File indexing completed on 2024-06-16 04:15:52

 /*
  * SPDX-FileCopyrightText: 2008 Cyrille Berger <cberger@cberger.net>
  * SPDX-FileCopyrightText: 2010 Geoffry Song <goffrie@gmail.com>
  * SPDX-FileCopyrightText: 2017 Scott Petrovic <scottpetrovic@gmail.com>
  *
  *  SPDX-License-Identifier: LGPL-2.0-or-later
  */
 
 #include "SplineAssistant.h"
 
 #include <klocalizedstring.h>
 
 #include <QPainter>
 #include <QPainterPath>
 #include <QLinearGradient>
 #include <QTransform>
 
 #include <kis_canvas2.h>
 #include <kis_coordinates_converter.h>
 #include "kis_debug.h"
 #include "KisBezierUtils.h"
 
 #include <math.h>
 #include <limits>
 #include <algorithm>
 
 struct GoldenSearchParams
 {
     GoldenSearchParams(qreal lbound
                 ,qreal ubound)
         :lbound(lbound)
         ,ubound(ubound)
     {
         samples = QVector<GoldenSearchPoint>(4);
     }
 
     struct GoldenSearchPoint {
         GoldenSearchPoint(qreal xval)
             : x(xval)
         {
         }
 
         GoldenSearchPoint(){}
 
         void inv_norm(qreal l, qreal u)
         {
             this->xnorm = this->x * (u - l) + l;
         }
 
         qreal fval;
         qreal xnorm;
         qreal x;
     };
 
 
     qreal lbound;
     qreal ubound;
     QVector<GoldenSearchPoint> samples;
 };
 
 
 struct SplineAssistant::Private {
     Private();
 
     QPointF prevStrokebegin;
     qreal prev_t {0};
 };
 
 SplineAssistant::Private::Private()
     : prevStrokebegin(0,0)
 {
 }
 
 SplineAssistant::SplineAssistant()
     : KisPaintingAssistant("spline", i18n("Spline assistant"))
     , m_d(new Private)
 {
 }
 
 SplineAssistant::SplineAssistant(const SplineAssistant &rhs, QMap<KisPaintingAssistantHandleSP, KisPaintingAssistantHandleSP> &handleMap)
     : KisPaintingAssistant(rhs, handleMap)
     , m_canvas(rhs.m_canvas)
     , m_d(new Private)
 {
 }
 
 KisPaintingAssistantSP SplineAssistant::clone(QMap<KisPaintingAssistantHandleSP, KisPaintingAssistantHandleSP> &handleMap) const
 {
     return KisPaintingAssistantSP(new SplineAssistant(*this, handleMap));
 }
 
 // parametric form of a cubic spline (B(t) = (1-t)^3 P0 + 3 (1-t)^2 t P1 + 3 (1-t) t^2 P2 + t^3 P3)
 inline QPointF B(qreal t, const QPointF& P0, const QPointF& P1, const QPointF& P2, const QPointF& P3)
 {
     const qreal tp = 1 - t;
     const qreal tp2 = tp * tp;
     const qreal t2 = t * t;
 
     return  (    tp2 * tp) * P0 +
             (3 * tp2 * t ) * P1 +
             (3 * tp  * t2) * P2 +
             (    t   * t2) * P3;
 }
 // squared distance from a point on the spline to given point: we want to minimize this
 inline qreal D(qreal t, const QPointF& P0, const QPointF& P1, const QPointF& P2, const QPointF& P3, const QPointF& p)
 {
     const qreal
             tp =  1 - t,
             tp2 = tp * tp,
             t2 =  t * t,
             a =   tp2 * tp,
             b =   3 * tp2 * t,
             c =   3 * tp  * t2,
             d =   t   * t2,
             x_dist = a*P0.x() + b*P1.x() + c*P2.x() + d*P3.x() - p.x(),
             y_dist = a*P0.y() + b*P1.y() + c*P2.y() + d*P3.y() - p.y();
 
     return x_dist * x_dist + y_dist * y_dist;
 }
 
 
 inline qreal goldenSearch(const QPointF& pt
                           , const QList<KisPaintingAssistantHandleSP> handles
                           , qreal low
                           , qreal high
                           , qreal tolerance
                           , uint max_iter)
 {
     GoldenSearchParams ovalues = GoldenSearchParams(low,high);
     QVector<GoldenSearchParams::GoldenSearchPoint> p = ovalues.samples;
     qreal u = ovalues.ubound;
     qreal l = ovalues.lbound;
 
