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 "context-fns.h"
  38 #include "sp-namedview.h"
  39 #include "xml/repr.h"
  40 #include "document.h"
  41 #include "desktop-style.h"
  42 #include "macros.h"
  43 #include "display/curve.h"
  44
  45 static void sp_pencil_context_class_init(SPPencilContextClass *klass);
  46 static void sp_pencil_context_init(SPPencilContext *pc);
  47 static void sp_pencil_context_setup(SPEventContext *ec);
  48 static void sp_pencil_context_dispose(GObject *object);
  49
  50 static gint sp_pencil_context_root_handler(SPEventContext *event_context, GdkEvent *event);
  51 static gint pencil_handle_button_press(SPPencilContext *const pc, GdkEventButton const &bevent);
  52 static gint pencil_handle_motion_notify(SPPencilContext *const pc, GdkEventMotion const &mevent);
  53 static gint pencil_handle_button_release(SPPencilContext *const pc, GdkEventButton const &revent);
  54 static gint pencil_handle_key_press(SPPencilContext *const pc, guint const keyval, guint const state);
  55
  56 static void spdc_set_startpoint(SPPencilContext *pc, NR::Point const p);
  57 static void spdc_set_endpoint(SPPencilContext *pc, NR::Point const p);
  58 static void spdc_finish_endpoint(SPPencilContext *pc);
  59 static void spdc_add_freehand_point(SPPencilContext *pc, NR::Point p, guint state);
  60 static void fit_and_split(SPPencilContext *pc);
  61
  62
  63 static SPDrawContextClass *pencil_parent_class;
  64 static NR::Point pencil_drag_origin_w(0, 0);
  65 static bool pencil_within_tolerance = false;
  66
  67 /**
  68  * Register SPPencilContext class with Gdk and return its type number.
  69  */
  70 GType
  71 sp_pencil_context_get_type()
  72 {
  73     static GType type = 0;
  74     if (!type) {
  75         GTypeInfo info = {
  76             sizeof(SPPencilContextClass),
  77             NULL, NULL,
  78             (GClassInitFunc) sp_pencil_context_class_init,
  79             NULL, NULL,
  80             sizeof(SPPencilContext),
  81             4,
  82             (GInstanceInitFunc) sp_pencil_context_init,
  83             NULL,   /* value_table */
  84         };
  85         type = g_type_register_static(SP_TYPE_DRAW_CONTEXT, "SPPencilContext", &info, (GTypeFlags)0);
  86     }
  87     return type;
  88 }
  89
  90 /**
  91  * Initialize SPPencilContext vtable.
  92  */
  93 static void
  94 sp_pencil_context_class_init(SPPencilContextClass *klass)
  95 {
  96     GObjectClass *object_class;
  97     SPEventContextClass *event_context_class;
  98
  99     object_class = (GObjectClass *) klass;
 100     event_context_class = (SPEventContextClass *) klass;
 101
 102     pencil_parent_class = (SPDrawContextClass*)g_type_class_peek_parent(klass);
 103
 104     object_class->dispose = sp_pencil_context_dispose;
 105
 106     event_context_class->setup = sp_pencil_context_setup;
 107     event_context_class->root_handler = sp_pencil_context_root_handler;
 108 }
 109
 110 /**
 111  * Callback to initialize SPPencilContext object.
 112  */
 113 static void
 114 sp_pencil_context_init(SPPencilContext *pc)
 115 {
 116     SPEventContext *event_context = SP_EVENT_CONTEXT(pc);
 117
 118     event_context->cursor_shape = cursor_pencil_xpm;
 119     event_context->hot_x = 4;
 120     event_context->hot_y = 4;
 121
 122     pc->npoints = 0;
 123     pc->state = SP_PENCIL_CONTEXT_IDLE;
 124     pc->req_tangent = NR::Point(0, 0);
 125 }
 126
 127 /**
 128  * Callback to setup SPPencilContext object.
