fix: stylistic changes + addObservers

vtk/src/layers/BackgroundImage.h

@@ -0,0 +1,37 @@
+#ifndef BACKGROUND_H
+#define BACKGROUND_H
+
+#include "Layer.h"
+#include <vtkImageReader2Factory.h>
+
+/** Implements the Layer class for the case of a background image.
+  * Specifically, reads a backgroundImage given by the imagePath attribute and puts it on layer 0.
+  */
+class BackgroundImage : public Layer {
+private:
+  std::string imagePath;
+  vtkSmartPointer<vtkImageReader2Factory> readerFactory;
+
+  /** This private function updates the background image using the imagePath attribute.
+   */
+  void updateImage();
+
+
+public:
+  /** Constructor.
+    * @param imagePath : String to the path of the image to use as background.
+    */
+  BackgroundImage(std::string imagePath);
+
+  /** Getter.
+    * @return the imagePath attribute.
+    */
+  std::string getImagePath();
+
+  /** Setter. Can be used to change the background image 
+    * @param imagePath : String to the path of the new image to use.
+    */
+  void setImagePath(std::string imagePath);
+};
+
+#endif