inkscape/src/removeoverlap.cpp

/** \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 LGPL.  Read the file 'COPYING' for more information.
*/
#include <utility>
#include <2geom/transforms.h>
#include "sp-item.h"
#include "sp-item-transform.h"
#include "libvpsc/generate-constraints.h"
#include "libvpsc/remove_rectangle_overlap.h"
#include "removeoverlap.h"

using vpsc::Rectangle;

namespace {
    struct Record {
        SPItem *item;
        Geom::Point midpoint;
        Rectangle *vspc_rect;

        Record() : item(0), vspc_rect(0) {}
        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 (std::vector<SPItem*>::iterator it(selected.begin());
        it != selected.end();
        ++it)
    {
        SPItem* item = *it;
        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.push_back(Record(item, item_box->midpoint(), vspc_rect));
            rs.push_back(vspc_rect);
        }
    }
    if (!rs.empty()) {
        removeRectangleOverlap(rs.size(), &rs[0], 0.0, 0.0);
    }
    for ( std::vector<Record>::iterator it = records.begin();
          it != records.end();
          ++it )
    {
        Geom::Point const curr = it->midpoint;
        Geom::Point const dest(it->vspc_rect->getCentreX(),
                     it->vspc_rect->getCentreY());
        sp_item_move_rel(it->item, Geom::Translate(dest - curr));
        delete it->vspc_rect;
    }
}