 129  */
 130 static void
 131 sp_pencil_context_setup(SPEventContext *ec)
 132 {
 133     if (prefs_get_int_attribute("tools.freehand.pencil", "selcue", 0) != 0) {
 134         ec->enableSelectionCue();
 135     }
 136
 137     if (((SPEventContextClass *) pencil_parent_class)->setup) {
 138         ((SPEventContextClass *) pencil_parent_class)->setup(ec);
 139     }
 140
 141     SPPencilContext *const pc = SP_PENCIL_CONTEXT(ec);
 142     pc->is_drawing = false;
 143
 144     pc->anchor_statusbar = false;
 145 }
 146
 147 static void
 148 sp_pencil_context_dispose(GObject *object)
 149 {
 150     G_OBJECT_CLASS(pencil_parent_class)->dispose(object);
 151 }
 152
 153 /** Snaps new node relative to the previous node. */
 154 static void
 155 spdc_endpoint_snap(SPPencilContext const *pc, NR::Point &p, guint const state)
 156 {
 157     if ((state & GDK_CONTROL_MASK)) { //CTRL enables constrained snapping
 158         spdc_endpoint_snap_rotation(pc, p, pc->p[0], state);
 159     } else {
 160         if (!(state & GDK_SHIFT_MASK)) { //SHIFT disables all snapping, except the angular snapping above
 161                                          //After all, the user explicitely asked for angular snapping by
 162                                          //pressing CTRL
 163             spdc_endpoint_snap_free(pc, p, state);
 164         }
 165     }
 166 }
 167
 168 /**
 169  * Callback for handling all pencil context events.
 170  */
 171 gint
 172 sp_pencil_context_root_handler(SPEventContext *const ec, GdkEvent *event)
 173 {
 174     SPPencilContext *const pc = SP_PENCIL_CONTEXT(ec);
 175
 176     gint ret = FALSE;
 177
 178     switch (event->type) {
 179         case GDK_BUTTON_PRESS:
 180             ret = pencil_handle_button_press(pc, event->button);
 181             break;
 182
 183         case GDK_MOTION_NOTIFY:
 184             ret = pencil_handle_motion_notify(pc, event->motion);
 185             break;
 186
 187         case GDK_BUTTON_RELEASE:
 188             ret = pencil_handle_button_release(pc, event->button);
 189             break;
 190
 191         case GDK_KEY_PRESS:
 192             ret = pencil_handle_key_press(pc, get_group0_keyval (&event->key), event->key.state);
 193             break;
 194
 195         default:
 196             break;
 197     }
 198
 199     if (!ret) {
 200         gint (*const parent_root_handler)(SPEventContext *, GdkEvent *)
 201             = ((SPEventContextClass *) pencil_parent_class)->root_handler;
 202         if (parent_root_handler) {
 203             ret = parent_root_handler(ec, event);
 204         }
 205     }
 206
 207     return ret;
 208 }
 209
 210 static gint
 211 pencil_handle_button_press(SPPencilContext *const pc, GdkEventButton const &bevent)
 212 {
 213     gint ret = FALSE;
 214     SPEventContext *event_context = SP_EVENT_CONTEXT(pc);
 215     if ( bevent.button == 1  && !event_context->space_panning) {
 216
 217         SPDrawContext *dc = SP_DRAW_CONTEXT (pc);
 218         SPDesktop *desktop = SP_EVENT_CONTEXT_DESKTOP(dc);
 219         Inkscape::Selection *selection = sp_desktop_selection(desktop);
 220
 221         if (Inkscape::have_viable_layer(desktop, dc->_message_context) == false) {
 222             return TRUE;
 223         }
 224
 225         NR::Point const button_w(bevent.x, bevent.y);
 226
 227         /* Find desktop coordinates */
 228         NR::Point p = pc->desktop->w2d(button_w);
 229
 230         /* Test whether we hit any anchor. */
 231         SPDrawAnchor *anchor = spdc_test_inside(pc, button_w);
 232
 233         pencil_drag_origin_w = NR::Point(bevent.x,bevent.y);
 234         pencil_within_tolerance = true;
 235
 236         switch (pc->state) {
 237             case SP_PENCIL_CONTEXT_ADDLINE:
 238                 /* Current segment will be finished with release */