     const qreal ratio = 1 - 2/(1 + sqrt(5));
     p[0].x = 0;
     p[1].x = ratio;
     p[2].x = 1 - p[1].x;
     p[3].x = 1;
 
     p[1].inv_norm(l,u);
     p[2].inv_norm(l,u);
 
     p[1].fval = D(p[1].xnorm, *handles[0], *handles[2], *handles[3], *handles[1], pt);
     p[2].fval = D(p[2].xnorm, *handles[0], *handles[2], *handles[3], *handles[1], pt);
 
     GoldenSearchParams::GoldenSearchPoint xtemp = GoldenSearchParams::GoldenSearchPoint(0);
 
     uint i = 0; // used to force early exit
     while ( qAbs(p[2].xnorm - p[1].xnorm) > tolerance && i < max_iter) {
 
         if (p[1].fval < p[2].fval) {
             xtemp = p[1];
             p[3] = p[2];
             p[1].x = p[0].x + (p[2].x - p[1].x);
             p[2] = xtemp;
 
             p[1].inv_norm(l,u);
             p[1].fval = D(p[1].xnorm, *handles[0], *handles[2], *handles[3], *handles[1], pt);
 
         } else {
             xtemp = p[2];
             p[0] = p[1];
             p[2].x = p[1].x + (p[3].x - p[2].x);
             p[1] = xtemp;
 
             p[2].inv_norm(l,u);
             p[2].fval = D(p[2].xnorm, *handles[0], *handles[2], *handles[3], *handles[1], pt);
 
         }
         i++;
     }
     return (p[2].xnorm + p[1].xnorm) / 2;
 }
 
 
 QPointF SplineAssistant::project(const QPointF& pt, const QPointF& strokeBegin) const
 {
     Q_ASSERT(isAssistantComplete());
 
     // minimize d(t), but keep t in the same neighbourhood as before (unless starting a new stroke)
     bool stayClose = (m_d->prevStrokebegin == strokeBegin)? true : false;
     qreal min_t;
 
     QList<QPointF> refs;
     QVector<int> hindex = {0,2,3,1}; // order handles as expected by KisBezierUtils
     Q_FOREACH(int i, hindex) {
         refs.append(*handles()[i]);
     }
 
     if (stayClose){
         // Search in the vicinity of previous t value.
         // This ensure unimodality for proper goldenSearch algorithm
         qreal delta = 1/10.0;
         qreal lbound = qBound(0.0,1.0, m_d->prev_t - delta);
         qreal ubound = qBound(0.0,1.0, m_d->prev_t + delta);
         min_t = goldenSearch(pt,handles(), lbound , ubound, 1e-6,1e+2);
 
     } else {
         min_t = KisBezierUtils::nearestPoint(refs,pt);
     }
 
     QPointF draw_pos = B(min_t, *handles()[0], *handles()[2], *handles()[3], *handles()[1]);
 
     m_d->prev_t = min_t;
     m_d->prevStrokebegin = strokeBegin;
 
     return draw_pos;
 }
 
 QPointF SplineAssistant::adjustPosition(const QPointF& pt, const QPointF& strokeBegin, const bool /*snapToAny*/, qreal /*moveThresholdPt*/)
 {
     return project(pt, strokeBegin);
 }
 
 void SplineAssistant::adjustLine(QPointF &point, QPointF &strokeBegin)
 {
     point = QPointF();
     strokeBegin = QPointF();
 }
 
 void SplineAssistant::drawAssistant(QPainter& gc, const QRectF& updateRect, const KisCoordinatesConverter* converter, bool cached, KisCanvas2* canvas, bool assistantVisible, bool previewVisible)
 {
     gc.save();
     gc.resetTransform();
     QPoint mousePos;
     
     if (canvas){
         //simplest, cheapest way to get the mouse-position//
         mousePos= canvas->canvasWidget()->mapFromGlobal(QCursor::pos());
         m_canvas = canvas;
     }
     else {
         //...of course, you need to have access to a canvas-widget for that.//
         mousePos = QCursor::pos();//this'll give an offset//
         dbgFile<<"canvas does not exist in spline, you may have passed arguments incorrectly:"<<canvas;
     }
     
 
     if (handles().size() > 1) {
 
         QTransform initialTransform = converter->documentToWidgetTransform();
 
