Clarify licenses

- add license headers to everything
- convert a few files from public domain or LGPL2.1+ to GPL2+
- some archaeology to clarify which files are from which library

9 files changed, 34 insertions, 13 deletions

diff --git a/src/ui/view/edit-widget-interface.h b/src/ui/view/edit-widget-interface.h
index 7004fea95..1bbbbc8bd 100644
--- a/src/ui/view/edit-widget-interface.h
+++ b/src/ui/view/edit-widget-interface.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Authors:
  *     Ralf Stephan <ralf@ark.in-berlin.de>
@@ -6,7 +7,7 @@
  * Copyright (C) 2006 John Bintz
  * Copyright (C) 2005 Ralf Stephan
  *
- * Released under GNU GPL.  Read the file 'COPYING' for more information.
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifndef INKSCAPE_UI_VIEW_EDIT_WIDGET_IFACE_H
diff --git a/src/ui/view/svg-view-widget.cpp b/src/ui/view/svg-view-widget.cpp
index e5bd8b866..c696a3ad2 100644
--- a/src/ui/view/svg-view-widget.cpp
+++ b/src/ui/view/svg-view-widget.cpp
@@ -1,10 +1,17 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/**
+ * @file
+ * A light-weight widget containing an SPCanvas with a View for rendering an SVG.
+ */
 /*
- * Author:
+ * Authors:
  *   Tavmjong Bah <tavmjong@free.fr>
  *
- * Copyright (C) 2018 Tavmong Bah
+ * Copyright (C) 2018 Authors
+ *
+ * The contents of this file may be used under the GNU General Public License Version 2 or later.
+ * Read the file 'COPYING' for more information.
  *
- * Released under GNU GPL.  Read the file 'COPYING' for more information.
  */
 
 #include "svg-view-widget.h"
diff --git a/src/ui/view/svg-view-widget.h b/src/ui/view/svg-view-widget.h
index 11bbba827..718e164cd 100644
--- a/src/ui/view/svg-view-widget.h
+++ b/src/ui/view/svg-view-widget.h
@@ -1,10 +1,17 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/**
+ * @file
+ * A light-weight widget containing an SPCanvas with a View for rendering an SVG.
+ */
 /*
- * Author:
+ * Authors:
  *   Tavmjong Bah <tavmjong@free.fr>
  *
- * Copyright (C) 2018 Tavmong Bah
+ * Copyright (C) 2018 Authors
+ *
+ * The contents of this file may be used under the GNU General Public License Version 2 or later.
+ * Read the file 'COPYING' for more information.
  *
- * Released under GNU GPL.  Read the file 'COPYING' for more information.
  */
 
 #ifndef INKSCAPE_UI_SVG_VIEW_WIDGET_VARIATIONS_H
diff --git a/src/ui/view/svg-view.cpp b/src/ui/view/svg-view.cpp
index 6b90e8ccd..6db3fa2a4 100644
--- a/src/ui/view/svg-view.cpp
+++ b/src/ui/view/svg-view.cpp
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Functions and callbacks for generic SVG view and widget.
  *
@@ -10,7 +11,7 @@
  * Copyright (C) 2001-2002 Lauris Kaplinski
  * Copyright (C) 2001 Ximian, Inc.
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include <2geom/transforms.h>
diff --git a/src/ui/view/svg-view.h b/src/ui/view/svg-view.h
index 23698eb36..8ec452ede 100644
--- a/src/ui/view/svg-view.h
+++ b/src/ui/view/svg-view.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 #ifndef SEEN_SVG_VIEW_H
 #define SEEN_SVG_VIEW_H
 /*
@@ -8,7 +9,7 @@
  * Copyright (C) 2001-2002 Lauris Kaplinski
  * Copyright (C) 2001 Ximian, Inc.
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include "ui/view/view.h"
diff --git a/src/ui/view/view-widget.cpp b/src/ui/view/view-widget.cpp
index fec18845b..ce9745d1b 100644
--- a/src/ui/view/view-widget.cpp
+++ b/src/ui/view/view-widget.cpp
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Authors:
  *   Lauris Kaplinski <lauris@kaplinski.com>
@@ -6,7 +7,7 @@
  * Copyright (C) 2001-2002 Lauris Kaplinski
  * Copyright (C) 2001 Ximian, Inc.
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include "view.h"
diff --git a/src/ui/view/view-widget.h b/src/ui/view/view-widget.h
index 7c299972a..410edeb7b 100644
--- a/src/ui/view/view-widget.h
+++ b/src/ui/view/view-widget.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 #ifndef INKSCAPE_UI_VIEW_VIEWWIDGET_H
 #define INKSCAPE_UI_VIEW_VIEWWIDGET_H
 
@@ -9,7 +10,7 @@
  * Copyright (C) 2001-2002 Lauris Kaplinski
  * Copyright (C) 2001 Ximian, Inc.
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include <gtk/gtk.h>
diff --git a/src/ui/view/view.cpp b/src/ui/view/view.cpp
index a265ed918..e8c3e32db 100644
--- a/src/ui/view/view.cpp
+++ b/src/ui/view/view.cpp
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Authors:
  *   Lauris Kaplinski <lauris@kaplinski.com>
@@ -7,7 +8,7 @@
  * Copyright (C) 2001-2002 Lauris Kaplinski
  * Copyright (C) 2001 Ximian, Inc.
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include <2geom/point.h>
diff --git a/src/ui/view/view.h b/src/ui/view/view.h
index 31b43d12c..fa28ec72e 100644
--- a/src/ui/view/view.h
+++ b/src/ui/view/view.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 #ifndef INKSCAPE_UI_VIEW_VIEW_H
 #define INKSCAPE_UI_VIEW_VIEW_H
 /*
@@ -8,7 +9,7 @@
  * Copyright (C) 2001-2002 Lauris Kaplinski
  * Copyright (C) 2001 Ximian, Inc.
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include <gdk/gdk.h>