path: root/src/display/curve.cpp

// SPDX-License-Identifier: GPL-2.0-or-later
/**
 * Authors:
 *   Lauris Kaplinski <lauris@kaplinski.com>
 *   Johan Engelen
 *
 * Copyright (C) 2000 Lauris Kaplinski
 * Copyright (C) 2000-2001 Ximian, Inc.
 * Copyright (C) 2002 Lauris Kaplinski
 * Copyright (C) 2008 Johan Engelen
 *
 * Released under GNU GPL v2+, read the file 'COPYING' for more information.
 */

#include "display/curve.h"

#include <glib.h> // g_error
#include <2geom/sbasis-geometric.h>
#include <2geom/sbasis-to-bezier.h>
#include <2geom/point.h>
#include "helper/geom.h"
#include "helper/geom-pathstroke.h"

/**
 * Routines for SPCurve and for its Geom::PathVector
 */

SPCurve::SPCurve(Geom::Rect const &rect, bool all_four_sides)
{
    moveto(rect.corner(0));

    for (int i = 3; i >= 1; --i) {
        lineto(rect.corner(i));
    }

    if (all_four_sides) {
        // When _constrained_ snapping to a path, the 2geom::SimpleCrosser will be invoked which doesn't consider the closing segment.
        // of a path. Consequently, in case we want to snap to for example the page border, we must provide all four sides of the
        // rectangle explicitly
        lineto(rect.corner(0));
    } else {
        // ... instead of just three plus a closing segment
        closepath();
    }
}

void SPCurve::set_pathvector(Geom::PathVector const &new_pathv)
{
    _pathv = new_pathv;
}

Geom::PathVector const &SPCurve::get_pathvector() const
{
    return _pathv;
}

/**
 * Returns the number of segments of all paths summed.
 * This count includes the closing line segment of a closed path.
 */
size_t SPCurve::get_segment_count() const
{
    return _pathv.curveCount();
}

/**
 * Returns a list of curves corresponding to the subpaths in \a curve.
 */
std::vector<SPCurve> SPCurve::split() const
{
    std::vector<SPCurve> result;

    for (auto const &path_it : _pathv) {
        Geom::PathVector newpathv;
        newpathv.push_back(path_it);
        result.emplace_back(std::move(newpathv));
    }

    return result;
}

/**
 * Returns a list of curves of non-overlapping subpath in \a curve.
 */
std::vector<SPCurve> SPCurve::split_non_overlapping() const
{
    std::vector<SPCurve> result;

    auto curves = Inkscape::split_non_intersecting_paths(Geom::PathVector(_pathv));

    for (auto &curve : curves) {
        result.emplace_back(std::move(curve));
    }

    return result;
}

/**
 * Transform all paths in curve by matrix.
 */
void SPCurve::transform(Geom::Affine const &m)
{
    _pathv *= m;
}

/**
 * Return a copy of the curve with all paths transformed by matrix.
 */
SPCurve SPCurve::transformed(const Geom::Affine &m) const
{
    return SPCurve(_pathv * m);
}

/**
 * Set curve to empty curve.
 * In more detail: this clears the internal pathvector from all its paths.
 */
void SPCurve::reset()
{
    _pathv.clear();
}

/** Several consecutive movetos are ALLOWED
 *  Ref: http://www.w3.org/TR/SVG11/implnote.html#PathElementImplementationNotes
 * (first subitem of the item about zero-length path segments) */
/**
 * Calls SPCurve::moveto() with point made of given coordinates.
 */
void SPCurve::moveto(double x, double y)
{
    moveto(Geom::Point(x, y));
}

/**
 * Perform a moveto to a point, thus starting a new subpath.
 * Point p must be finite.
 */
void SPCurve::moveto(Geom::Point const &p)
{
    Geom::Path path(p);
    path.setStitching(true);
    _pathv.push_back(path);
}

/**
 * Adds a line to the current subpath.
 * Point p must be finite.
 */
void SPCurve::lineto(Geom::Point const &p)
{
    if (_pathv.empty()) {
        g_message("SPCurve::lineto - path is empty!");
    } else {
        _pathv.back().appendNew<Geom::LineSegment>(p);
    }
}
/**
 * Calls SPCurve::lineto( Geom::Point(x,y) )
 */
void SPCurve::lineto(double x, double y)
{
    lineto(Geom::Point(x, y));
}

