gui: PreviewGenerator: Add get()

gui/previewgenerator.cpp

@@ -1 +1,15 @@
 #include "previewgenerator.h"
+#include "previewgeneratorpdf.h"
+#include "previewgeneratorplaintext.h"
+
+static PreviewGenerator *plainTextGenerator = new PreviewGeneratorPlainText();
+
+static QMap<QString, PreviewGenerator *> generators{
+	{"pdf", new PreviewGeneratorPdf()}, {"txt", plainTextGenerator},  {"md", plainTextGenerator},
+	{"py", plainTextGenerator},			{"java", plainTextGenerator}, {"js", plainTextGenerator},
+	{"cpp", plainTextGenerator},		{"c", plainTextGenerator},	  {"sql", plainTextGenerator}};
+
+PreviewGenerator *PreviewGenerator::get(QFileInfo &info)
+{
+	return generators.value(info.suffix(), nullptr);
+}

gui/previewgenerator.h

@@ -2,6 +2,7 @@
 #define PREVIEWGENERATOR_H
 #include <QVector>
 #include <QSharedPointer>
+#include <QFileInfo>
 #include "previewresult.h"
 #include "renderconfig.h"
 
@@ -12,6 +13,8 @@ class PreviewGenerator
 	virtual ~PreviewGenerator()
 	{
 	}
+
+	static PreviewGenerator *get(QFileInfo &info);
 };
 
 #endif // PREVIEWGENERATOR_H