Added copyright lines for files I've edited this year.

[synfig.git] / synfig-core / trunk / src / synfig / layer_pastecanvas.h

diff --git a/synfig-core/trunk/src/synfig/layer_pastecanvas.h b/synfig-core/trunk/src/synfig/layer_pastecanvas.h
index 7823b07..843ee1e 100644 (file)
--- a/synfig-core/trunk/src/synfig/layer_pastecanvas.h
+++ b/synfig-core/trunk/src/synfig/layer_pastecanvas.h
@@ -1,11 +1,12 @@
 /* === S Y N F I G ========================================================= */
 /*!    \file layer_pastecanvas.h
-**     \brief Template Header
+**     \brief Header file for implementation of the "Paste Canvas" layer
 **
 **     $Id$
 **
 **     \legal
 **     Copyright (c) 2002-2005 Robert B. Quattlebaum Jr., Adrian Bentley
+**     Copyright (c) 2007, 2008 Chris Moore
 **
 **     This package is free software; you can redistribute it and/or
 **     modify it under the terms of the GNU General Public License as
@@ -62,8 +63,6 @@ private:
 
        mutable Time curr_time;
 
-       bool optimize_layers(synfig::Context context,synfig::CanvasBase&)const;
-
        bool muck_with_time_;
 
        bool children_lock;
@@ -71,6 +70,33 @@ private:
        mutable Rect bounds;
 
        sigc::connection child_changed_connection;
+
+       // Nasty hack: Remember whether we called an extra ref() when
+       // setting the canvas, so we know whether to call an extra unref()
+       // when finished with the canvas.
+       //
+       // Here's the story:
+       //
+       // The root canvas is destructed first.  That sets the
+       // Layer::canvas_ (the parent canvas) of any PasteCanvas layer it
+       // contains to nil, due to a call to Layer::set_canvas(0),
+       // triggered by the connection made when Layer::set_canvas
+       // originally set its canvas_ member to point to the root canvas.
+       // ~Canvas does begin_delete() which triggers that connection.
+       //
+       // After ~Canvas has run, the members of the root canvas are
+       // freed, including its children_ list.  If this was the last
+       // reference to the child canvas that the pastecanvas uses, that
+       // child canvas will Layer_PasteCanvas::set_sub_canvas(0) on the
+       // PasteCanvas layer to set its canvas (the child, pasted canvas)
+       // not to refer to the soon-to-be destroys child canvas.  But
+       // set_sub_canvas() originally looked at the value of
+       // Layer::canvas_ (the parent canvas, obtained via
+       // Layer::get_canvas()) to decide whether to do an extra ref() on
+       // canvas (the child canvas).  We need to unref() it now if we
+       // did, but we've forgotten whether we did.  So we use this
+       // 'extra_reference' member to store that decision.
+       bool extra_reference;
 public:
 
        virtual void on_canvas_set();