Save document capability

PdfForQtLib/sources/pdfdocumentwriter.cpp

@@ -21,6 +21,7 @@
 #include "pdfparser.h"
 
 #include <QFile>
+#include <QSaveFile>
 
 namespace pdf
 {
@@ -170,19 +171,45 @@ void PDFWriteObjectVisitor::visitReference(const PDFObjectReference reference)
     m_device->write("R ");
 }
 
-PDFOperationResult PDFDocumentWriter::write(const QString& fileName, const PDFDocument* document)
+PDFOperationResult PDFDocumentWriter::write(const QString& fileName, const PDFDocument* document, bool safeWrite)
 {
-    QFile file(fileName);
-
-    if (file.open(QFile::WriteOnly | QFile::Truncate))
+    if (safeWrite)
     {
-        PDFOperationResult result = write(&file, document);
-        file.close();
-        return result;
+        QSaveFile file(fileName);
+        file.setDirectWriteFallback(true);
+
+        if (file.open(QFile::WriteOnly | QFile::Truncate))
+        {
+            PDFOperationResult result = write(&file, document);
+            if (result)
+            {
+                file.commit();
+            }
+            else
+            {
+                file.cancelWriting();
+            }
+            return result;
+        }
+        else
+        {
+            return tr("File '%1' can't be opened for writing. %2").arg(fileName, file.errorString());
+        }
     }
     else
     {
-        return tr("File '%1' can't be opened for writing. %2").arg(fileName, file.errorString());
+        QFile file(fileName);
+
+        if (file.open(QFile::WriteOnly | QFile::Truncate))
+        {
+            PDFOperationResult result = write(&file, document);
+            file.close();
+            return result;
+        }
+        else
+        {
+            return tr("File '%1' can't be opened for writing. %2").arg(fileName, file.errorString());
+        }
     }
 }
 

PdfForQtLib/sources/pdfdocumentwriter.h

@@ -40,7 +40,20 @@ public:
 
     }
 
-    PDFOperationResult write(const QString& fileName, const PDFDocument* document);
+    /// Writes document to the file. If \p safeWrite is true, then document is first
+    /// written to the temporary file, and then renamed to original file name atomically,
+    /// so no data can be lost on, for example, power failure. If it is not possible to
+    /// create temporary file, then writing operation will attempt to write to the file
+    /// directly.
+    /// \param fileName File name
+    /// \param document Document
+    /// \param safeWrite Write document to the temporary file and then rename
+    PDFOperationResult write(const QString& fileName, const PDFDocument* document, bool safeWrite);
+
+    /// Write document to the output device. Device must be writable (i.e. opened
+    /// for writing).
+    /// \param device Output device
+    /// \param document Document
     PDFOperationResult write(QIODevice* device, const PDFDocument* document);
 
     /// Calculates document file size, as if it is written to the disk.