// SPDX-License-Identifier: GPL-2.0-or-later /* * Class for pure transformations, such as translating, scaling, stretching, skewing, and rotating * * Authors: * Diederik van Lierop * * Copyright (C) 2015 Diederik van Lierop * * Released under GNU GPL v2+, read the file 'COPYING' for more information. */ #include "pure-transform.h" #include "snap.h" namespace Inkscape { void PureTransform::snap(::SnapManager *sm, std::vector const &points, Geom::Point const &pointer) { std::vector transformed_points; Geom::Rect bbox; long source_num = 0; for (std::vector::const_iterator i = points.begin(); i != points.end(); ++i) { /* Work out the transformed version of this point */ Geom::Point transformed = getTransformedPoint(*i); // _transformPoint(*i, transformation_type, transformation, origin, dim, uniform); // add the current transformed point to the box hulling all transformed points if (i == points.begin()) { bbox = Geom::Rect(transformed, transformed); } else { bbox.expandTo(transformed); } transformed_points.emplace_back(transformed, (*i).getSourceType(), source_num, Inkscape::SNAPTARGET_UNDEFINED, Geom::OptRect()); source_num++; } /* The current best metric for the best transformation; lower is better, whereas Geom::infinity() ** means that we haven't snapped anything. */ Inkscape::SnapCandidatePoint best_original_point; g_assert(best_snapped_point.getAlwaysSnap() == false); // Check initialization of snapped point g_assert(best_snapped_point.getAtIntersection() == false); g_assert(best_snapped_point.getSnapped() == false); // Check initialization to catch any regression std::vector::iterator j = transformed_points.begin(); // std::cout << std::endl; bool first_free_snap = true; for (std::vector::const_iterator i = points.begin(); i != points.end(); ++i) { // If we have a collection of SnapCandidatePoints, with mixed constrained snapping and free snapping // requirements (this can happen when scaling, see PureScale::snap()), then freeSnap might never see the // SnapCandidatePoint with source_num == 0. The freeSnap() method in the object snapper depends on this, // because only for source-num == 0 the target nodes will be collected. Therefore we enforce that the first // SnapCandidatePoint that is to be freeSnapped always has source_num == 0; // TODO: This is a bit ugly so fix this; do we need sourcenum for anything else? if we don't then get rid // of it and explicitly communicate to the object snapper that this is a first point if (first_free_snap) { (*j).setSourceNum(0); first_free_snap = false; } Inkscape::SnappedPoint snapped_point = snap(sm, *j, (*i).getPoint(), bbox); // Calls the snap() method of the derived classes snapped_point.setPointerDistance(Geom::L2(pointer - (*i).getPoint())); /*Find the transformation that describes where the snapped point has ** ended up, and also the metric for this transformation. */ bool store_best_snap = false; if (snapped_point.getSnapped()) { // We snapped; keep track of the best snap if (best_snapped_point.isOtherSnapBetter(snapped_point, true)) { store_best_snap = true; } } else { // So we didn't snap for this point if (!best_snapped_point.getSnapped()) { // ... and none of the points before snapped either // We might still need to apply a constraint though, if we tried a constrained snap. And // in case of a free snap we might have use for the transformed point, so let's return that // point, whether it's constrained or not if (best_snapped_point.isOtherSnapBetter(snapped_point, true) ) { // .. so we must keep track of the best non-snapped constrained point.. but what // is the best? There is no best, or is there? We cannot compare on snapped distance // because neither has snapped, and both have their snapped distance set to infinity. // There might be a difference in "constrainedness" though, 1D vs 2D snapping store_best_snap = true; } } } if (store_best_snap || i == points.begin()) { best_original_point = (*i); best_snapped_point = snapped_point; // Can be a point that didn't snap, but then at least we // return something meaningful; we might have use for the transformation. The default // snapped_point, as initialized before this loop, is not very meaningful at all. } ++j; } /* The current best transformation */ //Geom::Point best_transformation = getResult(best_original_point, best_snapped_point); storeTransform(best_original_point, best_snapped_point); Geom::Coord best_metric = best_snapped_point.getSnapDistance(); // Using " < 1e6" instead of " < Geom::infinity()" for catching some rounding errors // These rounding errors might be caused by NRRects, see bug #1584301 best_snapped_point.setSnapDistance(best_metric < 1e6 ? best_metric : Geom::infinity()); } Geom::Point PureTranslate::getTransformedPoint(SnapCandidatePoint const &p) const { return p.getPoint() + _vector; } void PureTranslate::storeTransform(SnapCandidatePoint const &original_point, SnappedPoint &snapped_point) { /* Consider the case in which a box is almost aligned with a grid in both * horizontal and vertical directions. The distance to the intersection of * the grid lines will always be larger then the distance to a single grid * line. If we prefer snapping to an intersection over to a single * grid line, then we cannot use "metric = Geom::L2(result)". Therefore the * snapped distance will be used as a metric. Please note that the snapped * distance to an intersection is defined as the distance to the nearest line * of the intersection, and not to the intersection itself! */ // Only for translations, the relevant metric will be the real snapped distance, // so we don't have to do anything special here _vector_snapped = snapped_point.getPoint() - original_point.getPoint(); } SnappedPoint PureTranslate::snap(::SnapManager *sm, SnapCandidatePoint const &p, Geom::Point /*pt_orig*/, Geom::OptRect const &bbox_to_snap) const { return sm->freeSnap(p, bbox_to_snap); } SnappedPoint PureTranslateConstrained::snap(::SnapManager *sm, SnapCandidatePoint const &p, Geom::Point pt_orig, Geom::OptRect const &bbox_to_snap) const { // Calculate a constraint dedicated for this specific point // When doing a constrained translation, all points will move in the same direction, i.e. // either horizontally or vertically. The lines along which they move are therefore all // parallel, but might not be co-linear. Therefore we will have to specify the point through // which the constraint-line runs here, for each point individually. Snapper::SnapConstraint dedicated_constraint = Snapper::SnapConstraint(pt_orig, _direction); return sm->constrainedSnap(p, dedicated_constraint, bbox_to_snap); } Geom::Point PureScale::getTransformedPoint(SnapCandidatePoint const &p) const { return (p.getPoint() - _origin) * _scale + _origin; } void PureScale::storeTransform(SnapCandidatePoint const &original_point, SnappedPoint &snapped_point) { _scale_snapped = Geom::Scale(Geom::infinity(), Geom::infinity()); // If this point *i is horizontally or vertically aligned with // the origin of the scaling, then it will scale purely in X or Y // We can therefore only calculate the scaling in this direction // and the scaling factor for the other direction should remain // untouched (unless scaling is uniform of course) Geom::Point const a = snapped_point.getPoint() - _origin; // vector to snapped point Geom::Point const b = original_point.getPoint() - _origin; // vector to original point (not the transformed point!) for (int index = 0; index < 2; index++) { if (fabs(b[index]) > 1e-4) { // if SCALING CAN occur in this direction if (fabs(fabs(a[index]/b[index]) - fabs(_scale[index])) > 1e-7) { // if SNAPPING DID occur in this direction _scale_snapped[index] = a[index] / b[index]; // then calculate it! // _scale_snapped will be (1,1) if we haven't snapped, because the snapped point equals the original point } // we might have left result[1-index] = Geom::infinity() if scaling didn't occur in the other direction } } if (_scale_snapped == Geom::Scale(Geom::infinity(), Geom::infinity())) { // This point must have been at the origin, so we cannot possibly snap; it won't scale (i.e. won't move while dragging) snapped_point.setSnapDistance(Geom::infinity()); snapped_point.setSecondSnapDistance(Geom::infinity()); return; } if (_uniform) { // Lock the scaling the be uniform, but keep the sign such that we don't change which quadrant we have dragged into if (fabs(_scale_snapped[0]) < fabs(_scale_snapped[1])) { _scale_snapped[1] = fabs(_scale_snapped[0]) * Geom::sgn(_scale[1]); } else { _scale_snapped[0] = fabs(_scale_snapped[1]) * Geom::sgn(_scale[0]); } } // Don't ever exit with one of scaling components uninitialized for (int index = 0; index < 2; index++) { if (_scale_snapped[index] == Geom::infinity()) { _scale_snapped[index] = _scale[index]; } } // Compare the resulting scaling with the desired scaling Geom::Point scale_metric = _scale_snapped.vector() - _scale.vector(); snapped_point.setSnapDistance(Geom::L2(scale_metric)); snapped_point.setSecondSnapDistance(Geom::infinity()); } // When scaling, a point aligned either horizontally or vertically with the origin can only // move in that specific direction; therefore it should only snap in that direction, so this // then becomes a constrained snap; otherwise we can use a free snap; SnappedPoint PureScale::snap(::SnapManager *sm, SnapCandidatePoint const &p, Geom::Point pt_orig, Geom::OptRect const &bbox_to_snap) const { Geom::Point const b = (pt_orig - _origin); // vector to original point (not the transformed point!) bool const c1 = fabs(b[Geom::X]) < 1e-6; bool const c2 = fabs(b[Geom::Y]) < 1e-6; if ((c1 || c2) && !(c1 && c2)) { Geom::Point cvec; cvec[c1] = 1.; Snapper::SnapConstraint dedicated_constraint = Inkscape::Snapper::SnapConstraint(_origin, cvec); return sm->constrainedSnap(p, dedicated_constraint, bbox_to_snap); } else { return sm->freeSnap(p, bbox_to_snap); } } SnappedPoint PureScaleConstrained::snap(::SnapManager *sm, SnapCandidatePoint const &p, Geom::Point pt_orig, Geom::OptRect const &bbox_to_snap) const { // When constrained scaling, only uniform scaling is supported. // When uniformly scaling, each point will have its own unique constraint line, // running from the scaling origin to the original untransformed point. We will // calculate that line here as a dedicated constraint Geom::Point b = pt_orig - _origin; Snapper::SnapConstraint dedicated_constraint = Inkscape::Snapper::SnapConstraint(_origin, b); return sm->constrainedSnap(p, dedicated_constraint, bbox_to_snap); } Geom::Point PureStretchConstrained::getTransformedPoint(SnapCandidatePoint const &p) const { Geom::Scale s(1, 1); if (_uniform) s[Geom::X] = s[Geom::Y] = _magnitude; else { s[_direction] = _magnitude; s[1 - _direction] = 1; } return ((p.getPoint() - _origin) * s) + _origin; } SnappedPoint PureStretchConstrained::snap(::SnapManager *sm, SnapCandidatePoint const &p, Geom::Point pt_orig, Geom::OptRect const &bbox_to_snap) const { Snapper::SnapConstraint dedicated_constraint; if (_uniform) { // When uniformly stretching, each point will have its own unique constraint line, // running from the scaling origin to the original untransformed point. We will // calculate that line here Geom::Point b = pt_orig - _origin; dedicated_constraint = Inkscape::Snapper::SnapConstraint(_origin, b); // dedicated constraint } else { Geom::Point cvec; cvec[_direction] = 1.; dedicated_constraint = Inkscape::Snapper::SnapConstraint(pt_orig, cvec); } return sm->constrainedSnap(p, dedicated_constraint, bbox_to_snap); } void PureStretchConstrained::storeTransform(SnapCandidatePoint const &original_point, SnappedPoint &snapped_point) { Geom::Point const a = snapped_point.getPoint() - _origin; // vector to snapped point Geom::Point const b = original_point.getPoint() - _origin; // vector to original point (not the transformed point!) _stretch_snapped = Geom::Scale(Geom::infinity(), Geom::infinity()); if (fabs(b[_direction]) > 1e-4) { // if STRETCHING will occur for this point _stretch_snapped[_direction] = a[_direction] / b[_direction]; _stretch_snapped[1-_direction] = _uniform ? _stretch_snapped[_direction] : 1; } else { // STRETCHING might occur for this point, but only when the stretching is uniform if (_uniform && fabs(b[1-_direction]) > 1e-4) { _stretch_snapped[1-_direction] = a[1-_direction] / b[1-_direction]; _stretch_snapped[_direction] = _stretch_snapped[1-_direction]; } } // _stretch_snapped might have one or both components at infinity! // Store the metric for this transformation as a virtual distance snapped_point.setSnapDistance(std::abs(_stretch_snapped[_direction] - _magnitude)); snapped_point.setSecondSnapDistance(Geom::infinity()); } Geom::Point PureSkewConstrained::getTransformedPoint(SnapCandidatePoint const &p) const { Geom::Point transformed; // Apply the skew factor transformed[_direction] = (p.getPoint())[_direction] + _skew * ((p.getPoint())[1 - _direction] - _origin[1 - _direction]); // While skewing, mirroring and scaling (by integer multiples) in the opposite direction is also allowed. // Apply that scale factor here transformed[1-_direction] = (p.getPoint() - _origin)[1 - _direction] * _scale + _origin[1 - _direction]; return transformed; } SnappedPoint PureSkewConstrained::snap(::SnapManager *sm, SnapCandidatePoint const &p, Geom::Point pt_orig, Geom::OptRect const &bbox_to_snap) const { // Snapping the nodes of the bounding box of a selection that is being transformed, will only work if // the transformation of the bounding box is equal to the transformation of the individual nodes. This is // NOT the case for example when rotating or skewing. The bounding box itself cannot possibly rotate or skew, // so it's corners have a different transformation. The snappers cannot handle this, therefore snapping // of bounding boxes is not allowed here. g_assert(!(p.getSourceType() & Inkscape::SNAPSOURCE_BBOX_CATEGORY)); Geom::Point constraint_vector; constraint_vector[1-_direction] = 0.0; constraint_vector[_direction] = 1.0; return sm->constrainedSnap(p, Inkscape::Snapper::SnapConstraint(constraint_vector), bbox_to_snap); } void PureSkewConstrained::storeTransform(SnapCandidatePoint const &original_point, SnappedPoint &snapped_point) { Geom::Point const b = original_point.getPoint() - _origin; // vector to original point (not the transformed point!) _skew_snapped = (snapped_point.getPoint()[_direction] - (original_point.getPoint())[_direction]) / b[1 - _direction]; // skew factor // Store the metric for this transformation as a virtual distance snapped_point.setSnapDistance(std::abs(_skew_snapped - _skew)); snapped_point.setSecondSnapDistance(Geom::infinity()); } Geom::Point PureRotateConstrained::getTransformedPoint(SnapCandidatePoint const &p) const { return (p.getPoint() - _origin) * Geom::Rotate(_angle) + _origin; } SnappedPoint PureRotateConstrained::snap(::SnapManager *sm, SnapCandidatePoint const &p, Geom::Point pt_orig, Geom::OptRect const &bbox_to_snap) const { // Snapping the nodes of the bounding box of a selection that is being transformed, will only work if // the transformation of the bounding box is equal to the transformation of the individual nodes. This is // NOT the case for example when rotating or skewing. The bounding box itself cannot possibly rotate or skew, // so it's corners have a different transformation. The snappers cannot handle this, therefore snapping // of bounding boxes is not allowed here. g_assert(!(p.getSourceType() & Inkscape::SNAPSOURCE_BBOX_CATEGORY)); // Calculate a constraint dedicated for this specific point Geom::Point b = pt_orig - _origin; Geom::Coord r = Geom::L2(b); // the radius of the circular constraint Snapper::SnapConstraint dedicated_constraint = Inkscape::Snapper::SnapConstraint(_origin, b, r); return sm->constrainedSnap(p, dedicated_constraint, bbox_to_snap); } void PureRotateConstrained::storeTransform(SnapCandidatePoint const &original_point, SnappedPoint &snapped_point) { Geom::Point const a = snapped_point.getPoint() - _origin; // vector to snapped point Geom::Point const b = (original_point.getPoint() - _origin); // vector to original point (not the transformed point!) // a is vector to snapped point; b is vector to original point; now lets calculate angle between a and b _angle_snapped = atan2(Geom::dot(Geom::rot90(b), a), Geom::dot(b, a)); if (Geom::L2(b) < 1e-9) { // points too close to the rotation center will not move. Don't try to snap these // as they will always yield a perfect snap result if they're already snapped beforehand (e.g. // when the transformation center has been snapped to a grid intersection in the selector tool) snapped_point.setSnapDistance(Geom::infinity()); // PS1: Apparently we don't have to do this for skewing, but why? // PS2: We cannot easily filter these points upstream, e.g. in the grab() method (seltrans.cpp) // because the rotation center will change when pressing shift, and grab() won't be recalled. // Filtering could be done in handleRequest() (again in seltrans.cpp), by iterating through // the snap candidates. But hey, we're iterating here anyway. } else { snapped_point.setSnapDistance(fabs(_angle_snapped - _angle)); } snapped_point.setSecondSnapDistance(Geom::infinity()); } }