/**
 * Adds a quadratic bezier segment to the current subpath.
 * All points must be finite.
 */
void SPCurve::quadto(Geom::Point const &p1, Geom::Point const &p2)
{
    if (_pathv.empty()) {
        g_message("SPCurve::quadto - path is empty!");
    } else {
        _pathv.back().appendNew<Geom::QuadraticBezier>(p1, p2);
    }
}
/**
 * Calls SPCurve::quadto( Geom::Point(x1,y1), Geom::Point(x2,y2) )
 * All coordinates must be finite.
 */
void SPCurve::quadto(double x1, double y1, double x2, double y2)
{
    quadto(Geom::Point(x1, y1), Geom::Point(x2, y2));
}

/**
 * Adds a bezier segment to the current subpath.
 * All points must be finite.
 */
void SPCurve::curveto(Geom::Point const &p0, Geom::Point const &p1, Geom::Point const &p2)
{
    if (_pathv.empty()) {
        g_message("SPCurve::curveto - path is empty!");
    } else {
        _pathv.back().appendNew<Geom::CubicBezier>(p0, p1, p2);
    }
}
/**
 * Calls SPCurve::curveto( Geom::Point(x0,y0), Geom::Point(x1,y1), Geom::Point(x2,y2) )
 * All coordinates must be finite.
 */
void SPCurve::curveto(double x0, double y0, double x1, double y1, double x2, double y2)
{
    curveto(Geom::Point(x0, y0), Geom::Point(x1, y1), Geom::Point(x2, y2));
}

/**
 * Close current subpath by possibly adding a line between start and end.
 */
void SPCurve::closepath()
{
    if (_pathv.empty()) {
        g_message("%s - path is empty", __PRETTY_FUNCTION__);
    } else {
        _pathv.back().close(true);
    }
}

/** Like SPCurve::closepath() but sets the end point of the last subpath
 *  to the subpath start point instead of adding a new lineto.
 *
 *  Used for freehand drawing when the user draws back to the start point.
 */
void SPCurve::closepath_current()
{
    if (_pathv.back().size() > 0 && dynamic_cast<Geom::LineSegment const *>(&_pathv.back().back_open())) {
        _pathv.back().erase_last();
    } else {
        _pathv.back().setFinal(_pathv.back().initialPoint());
    }
    _pathv.back().close(true);
}

/**
 * True if no paths are in curve. If it only contains a path with only a moveto, the path is considered NON-empty
 */
bool SPCurve::is_empty() const
{
    return _pathv.empty();
}

/**
 * True if paths are in curve. If it only contains a path with only a moveto, the path is considered as unset FALSE
 */
bool SPCurve::is_unset() const
{
    return get_segment_count() == 0;
}

/**
 * True iff all subpaths are closed.
 * Returns false if the curve is empty.
 */
bool SPCurve::is_closed() const
{
    if (is_empty()) {
        return false;
    } 
    
    for (auto const &it : _pathv) {
        if (!it.closed()) {
            return false;
        }
    }
    
    return true;    
}

/**
 * True if both curves are equal
 */
bool SPCurve::is_equal(SPCurve const *other) const
{
    return other && _pathv == other->get_pathvector();
}

/**
 * True if both curves are near
 */
bool SPCurve::is_similar(SPCurve const *other, double precision) const
{
    return other && pathv_similar(_pathv, other->get_pathvector(), precision);
}

/**
 * Return last pathsegment (possibly the closing path segment) of the last path in PathVector or NULL.
 * If the last path is empty (contains only a moveto), the function returns NULL
 */
Geom::Curve const *SPCurve::last_segment() const
{
    if (is_empty()) {
        return nullptr;
    }
    if (_pathv.back().empty()) {
        return nullptr;
    }

    return &_pathv.back().back_default();
}

/**
 * Return last path in PathVector or NULL.
 */
Geom::Path const *SPCurve::last_path() const
{
    if (is_empty()) {
        return nullptr;
    }

    return &_pathv.back();
}

/**
 * Return first pathsegment in PathVector or NULL.
 * equal in functionality to SPCurve::first_bpath()
 */
Geom::Curve const *SPCurve::first_segment() const
{
    if (is_empty()) {
        return nullptr;
    }
    if (_pathv.front().empty()) {
        return nullptr;
    }

    return &_pathv.front().front();
}

/**
 * Return first path in PathVector or NULL.
 */
Geom::Path const *SPCurve::first_path() const
{
    if (is_empty()) {
        return nullptr;
    }

    return &_pathv.front();
}

/**
 * Return first point of first subpath or nothing when the path is empty.
 */
std::optional<Geom::Point> SPCurve::first_point() const
{
    if (is_empty()) {
        return {};
    }

    return _pathv.front().initialPoint();
}

/**
 * Return the second point of first subpath or _movePos if curve too short.
 * If the pathvector is empty, this returns nothing. If the first path is only a moveto, this method
 * returns the first point of the second path, if it exists. If there is no 2nd path, it returns the
 * first point of the first path.
 */
std::optional<Geom::Point> SPCurve::second_point() const
{
    if (is_empty()) {
        return {};
    }

    if (_pathv.front().empty()) {
        // first path is only a moveto
        // check if there is second path
        if (_pathv.size() > 1) {
            return _pathv[1].initialPoint();
        } else {
            return _pathv[0].initialPoint();
        }
    }

    return _pathv.front()[0].finalPoint();
}

/**
 * Return the second-last point of last subpath or first point when that last subpath has only a moveto.
 */
std::optional<Geom::Point> SPCurve::penultimate_point() const
{
    if (is_empty()) {
        return {};
    }

    Geom::Path const &lastpath = _pathv.back();
    if (!lastpath.empty()) {
        return lastpath.back_default().initialPoint();
    } else {
        return lastpath.initialPoint();
    }
}

/**
 * Return last point of last subpath or nothing when the curve is empty.
 * If the last path is only a moveto, then return that point.
 */
std::optional<Geom::Point> SPCurve::last_point() const
{
    if (is_empty()) {
        return {};
    }

    return _pathv.back().finalPoint();
}

/**
 * Reverse the direction of all paths.
 */
void SPCurve::reverse()
{
    _pathv.reverse();
}

/**
 * Return a copy with the direction of all paths reversed.
 */
SPCurve SPCurve::reversed() const
{
    return SPCurve(_pathv.reversed());
}

/**
 * Append \a curve2 to \a this.
 * If \a use_lineto is false, simply add all paths in \a curve2 to \a this;
 * if \a use_lineto is true, combine \a this's last path and \a curve2's first path and add the rest of the paths in \a curve2 to \a this.
 */
void SPCurve::append(SPCurve const &curve2, bool use_lineto)
{
    append(curve2._pathv, use_lineto);
}

void SPCurve::append(Geom::PathVector const &pathv, bool use_lineto)
{
    if (pathv.empty()) {
        return;
    }

    if (use_lineto) {
        auto it = pathv.begin();
        if (!_pathv.empty()) {
            Geom::Path &lastpath = _pathv.back();
            lastpath.appendNew<Geom::LineSegment>(it->initialPoint());
            lastpath.append(*it);
        } else {
            _pathv.push_back(*it);
        }

        for (++it; it != pathv.end(); ++it) {
            _pathv.push_back(*it);
        }
    } else {
        for (auto const &it : pathv) {
            _pathv.push_back(it);
        }
    }
}

/**
 * Append \a c1 to \a this with possible fusing of close endpoints. If the end of this curve and the start of c1 are within tolerance distance,
 * then the startpoint of c1 is moved to the end of this curve and the first subpath of c1 is appended to the last subpath of this curve.
 * When one of the curves is empty, this curves path becomes the non-empty path.
 *
 * @param tolerance Tolerance for endpoint fusion (applied to x and y separately)
 * @return False if one of the curves (this curve or the argument curve) is closed, true otherwise.
 */
bool SPCurve::append_continuous(SPCurve const &c1, double tolerance)
{
    if (is_closed() || c1.is_closed()) {
        return false;
    }

    if (c1.is_empty()) {
        return true;
    }

    if (this->is_empty()) {
        _pathv = c1._pathv;
        return true;
    }

    if ((fabs(last_point()->x() - c1.first_point()->x()) <= tolerance) &&
        (fabs(last_point()->y() - c1.first_point()->y()) <= tolerance)) {
    // c1's first subpath can be appended to this curve's last subpath
        Geom::PathVector::const_iterator path_it = c1._pathv.begin();
        Geom::Path & lastpath = _pathv.back();

        Geom::Path newfirstpath(*path_it);
        newfirstpath.setInitial(lastpath.finalPoint());
        lastpath.append(newfirstpath);

        for (++path_it; path_it != c1._pathv.end(); ++path_it) {
            _pathv.push_back(*path_it);
        }

