add supportedFormatExtensions() method to QgsRasterFileWriter

python/core/raster/qgsrasterfilewriter.sip

@@ -194,6 +194,18 @@ Filter string for file picker dialogs
  :rtype: list of QgsRasterFileWriter.FilterFormatDetails
 %End
 
+    static QStringList supportedFormatExtensions( RasterFormatOptions options = SortRecommended );
+%Docstring
+ Returns a list of file extensions for supported formats.
+
+ The ``options`` argument can be used to control the sorting and filtering of
+ returned formats.
+
+.. versionadded:: 3.0
+.. seealso:: :py:func:`supportedFiltersAndFormats()`
+ :rtype: list of str
+%End
+
     static QString driverForExtension( const QString &extension );
 %Docstring
  Returns the GDAL driver name for a specified file ``extension``. E.g. the

src/core/raster/qgsrasterfilewriter.cpp

@@ -1103,3 +1103,23 @@ QList< QgsRasterFileWriter::FilterFormatDetails > QgsRasterFileWriter::supported
 
   return results;
 }
+
+QStringList QgsRasterFileWriter::supportedFormatExtensions( const RasterFormatOptions options )
+{
+  const auto formats = supportedFiltersAndFormats( options );
+  QStringList extensions;
+
+  QRegularExpression rx( QStringLiteral( "\\*\\.([a-zA-Z0-9]*)" ) );
+
+  for ( const FilterFormatDetails &format : formats )
+  {
+    QString ext = format.filterString;
+    QRegularExpressionMatch match = rx.match( ext );
+    if ( !match.hasMatch() )
+      continue;
+
+    QString matched = match.captured( 1 );
+    extensions << matched;
+  }
+  return extensions;
+}

src/core/raster/qgsrasterfilewriter.h

@@ -171,6 +171,17 @@ class CORE_EXPORT QgsRasterFileWriter
      */
     static QList< QgsRasterFileWriter::FilterFormatDetails > supportedFiltersAndFormats( RasterFormatOptions options = SortRecommended );
 
+    /**
+     * Returns a list of file extensions for supported formats.
+     *
+     * The \a options argument can be used to control the sorting and filtering of
+     * returned formats.
+     *
+     * \since QGIS 3.0
+     * \see supportedFiltersAndFormats()
+     */
+    static QStringList supportedFormatExtensions( RasterFormatOptions options = SortRecommended );
+
     /**
      * Returns the GDAL driver name for a specified file \a extension. E.g. the
      * driver name for the ".tif" extension is "GTiff".