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.cpp

@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "pictureobj.h"
+#include "qthelper.h"
+
+PictureObj::PictureObj() : offset({ 0 }), location({ 0 })
+{
+}
+
+PictureObj::PictureObj(const picture &pic) : filename(pic.filename), offset(pic.offset), location(pic.location)
+{
+}
+
+picture PictureObj::toCore() const
+{
+	return picture {
+		strdup(filename.c_str()),
+		offset,
+		location
+	};
+}
+
+bool PictureObj::operator<(const PictureObj &p2) const
+{
+	if (offset.seconds != p2.offset.seconds)
+		return offset.seconds < p2.offset.seconds;
+	return strcmp(filename.c_str(), p2.filename.c_str()) < 0;
+}