#define __SP_ITEM_TRANSFORM_C__ /* * Transforming single items * * Authors: * Lauris Kaplinski * Frank Felfe * bulia byak * * Copyright (C) 1999-2005 authors * * Released under GNU GPL, read the file 'COPYING' for more information */ #include #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 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); gdouble h0 = bbox.extent(NR::Y); gdouble w1 = x1 - x0; 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 } // Flip when the width or height changes sign int flip_x = ((w1 < 0) == (w0 < 0)) ? 1 : -1; int flip_y = ((h1 < 0) == (h0 < 0)) ? 1 : -1; // w1 and h1 can be negative, but if so then e.g. w1-r0 won't make sense // therefore we should use fabs() all over the place gdouble ratio_x = (fabs(w1) - fabs(r0)) / (fabs(w0) - fabs(r0)); gdouble ratio_y = (fabs(h1) - fabs(r0)) / (fabs(h0) - fabs(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 // In fact, we're trying to solve this equation: // r1 = r0 * sqrt (((w1-r0)/(w0-r0))*((h1-r1)/(h0-r0))) // To make sense of this, the operant of the sqrt() should // be positive, hence all the fabs() below // (w1 and h1 will be negative when mirroring, w0 and h0 will probably never be negative) gdouble A = -fabs(w0*h0) + fabs(r0)*(fabs(w0) + fabs(h0)); gdouble B = -(fabs(w1) + fabs(h1)) * r0*r0; gdouble C = fabs(w1 * h1 * r0*r0); if (B*B - 4*A*C > 0) { gdouble r1 = (-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"; // // I think r1 will always be positive if r0 is (mathematical proof?) // but if w1 becomes negative, then the scale will be wrong if we just do // gdouble scale_x = (w1 - r1)/(w0 - r0); // gdouble scale_y = (h1 - r1)/(h0 - r0); // So let's do it like this: Calculate the absolute scale gdouble scale_x = (fabs(w1) - fabs(r1))/(fabs(w0) - fabs(r0)); gdouble scale_y = (fabs(h1) - fabs(r1))/(fabs(h0) - fabs(r0)); scale *= NR::scale(flip_x*scale_x, flip_y*scale_y); unbudge *= NR::translate (-flip_x * 0.5 * (fabs(r0) * scale_x - fabs(r1)), -flip_y * 0.5 * (fabs(r0) * scale_y - fabs(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 * fabs(r0) * (1 - ratio_x), flip_y * 0.5 * fabs(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 :