Implementation of masks (double texturing ImageShader) for sources.

ImageShader.h

@@ -1,6 +1,9 @@
 #ifndef IMAGESHADER_H
 #define IMAGESHADER_H
 
+#include <string>
+#include <map>
+
 #include "Shader.h"
 
 class ImageShader : public Shader
@@ -14,8 +17,12 @@ public:
     void reset() override;
     void accept(Visitor& v) override;
 
+
     uint mask;
     float stipple;
+
+    static const char* mask_names[];
+    static std::vector< uint > mask_presets;
 };
 
 #endif // IMAGESHADER_H