src/pencil-context.cpp

   1 /** \file
   2  * Pencil event context implementation.
   3  */
   4
   5 /*
   6  * Authors:
   7  *   Lauris Kaplinski <lauris@kaplinski.com>
   8  *   bulia byak <buliabyak@users.sf.net>
   9  *
  10  * Copyright (C) 2000 Lauris Kaplinski
  11  * Copyright (C) 2000-2001 Ximian, Inc.
  12  * Copyright (C) 2002 Lauris Kaplinski
  13  * Copyright (C) 2004 Monash University
  14  *
  15  * Released under GNU GPL, read the file 'COPYING' for more information
  16  */
  17
  18 #include <gdk/gdkkeysyms.h>
  19
  20 #include "pencil-context.h"
  21 #include "desktop.h"
  22 #include "desktop-handles.h"
  23 #include "selection.h"
  24 #include "selection-chemistry.h"
  25 #include "draw-anchor.h"
  26 #include "message-stack.h"
  27 #include "message-context.h"
  28 #include "modifier-fns.h"
  29 #include "sp-path.h"
  30 #include "prefs-utils.h"
  31 #include "snap.h"
  32 #include "pixmaps/cursor-pencil.xpm"
  33 #include "display/bezier-utils.h"
  34 #include "display/canvas-bpath.h"
  35 #include <glibmm/i18n.h>
  36 #include "libnr/in-svg-plane.h"
  37 #include "libnr/n-art-bpath.h"
  38 #include "context-fns.h"
  39 #include "sp-namedview.h"
  40 #include "xml/repr.h"
  41 #include "document.h"
  42 #include "desktop-style.h"
  43 #include "macros.h"
  44 #include "display/curve.h"
  45
  46 static void sp_pencil_context_class_init(SPPencilContextClass *klass);
  47 static void sp_pencil_context_init(SPPencilContext *pc);
  48 static void sp_pencil_context_setup(SPEventContext *ec);
  49 static void sp_pencil_context_dispose(GObject *object);
  50
  51 static gint sp_pencil_context_root_handler(SPEventContext *event_context, GdkEvent *event);
  52 static gint pencil_handle_button_press(SPPencilContext *const pc, GdkEventButton const &bevent);
  53 static gint pencil_handle_motion_notify(SPPencilContext *const pc, GdkEventMotion const &mevent);
  54 static gint pencil_handle_button_release(SPPencilContext *const pc, GdkEventButton const &revent);
  55 static gint pencil_handle_key_press(SPPencilContext *const pc, guint const keyval, guint const state);
  56
  57 static void spdc_set_startpoint(SPPencilContext *pc, NR::Point const p);
  58 static void spdc_set_endpoint(SPPencilContext *pc, NR::Point const p);
  59 static void spdc_finish_endpoint(SPPencilContext *pc);
  60 static void spdc_add_freehand_point(SPPencilContext *pc, NR::Point p, guint state);
  61 static void fit_and_split(SPPencilContext *pc);
  62
  63
  64 static SPDrawContextClass *pencil_parent_class;
  65
  66 /**
  67  * Register SPPencilContext class with Gdk and return its type number.
  68  */
  69 GType
  70 sp_pencil_context_get_type()
  71 {
  72     static GType type = 0;
  73     if (!type) {
  74         GTypeInfo info = {
  75             sizeof(SPPencilContextClass),
  76             NULL, NULL,
  77             (GClassInitFunc) sp_pencil_context_class_init,
  78             NULL, NULL,
  79             sizeof(SPPencilContext),
  80             4,
  81             (GInstanceInitFunc) sp_pencil_context_init,
  82             NULL,   /* value_table */
  83         };
  84         type = g_type_register_static(SP_TYPE_DRAW_CONTEXT, "SPPencilContext", &info, (GTypeFlags)0);
  85     }
  86     return type;
  87 }
  88
  89 /**
  90  * Initialize SPPencilContext vtable.
  91  */
  92 static void
  93 sp_pencil_context_class_init(SPPencilContextClass *klass)
  94 {
  95     GObjectClass *object_class;
  96     SPEventContextClass *event_context_class;
  97
  98     object_class = (GObjectClass *) klass;
  99     event_context_class = (SPEventContextClass *) klass;
 100
 101     pencil_parent_class = (SPDrawContextClass*)g_type_class_peek_parent(klass);
 102
 103     object_class->dispose = sp_pencil_context_dispose;
 104
 105     event_context_class->setup = sp_pencil_context_setup;
 106     event_context_class->root_handler = sp_pencil_context_root_handler;
 107 }
 108
 109 /**
 110  * Callback to initialize SPPencilContext object.
 111  */
 112 static void
 113 sp_pencil_context_init(SPPencilContext *pc)
 114 {
 115     SPEventContext *event_context = SP_EVENT_CONTEXT(pc);
 116
 117     event_context->cursor_shape = cursor_pencil_xpm;
 118     event_context->hot_x = 4;
 119     event_context->hot_y = 4;
 120
 121     pc->npoints = 0;
 122     pc->state = SP_PENCIL_CONTEXT_IDLE;
 123     pc->req_tangent = NR::Point(0, 0);
 124 }
 125
 126 /**
 127  * Callback to setup SPPencilContext object.
 128  */
 129 static void
 130 sp_pencil_context_setup(SPEventContext *ec)
 131 {
 132     if (prefs_get_int_attribute("tools.freehand.pencil", "selcue", 0) != 0) {
 133         ec->enableSelectionCue();
 134     }
 135
 136     if (((SPEventContextClass *) pencil_parent_class)->setup) {
 137         ((SPEventContextClass *) pencil_parent_class)->setup(ec);
 138     }
 139
 140     SPPencilContext *const pc = SP_PENCIL_CONTEXT(ec);
 141     pc->is_drawing = false;
 142
 143     pc->anchor_statusbar = false;
 144 }
 145
 146 static void
 147 sp_pencil_context_dispose(GObject *object)
 148 {
 149     G_OBJECT_CLASS(pencil_parent_class)->dispose(object);
 150 }
 151
 152 /** Snaps new node relative to the previous node. */
 153 static void
 154 spdc_endpoint_snap(SPPencilContext const *pc, NR::Point &p, guint const state)
 155 {
 156     spdc_endpoint_snap_rotation(pc, p, pc->p[0], state);
 157     spdc_endpoint_snap_free(pc, p, state);
 158 }
 159
 160 /**
 161  * Callback for handling all pencil context events.
 162  */
 163 gint
 164 sp_pencil_context_root_handler(SPEventContext *const ec, GdkEvent *event)
 165 {
 166     SPPencilContext *const pc = SP_PENCIL_CONTEXT(ec);
 167
 168     gint ret = FALSE;
 169
 170     switch (event->type) {
 171         case GDK_BUTTON_PRESS:
 172             ret = pencil_handle_button_press(pc, event->button);
 173             break;
 174
 175         case GDK_MOTION_NOTIFY:
 176             ret = pencil_handle_motion_notify(pc, event->motion);
 177             break;
 178
 179         case GDK_BUTTON_RELEASE:
 180             ret = pencil_handle_button_release(pc, event->button);
 181             break;
 182
 183         case GDK_KEY_PRESS:
 184             ret = pencil_handle_key_press(pc, get_group0_keyval (&event->key), event->key.state);
 185             break;
 186
 187         default:
 188             break;
 189     }
 190
 191     if (!ret) {
 192         gint (*const parent_root_handler)(SPEventContext *, GdkEvent *)
 193             = ((SPEventContextClass *) pencil_parent_class)->root_handler;
 194         if (parent_root_handler) {
 195             ret = parent_root_handler(ec, event);
 196         }
 197     }
 198
 199     return ret;
 200 }
 201
 202 static gint
 203 pencil_handle_button_press(SPPencilContext *const pc, GdkEventButton const &bevent)
 204 {
 205     gint ret = FALSE;
 206     SPEventContext *event_context = SP_EVENT_CONTEXT(pc);
 207     if ( bevent.button == 1  && !event_context->space_panning) {
 208
 209         SPDrawContext *dc = SP_DRAW_CONTEXT (pc);
 210         SPDesktop *desktop = SP_EVENT_CONTEXT_DESKTOP(dc);
 211         Inkscape::Selection *selection = sp_desktop_selection(desktop);
 212
 213         if (Inkscape::have_viable_layer(desktop, dc->_message_context) == false) {
 214             return TRUE;
 215         }
 216
 217         NR::Point const button_w(bevent.x, bevent.y);
 218
 219         /* Find desktop coordinates */
 220         NR::Point p = pc->desktop->w2d(button_w);
 221
 222         /* Test whether we hit any anchor. */
 223         SPDrawAnchor *anchor = spdc_test_inside(pc, button_w);
 224
 225         switch (pc->state) {
 226             case SP_PENCIL_CONTEXT_ADDLINE:
 227                 /* Current segment will be finished with release */
 228                 ret = TRUE;
 229                 break;
 230             default:
 231                 /* Set first point of sequence */
 232                 if (bevent.state & GDK_CONTROL_MASK) {
 233                     freehand_create_single_dot(event_context, p, "tools.freehand.pencil", bevent.state);
 234                     ret = true;
 235                     break;
 236                 }
 237                 if (anchor) {
 238                     p = anchor->dp;
 239                     desktop->messageStack()->flash(Inkscape::NORMAL_MESSAGE, _("Continuing selected path"));
 240                 } else {
 241
 242                     if (!(bevent.state & GDK_SHIFT_MASK)) {
 243
 244                         // This is the first click of a new curve; deselect item so that
 245                         // this curve is not combined with it (unless it is drawn from its
 246                         // anchor, which is handled by the sibling branch above)
 247                         selection->clear();
 248                         desktop->messageStack()->flash(Inkscape::NORMAL_MESSAGE, _("Creating new path"));
 249                         SnapManager &m = desktop->namedview->snap_manager;
 250                         m.setup(desktop);
 251                         m.freeSnap(Inkscape::Snapper::SNAPPOINT_NODE, p);
 252                     } else if (selection->singleItem() && SP_IS_PATH(selection->singleItem())) {
 253                         desktop->messageStack()->flash(Inkscape::NORMAL_MESSAGE, _("Appending to selected path"));
 254                     }
 255                 }
 256                 pc->sa = anchor;
 257                 spdc_set_startpoint(pc, p);
 258                 ret = TRUE;
 259                 break;
 260         }
 261
 262         pc->is_drawing = true;
 263     }
 264     return ret;
 265 }
 266
 267 static gint
 268 pencil_handle_motion_notify(SPPencilContext *const pc, GdkEventMotion const &mevent)
 269 {
 270     if ((mevent.state & GDK_CONTROL_MASK) && (mevent.state & GDK_BUTTON1_MASK)) {
 271         // mouse was accidentally moved during Ctrl+click;
 272         // ignore the motion and create a single point
 273         pc->is_drawing = false;
 274         return TRUE;
 275     }
 276     gint ret = FALSE;
 277     SPDesktop *const dt = pc->desktop;
 278
 279     SPEventContext *event_context = SP_EVENT_CONTEXT(pc);
 280     if (event_context->space_panning || mevent.state & GDK_BUTTON2_MASK || mevent.state & GDK_BUTTON3_MASK) {
 281         // allow scrolling
 282         return FALSE;
 283     }
 284
 285     if ( ( mevent.state & GDK_BUTTON1_MASK ) && !pc->grab && pc->is_drawing) {
 286         /* Grab mouse, so release will not pass unnoticed */
 287         pc->grab = SP_CANVAS_ITEM(dt->acetate);
 288         sp_canvas_item_grab(pc->grab, ( GDK_KEY_PRESS_MASK | GDK_BUTTON_PRESS_MASK   |
 289                                         GDK_BUTTON_RELEASE_MASK |
 290                                         GDK_POINTER_MOTION_MASK  ),
 291                             NULL, mevent.time);
 292     }
 293
 294     /* Find desktop coordinates */
 295     NR::Point p = dt->w2d(NR::Point(mevent.x, mevent.y));
 296
 297     /* Test whether we hit any anchor. */
 298     SPDrawAnchor *anchor = spdc_test_inside(pc, NR::Point(mevent.x, mevent.y));
 299
 300     switch (pc->state) {
 301         case SP_PENCIL_CONTEXT_ADDLINE:
 302             /* Set red endpoint */
 303             if (anchor) {
 304                 p = anchor->dp;
 305             } else {
 306                 spdc_endpoint_snap(pc, p, mevent.state);
 307             }
 308             spdc_set_endpoint(pc, p);
 309             ret = TRUE;
 310             break;
 311         default:
 312             /* We may be idle or already freehand */
 313             if ( mevent.state & GDK_BUTTON1_MASK && pc->is_drawing ) {
 314                 pc->state = SP_PENCIL_CONTEXT_FREEHAND;
 315                 if ( !pc->sa && !pc->green_anchor ) {
 316                     /* Create green anchor */
 317                     pc->green_anchor = sp_draw_anchor_new(pc, pc->green_curve, TRUE, pc->p[0]);
 318                 }
 319                 /** \todo
 320                  * fixme: I am not sure whether we want to snap to anchors
 321                  * in middle of freehand (Lauris)
 322                  */
 323                 if (anchor) {
 324                     p = anchor->dp;
 325                 } else if ((mevent.state & GDK_SHIFT_MASK) == 0) {
 326                     SnapManager &m = dt->namedview->snap_manager;
 327                     m.setup(dt, NULL);
 328                     m.freeSnap(Inkscape::Snapper::SNAPPOINT_NODE, p);
 329                 }
 330                 if ( pc->npoints != 0 ) { // buttonpress may have happened before we entered draw context!
 331                     spdc_add_freehand_point(pc, p, mevent.state);
 332                     ret = TRUE;
 333                 }
 334
 335                 if (anchor && !pc->anchor_statusbar) {
 336                     pc->_message_context->set(Inkscape::NORMAL_MESSAGE, _("<b>Release</b> here to close and finish the path."));
 337                     pc->anchor_statusbar = true;
 338                 } else if (!anchor && pc->anchor_statusbar) {
 339                     pc->_message_context->clear();
 340                     pc->anchor_statusbar = false;
 341                 } else if (!anchor) {
 342                     pc->_message_context->set(Inkscape::NORMAL_MESSAGE, _("Drawing a freehand path"));
 343                 }
 344
 345             } else {
 346                 if (anchor && !pc->anchor_statusbar) {
 347                     pc->_message_context->set(Inkscape::NORMAL_MESSAGE, _("<b>Drag</b> to continue the path from this point."));
 348                     pc->anchor_statusbar = true;
 349                 } else if (!anchor && pc->anchor_statusbar) {
 350                     pc->_message_context->clear();
 351                     pc->anchor_statusbar = false;
 352                 }
 353             }
 354             break;
 355     }
 356     return ret;
 357 }
 358
 359 static gint
 360 pencil_handle_button_release(SPPencilContext *const pc, GdkEventButton const &revent)
 361 {
 362     gint ret = FALSE;
 363
 364     SPEventContext *event_context = SP_EVENT_CONTEXT(pc);
 365     if ( revent.button == 1 && pc->is_drawing && !event_context->space_panning) {
 366         SPDesktop *const dt = pc->desktop;
 367
 368         pc->is_drawing = false;
 369
 370         /* Find desktop coordinates */
 371         NR::Point p = dt->w2d(NR::Point(revent.x, revent.y));
 372
 373         /* Test whether we hit any anchor. */
 374         SPDrawAnchor *anchor = spdc_test_inside(pc, NR::Point(revent.x,
 375                                                               revent.y));
 376
 377         switch (pc->state) {
 378             case SP_PENCIL_CONTEXT_IDLE:
 379                 /* Releasing button in idle mode means single click */
 380                 /* We have already set up start point/anchor in button_press */
 381                 if (!(revent.state & GDK_CONTROL_MASK)) {
 382                     // Ctrl+click creates a single point so only set context in ADDLINE mode when Ctrl isn't pressed
 383                     pc->state = SP_PENCIL_CONTEXT_ADDLINE;
 384                 }
 385                 ret = TRUE;
 386                 break;
 387             case SP_PENCIL_CONTEXT_ADDLINE:
 388                 /* Finish segment now */
 389                 if (anchor) {
 390                     p = anchor->dp;
 391                 } else {
 392                     spdc_endpoint_snap(pc, p, revent.state);
 393                 }
 394                 pc->ea = anchor;
 395                 spdc_set_endpoint(pc, p);
 396                 spdc_finish_endpoint(pc);
 397                 pc->state = SP_PENCIL_CONTEXT_IDLE;
 398                 ret = TRUE;
 399                 break;
 400             case SP_PENCIL_CONTEXT_FREEHAND:
 401                 /* Finish segment now */
 402                 /// \todo fixme: Clean up what follows (Lauris)
 403                 if (anchor) {
 404                     p = anchor->dp;
 405                 }
 406                 pc->ea = anchor;
 407                 /* Write curves to object */
 408
 409                 dt->messageStack()->flash(Inkscape::NORMAL_MESSAGE, _("Finishing freehand"));
 410
 411                 spdc_concat_colors_and_flush(pc, FALSE);
 412                 pc->sa = NULL;
 413                 pc->ea = NULL;
 414                 if (pc->green_anchor) {
 415                     pc->green_anchor = sp_draw_anchor_destroy(pc->green_anchor);
 416                 }
 417                 pc->state = SP_PENCIL_CONTEXT_IDLE;
 418                 ret = TRUE;
 419                 break;
 420             default:
 421                 break;
 422         }
 423
 424         if (pc->grab) {
 425             /* Release grab now */
 426             sp_canvas_item_ungrab(pc->grab, revent.time);
 427             pc->grab = NULL;
 428         }
 429
 430         ret = TRUE;
 431     }
 432     return ret;
 433 }
 434
 435 static void
 436 pencil_cancel (SPPencilContext *const pc)
 437 {
 438     if (pc->grab) {
 439         /* Release grab now */
 440         sp_canvas_item_ungrab(pc->grab, 0);
 441         pc->grab = NULL;
 442     }
 443
 444     pc->is_drawing = false;
 445
 446     pc->state = SP_PENCIL_CONTEXT_IDLE;
 447
 448     pc->red_curve->reset();
 449     sp_canvas_bpath_set_bpath(SP_CANVAS_BPATH(pc->red_bpath), NULL);
 450     while (pc->green_bpaths) {
 451         gtk_object_destroy(GTK_OBJECT(pc->green_bpaths->data));
 452         pc->green_bpaths = g_slist_remove(pc->green_bpaths, pc->green_bpaths->data);
 453     }
 454     pc->green_curve->reset();
 455     if (pc->green_anchor) {
 456         pc->green_anchor = sp_draw_anchor_destroy(pc->green_anchor);
 457     }
 458
 459     pc->_message_context->clear();
 460     pc->_message_context->flash(Inkscape::NORMAL_MESSAGE, _("Drawing cancelled"));
 461
 462     sp_canvas_end_forced_full_redraws(pc->desktop->canvas);
 463 }
 464
 465
 466 static gint
 467 pencil_handle_key_press(SPPencilContext *const pc, guint const keyval, guint const state)
 468 {
 469     gint ret = FALSE;
 470     switch (keyval) {
 471         case GDK_Up:
 472         case GDK_Down:
 473         case GDK_KP_Up:
 474         case GDK_KP_Down:
 475             // Prevent the zoom field from activation.
 476             if (!mod_ctrl_only(state)) {
 477                 ret = TRUE;
 478             }
 479             break;
 480         case GDK_Escape:
 481             if (pc->npoints != 0) {
 482                 // if drawing, cancel, otherwise pass it up for deselecting
 483                 if (pc->is_drawing) {
 484                     pencil_cancel (pc);
 485                     ret = TRUE;
 486                 }
 487             }
 488             break;
 489         case GDK_z:
 490         case GDK_Z:
 491             if (mod_ctrl_only(state) && pc->npoints != 0) {
 492                 // if drawing, cancel, otherwise pass it up for undo
 493                 if (pc->is_drawing) {
 494                     pencil_cancel (pc);
 495                     ret = TRUE;
 496                 }
 497             }
 498             break;
 499         case GDK_g:
 500         case GDK_G:
 501             if (mod_shift_only(state)) {
 502                 sp_selection_to_guides();
 503                 ret = true;
 504             }
 505             break;
 506         default:
 507             break;
 508     }
 509     return ret;
 510 }
 511
 512 /**
 513  * Reset points and set new starting point.
 514  */
 515 static void
 516 spdc_set_startpoint(SPPencilContext *const pc, NR::Point const p)
 517 {
 518     pc->npoints = 0;
 519     pc->red_curve_is_valid = false;
 520     if (in_svg_plane(p)) {
 521         pc->p[pc->npoints++] = p;
 522     }
 523 }
 524
 525 /**
 526  * Change moving endpoint position.
 527  * <ul>
 528  * <li>Ctrl constrains to moving to H/V direction, snapping in given direction.
 529  * <li>Otherwise we snap freely to whatever attractors are available.
 530  * </ul>
 531  *
 532  * Number of points is (re)set to 2 always, 2nd point is modified.
 533  * We change RED curve.
 534  */
 535 static void
 536 spdc_set_endpoint(SPPencilContext *const pc, NR::Point const p)
 537 {
 538     if (pc->npoints == 0) {
 539         return;
 540         /* May occur if first point wasn't in SVG plane (e.g. weird w2d transform, perhaps from bad
 541          * zoom setting).
 542          */
 543     }
 544     g_return_if_fail( pc->npoints > 0 );
 545
 546     pc->red_curve->reset();
 547     if ( ( p == pc->p[0] )
 548          || !in_svg_plane(p) )
 549     {
 550         pc->npoints = 1;
 551     } else {
 552         pc->p[1] = p;
 553         pc->npoints = 2;
 554
 555         pc->red_curve->moveto(pc->p[0]);
 556         pc->red_curve->lineto(pc->p[1]);
 557         pc->red_curve_is_valid = true;
 558
 559         sp_canvas_bpath_set_bpath(SP_CANVAS_BPATH(pc->red_bpath), pc->red_curve);
 560     }
 561 }
 562
 563 /**
 564  * Finalize addline.
 565  *
 566  * \todo
 567  * fixme: I'd like remove red reset from concat colors (lauris).
 568  * Still not sure, how it will make most sense.
 569  */
 570 static void
 571 spdc_finish_endpoint(SPPencilContext *const pc)
 572 {
 573     if ( ( SP_CURVE_LENGTH(pc->red_curve) != 2 )
 574          || ( SP_CURVE_SEGMENT(pc->red_curve, 0)->c(3) ==
 575               SP_CURVE_SEGMENT(pc->red_curve, 1)->c(3)   ) )
 576     {
 577         pc->red_curve->reset();
 578         sp_canvas_bpath_set_bpath(SP_CANVAS_BPATH(pc->red_bpath), NULL);
 579     } else {
 580         /* Write curves to object. */
 581         spdc_concat_colors_and_flush(pc, FALSE);
 582         pc->sa = NULL;
 583         pc->ea = NULL;
 584     }
 585 }
 586
 587 static void
 588 spdc_add_freehand_point(SPPencilContext *pc, NR::Point p, guint /*state*/)
 589 {
 590     g_assert( pc->npoints > 0 );
 591     g_return_if_fail(unsigned(pc->npoints) < G_N_ELEMENTS(pc->p));
 592
 593     if ( ( p != pc->p[ pc->npoints - 1 ] )
 594          && in_svg_plane(p) )
 595     {
 596         pc->p[pc->npoints++] = p;
 597         fit_and_split(pc);
 598     }
 599 }
 600
 601 static inline double
 602 square(double const x)
 603 {
 604     return x * x;
 605 }
 606
 607 static void
 608 fit_and_split(SPPencilContext *pc)
 609 {
 610     g_assert( pc->npoints > 1 );
 611
 612     double const tolerance_sq = square( NR::expansion(pc->desktop->w2d())
 613                                         * prefs_get_double_attribute_limited("tools.freehand.pencil",
 614                                                                              "tolerance", 10.0, 1.0, 100.0) );
 615
 616     NR::Point b[4];
 617     g_assert(is_zero(pc->req_tangent)
 618              || is_unit_vector(pc->req_tangent));
 619     NR::Point const tHatEnd(0, 0);
 620     int const n_segs = sp_bezier_fit_cubic_full(b, NULL, pc->p, pc->npoints,
 621                                                 pc->req_tangent, tHatEnd, tolerance_sq, 1);
 622     if ( n_segs > 0
 623          && unsigned(pc->npoints) < G_N_ELEMENTS(pc->p) )
 624     {
 625         /* Fit and draw and reset state */
 626         pc->red_curve->reset();
 627         pc->red_curve->moveto(b[0]);
 628         pc->red_curve->curveto(b[1], b[2], b[3]);
 629         sp_canvas_bpath_set_bpath(SP_CANVAS_BPATH(pc->red_bpath), pc->red_curve);
 630         pc->red_curve_is_valid = true;
 631     } else {
 632         /* Fit and draw and copy last point */
 633
 634         g_assert(!pc->red_curve->is_empty());
 635
 636         /* Set up direction of next curve. */
 637         {
 638             NArtBpath const &last_seg = *pc->red_curve->last_bpath();
 639             pc->p[0] = last_seg.c(3);
 640             pc->npoints = 1;
 641             g_assert( last_seg.code == NR_CURVETO );
 642             /* Relevance: validity of last_seg.c(2). */
 643             NR::Point const req_vec( pc->p[0] - last_seg.c(2) );
 644             pc->req_tangent = ( ( NR::is_zero(req_vec) || !in_svg_plane(req_vec) )
 645                                 ? NR::Point(0, 0)
 646                                 : NR::unit_vector(req_vec) );
 647         }
 648
 649         pc->green_curve->append_continuous(pc->red_curve, 0.0625);
 650         SPCurve *curve = pc->red_curve->copy();
 651
 652         /// \todo fixme:
 653         SPCanvasItem *cshape = sp_canvas_bpath_new(sp_desktop_sketch(pc->desktop), curve);
 654         curve->unref();
 655         sp_canvas_bpath_set_stroke(SP_CANVAS_BPATH(cshape), pc->green_color, 1.0, SP_STROKE_LINEJOIN_MITER, SP_STROKE_LINECAP_BUTT);
 656
 657         pc->green_bpaths = g_slist_prepend(pc->green_bpaths, cshape);
 658
 659         pc->red_curve_is_valid = false;
 660     }
 661 }
 662
 663
 664 /*
 665   Local Variables:
 666   mode:c++
 667   c-file-style:"stroustrup"
 668   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 669   indent-tabs-mode:nil
 670   fill-column:99
 671   End:
 672 */
 673 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :