src/display/inkscape-cairo.cpp

   1 /*
   2  * Helper functions to use cairo with inkscape
   3  *
   4  * Copyright (C) 2007 bulia byak
   5  * Copyright (C) 2008 Johan Engelen
   6  *
   7  * Released under GNU GPL
   8  *
   9  */
  10
  11 #include <cairo.h>
  12
  13 #ifdef HAVE_CONFIG_H
  14 # include <config.h>
  15 #endif
  16 #include <libnr/n-art-bpath.h>
  17 #include <libnr/nr-matrix-ops.h>
  18 #include <libnr/nr-matrix-fns.h>
  19 #include <libnr/nr-pixblock.h>
  20 #include <libnr/nr-convert2geom.h>
  21 #include "../style.h"
  22 #include "nr-arena.h"
  23 #include "sp-canvas.h"
  24 #include <2geom/pathvector.h>
  25 #include <2geom/matrix.h>
  26 #include <2geom/point.h>
  27 #include <2geom/path.h>
  28 #include <2geom/transforms.h>
  29 #include <2geom/sbasis-to-bezier.h>
  30
  31 /** Creates a cairo context to render to the given pixblock on the given area */
  32 cairo_t *
  33 nr_create_cairo_context_for_data (NRRectL *area, NRRectL *buf_area, unsigned char *px, unsigned int rowstride)
  34 {
  35     if (!nr_rect_l_test_intersect (buf_area, area))
  36         return NULL;
  37
  38     NRRectL clip;
  39     nr_rect_l_intersect (&clip, buf_area, area);
  40     unsigned char *dpx = px + (clip.y0 - buf_area->y0) * rowstride + 4 * (clip.x0 - buf_area->x0);
  41     int width = area->x1 - area->x0;
  42     int height = area->y1 - area->y0;
  43     // even though cairo cannot draw in nonpremul mode, select ARGB32 for R8G8B8A8N as the closest; later eliminate R8G8B8A8N everywhere
  44     cairo_surface_t* cst = cairo_image_surface_create_for_data
  45         (dpx,
  46          CAIRO_FORMAT_ARGB32,
  47          width,
  48          height,
  49          rowstride);
  50     cairo_t *ct = cairo_create (cst);
  51
  52     return ct;
  53 }
  54
  55 /** Creates a cairo context to render to the given SPCanvasBuf on the given area */
  56 cairo_t *
  57 nr_create_cairo_context_canvasbuf (NRRectL *area, SPCanvasBuf *b)
  58 {
  59     return nr_create_cairo_context_for_data (&(b->rect), &(b->rect), b->buf, b->buf_rowstride);
  60 }
  61
  62
  63 /** Creates a cairo context to render to the given NRPixBlock on the given area */
  64 cairo_t *
  65 nr_create_cairo_context (NRRectL *area, NRPixBlock *pb)
  66 {
  67     return nr_create_cairo_context_for_data (area, &(pb->area), NR_PIXBLOCK_PX (pb), pb->rs);
  68 }
  69
  70 /** Feeds path-creating calls to the cairo context translating them from the SPCurve, with the given transform and shift */
  71 void
  72 feed_curve_to_cairo (cairo_t *ct, NArtBpath const *bpath, NR::Matrix trans, NR::Maybe<NR::Rect> area, bool optimize_stroke, double stroke_width)
  73 {
  74     NR::Point next(0,0), last(0,0);
  75     if (!area || area->isEmpty())
  76         return;
  77     NR::Point shift = area->min();
  78     NR::Rect view = *area;
  79     view.growBy (stroke_width);
  80     NR::Rect swept;
  81     bool  closed = false;
  82     NR::Point startpath(0,0);
  83     for (int i = 0; bpath[i].code != NR_END; i++) {
  84         switch (bpath[i].code) {
  85             case NR_MOVETO_OPEN:
  86             case NR_MOVETO:
  87                 if (closed) {
  88                     // we cannot use close_path because some of the curves/lines may have been optimized out
  89                     cairo_line_to(ct, startpath[NR::X], startpath[NR::Y]);
  90                 }
  91                 next[NR::X] = bpath[i].x3;
  92                 next[NR::Y] = bpath[i].y3;
  93                 next *= trans;
  94                 last = next;
  95                 next -= shift;
  96                 if (bpath[i].code == NR_MOVETO) {
  97                     // remember the start point of the subpath, for closing it later
  98                     closed = true;
  99                     startpath = next;
 100                 } else {
 101                     closed = false;
 102                 }
 103                 cairo_move_to(ct, next[NR::X], next[NR::Y]);
 104                 break;
 105
 106             case NR_LINETO:
 107                 next[NR::X] = bpath[i].x3;
 108                 next[NR::Y] = bpath[i].y3;
 109                 next *= trans;
 110                 if (optimize_stroke) {
 111                     swept = NR::Rect(last, next);
 112                     //std::cout << "swept: " << swept;
 113                     //std::cout << "view: " << view;
 114                     //std::cout << "intersects? " << (swept.intersects(view)? "YES" : "NO") << "\n";
 115                 }
 116                 last = next;
 117                 next -= shift;
 118                 if (!optimize_stroke || swept.intersects(view))
 119                     cairo_line_to(ct, next[NR::X], next[NR::Y]);
 120                 else
 121                     cairo_move_to(ct, next[NR::X], next[NR::Y]);
 122                 break;
 123
 124             case NR_CURVETO: {
 125                 NR::Point  tm1, tm2, tm3;
 126                 tm1[0]=bpath[i].x1;
 127                 tm1[1]=bpath[i].y1;
 128                 tm2[0]=bpath[i].x2;
 129                 tm2[1]=bpath[i].y2;
 130                 tm3[0]=bpath[i].x3;
 131                 tm3[1]=bpath[i].y3;
 132                 tm1 *= trans;
 133                 tm2 *= trans;
 134                 tm3 *= trans;
 135                 if (optimize_stroke) {
 136                     swept = NR::Rect(last, last);
 137                     swept.expandTo(tm1);
 138                     swept.expandTo(tm2);
 139                     swept.expandTo(tm3);
 140                 }
 141                 last = tm3;
 142                 tm1 -= shift;
 143                 tm2 -= shift;
 144                 tm3 -= shift;
 145                 if (!optimize_stroke || swept.intersects(view))
 146                     cairo_curve_to (ct, tm1[NR::X], tm1[NR::Y], tm2[NR::X], tm2[NR::Y], tm3[NR::X], tm3[NR::Y]);
 147                 else
 148                     cairo_move_to(ct, tm3[NR::X], tm3[NR::Y]);
 149                 break;
 150             }
 151
 152             default:
 153                 break;
 154         }
 155     }
 156 }
 157
 158
 159 static void
 160 feed_curve_to_cairo(cairo_t *cr, Geom::Curve const &c, Geom::Rect view, bool optimize_stroke)
 161 {
 162     if(Geom::LineSegment const* line_segment = dynamic_cast<Geom::LineSegment const*>(&c)) {
 163         if (!optimize_stroke) {
 164             cairo_line_to(cr, (*line_segment)[1][0], (*line_segment)[1][1]);
 165         } else {
 166             Geom::Rect swept((*line_segment)[0], (*line_segment)[1]);
 167             if (swept.intersects(view)) {
 168                 cairo_line_to(cr, (*line_segment)[1][0], (*line_segment)[1][1]);
 169             } else {
 170                 cairo_move_to(cr, (*line_segment)[1][0], (*line_segment)[1][1]);
 171             }
 172         }
 173     }
 174     else if(Geom::QuadraticBezier const *quadratic_bezier = dynamic_cast<Geom::QuadraticBezier const*>(&c)) {
 175         std::vector<Geom::Point> points = quadratic_bezier->points();
 176         Geom::Point b1 = points[0] + (2./3) * (points[1] - points[0]);
 177         Geom::Point b2 = b1 + (1./3) * (points[2] - points[0]);
 178         if (!optimize_stroke) {
 179             cairo_curve_to(cr, b1[0], b1[1], b2[0], b2[1], points[2][0], points[2][1]);
 180         } else {
 181             Geom::Rect swept(points[0], points[2]);
 182             swept.expandTo(points[1]);
 183             if (swept.intersects(view)) {