         // first we find the path that our point create.
         QPointF pts[4];
         pts[0] = *handles()[0];
         pts[1] = *handles()[1];
         pts[2] = (handles().size() >= 3) ? (*handles()[2]) : (*handles()[0]);
         pts[3] = (handles().size() >= 4) ? (*handles()[3]) : (handles().size() >= 3) ? (*handles()[2]) : (*handles()[1]);
         gc.setTransform(initialTransform);
 
         // Draw the spline
         QPainterPath path;
         path.moveTo(pts[0]);
         path.cubicTo(pts[2], pts[3], pts[1]);
         
         //then we use this path to check the bounding rectangle//
         if (isSnappingActive() && path.boundingRect().contains(initialTransform.inverted().map(mousePos)) && previewVisible==true){
             drawPreview(gc, path);//and we draw the preview.
         }
     }
     gc.restore();
 
    // there is some odd rectangle that is getting rendered when there is only one point, so don't start rendering the line until after 2
    // this issue only exists with this spline assistant...none of the others
    if (handles().size() > 2) {
       KisPaintingAssistant::drawAssistant(gc, updateRect, converter, cached, canvas, assistantVisible, previewVisible);
    }
 }
 
 void SplineAssistant::drawCache(QPainter& gc, const KisCoordinatesConverter *converter, bool assistantVisible)
 {
     if (assistantVisible == false || handles().size() < 2 ){
         return;
     }
 
     QTransform initialTransform = converter->documentToWidgetTransform();
 
     QPointF pts[4];
     pts[0] = *handles()[0];
     pts[1] = *handles()[1];
     pts[2] = (handles().size() >= 3) ? (*handles()[2]) : (*handles()[0]);
     pts[3] = (handles().size() >= 4) ? (*handles()[3]) : (handles().size() >= 3) ? (*handles()[2]) : (*handles()[1]);
 
     gc.setTransform(initialTransform);
 
 
     {  // Draw bezier handles control lines only if we are editing the assistant
         gc.save();
         QColor assistantColor = effectiveAssistantColor();
         QPen bezierlinePen(assistantColor);
         bezierlinePen.setStyle(Qt::DotLine);
         bezierlinePen.setWidth(2);
 
         if (m_canvas->paintingAssistantsDecoration()->isEditingAssistants()) {
 
             if (!isSnappingActive()) {
                 QColor snappingColor = assistantColor;
                 snappingColor.setAlpha(snappingColor.alpha() * 0.2);
 
                 bezierlinePen.setColor(snappingColor);
             }
             bezierlinePen.setCosmetic(true);
 
             gc.setPen(bezierlinePen);
             gc.drawLine(pts[0], pts[2]);
 
             if (isAssistantComplete()) {
                 gc.drawLine(pts[1], pts[3]);
             }
             gc.setPen(QColor(0, 0, 0, 125));
         }
         gc.restore();
     }
 
 
     // Draw the spline
     QPainterPath path;
     path.moveTo(pts[0]);
     path.cubicTo(pts[2], pts[3], pts[1]);
     drawPath(gc, path, isSnappingActive());
 
 
 }
 
 QPointF SplineAssistant::getDefaultEditorPosition() const
 {
     return B(0.5, *handles()[0], *handles()[2], *handles()[3], *handles()[1]);
 }
 
 bool SplineAssistant::isAssistantComplete() const
 {
     return handles().size() >= 4; // specify 4 corners to make assistant complete
 }
 
 SplineAssistantFactory::SplineAssistantFactory()
 {
 }
 
 SplineAssistantFactory::~SplineAssistantFactory()
 {
 }
 
 QString SplineAssistantFactory::id() const
 {
     return "spline";
 }
 
 QString SplineAssistantFactory::name() const
 {
     return i18nc("A type of drawing assistants", "Spline");
 }
 
 KisPaintingAssistant* SplineAssistantFactory::createPaintingAssistant() const
 {
     return new SplineAssistant;
 }