Add method to determine file path for exports which encountered errors

Author: nyalldawson

python/core/layout/qgslayoutexporter.sip

@@ -151,10 +151,18 @@ Resolution to export layout at
  be generated by appending "_1", "_2", etc to the image file's base name.
 
  Returns a result code indicating whether the export was successful or an
- error was encountered.
+ error was encountered. If an error code is returned, errorFile() can be called
+ to determine the filename for the export which encountered the error.
  :rtype: ExportResult
 %End
 
+    QString errorFile() const;
+%Docstring
+ Returns the file name corresponding to the last error encountered during
+ an export.
+ :rtype: str
+%End
+
     bool georeferenceOutput( const QString &file, QgsLayoutItemMap *referenceMap = 0,
                              const QRectF &exportRegion = QRectF(), double dpi = -1 ) const;
 %Docstring

src/core/layout/qgslayoutexporter.cpp

@@ -155,6 +155,8 @@ class LayoutDpiRestorer
 
 QgsLayoutExporter::ExportResult QgsLayoutExporter::exportToImage( const QString &filePath, const QgsLayoutExporter::ImageExportSettings &settings )
 {
+  mErrorFileName.clear();
+
   int worldFilePageNo = -1;
   if ( QgsLayoutItemMap *referenceMap = mLayout->referenceMap() )
   {
@@ -199,14 +201,17 @@ QgsLayoutExporter::ExportResult QgsLayoutExporter::exportToImage( const QString
     if ( skip )
       continue; // should skip this page, e.g. null size
 
+    QString outputFilePath = generateFileName( path, baseName, extension, page );
+
     if ( image.isNull() )
     {
+      mErrorFileName = outputFilePath;
       return MemoryError;
     }
 
-    QString outputFilePath = generateFileName( path, baseName, extension, page );
     if ( !saveImage( image, outputFilePath, extension ) )
     {
+      mErrorFileName = outputFilePath;
       return FileError;
     }
 

src/core/layout/qgslayoutexporter.h

@@ -164,10 +164,17 @@ class CORE_EXPORT QgsLayoutExporter
      * be generated by appending "_1", "_2", etc to the image file's base name.
      *
      * Returns a result code indicating whether the export was successful or an
-     * error was encountered.
+     * error was encountered. If an error code is returned, errorFile() can be called
+     * to determine the filename for the export which encountered the error.
      */
     ExportResult exportToImage( const QString &filePath, const ImageExportSettings &settings );
 
+    /**
+     * Returns the file name corresponding to the last error encountered during
+     * an export.
+     */
+    QString errorFile() const { return mErrorFileName; }
+
     /**
      * Georeferences a \a file (image of PDF) exported from the layout.
      *
@@ -206,6 +213,8 @@ class CORE_EXPORT QgsLayoutExporter
 
     QPointer< QgsLayout > mLayout;
 
+    QString mErrorFileName;
+
     QImage createImage( const ImageExportSettings &settings, int page, QRectF &bounds, bool &skipPage ) const;
 
     QString generateFileName( const QString &path, const QString &baseName, const QString &suffix, int page ) const;