utility: graph export linux

qfiledialog on linux does not add extension of filter to filename

src/lib_gui/qt/graphics/QtGraphicsView.cpp

@@ -244,9 +244,45 @@ void QtGraphicsView::stopTimer()
 	m_timer->stop();
 }
 
+QString ShowSaveFileDialog(QWidget *parent,
+		const QString &title,
+		const QString &directory,
+		const QString &filter) {
+#if defined(Q_WS_WIN) || defined(Q_WS_MAC)
+	return QFileDialog::getSaveFileName(parent,
+			title,
+			directory,
+			filter);
+#else
+	QFileDialog dialog(parent, title, directory, filter);
+	if (parent) {
+		dialog.setWindowModality(Qt::WindowModal);
+	}
+	QRegExp filter_regex(QLatin1String("(?:^\\*\\.(?!.*\\()|\\(\\*\\.)(\\w+)"));
+	QStringList filters = filter.split(QLatin1String(";;"));
+	if (!filters.isEmpty()) {
+		dialog.setNameFilters(filters);
+	}
+	dialog.setAcceptMode(QFileDialog::AcceptSave);
+	if (dialog.exec() == QDialog::Accepted) {
+		QString file_name = dialog.selectedFiles().first();
+		QFileInfo info(file_name);
+		if (info.suffix().isEmpty() && !dialog.selectedNameFilter().isEmpty()) {
+			if (filter_regex.indexIn(dialog.selectedNameFilter()) != -1) {
+				QString extension = filter_regex.cap(1);
+				file_name += QLatin1String(".") + extension;
+			}
+		}
+		return file_name;
+	} else {
+		return QString();
+	}
+#endif  // Q_WS_MAC || Q_WS_WIN
+}
+
 void QtGraphicsView::exportGraph()
 {
-	QString fileName = QFileDialog::getSaveFileName(
+	QString fileName = ShowSaveFileDialog(
 		this, "Save image", QDir::homePath(), "PNG (*.png);;JPEG (*.JPEG);;BMP Files (*.bmp)");
 
 	if (!fileName.isNull())