }
+  return res;
+#else
+  return QStringList();
+#endif
+}
diff --git a/src/core/qgsprojutils.h b/src/core/qgsprojutils.h
@@ -53,6 +53,14 @@ class CORE_EXPORT QgsProjUtils
       return PROJ_VERSION_MAJOR;
     }
 
+    /**
+     * Returns the current list of Proj file search paths.
+     *
+     * \note Only available on builds based on Proj >= 6.0. Builds based on
+     * earlier Proj versions will always return an empty list.
+     */
+    static QStringList searchPaths();
+
 #ifndef SIP_RUN
 #if PROJ_VERSION_MAJOR >= 6
 

diff --git a/tests/src/core/testqgsprojutils.cpp b/tests/src/core/testqgsprojutils.cpp
@@ -35,6 +35,7 @@ class TestQgsProjUtils: public QObject
     void threadSafeContext();
     void usesAngularUnits();
     void axisOrderIsSwapped();
+    void searchPath();
 
 };
 
@@ -97,5 +98,14 @@ void TestQgsProjUtils::axisOrderIsSwapped()
 #endif
 }
 
+void TestQgsProjUtils::searchPath()
+{
+#if PROJ_VERSION_MAJOR>=6
+  // ensure local user-writable path is present in Proj search paths
+  const QStringList paths = QgsProjUtils::searchPaths();
+  QVERIFY( paths.contains( QgsApplication::qgisSettingsDirPath() + QStringLiteral( "proj" ) ) );
+#endif
+}
+
 QGSTEST_MAIN( TestQgsProjUtils )
 #include "testqgsprojutils.moc"