    } else {
        append(c1, true);
    }

    return true;
}

/**
 * Remove last segment of curve.
 */
void SPCurve::backspace()
{
    if (is_empty()) {
        return;
    }

    if (!_pathv.back().empty()) {
        _pathv.back().erase_last();
        _pathv.back().close(false);
    }
}

/**
 * TODO: add comments about what this method does and what assumptions are made and requirements are put on SPCurve
 (2:08:18 AM) Johan: basically, i convert the path to pw<d2>
(2:08:27 AM) Johan: then i calculate an offset path
(2:08:29 AM) Johan: to move the knots
(2:08:36 AM) Johan: then i add it
(2:08:40 AM) Johan: then convert back to path
If I remember correctly, this moves the firstpoint to new_p0, and the lastpoint to new_p1, and moves all nodes in between according to their arclength (interpolates the movement amount)
 */
void SPCurve::stretch_endpoints(Geom::Point const &new_p0, Geom::Point const &new_p1)
{
    if (is_empty()) {
        return;
    }

    auto const offset0 = new_p0 - *first_point();
    auto const offset1 = new_p1 - *last_point();

    Geom::Piecewise<Geom::D2<Geom::SBasis>> pwd2 = _pathv.front().toPwSb();
    Geom::Piecewise<Geom::SBasis> arclength = Geom::arcLengthSb(pwd2);
    if (arclength.lastValue() <= 0) {
        g_error("SPCurve::stretch_endpoints - arclength <= 0");
    }
    arclength *= 1./arclength.lastValue();
    auto const A = offset0;
    auto const B = offset1;
    Geom::Piecewise<Geom::SBasis> offsetx = (arclength*-1.+1)*A[0] + arclength*B[0];
    Geom::Piecewise<Geom::SBasis> offsety = (arclength*-1.+1)*A[1] + arclength*B[1];
    Geom::Piecewise<Geom::D2<Geom::SBasis>> offsetpath = Geom::sectionize(Geom::D2<Geom::Piecewise<Geom::SBasis>>(offsetx, offsety));
    pwd2 += offsetpath;
    _pathv = Geom::path_from_piecewise(pwd2, 0.001);
}

/**
 *  sets start of first path to new_p0, and end of first path to  new_p1
 */
void SPCurve::move_endpoints(Geom::Point const &new_p0, Geom::Point const &new_p1)
{
    if (is_empty()) {
        return;
    }
    _pathv.front().setInitial(new_p0);
    _pathv.front().setFinal(new_p1);
}

/**
 * returns the number of nodes in a path, used for statusbar text when selecting an spcurve.
 * Sum of nodes in all the paths. When a path is closed, and its closing line segment is of zero-length,
 * this function will not count the closing knot double (so basically ignores the closing line segment when it has zero length)
 */
size_t SPCurve::nodes_in_path() const
{
    size_t nr = 0;

    for (auto const &it : _pathv) {
        // if the path does not have any segments, it is a naked moveto,
        // and therefore any path has at least one valid node
        size_t psize = std::max<size_t>(1, it.size_closed());
        nr += psize;
        if (it.closed() && it.size_closed() > 0) {
            Geom::Curve const &closingline = it.back_closed();
            // the closing line segment is always of type
            // Geom::LineSegment.
            if (are_near(closingline.initialPoint(), closingline.finalPoint())) {
                // closingline.isDegenerate() did not work, because it only checks for
                // *exact* zero length, which goes wrong for relative coordinates and
                // rounding errors...
                // the closing line segment has zero-length. So stop before that one!
                nr -= 1;
            }
        }
    }

    return nr;
}

/**
 *  Adds p to the last point (and last handle if present) of the last path
 */
void SPCurve::last_point_additive_move(Geom::Point const &p)
{
    if (is_empty()) {
        return;
    }

    _pathv.back().setFinal(_pathv.back().finalPoint() + p);

    // Move handle as well when the last segment is a cubic bezier segment:
    // TODO: what to do for quadratic beziers?
    if (auto const lastcube = dynamic_cast<Geom::CubicBezier const *>(&_pathv.back().back())) {
        Geom::CubicBezier newcube(*lastcube);
        newcube.setPoint(2, newcube[2] + p);
        _pathv.back().replace(--_pathv.back().end(), newcube);
    }
}

/*
  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: