1 #define __SP_ITEM_TRANSFORM_C__
3 /*
4 * Transforming single items
5 *
6 * Authors:
7 * Lauris Kaplinski <lauris@kaplinski.com>
8 * Frank Felfe <innerspace@iname.com>
9 * bulia byak <buliabyak@gmail.com>
10 *
11 * Copyright (C) 1999-2005 authors
12 *
13 * Released under GNU GPL, read the file 'COPYING' for more information
14 */
16 #include <libnr/nr-matrix-ops.h>
17 #include "libnr/nr-matrix-rotate-ops.h"
18 #include "libnr/nr-matrix-scale-ops.h"
19 #include "libnr/nr-matrix-translate-ops.h"
20 #include "sp-item.h"
22 static NR::translate inverse(NR::translate const m)
23 {
24 /* TODO: Move this to nr-matrix-fns.h or the like. */
25 return NR::translate(-m[0], -m[1]);
26 }
28 void
29 sp_item_rotate_rel(SPItem *item, NR::rotate const &rotation)
30 {
31 NR::Point center = item->getCenter();
32 NR::translate const s(item->getCenter());
33 NR::Matrix affine = NR::Matrix(inverse(s)) * NR::Matrix(rotation) * NR::Matrix(s);
35 // Rotate item.
36 sp_item_set_i2d_affine(item, sp_item_i2d_affine(item) * affine);
37 // Use each item's own transform writer, consistent with sp_selection_apply_affine()
38 sp_item_write_transform(item, SP_OBJECT_REPR(item), item->transform);
40 // Restore the center position (it's changed because the bbox center changed)
41 if (item->isCenterSet()) {
42 item->setCenter(center * affine);
43 }
44 }
46 void
47 sp_item_scale_rel (SPItem *item, NR::scale const &scale)
48 {
49 NR::translate const s(sp_item_bbox_desktop(item).midpoint()); // use getCenter?
51 sp_item_set_i2d_affine(item,
52 sp_item_i2d_affine(item) * inverse(s) * scale * s);
53 sp_item_write_transform(item, SP_OBJECT_REPR(item), item->transform);
54 }
56 void
57 sp_item_skew_rel (SPItem *item, double skewX, double skewY)
58 {
59 NR::Point center = item->getCenter();
60 NR::translate const s(item->getCenter());
62 NR::Matrix const skew(1, skewY, skewX, 1, 0, 0);
63 NR::Matrix affine = NR::Matrix(inverse(s)) * skew * NR::Matrix(s);
65 sp_item_set_i2d_affine(item, sp_item_i2d_affine(item) * affine);
66 sp_item_write_transform(item, SP_OBJECT_REPR(item), item->transform);
68 // Restore the center position (it's changed because the bbox center changed)
69 if (item->isCenterSet()) {
70 item->setCenter(center * affine);
71 }
72 }
74 void sp_item_move_rel(SPItem *item, NR::translate const &tr)
75 {
76 sp_item_set_i2d_affine(item, sp_item_i2d_affine(item) * tr);
78 sp_item_write_transform(item, SP_OBJECT_REPR(item), item->transform);
79 }
81 /*
82 ** Returns the matrix you need to apply to an object with given bbox and strokewidth to
83 scale/move it to the new box x0/y0/x1/y1. Takes into account the "scale stroke"
84 preference value passed to it. Has to solve a quadratic equation to make sure
85 the goal is met exactly and the stroke scaling is obeyed.
86 */
88 NR::Matrix
89 get_scale_transform_with_stroke (NR::Rect &bbox_param, gdouble strokewidth, bool transform_stroke, gdouble x0, gdouble y0, gdouble x1, gdouble y1)
90 {
91 NR::Rect bbox (bbox_param);
93 NR::Matrix p2o = NR::Matrix (NR::translate (-bbox.min()));
94 NR::Matrix o2n = NR::Matrix (NR::translate (x0, y0));
96 NR::Matrix scale = NR::Matrix (NR::scale (1, 1)); // scale component
97 NR::Matrix unbudge = NR::Matrix (NR::translate (0, 0)); // move component to compensate for the drift caused by stroke width change
99 gdouble w0 = bbox.extent(NR::X);
100 gdouble h0 = bbox.extent(NR::Y);
101 gdouble w1 = x1 - x0;
102 gdouble h1 = y1 - y0;
103 gdouble r0 = strokewidth;
105 if (bbox.isEmpty() || bbox.extent(NR::X) < 1e-06 || bbox.extent(NR::Y) < 1e-06 ||
106 fabs(w0 - r0) < 1e-6 || fabs(h0 - r0) < 1e-6 ||
107 (!transform_stroke && (fabs(w1 - r0) < 1e-6 || fabs(h1 - r0) < 1e-6))
108 ) {
109 NR::Matrix move = NR::Matrix(NR::translate(x0 - bbox.min()[NR::X], y0 - bbox.min()[NR::Y]));
110 return (move); // sorry, cannot scale from or to empty boxes, so only translate
111 }
113 NR::Matrix direct = NR::Matrix (NR::scale(w1 / w0, h1 / h0));
114 gdouble ratio_x = (w1 - r0) / (w0 - r0);
115 gdouble ratio_y = (h1 - r0) / (h0 - r0);
116 NR::Matrix direct_constant_r = NR::Matrix (NR::scale(ratio_x, ratio_y));
118 if (transform_stroke && r0 != 0 && r0 != NR_HUGE) { // there's stroke, and we need to scale it
119 // These coefficients are obtained from the assumption that scaling applies to the
120 // non-stroked "shape proper" and that stroke scale is scaled by the expansion of that
121 // matrix
122 gdouble A = -(w0 *h0) + r0*(w0 + h0);
123 gdouble B = -(w1 + h1) * r0*r0;
124 gdouble C = w1 * h1 * r0*r0;
125 if (B*B - 4*A*C > 0) {
126 gdouble r1 = (-B - sqrt (B*B - 4*A*C))/(2*A);
127 //gdouble r2 = (-B + sqrt (B*B - 4*A*C))/(2*A);
128 //std::cout << "r0" << r0 << " r1" << r1 << " r2" << r2 << "\n";
129 gdouble scale_x = (w1 - r1)/(w0 - r0);
130 gdouble scale_y = (h1 - r1)/(h0 - r0);
131 scale *= NR::scale(scale_x, scale_y);
132 unbudge *= NR::translate (-0.5 * (r0 * scale_x - r1), -0.5 * (r0 * scale_y - r1));
133 } else {
134 scale *= direct;
135 }
136 } else {
137 if (r0 == 0 || r0 == NR_HUGE) { // no stroke to scale
138 scale *= direct;
139 } else {// nonscaling strokewidth
140 scale *= direct_constant_r;
141 unbudge *= NR::translate (0.5 * r0 * (1 - ratio_x), 0.5 * r0 * (1 - ratio_y));
142 }
143 }
145 return (p2o * scale * unbudge * o2n);
146 }
148 /*
149 Local Variables:
150 mode:c++
151 c-file-style:"stroustrup"
152 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
153 indent-tabs-mode:nil
154 fill-column:99
155 End:
156 */
157 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :