media: add small C++ helper describing a picture struct

By using a std::string instead of a C-string, memory management
becomes so much simpler! This class will be used for keeping track
of deleted/added pictures in the undo system.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

core/pictureobj.h

@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#ifndef PICTUREOBJ_H
+#define PICTUREOBJ_H
+
+// A tiny helper class that represents a struct picture of the core
+// It does, however, keep the filename as a std::string so that C++ code
+// doesn't have do its own memory-management.
+
+#include "core/units.h"
+#include "core/picture.h"
+#include <string>
+
+struct PictureObj {
+	std::string filename;
+	offset_t offset;
+	location_t location;
+
+	PictureObj();			// Initialize to empty picture.
+	PictureObj(const picture &pic); // Create from core struct picture.
+	picture toCore() const;		// Turn into core structure. Caller responsible for freeing.
+	bool operator<(const PictureObj &p2) const;
+};
+
+#endif // PICTUREOBJ_H