 239                 ret = TRUE;
 240                 break;
 241             default:
 242                 /* Set first point of sequence */
 243                 if (bevent.state & GDK_CONTROL_MASK) {
 244                     freehand_create_single_dot(event_context, p, "tools.freehand.pencil", bevent.state);
 245                     ret = true;
 246                     break;
 247                 }
 248                 if (anchor) {
 249                     p = anchor->dp;
 250                     desktop->messageStack()->flash(Inkscape::NORMAL_MESSAGE, _("Continuing selected path"));
 251                 } else {
 252
 253                     if (!(bevent.state & GDK_SHIFT_MASK)) {
 254
 255                         // This is the first click of a new curve; deselect item so that
 256                         // this curve is not combined with it (unless it is drawn from its
 257                         // anchor, which is handled by the sibling branch above)
 258                         selection->clear();
 259                         desktop->messageStack()->flash(Inkscape::NORMAL_MESSAGE, _("Creating new path"));
 260                         SnapManager &m = desktop->namedview->snap_manager;
 261                         m.setup(desktop);
 262                         m.freeSnapReturnByRef(Inkscape::Snapper::SNAPPOINT_NODE, p);
 263                     } else if (selection->singleItem() && SP_IS_PATH(selection->singleItem())) {
 264                         desktop->messageStack()->flash(Inkscape::NORMAL_MESSAGE, _("Appending to selected path"));
 265                     }
 266                 }
 267                 pc->sa = anchor;
 268                 spdc_set_startpoint(pc, p);
 269                 ret = TRUE;
 270                 break;
 271         }
 272
 273         pc->is_drawing = true;
 274     }
 275     return ret;
 276 }
 277
 278 static gint
 279 pencil_handle_motion_notify(SPPencilContext *const pc, GdkEventMotion const &mevent)
 280 {
 281     if ((mevent.state & GDK_CONTROL_MASK) && (mevent.state & GDK_BUTTON1_MASK)) {
 282         // mouse was accidentally moved during Ctrl+click;
 283         // ignore the motion and create a single point
 284         pc->is_drawing = false;
 285         return TRUE;
 286     }
 287     gint ret = FALSE;
 288     SPDesktop *const dt = pc->desktop;
 289
 290     SPEventContext *event_context = SP_EVENT_CONTEXT(pc);
 291     if (event_context->space_panning || mevent.state & GDK_BUTTON2_MASK || mevent.state & GDK_BUTTON3_MASK) {
 292         // allow scrolling
 293         return FALSE;
 294     }
 295
 296     if ( ( mevent.state & GDK_BUTTON1_MASK ) && !pc->grab && pc->is_drawing) {
 297         /* Grab mouse, so release will not pass unnoticed */
 298         pc->grab = SP_CANVAS_ITEM(dt->acetate);
 299         sp_canvas_item_grab(pc->grab, ( GDK_KEY_PRESS_MASK | GDK_BUTTON_PRESS_MASK   |
 300                                         GDK_BUTTON_RELEASE_MASK |
 301                                         GDK_POINTER_MOTION_MASK  ),
 302                             NULL, mevent.time);
 303     }
 304
 305     /* Find desktop coordinates */
 306     NR::Point p = dt->w2d(NR::Point(mevent.x, mevent.y));
 307
 308     /* Test whether we hit any anchor. */
 309     SPDrawAnchor *anchor = spdc_test_inside(pc, NR::Point(mevent.x, mevent.y));
 310
 311     if (pencil_within_tolerance) {
 312         gint const tolerance = prefs_get_int_attribute_limited("options.dragtolerance",
 313                                                                "value", 0, 0, 100);
 314         if ( NR::LInfty( NR::Point(mevent.x,mevent.y) - pencil_drag_origin_w ) < tolerance ) {
 315             return FALSE;   // Do not drag if we're within tolerance from origin.
 316         }
 317     }
 318
 319     // Once the user has moved farther than tolerance from the original location
 320     // (indicating they intend to move the object, not click), then always process the
 321     // motion notify coordinates as given (no snapping back to origin)
 322     pencil_within_tolerance = false;
 323
 324     switch (pc->state) {
 325         case SP_PENCIL_CONTEXT_ADDLINE:
 326             /* Set red endpoint */
 327             if (anchor) {
 328                 p = anchor->dp;
 329             } else {
 330                 spdc_endpoint_snap(pc, p, mevent.state);
 331             }
 332             spdc_set_endpoint(pc, p);
 333             ret = TRUE;
 334             break;
 335         default:
 336             /* We may be idle or already freehand */
 337             if ( mevent.state & GDK_BUTTON1_MASK && pc->is_drawing ) {
 338                 pc->state = SP_PENCIL_CONTEXT_FREEHAND;
 339                 if ( !pc->sa && !pc->green_anchor ) {
 340                     /* Create green anchor */
 341                     pc->green_anchor = sp_draw_anchor_new(pc, pc->green_curve, TRUE, pc->p[0]);
 342                 }
 343                 /** \todo
 344                  * fixme: I am not sure whether we want to snap to anchors
 345                  * in middle of freehand (Lauris)
 346                  */
 347                 if (anchor) {
 348                     p = anchor->dp;
 349                 } else if ((mevent.state & GDK_SHIFT_MASK) == 0) {
 350                     SnapManager &m = dt->namedview->snap_manager;
 351                     m.setup(dt, NULL);
 352                     m.freeSnapReturnByRef(Inkscape::Snapper::SNAPPOINT_NODE, p);
 353                 }
 354                 if ( pc->npoints != 0 ) { // buttonpress may have happened before we entered draw context!
 355                     spdc_add_freehand_point(pc, p, mevent.state);
 356                     ret = TRUE;
 357                 }
 358
 359                 if (anchor && !pc->anchor_statusbar) {
 360                     pc->_message_context->set(Inkscape::NORMAL_MESSAGE, _("<b>Release</b> here to close and finish the path."));
 361                     pc->anchor_statusbar = true;
 362                 } else if (!anchor && pc->anchor_statusbar) {
 363                     pc->_message_context->clear();
 364                     pc->anchor_statusbar = false;
 365                 } else if (!anchor) {
 366                     pc->_message_context->set(Inkscape::NORMAL_MESSAGE, _("Drawing a freehand path"));
 367                 }
 368
 369             } else {
 370                 if (anchor && !pc->anchor_statusbar) {
 371                     pc->_message_context->set(Inkscape::NORMAL_MESSAGE, _("<b>Drag</b> to continue the path from this point."));
 372                     pc->anchor_statusbar = true;
 373                 } else if (!anchor && pc->anchor_statusbar) {
 374                     pc->_message_context->clear();
 375                     pc->anchor_statusbar = false;
 376                 }
 377             }
 378             break;
 379     }
 380     return ret;
 381 }
 382
 383 static gint
 384 pencil_handle_button_release(SPPencilContext *const pc, GdkEventButton const &revent)
 385 {
 386     gint ret = FALSE;
 387
 388     SPEventContext *event_context = SP_EVENT_CONTEXT(pc);
 389     if ( revent.button == 1 && pc->is_drawing && !event_context->space_panning) {
 390         SPDesktop *const dt = pc->desktop;
 391
 392         pc->is_drawing = false;
 393
 394         /* Find desktop coordinates */
 395         NR::Point p = dt->w2d(NR::Point(revent.x, revent.y));
 396
 397         /* Test whether we hit any anchor. */
 398         SPDrawAnchor *anchor = spdc_test_inside(pc, NR::Point(revent.x,
 399                                                               revent.y));
 400
 401         switch (pc->state) {
 402             case SP_PENCIL_CONTEXT_IDLE:
 403                 /* Releasing button in idle mode means single click */
 404                 /* We have already set up start point/anchor in button_press */
 405                 if (!(revent.state & GDK_CONTROL_MASK)) {
 406                     // Ctrl+click creates a single point so only set context in ADDLINE mode when Ctrl isn't pressed
 407                     pc->state = SP_PENCIL_CONTEXT_ADDLINE;
 408                 }
 409                 ret = TRUE;
 410                 break;
 411             case SP_PENCIL_CONTEXT_ADDLINE:
 412                 /* Finish segment now */
 413                 if (anchor) {
 414                     p = anchor->dp;
 415                 } else {
 416                     spdc_endpoint_snap(pc, p, revent.state);
 417                 }
 418                 pc->ea = anchor;
 419                 spdc_set_endpoint(pc, p);
 420                 spdc_finish_endpoint(pc);
 421                 pc->state = SP_PENCIL_CONTEXT_IDLE;
 422                 ret = TRUE;
 423                 break;
 424             case SP_PENCIL_CONTEXT_FREEHAND:
 425                 /* Finish segment now */
 426                 /// \todo fixme: Clean up what follows (Lauris)
 427                 if (anchor) {
 428                     p = anchor->dp;
 429                 }
 430                 pc->ea = anchor;
 431                 /* Write curves to object */
 432
 433                 dt->messageStack()->flash(Inkscape::NORMAL_MESSAGE, _("Finishing freehand"));
 434
 435                 spdc_concat_colors_and_flush(pc, FALSE);
 436                 pc->sa = NULL;
 437                 pc->ea = NULL;
 438                 if (pc->green_anchor) {
 439                     pc->green_anchor = sp_draw_anchor_destroy(pc->green_anchor);
 440                 }
 441                 pc->state = SP_PENCIL_CONTEXT_IDLE;
 442                 ret = TRUE;
 443                 break;
 444             default:
 445                 break;
 446         }
 447
 448         if (pc->grab) {
 449             /* Release grab now */
 450             sp_canvas_item_ungrab(pc->grab, revent.time);
 451             pc->grab = NULL;
 452         }
 453
 454         ret = TRUE;
 455     }
 456     return ret;
 457 }
 458
 459 static void
 460 pencil_cancel (SPPencilContext *const pc)
 461 {
 462     if (pc->grab) {
 463         /* Release grab now */
 464         sp_canvas_item_ungrab(pc->grab, 0);
 465         pc->grab = NULL;
 466     }
 467
 468     pc->is_drawing = false;
 469
 470     pc->state = SP_PENCIL_CONTEXT_IDLE;
 471
 472     pc->red_curve->reset();
 473     sp_canvas_bpath_set_bpath(SP_CANVAS_BPATH(pc->red_bpath), NULL);
 474     while (pc->green_bpaths) {
 475         gtk_object_destroy(GTK_OBJECT(pc->green_bpaths->data));
 476         pc->green_bpaths = g_slist_remove(pc->green_bpaths, pc->green_bpaths->data);
 477     }
 478     pc->green_curve->reset();
 479     if (pc->green_anchor) {
 480         pc->green_anchor = sp_draw_anchor_destroy(pc->green_anchor);
 481     }
 482
 483     pc->_message_context->clear();
 484     pc->_message_context->flash(Inkscape::NORMAL_MESSAGE, _("Drawing cancelled"));
 485
 486     sp_canvas_end_forced_full_redraws(pc->desktop->canvas);
 487 }
 488
 489
 490 static gint
 491 pencil_handle_key_press(SPPencilContext *const pc, guint const keyval, guint const state)
 492 {
 493     gint ret = FALSE;
 494     switch (keyval) {
 495         case GDK_Up:
 496         case GDK_Down:
 497         case GDK_KP_Up:
 498         case GDK_KP_Down:
 499             // Prevent the zoom field from activation.
