#define __SP_ITEM_TRANSFORM_C__ /* * Transforming single items * * Authors: * Lauris Kaplinski <lauris@kaplinski.com> * Frank Felfe <innerspace@iname.com> * bulia byak <buliabyak@gmail.com> * * Copyright (C) 1999-2005 authors * * Released under GNU GPL, read the file 'COPYING' for more information */ #include <libnr/nr-matrix-ops.h> #include "libnr/nr-matrix-rotate-ops.h" #include "libnr/nr-matrix-scale-ops.h" #include "libnr/nr-matrix-translate-ops.h" #include "sp-item.h" static NR::translate inverse(NR::translate const m) { /* TODO: Move this to nr-matrix-fns.h or the like. */ return NR::translate(-m[0], -m[1]); } void sp_item_rotate_rel(SPItem *item, NR::rotate const &rotation) { NR::Point center = item->getCenter(); NR::translate const s(item->getCenter()); NR::Matrix affine = NR::Matrix(inverse(s)) * NR::Matrix(rotation) * NR::Matrix(s); // Rotate item. sp_item_set_i2d_affine(item, sp_item_i2d_affine(item) * affine); // Use each item's own transform writer, consistent with sp_selection_apply_affine() sp_item_write_transform(item, SP_OBJECT_REPR(item), item->transform); // Restore the center position (it's changed because the bbox center changed) if (item->isCenterSet()) { item->setCenter(center * affine); } } void sp_item_scale_rel (SPItem *item, NR::scale const &scale) { NR::Maybe<NR::Rect> bbox = sp_item_bbox_desktop(item); if (bbox) { NR::translate const s(bbox->midpoint()); // use getCenter? sp_item_set_i2d_affine(item, sp_item_i2d_affine(item) * inverse(s) * scale * s); sp_item_write_transform(item, SP_OBJECT_REPR(item), item->transform); } } void sp_item_skew_rel (SPItem *item, double skewX, double skewY) { NR::Point center = item->getCenter(); NR::translate const s(item->getCenter()); NR::Matrix const skew(1, skewY, skewX, 1, 0, 0); NR::Matrix affine = NR::Matrix(inverse(s)) * skew * NR::Matrix(s); sp_item_set_i2d_affine(item, sp_item_i2d_affine(item) * affine); sp_item_write_transform(item, SP_OBJECT_REPR(item), item->transform); // Restore the center position (it's changed because the bbox center changed) if (item->isCenterSet()) { item->setCenter(center * affine); } } void sp_item_move_rel(SPItem *item, NR::translate const &tr) { sp_item_set_i2d_affine(item, sp_item_i2d_affine(item) * tr); sp_item_write_transform(item, SP_OBJECT_REPR(item), item->transform); } /* ** Returns the matrix you need to apply to an object with given bbox and strokewidth to scale/move it to the new box x0/y0/x1/y1. Takes into account the "scale stroke" preference value passed to it. Has to solve a quadratic equation to make sure the goal is met exactly and the stroke scaling is obeyed. */ NR::Matrix get_scale_transform_with_stroke (NR::Rect &bbox_param, gdouble strokewidth, bool transform_stroke, gdouble x0, gdouble y0, gdouble x1, gdouble y1) { NR::Rect bbox (bbox_param); NR::Matrix p2o = NR::Matrix (NR::translate (-bbox.min())); NR::Matrix o2n = NR::Matrix (NR::translate (x0, y0)); NR::Matrix scale = NR::Matrix (NR::scale (1, 1)); // scale component NR::Matrix unbudge = NR::Matrix (NR::translate (0, 0)); // move component to compensate for the drift caused by stroke width change gdouble w0 = bbox.extent(NR::X); // will return a value >= 0, as required further down the road gdouble h0 = bbox.extent(NR::Y); gdouble w1 = x1 - x0; // can have any sign gdouble h1 = y1 - y0; gdouble r0 = strokewidth; if (bbox.isEmpty()) { NR::Matrix move = NR::Matrix(NR::translate(x0 - bbox.min()[NR::X], y0 - bbox.min()[NR::Y])); return (move); // cannot scale from empty boxes at all, so only translate } NR::Matrix direct = NR::Matrix (NR::scale(w1 / w0, h1 / h0)); if (fabs(w0 - r0) < 1e-6 || fabs(h0 - r0) < 1e-6 || (!transform_stroke && (fabs(w1 - r0) < 1e-6 || fabs(h1 - r0) < 1e-6))) { return (p2o * direct * o2n); // can't solve the equation: one of the dimensions is equal to stroke width, so return the straightforward scaler } int flip_x = (w1 > 0) ? 1 : -1; int flip_y = (h1 > 0) ? 1 : -1; // w1 and h1 will be negative when mirroring, but if so then e.g. w1-r0 won't make sense // Therefore we will use the absolute values from this point on w1 = fabs(w1); h1 = fabs(h1); r0 = fabs(r0); // w0 and h0 will always be positive due to the definition extent() gdouble ratio_x = (w1 - r0) / (w0 - r0); gdouble ratio_y = (h1 - r0) / (h0 - r0); NR::Matrix direct_constant_r = NR::Matrix (NR::scale(flip_x * ratio_x, flip_y * ratio_y)); if (transform_stroke && r0 != 0 && r0 != NR_HUGE) { // there's stroke, and we need to scale it // These coefficients are obtained from the assumption that scaling applies to the // non-stroked "shape proper" and that stroke scale is scaled by the expansion of that // matrix. We're trying to solve this equation: // r1 = r0 * sqrt (((w1-r0)/(w0-r0))*((h1-r1)/(h0-r0))) // The operant of the sqrt() must be positive, which is ensured by the fabs() a few lines above gdouble A = -w0*h0 + r0*(w0 + h0); gdouble B = -(w1 + h1) * r0*r0; gdouble C = w1 * h1 * r0*r0; if (B*B - 4*A*C > 0) { gdouble r1 = fabs((-B - sqrt(B*B - 4*A*C))/(2*A)); //gdouble r2 = (-B + sqrt (B*B - 4*A*C))/(2*A); //std::cout << "r0" << r0 << " r1" << r1 << " r2" << r2 << "\n"; // // If w1 < 0 then the scale will be wrong if we just do // gdouble scale_x = (w1 - r1)/(w0 - r0); // Here we also need the absolute values of w0, w1, h0, h1, and r1 gdouble scale_x = (w1 - r1)/(w0 - r0); gdouble scale_y = (h1 - r1)/(h0 - r0); scale *= NR::scale(flip_x * scale_x, flip_y * scale_y); unbudge *= NR::translate (-flip_x * 0.5 * (r0 * scale_x - r1), -flip_y * 0.5 * (r0 * scale_y - r1)); } else { scale *= direct; } } else { if (r0 == 0 || r0 == NR_HUGE) { // no stroke to scale scale *= direct; } else {// nonscaling strokewidth scale *= direct_constant_r; unbudge *= NR::translate (flip_x * 0.5 * r0 * (1 - ratio_x), flip_y * 0.5 * r0 * (1 - ratio_y)); } } return (p2o * scale * unbudge * o2n); } /* 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:encoding=utf-8:textwidth=99 :