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/** \file
* Inkscape::ObjectHierarchy - tracks a hierarchy of active SPObjects
*
* Authors:
* MenTaLguY <mental@rydia.net>
*
* Copyright (C) 2004 MenTaLguY
*
* Released under GNU GPL, read the file 'COPYING' for more information
*/
#ifndef SEEN_INKSCAPE_OBJECT_HIERARCHY_H
#define SEEN_INKSCAPE_OBJECT_HIERARCHY_H
#include <exception>
#include <list>
#include <sigc++/connection.h>
#include <sigc++/signal.h>
#include <glib/gmessages.h>
class SPObject;
namespace Inkscape {
/**
* An Inkscape::ObjectHierarchy is useful for situations where one wishes
* to keep a reference to an SPObject, but fall back on one of its ancestors
* when that object is removed.
*
* That cannot be accomplished simply by hooking the "release" signal of the
* SPObject, as by the time that signal is emitted, the object's parent
* field has already been cleared.
*
* There are also some subtle refcounting issues to take into account.
*
* @see SPObject
*/
class ObjectHierarchy {
public:
ObjectHierarchy(SPObject *top=NULL);
~ObjectHierarchy();
bool contains(SPObject *object);
sigc::connection connectAdded(const sigc::slot<void, SPObject *> &slot) {
return _added_signal.connect(slot);
}
sigc::connection connectRemoved(const sigc::slot<void, SPObject *> &slot) {
return _removed_signal.connect(slot);
}
sigc::connection connectChanged(const sigc::slot<void, SPObject *, SPObject *> &slot)
{
return _changed_signal.connect(slot);
}
void clear();
SPObject *top() {
return !_hierarchy.empty() ? _hierarchy.back().object : NULL;
}
void setTop(SPObject *object);
SPObject *bottom() {
return !_hierarchy.empty() ? _hierarchy.front().object : NULL;
}
void setBottom(SPObject *object);
private:
struct Record {
Record(SPObject *o, sigc::connection c)
: object(o), connection(c) {}
SPObject *object;
sigc::connection connection;
};
ObjectHierarchy(ObjectHierarchy const &); // no copy
void operator=(ObjectHierarchy const &); // no assign
/// @brief adds objects in range [senior, junior) to the top
void _addTop(SPObject *senior, SPObject *junior);
/// @brief adds one object to the top
void _addTop(SPObject *object);
/// @brief removes all objects above the limit object
void _trimAbove(SPObject *limit);
/// @brief adds objects in range (senior, junior] to the bottom
void _addBottom(SPObject *senior, SPObject *junior);
/// @brief adds one object to the bottom
void _addBottom(SPObject *object);
/// @brief removes all objects below the limit object
void _trimBelow(SPObject *limit);
Record _attach(SPObject *object);
void _detach(Record &record);
void _clear() { _trimBelow(NULL); }
void _trim_for_release(SPObject *released);
std::list<Record> _hierarchy;
sigc::signal<void, SPObject *> _added_signal;
sigc::signal<void, SPObject *> _removed_signal;
sigc::signal<void, SPObject *, SPObject *> _changed_signal;
};
}
#endif
/*
Local Variables:
mode:c++
c-file-style:"stroustrup"
c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
indent-tabs-mode:nil
fill-column:99
End:
*/
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :
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