Generalize previews: Add PreviewGenerator*

gui/previewgenerator.h

@@ -0,0 +1,17 @@
+#ifndef PREVIEWGENERATOR_H
+#define PREVIEWGENERATOR_H
+#include <QVector>
+#include <QSharedPointer>
+#include "previewresult.h"
+#include "renderconfig.h"
+
+class PreviewGenerator
+{
+  public:
+	virtual PreviewResult *generate(RenderConfig config, QString documentPath, unsigned int page) = 0;
+	virtual ~PreviewGenerator()
+	{
+	}
+};
+
+#endif // PREVIEWGENERATOR_H