Adding upstream version 1.2.2.upstream/1.2.2upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

8 files changed, 852 insertions, 0 deletions

diff --git a/src/object/algorithms/CMakeLists.txt b/src/object/algorithms/CMakeLists.txt
new file mode 100644
index 0000000..3101ab2
--- /dev/null
+++ b/src/object/algorithms/CMakeLists.txt
@@ -0,0 +1,16 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+set(object_algorithms_SRC
+  graphlayout.cpp
+  removeoverlap.cpp
+  unclump.cpp
+
+  # -------
+  # Headers
+  bboxsort.h
+  graphlayout.h
+  removeoverlap.h
+  unclump.h
+)
+
+add_inkscape_source("${object_algorithms_SRC}")
diff --git a/src/object/algorithms/bboxsort.h b/src/object/algorithms/bboxsort.h
new file mode 100644
index 0000000..6d15c12
--- /dev/null
+++ b/src/object/algorithms/bboxsort.h
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#ifndef SEEN_BBOXSORT_H
+#define SEEN_BBOXSORT_H
+
+/** @file
+ * @brief Simple helper class for sorting objects based on their bounding boxes.
+ */
+/* Authors:
+ *   MenTaLguY
+ *   Dmitry Kirsanov
+ *   Krzysztof Kosiński
+ *
+ * Copyright (C) 2007-2012 Authors
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+/*
+ * Previously part of the Align and Distribute dialog.
+ */
+
+class BBoxSort {
+
+public:
+    BBoxSort(SPItem *item, Geom::Rect const &bounds, Geom::Dim2 orientation, double begin, double end)
+        : item(item)
+        , bbox(bounds)
+    {
+        anchor = begin * bbox.min()[orientation] + end * bbox.max()[orientation];
+    }
+
+    BBoxSort(const BBoxSort &rhs) = default; // Should really be vector of pointers to avoid copying class when sorting.
+    ~BBoxSort() = default;
+
+    double anchor = 0.0;
+    SPItem* item = nullptr;
+    Geom::Rect bbox;
+};
+
+static bool operator< (const BBoxSort &a, const BBoxSort &b) {
+    return a.anchor < b.anchor;
+}
+
+#endif // SEEN_BBOXSORT_H
+
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :
diff --git a/src/object/algorithms/graphlayout.cpp b/src/object/algorithms/graphlayout.cpp
new file mode 100644
index 0000000..b31454f
--- /dev/null
+++ b/src/object/algorithms/graphlayout.cpp
@@ -0,0 +1,216 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/**
+ * @file
+ * Interface between Inkscape code (SPItem) and graphlayout functions.
+ */
+/*
+ * Authors:
+ *   Tim Dwyer <Tim.Dwyer@infotech.monash.edu.au>
+ *   Abhishek Sharma
+ *
+ * Copyright (C) 2005 Authors
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#include <algorithm>
+#include <cstring>
+#include <iostream>
+#include <list>
+#include <map>
+#include <string>
+#include <valarray>
+#include <vector>
+
+#include <2geom/transforms.h>
+
+#include "conn-avoid-ref.h"
+#include "desktop.h"
+#include "graphlayout.h"
+#include "inkscape.h"
+
+#include "3rdparty/adaptagrams/libavoid/router.h"
+
+#include "3rdparty/adaptagrams/libcola/cola.h"
+#include "3rdparty/adaptagrams/libcola/connected_components.h"
+
+#include "object/sp-item-transform.h"
+#include "object/sp-namedview.h"
+#include "object/sp-path.h"
+#include "style.h"
+
+using namespace cola;
+using namespace vpsc;
+
+/**
+ * Returns true if item is a connector
+ */
+bool isConnector(SPItem const * const item) {
+    auto path = dynamic_cast<SPPath const *>(item);
+    return path && path->connEndPair.isAutoRoutingConn();
+}
+
+struct CheckProgress: TestConvergence {
+    CheckProgress(double d, unsigned i, std::list<SPItem*> & selected, Rectangles & rs,
+            std::map<std::string, unsigned> & nodelookup)
+        : TestConvergence(d, i)
+        , selected(selected)
+        , rs(rs)
+        , nodelookup(nodelookup)
+    {}
+    bool operator()(const double new_stress, std::valarray<double> & X, std::valarray<double> & Y) override {
+        /* This is where, if we wanted to animate the layout, we would need to update
+         * the positions of all objects and redraw the canvas and maybe sleep a bit
+         cout << "stress="<<new_stress<<endl;
+        cout << "x[0]="<<rs[0]->getMinX()<<endl;
+        for (std::list<SPItem *>::iterator it(selected.begin());
+            it != selected.end();
+            ++it)
+        {
+            SPItem *u=*it;
+            if(!isConnector(u)) {
+                Rectangle* r=rs[nodelookup[u->id]];
+                Geom::Rect const item_box(sp_item_bbox_desktop(u));
+                Geom::Point const curr(item_box.midpoint());
+                Geom::Point const dest(r->getCentreX(),r->getCentreY());
+                u->move_rel(Geom::Translate(dest - curr));
+            }
+        }
+        */
+        return TestConvergence::operator()(new_stress, X, Y);
+    }
+    std::list<SPItem*> & selected;
+    Rectangles & rs;
+    std::map<std::string, unsigned> & nodelookup;
+};
+
+/**
+ * Scans the items list and places those items that are
+ * not connectors in filtered
+ */
+void filterConnectors(std::vector<SPItem*> const & items, std::list<SPItem*> & filtered) {
+    for (SPItem * item: items) {
+        if (!isConnector(item)) {
+            filtered.push_back(item);
+        }
+    }
+}
+
+/**
+ * Takes a list of inkscape items, extracts the graph defined by
+ * connectors between them, and uses graph layout techniques to find
+ * a nice layout
+ */
+void graphlayout(std::vector<SPItem*> const & items) {
+    if (items.empty()) return;
+
+    std::list<SPItem*> selected;
+    filterConnectors(items, selected);
+    std::vector<SPItem*> connectors;
+    std::copy_if(items.begin(), items.end(), std::back_inserter(connectors), [](SPItem* item){return isConnector(item); });
+
+    if (selected.size() < 2) return;
+
+    // add the connector spacing to the size of node bounding boxes
+    // so that connectors can always be routed between shapes
+    SPDesktop * desktop = SP_ACTIVE_DESKTOP;
+    double spacing = 0;
+    if (desktop) spacing = desktop->namedview->connector_spacing + 0.1;
+
+    std::map<std::string, unsigned> nodelookup;
+    Rectangles rs;
+    std::vector<Edge> es;
+    for (SPItem * item: selected) {
+        Geom::OptRect const item_box = item->desktopVisualBounds();
+        if (item_box) {
+            Geom::Point ll(item_box->min());
+            Geom::Point ur(item_box->max());
+            nodelookup[item->getId()] = rs.size();
+            rs.push_back(new Rectangle(ll[0] - spacing, ur[0] + spacing,
+                    ll[1] - spacing, ur[1] + spacing));
+        } else {
+            // I'm not actually sure if it's possible for something with a
+            // NULL item-box to be attached to a connector in which case we
+            // should never get to here... but if such a null box can occur it's
+            // probably pretty safe to simply ignore
+            //fprintf(stderr, "NULL item_box found in graphlayout, ignoring!\n");
+        }
+    }
+
+    Inkscape::Preferences * prefs = Inkscape::Preferences::get();
+    CompoundConstraints constraints;
+    double ideal_connector_length = prefs->getDouble("/tools/connector/length", 100.0);
+    double directed_edge_height_modifier = 1.0;
+
+    bool directed       = prefs->getBool("/tools/connector/directedlayout");
+    bool avoid_overlaps = prefs->getBool("/tools/connector/avoidoverlaplayout");
+
+    for (SPItem* conn: connectors) {
+        SPPath* path = SP_PATH(conn);
+        std::array<SPItem*, 2> attachedItems;
+        path->connEndPair.getAttachedItems(attachedItems.data());
+        if (attachedItems[0] == nullptr) continue;
+        if (attachedItems[1] == nullptr) continue;
+        std::map<std::string, unsigned>::iterator i_iter=nodelookup.find(attachedItems[0]->getId());
+        if (i_iter == nodelookup.end()) continue;
+        unsigned rect_index_first = i_iter->second;
+        i_iter = nodelookup.find(attachedItems[1]->getId());
+        if (i_iter == nodelookup.end()) continue;
+        unsigned rect_index_second = i_iter->second;
+        es.emplace_back(rect_index_first, rect_index_second);
+
+        if (conn->style->marker_end.set) {
+            if (directed && strcmp(conn->style->marker_end.value(), "none")) {
+                constraints.push_back(new SeparationConstraint(YDIM, rect_index_first, rect_index_second,
+                                                               ideal_connector_length * directed_edge_height_modifier));
+            }
+        }
+    }
+
+    EdgeLengths elengths(es.size(), 1);
+    std::vector<Component*> cs;
+    connectedComponents(rs, es, cs);
+    for (Component * c: cs) {
+        if (c->edges.size() < 2) continue;
+        CheckProgress test(0.0001, 100, selected, rs, nodelookup);
+        ConstrainedMajorizationLayout alg(c->rects, c->edges, nullptr, ideal_connector_length, elengths, &test);
+        if (avoid_overlaps) alg.setAvoidOverlaps();
+        alg.setConstraints(&constraints);
+        alg.run();
+    }
+    separateComponents(cs);
+
+    for (SPItem * item: selected) {
+        if (!isConnector(item)) {
+            std::map<std::string, unsigned>::iterator i = nodelookup.find(item->getId());
+            if (i != nodelookup.end()) {
+                Rectangle * r = rs[i->second];
+                Geom::OptRect item_box = item->desktopVisualBounds();
+                if (item_box) {
+                    Geom::Point const curr(item_box->midpoint());
+                    Geom::Point const dest(r->getCentreX(),r->getCentreY());
+                    item->move_rel(Geom::Translate(dest - curr));
+                }
+            }
+        }
+    }
+    for (CompoundConstraint * c: constraints) {
+        delete c;
+    }
+    for (Rectangle * r: rs) {
+        delete r;
+    }
+}
+// vim: set cindent
+// vim: ts=4 sw=4 et tw=0 wm=0
+
+/*
+  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 :
diff --git a/src/object/algorithms/graphlayout.h b/src/object/algorithms/graphlayout.h
new file mode 100644
index 0000000..6c6b601
--- /dev/null
+++ b/src/object/algorithms/graphlayout.h
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/**
+ * @file
+ * graph layout functions.
+ */
+/*
+ * Authors:
+ *   Tim Dwyer <tgdwyer@gmail.com>
+ *
+ * Copyright (C) 2005 Authors
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#ifndef SEEN_GRAPHLAYOUT_H
+#define SEEN_GRAPHLAYOUT_H
+
+#include <list>
+#include <vector>
+
+class SPItem;
+
+void graphlayout(std::vector<SPItem*> const &items);
+
+bool isConnector(SPItem const *const item);
+
+void filterConnectors(std::vector<SPItem*> const &items, std::list<SPItem *> &filtered);
+
+#endif // SEEN_GRAPHLAYOUT_H
diff --git a/src/object/algorithms/removeoverlap.cpp b/src/object/algorithms/removeoverlap.cpp
new file mode 100644
index 0000000..8b3064b
--- /dev/null
+++ b/src/object/algorithms/removeoverlap.cpp
@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** \file
+ * Interface between Inkscape code (SPItem) and remove-overlaps function.
+ */
+/*
+ * Authors:
+ *   Tim Dwyer <tgdwyer@gmail.com>
+ *   Abhishek Sharma
+ *
+ * Copyright (C) 2005 Authors
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#include <utility>
+
+#include <2geom/transforms.h>
+
+#include "removeoverlap.h"
+
+#include "libvpsc/rectangle.h"
+
+#include "object/sp-item.h"
+#include "object/sp-item-transform.h"
+
+
+using vpsc::Rectangle;
+
+namespace {
+
+struct Record {
+    SPItem * item;
+    Geom::Point midpoint;
+    Rectangle * vspc_rect;
+
+    Record() : item(nullptr), vspc_rect(nullptr) {}
+    Record(SPItem * i, Geom::Point m, Rectangle * r)
+        : item(i), midpoint(m), vspc_rect(r) {}
+};
+
+}
+
+/**
+* Takes a list of inkscape items and moves them as little as possible
+* such that rectangular bounding boxes are separated by at least xGap
+* horizontally and yGap vertically
+*/
+void removeoverlap(std::vector<SPItem*> const & items, double const xGap, double const yGap) {
+    std::vector<SPItem*> selected = items;
+    std::vector<Record> records;
+    std::vector<Rectangle*> rs;
+
+    Geom::Point const gap(xGap, yGap);
+    for (SPItem * item: selected) {
+        using Geom::X; using Geom::Y;
+        Geom::OptRect item_box(item->desktopVisualBounds());
+        if (item_box) {
+            Geom::Point min(item_box->min() - .5 * gap);
+            Geom::Point max(item_box->max() + .5 * gap);
+            // A negative gap is allowed, but will lead to problems when the gap is larger than
+            // the bounding box (in either X or Y direction, or both); min will have become max
+            // now, which cannot be handled by Rectangle() which is called below. And how will
+            // removeRectangleOverlap handle such a case?
+            // That's why we will enforce some boundaries on min and max here:
+            if (max[X] < min[X]) {
+                min[X] = max[X] = (min[X] + max[X]) / 2.;
+            }
+            if (max[Y] < min[Y]) {
+                min[Y] = max[Y] = (min[Y] + max[Y]) / 2.;
+            }
+            Rectangle * vspc_rect = new Rectangle(min[X], max[X], min[Y], max[Y]);
+            records.emplace_back(item, item_box->midpoint(), vspc_rect);
+            rs.push_back(vspc_rect);
+        }
+    }
+    if (!rs.empty()) {
+        removeoverlaps(rs);
+    }
+    for (Record & rec: records) {
+        Geom::Point const curr = rec.midpoint;
+        Geom::Point const dest(rec.vspc_rect->getCentreX(), rec.vspc_rect->getCentreY());
+        rec.item->move_rel(Geom::Translate(dest - curr));
+        delete rec.vspc_rect;
+    }
+}
diff --git a/src/object/algorithms/removeoverlap.h b/src/object/algorithms/removeoverlap.h
new file mode 100644
index 0000000..619b091
--- /dev/null
+++ b/src/object/algorithms/removeoverlap.h
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** \file
+ * \brief Remove overlaps function
+ */
+/*
+ * Authors:
+ *   Tim Dwyer <tgdwyer@gmail.com>
+ *
+ * Copyright (C) 2005 Authors
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#ifndef SEEN_REMOVEOVERLAP_H
+#define SEEN_REMOVEOVERLAP_H
+
+#include <vector>
+
+class SPItem;
+
+void removeoverlap(std::vector<SPItem*> const &items, double xGap, double yGap);
+
+#endif // SEEN_REMOVEOVERLAP_H
diff --git a/src/object/algorithms/unclump.cpp b/src/object/algorithms/unclump.cpp
new file mode 100644
index 0000000..df59f88
--- /dev/null
+++ b/src/object/algorithms/unclump.cpp
@@ -0,0 +1,397 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/**
+ * @file
+ * Unclumping objects.
+ */
+/* Authors:
+ *   bulia byak
+ *   Jon A. Cruz <jon@joncruz.org>
+ *   Abhishek Sharma
+ *
+ * Copyright (C) 2005 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#include "unclump.h"
+
+#include <2geom/transforms.h>
+#include <algorithm>
+#include <map>
+
+#include "object/sp-item.h"
+
+class Unclump
+{
+public:
+    double dist(SPItem *item1, SPItem *item2);
+    double average(SPItem *item, std::list<SPItem *> &others);
+    SPItem *closest(SPItem *item, std::list<SPItem *> &others);
+    SPItem *farthest(SPItem *item, std::list<SPItem *> &others);
+    std::vector<SPItem *> unclump_remove_behind(SPItem *item, SPItem *closest, std::list<SPItem *> &rest);
+    void push(SPItem *from, SPItem *what, double dist);
+    void pull(SPItem *to, SPItem *what, double dist);
+
+private:
+    Geom::Point unclump_center(SPItem *item);
+    Geom::Point unclump_wh(SPItem *item);
+
+    // Taking bbox of an item is an expensive operation, and we need to do it many times, so here we
+    // cache the centers, widths, and heights of items
+
+    std::map<const gchar *, Geom::Point> c_cache;
+    std::map<const gchar *, Geom::Point> wh_cache;
+};
+
+/**
+Center of bbox of item
+*/
+Geom::Point Unclump::unclump_center(SPItem *item)
+{
+    std::map<const gchar *, Geom::Point>::iterator i = c_cache.find(item->getId());
+    if (i != c_cache.end()) {
+        return i->second;
+    }
+
+    Geom::OptRect r = item->desktopVisualBounds();
+    if (r) {
+        Geom::Point const c = r->midpoint();
+        c_cache[item->getId()] = c;
+        return c;
+    } else {
+        // FIXME
+        return Geom::Point(0, 0);
+    }
+}
+
+Geom::Point Unclump::unclump_wh(SPItem *item)
+{
+    Geom::Point wh;
+    std::map<const gchar *, Geom::Point>::iterator i = wh_cache.find(item->getId());
+    if (i != wh_cache.end()) {
+        wh = i->second;
+    } else {
+        Geom::OptRect r = item->desktopVisualBounds();
+        if (r) {
+            wh = r->dimensions();
+            wh_cache[item->getId()] = wh;
+        } else {
+            wh = Geom::Point(0, 0);
+        }
+    }
+
+    return wh;
+}
+
+/**
+Distance between "edges" of item1 and item2. An item is considered to be an ellipse inscribed into its w/h,
+so its radius (distance from center to edge) depends on the w/h and the angle towards the other item.
+May be negative if the edge of item1 is between the center and the edge of item2.
+*/
+double Unclump::dist(SPItem *item1, SPItem *item2)
+{
+    Geom::Point c1 = unclump_center(item1);
+    Geom::Point c2 = unclump_center(item2);
+
+    Geom::Point wh1 = unclump_wh(item1);
+    Geom::Point wh2 = unclump_wh(item2);
+
+    // angle from each item's center to the other's, unsqueezed by its w/h, normalized to 0..pi/2
+    double a1 = atan2((c2 - c1)[Geom::Y], (c2 - c1)[Geom::X] * wh1[Geom::Y] / wh1[Geom::X]);
+    a1 = fabs(a1);
+    if (a1 > M_PI / 2)
+        a1 = M_PI - a1;
+
+    double a2 = atan2((c1 - c2)[Geom::Y], (c1 - c2)[Geom::X] * wh2[Geom::Y] / wh2[Geom::X]);
+    a2 = fabs(a2);
+    if (a2 > M_PI / 2)
+        a2 = M_PI - a2;
+
+    // get the radius of each item for the given angle
+    double r1 = 0.5 * (wh1[Geom::X] + (wh1[Geom::Y] - wh1[Geom::X]) * (a1 / (M_PI / 2)));
+    double r2 = 0.5 * (wh2[Geom::X] + (wh2[Geom::Y] - wh2[Geom::X]) * (a2 / (M_PI / 2)));
+
+    // dist between centers minus angle-adjusted radii
+    double dist_r = (Geom::L2(c2 - c1) - r1 - r2);
+
+    double stretch1 = wh1[Geom::Y] / wh1[Geom::X];
+    double stretch2 = wh2[Geom::Y] / wh2[Geom::X];
+
+    if ((stretch1 > 1.5 || stretch1 < 0.66) && (stretch2 > 1.5 || stretch2 < 0.66)) {
+        std::vector<double> dists;
+        dists.push_back(dist_r);
+
+        // If both objects are not circle-like, find dists between four corners
+        std::vector<Geom::Point> c1_points(2);
+        {
+            double y_closest;
+            if (c2[Geom::Y] > c1[Geom::Y] + wh1[Geom::Y] / 2) {
+                y_closest = c1[Geom::Y] + wh1[Geom::Y] / 2;
+            } else if (c2[Geom::Y] < c1[Geom::Y] - wh1[Geom::Y] / 2) {
+                y_closest = c1[Geom::Y] - wh1[Geom::Y] / 2;
+            } else {
+                y_closest = c2[Geom::Y];
+            }
+            c1_points[0] = Geom::Point(c1[Geom::X], y_closest);
+            double x_closest;
+            if (c2[Geom::X] > c1[Geom::X] + wh1[Geom::X] / 2) {
+                x_closest = c1[Geom::X] + wh1[Geom::X] / 2;
+            } else if (c2[Geom::X] < c1[Geom::X] - wh1[Geom::X] / 2) {
+                x_closest = c1[Geom::X] - wh1[Geom::X] / 2;
+            } else {
+                x_closest = c2[Geom::X];
+            }
+            c1_points[1] = Geom::Point(x_closest, c1[Geom::Y]);
+        }
+
+        std::vector<Geom::Point> c2_points(2);
+        {
+            double y_closest;
+            if (c1[Geom::Y] > c2[Geom::Y] + wh2[Geom::Y] / 2) {
+                y_closest = c2[Geom::Y] + wh2[Geom::Y] / 2;
+            } else if (c1[Geom::Y] < c2[Geom::Y] - wh2[Geom::Y] / 2) {
+                y_closest = c2[Geom::Y] - wh2[Geom::Y] / 2;
+            } else {
+                y_closest = c1[Geom::Y];
+            }
+            c2_points[0] = Geom::Point(c2[Geom::X], y_closest);
+            double x_closest;
+            if (c1[Geom::X] > c2[Geom::X] + wh2[Geom::X] / 2) {
+                x_closest = c2[Geom::X] + wh2[Geom::X] / 2;
+            } else if (c1[Geom::X] < c2[Geom::X] - wh2[Geom::X] / 2) {
+                x_closest = c2[Geom::X] - wh2[Geom::X] / 2;
+            } else {
+                x_closest = c1[Geom::X];
+            }
+            c2_points[1] = Geom::Point(x_closest, c2[Geom::Y]);
+        }
+
+        for (int i = 0; i < 2; i++) {
+            for (int j = 0; j < 2; j++) {
+                dists.push_back(Geom::L2(c1_points[i] - c2_points[j]));
+            }
+        }
+
+        // return the minimum of all dists
+        return *std::min_element(dists.begin(), dists.end());
+    } else {
+        return dist_r;
+    }
+}
+
+/**
+Average dist from item to others
+*/
+double Unclump::average(SPItem *item, std::list<SPItem *> &others)
+{
+    int n = 0;
+    double sum = 0;
+    for (SPItem *other : others) {
+        if (other == item)
+            continue;
+
+        n++;
+        sum += dist(item, other);
+    }
+
+    if (n != 0)
+        return sum / n;
+    else
+        return 0;
+}
+
+/**
+Closest to item among others
+ */
