unclump.cpp

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// SPDX-License-Identifier: GPL-2.0-or-later
/* 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;
};
 
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;
}
 
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;
    }
}
 
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;
}
 
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;
}
 
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;
}
 
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;
}
 
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);
}
 
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);
}
 
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 :