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diff --git a/src/ui/tool/node.h b/src/ui/tool/node.h
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+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * Editable node and associated data structures.
+ */
+/* Authors:
+ *   Krzysztof Kosiński <tweenk.pl@gmail.com>
+ *   Jon A. Cruz <jon@joncruz.org>
+ *
+ * Copyright (C) 2009 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#ifndef SEEN_UI_TOOL_NODE_H
+#define SEEN_UI_TOOL_NODE_H
+
+#include <iterator>
+#include <iosfwd>
+#include <stdexcept>
+#include <cstddef>
+#include <functional>
+
+#include "ui/tool/selectable-control-point.h"
+#include "snapped-point.h"
+#include "ui/tool/node-types.h"
+
+namespace Inkscape {
+class CanvasItemGroup;
+class CanvasItemCurve;
+
+namespace UI {
+template <typename> class NodeIterator;
+}
+}
+
+namespace Inkscape {
+namespace UI {
+
+class PathManipulator;
+class MultiPathManipulator;
+
+class Node;
+class Handle;
+class NodeList;
+class SubpathList;
+template <typename> class NodeIterator;
+
+std::ostream &operator<<(std::ostream &, NodeType);
+
+/*
+template <typename T>
+struct ListMember {
+    T *next;
+    T *prev;
+};
+struct SubpathMember : public ListMember<NodeListMember> {
+    Subpath *list;
+};
+struct SubpathListMember : public ListMember<SubpathListMember> {
+    SubpathList *list;
+};
+*/
+
+struct ListNode {
+    ListNode *ln_next;
+    ListNode *ln_prev;
+    NodeList *ln_list;
+};
+
+struct NodeSharedData {
+    SPDesktop *desktop;
+    ControlPointSelection *selection;
+    Inkscape::CanvasItemGroup *node_group;
+    Inkscape::CanvasItemGroup *handle_group;
+    Inkscape::CanvasItemGroup *handle_line_group;
+};
+
+class Handle : public ControlPoint {
+public:
+
+    ~Handle() override;
+    inline Geom::Point relativePos() const;
+    inline double length() const;
+    bool isDegenerate() const { return _degenerate; } // True if the handle is retracted, i.e. has zero length.
+
+    void setVisible(bool) override;
+    void move(Geom::Point const &p) override;
+
+    void setPosition(Geom::Point const &p) override;
+    inline void setRelativePos(Geom::Point const &p);
+    void setLength(double len);
+    void retract();
+    void setDirection(Geom::Point const &from, Geom::Point const &to);
+    void setDirection(Geom::Point const &dir);
+    Node *parent() { return _parent; }
+    Handle *other();
+    Handle const *other() const;
+
+    static char const *handle_type_to_localized_string(NodeType type);
+
+protected:
+
+    Handle(NodeSharedData const &data, Geom::Point const &initial_pos, Node *parent);
+    virtual void handle_2button_press();
+    bool _eventHandler(Inkscape::UI::Tools::ToolBase *event_context, GdkEvent *event) override;
+    void dragged(Geom::Point &new_pos, GdkEventMotion *event) override;
+    bool grabbed(GdkEventMotion *event) override;
+    void ungrabbed(GdkEventButton *event) override;
+    bool clicked(GdkEventButton *event) override;
+
+    Glib::ustring _getTip(unsigned state) const override;
+    Glib::ustring _getDragTip(GdkEventMotion *event) const override;
+    bool _hasDragTips() const override { return true; }
+
+private:
+
+    inline PathManipulator &_pm();
+    inline PathManipulator &_pm() const;
+    Node *_parent; // the handle's lifetime does not extend beyond that of the parent node,
+    // so a naked pointer is OK and allows setting it during Node's construction
+    CanvasItemCurve *_handle_line;
+    bool _degenerate; // True if the handle is retracted, i.e. has zero length. This is used often internally so it makes sense to cache this
+
+    /**
+     * Control point of a cubic Bezier curve in a path.
+     *
+     * Handle keeps the node type invariant only for the opposite handle of the same node.
+     * Keeping the invariant on node moves is left to the %Node class.
+     */
+    static Geom::Point _saved_other_pos;
+
+    static double _saved_length;
+    static bool _drag_out;
+    static ColorSet _handle_colors;
+    friend class Node;
+};
+
+class Node : ListNode, public SelectableControlPoint {
+public:
+
+    /**
+     * Curve endpoint in an editable path.
+     *
+     * The method move() keeps node type invariants during translations.
+     */
+    Node(NodeSharedData const &data, Geom::Point const &pos);
+
+    Node(Node const &) = delete;
+
+    void move(Geom::Point const &p) override;
+    void transform(Geom::Affine const &m) override;
+    void fixNeighbors() override;
+    Geom::Rect bounds() const override;
+
+    NodeType type() const { return _type; }
+
+    /**
+     * Sets the node type and optionally restores the invariants associated with the given type.
+     * @param type The type to set.
+     * @param update_handles Whether to restore invariants associated with the given type.
+     *                       Passing false is useful e.g. when initially creating the path,
+     *                       and when making cusp nodes during some node algorithms.
+     *                       Pass true when used in response to an UI node type button.
+     */
+    void setType(NodeType type, bool update_handles = true);
+
+    void showHandles(bool v);
+
+    void updateHandles();
+
+
+    /**
+     * Pick the best type for this node, based on the position of its handles.
+     * This is what assigns types to nodes created using the pen tool.
+     */
+    void pickBestType(); // automatically determine the type from handle positions
+
+    bool isDegenerate() const { return _front.isDegenerate() && _back.isDegenerate(); }
+    bool isEndNode() const;
+    Handle *front() { return &_front; }
+    Handle *back()  { return &_back;  }
+
+    /**
+     * Gets the handle that faces the given adjacent node.
+     * Will abort with error if the given node is not adjacent.
+     */
+    Handle *handleToward(Node *to);
+
+    /**
+     * Gets the node in the direction of the given handle.
+     * Will abort with error if the handle doesn't belong to this node.
+     */
+    Node *nodeToward(Handle *h);
+
+    /**
+     * Gets the handle that goes in the direction opposite to the given adjacent node.
+     * Will abort with error if the given node is not adjacent.
+     */
+    Handle *handleAwayFrom(Node *to);
+
+    /**
+     * Gets the node in the direction opposite to the given handle.
+     * Will abort with error if the handle doesn't belong to this node.
+     */
+    Node *nodeAwayFrom(Handle *h);
+
+    NodeList &nodeList() { return *(static_cast<ListNode*>(this)->ln_list); }
+    NodeList &nodeList() const { return *(static_cast<ListNode const*>(this)->ln_list); }
+
+    /**
+     * Move the node to the bottom of its canvas group.
+     * Useful for node break, to ensure that the selected nodes are above the unselected ones.
+     */
+    void sink();
+
+    static NodeType parse_nodetype(char x);
+    static char const *node_type_to_localized_string(NodeType type);
+
+    // temporarily public
+    /** Customized event handler to catch scroll events needed for selection grow/shrink. */
+    bool _eventHandler(Inkscape::UI::Tools::ToolBase *event_context, GdkEvent *event) override;
+
+    Inkscape::SnapCandidatePoint snapCandidatePoint();
+
+protected:
+
+    void dragged(Geom::Point &new_pos, GdkEventMotion *event) override;
+    bool grabbed(GdkEventMotion *event) override;
+    bool clicked(GdkEventButton *event) override;
+
+    void _setState(State state) override;
+    Glib::ustring _getTip(unsigned state) const override;
+    Glib::ustring _getDragTip(GdkEventMotion *event) const override;
+    bool _hasDragTips() const override { return true; }
+
+private:
+
+    void _updateAutoHandles();
+
+    /**
+     * Select or deselect a node in this node's subpath based on its path distance from this node.
+     * @param dir If negative, shrink selection by one node; if positive, grow by one node.
+     */
+    void _linearGrow(int dir);
+
+    Node *_next();
+    Node const *_next() const;
+    Node *_prev();
+    Node const *_prev() const;
+    Inkscape::SnapSourceType _snapSourceType() const;
+    Inkscape::SnapTargetType _snapTargetType() const;
+    inline PathManipulator &_pm();
+    inline PathManipulator &_pm() const;
+
+    /** Determine whether two nodes are joined by a linear segment. */
+    static bool _is_line_segment(Node *first, Node *second);
+
+    // Handles are always present, but are not visible if they coincide with the node
+    // (are degenerate). A segment that has both handles degenerate is always treated
+    // as a line segment
+    Handle _front; ///< Node handle in the backward direction of the path
+    Handle _back; ///< Node handle in the forward direction of the path
+    NodeType _type; ///< Type of node - cusp, smooth...
+    bool _handles_shown;
+    static ColorSet node_colors;
+
+    // This is used by fixNeighbors to repair smooth nodes after all move
+    // operations have been completed. If this is empty, no fixing is needed.
+    std::optional<Geom::Point> _unfixed_pos;
+
+    friend class Handle;
+    friend class NodeList;
+    friend class NodeIterator<Node>;
+    friend class NodeIterator<Node const>;
+};
+
+/// Iterator for editable nodes
+/** Use this class for all operations that require some knowledge about the node's
+ * neighbors. It is a bidirectional iterator.
+ *
+ * Because paths can be cyclic, node iterators have two different ways to
+ * increment and decrement them. When using ++/--, the end iterator will eventually
+ * be returned. When using advance()/retreat(), the end iterator will only be returned
+ * when the path is open. If it's closed, calling advance() will cycle indefinitely.
+ * This is particularly useful for cases where the adjacency of nodes is more important
+ * than their sequence order.
+ *
+ * When @a i is a node iterator, then:
+ * - <code>++i</code> moves the iterator to the next node in sequence order;
+ * - <code>--i</code> moves the iterator to the previous node in sequence order;
+ * - <code>i.next()</code> returns the next node with wrap-around;
+ * - <code>i.prev()</code> returns the previous node with wrap-around;
+ * - <code>i.advance()</code> moves the iterator to the next node with wrap-around;
+ * - <code>i.retreat()</code> moves the iterator to the previous node with wrap-around.
+ *
+ * next() and prev() do not change their iterator. They can return the end iterator
+ * if the path is open.
+ *
+ * Unlike most other iterators, you can check whether you've reached the end of the list
+ * without having access to the iterator's container.
+ * Simply use <code>if (i) { ...</code>
+ * */
+template <typename N>
+class NodeIterator
+    : public boost::bidirectional_iterator_helper<NodeIterator<N>, N, std::ptrdiff_t,
+        N *, N &>
+{
+public:
+    typedef NodeIterator self;
+    NodeIterator()
+        : _node(nullptr)
+    {}
+    // default copy, default assign
+
+    self &operator++() {
+        _node = (_node?_node->ln_next:nullptr);
+        return *this;
+    }
+    self &operator--() {
+        _node = (_node?_node->ln_prev:nullptr);
+        return *this;
+    }
+    bool operator==(self const &other) const { return _node == other._node; }
+    N &operator*() const { return *static_cast<N*>(_node); }
+    inline operator bool() const; // define after NodeList
+    /// Get a pointer to the underlying node. Equivalent to <code>&*i</code>.
+    N *get_pointer() const { return static_cast<N*>(_node); }
+    /// @see get_pointer()
+    N *ptr() const { return static_cast<N*>(_node); }
+
+    self next() const {
+        self r(*this);
+        r.advance();
+        return r;
+    }
+    self prev() const {
+        self r(*this);
+        r.retreat();
+        return r;
+    }
+    self &advance();
+    self &retreat();
+private:
+    NodeIterator(ListNode const *n)
+        : _node(const_cast<ListNode*>(n))
+    {}
+    ListNode *_node;
+    friend class NodeList;
+};
+
+class NodeList : ListNode, boost::noncopyable {
+public:
+    typedef std::size_t size_type;
+    typedef Node &reference;
+    typedef Node const &const_reference;
+    typedef Node *pointer;
+    typedef Node const *const_pointer;
+    typedef Node value_type;
+    typedef NodeIterator<value_type> iterator;
+    typedef NodeIterator<value_type const> const_iterator;
+
+    // TODO Lame. Make this private and make SubpathList a factory
+    /**
+     * An editable list of nodes representing a subpath.
+     *
+     * It can optionally be cyclic to represent a closed path.
+     * The list has iterators that act like plain node iterators, but can also be used
+     * to obtain shared pointers to nodes.
+     */
+    NodeList(SubpathList &_list);
+
+    ~NodeList();
+
+    // no copy or assign
+    NodeList(NodeList const &) = delete;
+    void operator=(NodeList const &) = delete;
+
+    // iterators
+    iterator begin() { return iterator(ln_next); }
+    iterator end() { return iterator(this); }
+    const_iterator begin() const { return const_iterator(ln_next); }
+    const_iterator end() const { return const_iterator(this); }
+
+    // size
+    bool empty();
+    size_type size();
+
+    // extra node-specific methods
+    bool closed();
+
+    /**
+     * A subpath is degenerate if it has no segments - either one node in an open path
+     * or no nodes in a closed path.
+     */
+    bool degenerate();
+
+    void setClosed(bool c) { _closed = c; }
+    iterator before(double t, double *fracpart = nullptr);
+    iterator before(Geom::PathTime const &pvp);
+    const_iterator before(double t, double *fracpart = nullptr) const {
+        return const_cast<NodeList *>(this)->before(t, fracpart)._node;
+    }
+    const_iterator before(Geom::PathTime const &pvp) const {
+        return const_cast<NodeList *>(this)->before(pvp)._node;
+    }
+
+    // list operations
+
+    /** insert a node before pos. */
+    iterator insert(iterator pos, Node *x);
+
+    template <class InputIterator>
+    void insert(iterator pos, InputIterator first, InputIterator last) {
+        for (; first != last; ++first) insert(pos, *first);
+    }
+    void splice(iterator pos, NodeList &list);
+    void splice(iterator pos, NodeList &list, iterator i);
+    void splice(iterator pos, NodeList &list, iterator first, iterator last);
+    void reverse();
+    void shift(int n);
+    void push_front(Node *x) { insert(begin(), x); }
+    void pop_front() { erase(begin()); }
+    void push_back(Node *x) { insert(end(), x); }
+    void pop_back() { erase(--end()); }
+    void clear();
+    iterator erase(iterator pos);
+    iterator erase(iterator first, iterator last) {
+        NodeList::iterator ret = first;
+        while (first != last) ret = erase(first++);
+        return ret;
+    }
+
+    // member access - undefined results when the list is empty
+    Node &front() { return *static_cast<Node*>(ln_next); }
+    Node &back() { return *static_cast<Node*>(ln_prev); }
+
+    // HACK remove this subpath from its path. This will be removed later.
+    void kill();
+    SubpathList &subpathList() { return _list; }
+
+    static iterator get_iterator(Node *n) { return iterator(n); }
+    static const_iterator get_iterator(Node const *n) { return const_iterator(n); }
+    static NodeList &get(Node *n);
+    static NodeList &get(iterator const &i);
+private:
+
+    SubpathList &_list;
+    bool _closed;
+
+    friend class Node;
+    friend class Handle; // required to access handle and handle line groups
+    friend class NodeIterator<Node>;
+    friend class NodeIterator<Node const>;
+};
+
+/**
+ * List of node lists. Represents an editable path.
+ * Editable path composed of one or more subpaths.
+ */
+class SubpathList : public std::list< std::shared_ptr<NodeList> > {
+public:
+    typedef std::list< std::shared_ptr<NodeList> > list_type;
+
+    SubpathList(PathManipulator &pm) : _path_manipulator(pm) {}
+    PathManipulator &pm() { return _path_manipulator; }
+
+private:
+    list_type _nodelists;
+    PathManipulator &_path_manipulator;
+    friend class NodeList;
+    friend class Node;
+    friend class Handle;
+};
+
+
+
+// define inline Handle funcs after definition of Node
+inline Geom::Point Handle::relativePos() const {
+    return position() - _parent->position();
+}
+inline void Handle::setRelativePos(Geom::Point const &p) {
+    setPosition(_parent->position() + p);
+}
+inline double Handle::length() const {
+    return relativePos().length();
+}
+inline PathManipulator &Handle::_pm() {
+    return _parent->_pm();
+}
+inline PathManipulator &Handle::_pm() const {
+    return _parent->_pm();
+}
+inline PathManipulator &Node::_pm() {
+    return nodeList().subpathList().pm();
+}
+
+inline PathManipulator &Node::_pm() const {
+    return nodeList().subpathList().pm();
+}
+
+// definitions for node iterator
+template <typename N>
+NodeIterator<N>::operator bool() const {
+    return _node && static_cast<ListNode*>(_node->ln_list) != _node;
+}
+template <typename N>
+NodeIterator<N> &NodeIterator<N>::advance() {
+    ++(*this);
+    if (G_UNLIKELY(!*this) && _node->ln_list->closed()) ++(*this);
+    return *this;
+}
+template <typename N>
+NodeIterator<N> &NodeIterator<N>::retreat() {
+    --(*this);
+    if (G_UNLIKELY(!*this) && _node->ln_list->closed()) --(*this);
+    return *this;
+}
+
+} // namespace UI
+} // namespace Inkscape
+
+#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:fileencoding=utf-8:textwidth=99 :