+SPItem *Unclump::closest(SPItem *item, std::list<SPItem *> &others)
+{
+    double min = HUGE_VAL;
+    SPItem *closest = nullptr;
+
+    for (SPItem *other : others) {
+        if (other == item)
+            continue;
+
+        double dist = this->dist(item, other);
+        if (dist < min && fabs(dist) < 1e6) {
+            min = dist;
+            closest = other;
+        }
+    }
+
+    return closest;
+}
+
+/**
+Most distant from item among others
+ */
+SPItem *Unclump::farthest(SPItem *item, std::list<SPItem *> &others)
+{
+    double max = -HUGE_VAL;
+    SPItem *farthest = nullptr;
+
+    for (SPItem *other : others) {
+        if (other == item)
+            continue;
+
+        double dist = this->dist(item, other);
+        if (dist > max && fabs(dist) < 1e6) {
+            max = dist;
+            farthest = other;
+        }
+    }
+
+    return farthest;
+}
+
+/**
+Removes from the \a rest list those items that are "behind" \a closest as seen from \a item,
+i.e. those on the other side of the line through \a closest perpendicular to the direction from \a
+item to \a closest. Returns a newly created list which must be freed.
+ */
+std::vector<SPItem *> Unclump::unclump_remove_behind(SPItem *item, SPItem *closest, std::list<SPItem *> &rest)
+{
+    Geom::Point it = unclump_center(item);
+    Geom::Point p1 = unclump_center(closest);
+
+    // perpendicular through closest to the direction to item:
+    Geom::Point perp = Geom::rot90(it - p1);
+    Geom::Point p2 = p1 + perp;
+
+    // get the standard Ax + By + C = 0 form for p1-p2:
+    double A = p1[Geom::Y] - p2[Geom::Y];
+    double B = p2[Geom::X] - p1[Geom::X];
+    double C = p2[Geom::Y] * p1[Geom::X] - p1[Geom::Y] * p2[Geom::X];
+
+    // substitute the item into it:
+    double val_item = A * it[Geom::X] + B * it[Geom::Y] + C;
+
+    std::vector<SPItem *> out;
+    for (SPItem *other : rest) {
+        if (other == item)
+            continue;
+
+        Geom::Point o = unclump_center(other);
+        double val_other = A * o[Geom::X] + B * o[Geom::Y] + C;
+
+        if (val_item * val_other <= 1e-6) {
+            // different signs, which means item and other are on the different sides of p1-p2 line; skip
+        } else {
+            out.push_back(other);
+        }
+    }
+
+    return out;
+}
+
+/**
+Moves \a what away from \a from by \a dist
+ */
+void Unclump::push(SPItem *from, SPItem *what, double dist)
+{
+    Geom::Point it = unclump_center(what);
+    Geom::Point p = unclump_center(from);
+    Geom::Point by = dist * Geom::unit_vector(-(p - it));
+
+    Geom::Affine move = Geom::Translate(by);
+
+    std::map<const gchar *, Geom::Point>::iterator i = c_cache.find(what->getId());
+    if (i != c_cache.end()) {
+        i->second *= move;
+    }
+
+    // g_print ("push %s at %g,%g from %g,%g by %g,%g, dist %g\n", what->getId(), it[Geom::X],it[Geom::Y],
+    // p[Geom::X],p[Geom::Y], by[Geom::X],by[Geom::Y], dist);
+
+    what->set_i2d_affine(what->i2dt_affine() * move);
+    what->doWriteTransform(what->transform);
+}
+
+/**
+Moves \a what towards \a to by \a dist
+ */
+void Unclump::pull(SPItem *to, SPItem *what, double dist)
+{
+    Geom::Point it = unclump_center(what);
+    Geom::Point p = unclump_center(to);
+    Geom::Point by = dist * Geom::unit_vector(p - it);
+
+    Geom::Affine move = Geom::Translate(by);
+
+    std::map<const gchar *, Geom::Point>::iterator i = c_cache.find(what->getId());
+    if (i != c_cache.end()) {
+        i->second *= move;
+    }
+
+    // g_print ("pull %s at %g,%g to %g,%g by %g,%g, dist %g\n", what->getId(), it[Geom::X],it[Geom::Y],
+    // p[Geom::X],p[Geom::Y], by[Geom::X],by[Geom::Y], dist);
+
+    what->set_i2d_affine(what->i2dt_affine() * move);
+    what->doWriteTransform(what->transform);
+}
+
+/**
+Unclumps the items in \a items, reducing local unevenness in their distribution. Produces an effect
+similar to "engraver dots". The only distribution which is unchanged by unclumping is a hexagonal
+grid. May be called repeatedly for stronger effect.
+ */
+void unclump(std::vector<SPItem *> &items)
+{
+    Unclump unclump;
+
+    for (SPItem *item : items) { //  for each original/clone x:
+        std::list<SPItem *> nei;
+
+        std::list<SPItem *> rest;
+        for (size_t i = 0; i < items.size(); i++) {
+            rest.push_front(items[items.size() - i - 1]);
+        }
+        rest.remove(item);
+
+        while (!rest.empty()) {
+            SPItem *closest = unclump.closest(item, rest);
+            if (closest) {
+                nei.push_front(closest);
+                rest.remove(closest);
+                std::vector<SPItem *> new_rest = unclump.unclump_remove_behind(item, closest, rest);
+                rest.clear();
+                for (size_t i = 0; i < new_rest.size(); i++) {
+                    rest.push_front(new_rest[new_rest.size() - i - 1]);
+                }
+            } else {
+                break;
+            }
+        }
+
+        if ((nei.size()) >= 2) {
+            double ave = unclump.average(item, nei);
+
+            SPItem *closest = unclump.closest(item, nei);
+            SPItem *farthest = unclump.farthest(item, nei);
+
+            double dist_closest = unclump.dist(closest, item);
+            double dist_farthest = unclump.dist(farthest, item);
+
+            // g_print ("NEI %d for item %s    closest %s at %g  farthest %s at %g  ave %g\n", g_slist_length(nei),
+            // item->getId(), closest->getId(), dist_closest, farthest->getId(), dist_farthest, ave);
+
+            if (fabs(ave) < 1e6 && fabs(dist_closest) < 1e6 && fabs(dist_farthest) < 1e6) { // otherwise the items are
+                                                                                            // bogus
+                // increase these coefficients to make unclumping more aggressive and less stable
+                // the pull coefficient is a bit bigger to counteract the long-term expansion trend
+                unclump.push(closest, item, 0.3 * (ave - dist_closest));
+                unclump.pull(farthest, item, 0.35 * (dist_farthest - ave));
+            }
+        }
+    }
+}
+
+/*
+  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 :
diff --git a/src/object/algorithms/unclump.h b/src/object/algorithms/unclump.h
new file mode 100644
index 0000000..313e12d
--- /dev/null
+++ b/src/object/algorithms/unclump.h
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * @brief Unclumping objects
+ */
+/* Authors:
+ *   bulia byak
+ *
+ * Copyright (C) 2005 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#ifndef SEEN_DIALOGS_UNCLUMP_H
+#define SEEN_DIALOGS_UNCLUMP_H
+
+#include <vector>
+
+class SPItem;
+
+void unclump(std::vector<SPItem *> &items);
+
+#endif /* !UNCLUMP_H_SEEN */
+
+/*
+  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 :