 184                 cairo_curve_to(cr, b1[0], b1[1], b2[0], b2[1], points[2][0], points[2][1]);
 185             } else {
 186                 cairo_move_to(cr, points[2][0], points[2][1]);
 187             }
 188         }
 189     }
 190     else if(Geom::CubicBezier const *cubic_bezier = dynamic_cast<Geom::CubicBezier const*>(&c)) {
 191         std::vector<Geom::Point> points = cubic_bezier->points();
 192         if (!optimize_stroke) {
 193             cairo_curve_to(cr, points[1][0], points[1][1], points[2][0], points[2][1], points[3][0], points[3][1]);
 194         } else {
 195             Geom::Rect swept(points[0], points[3]);
 196             swept.expandTo(points[1]);
 197             swept.expandTo(points[2]);
 198             if (swept.intersects(view)) {
 199                 cairo_curve_to(cr, points[1][0], points[1][1], points[2][0], points[2][1], points[3][0], points[3][1]);
 200             } else {
 201                 cairo_move_to(cr, points[3][0], points[3][1]);
 202             }
 203         }
 204     }
 205 //    else if(Geom::EllipticalArc const *svg_elliptical_arc = dynamic_cast<Geom::EllipticalArc *>(c)) {
 206 //        //TODO: get at the innards and spit them out to cairo
 207 //    }
 208     else {
 209         //this case handles sbasis as well as all other curve types
 210         Geom::Path sbasis_path = path_from_sbasis(c.toSBasis(), 0.1);
 211
 212         //recurse to convert the new path resulting from the sbasis to svgd
 213         for(Geom::Path::iterator iter = sbasis_path.begin(); iter != sbasis_path.end(); ++iter) {
 214             feed_curve_to_cairo(cr, *iter, view, optimize_stroke);
 215         }
 216     }
 217 }
 218
 219
 220 /** Feeds path-creating calls to the cairo context translating them from the SPCurve, with the given transform and shift */
 221 void
 222 feed_path_to_cairo (cairo_t *ct, Geom::Path const &path, Geom::Matrix trans, NR::Maybe<NR::Rect> area, bool optimize_stroke, double stroke_width)
 223 {
 224     if (!area || area->isEmpty())
 225         return;
 226     if (path.empty())
 227         return;
 228
 229     // Transform all coordinates to coords within "area"
 230     Geom::Point shift = to_2geom(area->min());
 231     NR::Rect view = *area;
 232     view.growBy (stroke_width);
 233     view = view * from_2geom(Geom::Translate(-shift));
 234     Geom::Path const path_trans = path * (trans * Geom::Translate(-shift));
 235
 236     cairo_move_to(ct, path_trans.initialPoint()[0], path_trans.initialPoint()[1] );
 237
 238     for(Geom::Path::const_iterator cit = path_trans.begin(); cit != path_trans.end_open(); ++cit) {
 239         feed_curve_to_cairo(ct, *cit, to_2geom(view), optimize_stroke);
 240     }
 241
 242     if (path_trans.closed()) {
 243         cairo_line_to(ct, path_trans.initialPoint()[0], path_trans.initialPoint()[1] );
 244     }
 245 }
 246
 247 /** Feeds path-creating calls to the cairo context translating them from the SPCurve, with the given transform and shift */
 248 void
 249 feed_pathvector_to_cairo (cairo_t *ct, Geom::PathVector const &pathv, Geom::Matrix trans, NR::Maybe<NR::Rect> area, bool optimize_stroke, double stroke_width)
 250 {
 251     if (!area || area->isEmpty())
 252         return;
 253     if (pathv.empty())
 254         return;
 255
 256     for(Geom::PathVector::const_iterator it = pathv.begin(); it != pathv.end(); ++it) {
 257         feed_path_to_cairo(ct, *it, trans, area, optimize_stroke, stroke_width);
 258     }
 259 }
 260
 261 /*
 262   Local Variables:
 263   mode:c++
 264   c-file-style:"stroustrup"
 265   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 266   indent-tabs-mode:nil
 267   fill-column:99
 268   End:
 269 */
 270 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :