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+// 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 <algorithm>
+#include <map>
+
+#include <2geom/transforms.h>
+
+#include "unclump.h"
+
+#include "object/sp-item.h"
+
+
+// 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
+
+//FIXME: make a class with these cashes as members instead of globals
+std::map<const gchar *, Geom::Point> c_cache;
+std::map<const gchar *, Geom::Point> wh_cache;
+
+/**
+Center of bbox of item
+*/
+static Geom::Point
+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);
+ }
+}
+
+static Geom::Point
+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.
+*/
+static 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 unclump_dist from item to others
+*/
+static double unclump_average (SPItem *item, std::list<SPItem*> &others)
+{
+ int n = 0;
+ double sum = 0;
+ for (std::list<SPItem*>::const_iterator i = others.begin(); i != others.end();++i) {
+ SPItem *other = *i;
+
+ if (other == item)
+ continue;
+
+ n++;
+ sum += unclump_dist (item, other);
+ }
+
+ if (n != 0)
+ return sum/n;
+ else
+ return 0;
+}
+
+/**
+Closest to item among others
+ */
+static SPItem *unclump_closest (SPItem *item, std::list<SPItem*> &others)
+{
+ double min = HUGE_VAL;
+ SPItem *closest = nullptr;
+
+ for (std::list<SPItem*>::const_iterator i = others.begin(); i != others.end();++i) {
+ SPItem *other = *i;
+
+ if (other == item)
+ continue;
+
+ double dist = unclump_dist (item, other);
+ if (dist < min && fabs (dist) < 1e6) {
+ min = dist;
+ closest = other;
+ }
+ }
+
+ return closest;
+}
+
+/**
+Most distant from item among others
+ */
+static SPItem *unclump_farest (SPItem *item, std::list<SPItem*> &others)
+{
+ double max = -HUGE_VAL;
+ SPItem *farest = nullptr;
+ for (std::list<SPItem*>::const_iterator i = others.begin(); i != others.end();++i) {
+ SPItem *other = *i;
+
+ if (other == item)
+ continue;
+
+ double dist = unclump_dist (item, other);
+ if (dist > max && fabs (dist) < 1e6) {
+ max = dist;
+ farest = other;
+ }
+ }
+
+ return farest;
+}
+
+/**
+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.
+ */
+static std::vector<SPItem*>
+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 (std::list<SPItem*>::const_reverse_iterator i = rest.rbegin(); i != rest.rend();++i) {
+ SPItem *other = *i;
+
+ 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
+ */
+static 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
+ */
+static 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)
+{
+ c_cache.clear();
+ wh_cache.clear();
+
+ for (std::vector<SPItem*>::const_iterator i = items.begin(); i != items.end();++i) { // for each original/clone x:
+ SPItem *item = *i;
+
+ std::list<SPItem*> nei;
+
+ std::list<SPItem*> rest;
+ for (int i=0; i < static_cast<int>(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_remove_behind (item, closest, rest);
+ rest.clear();
+ for (int i=0; i < static_cast<int>(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 *farest = unclump_farest (item, nei);
+
+ double dist_closest = unclump_dist (closest, item);
+ double dist_farest = unclump_dist (farest, item);
+
+ //g_print ("NEI %d for item %s closest %s at %g farest %s at %g ave %g\n", g_slist_length(nei), item->getId(), closest->getId(), dist_closest, farest->getId(), dist_farest, ave);
+
+ if (fabs (ave) < 1e6 && fabs (dist_closest) < 1e6 && fabs (dist_farest) < 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 (farest, item, 0.35 * (dist_farest - 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 :
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