 500             if (!mod_ctrl_only(state)) {
 501                 ret = TRUE;
 502             }
 503             break;
 504         case GDK_Escape:
 505             if (pc->npoints != 0) {
 506                 pencil_cancel (pc);
 507                 ret = TRUE;
 508             }
 509             break;
 510         case GDK_z:
 511         case GDK_Z:
 512             if (mod_ctrl_only(state) && pc->npoints != 0) {
 513                 // if drawing, cancel, otherwise pass it up for undo
 514                 pencil_cancel (pc);
 515                 ret = TRUE;
 516             }
 517             break;
 518         case GDK_g:
 519         case GDK_G:
 520             if (mod_shift_only(state)) {
 521                 sp_selection_to_guides();
 522                 ret = true;
 523             }
 524             break;
 525         default:
 526             break;
 527     }
 528     return ret;
 529 }
 530
 531 /**
 532  * Reset points and set new starting point.
 533  */
 534 static void
 535 spdc_set_startpoint(SPPencilContext *const pc, NR::Point const p)
 536 {
 537     pc->npoints = 0;
 538     pc->red_curve_is_valid = false;
 539     if (in_svg_plane(p)) {
 540         pc->p[pc->npoints++] = p;
 541     }
 542 }
 543
 544 /**
 545  * Change moving endpoint position.
 546  * <ul>
 547  * <li>Ctrl constrains to moving to H/V direction, snapping in given direction.
 548  * <li>Otherwise we snap freely to whatever attractors are available.
 549  * </ul>
 550  *
 551  * Number of points is (re)set to 2 always, 2nd point is modified.
 552  * We change RED curve.
 553  */
 554 static void
 555 spdc_set_endpoint(SPPencilContext *const pc, NR::Point const p)
 556 {
 557     if (pc->npoints == 0) {
 558         return;
 559         /* May occur if first point wasn't in SVG plane (e.g. weird w2d transform, perhaps from bad
 560          * zoom setting).
 561          */
 562     }
 563     g_return_if_fail( pc->npoints > 0 );
 564
 565     pc->red_curve->reset();
 566     if ( ( p == pc->p[0] )
 567          || !in_svg_plane(p) )
 568     {
 569         pc->npoints = 1;
 570     } else {
 571         pc->p[1] = p;
 572         pc->npoints = 2;
 573
 574         pc->red_curve->moveto(pc->p[0]);
 575         pc->red_curve->lineto(pc->p[1]);
 576         pc->red_curve_is_valid = true;
 577
 578         sp_canvas_bpath_set_bpath(SP_CANVAS_BPATH(pc->red_bpath), pc->red_curve);
 579     }
 580 }
 581
 582 /**
 583  * Finalize addline.
 584  *
 585  * \todo
 586  * fixme: I'd like remove red reset from concat colors (lauris).
 587  * Still not sure, how it will make most sense.
 588  */
 589 static void
 590 spdc_finish_endpoint(SPPencilContext *const pc)
 591 {
 592     if ( ( pc->red_curve->is_empty() )
 593          || ( pc->red_curve->first_point() == pc->red_curve->second_point()   ) )
 594     {
 595         pc->red_curve->reset();
 596         sp_canvas_bpath_set_bpath(SP_CANVAS_BPATH(pc->red_bpath), NULL);
 597     } else {
 598         /* Write curves to object. */
 599         spdc_concat_colors_and_flush(pc, FALSE);
 600         pc->sa = NULL;
 601         pc->ea = NULL;
 602     }
 603 }
 604
 605 static void
 606 spdc_add_freehand_point(SPPencilContext *pc, NR::Point p, guint /*state*/)
 607 {
 608     g_assert( pc->npoints > 0 );
 609     g_return_if_fail(unsigned(pc->npoints) < G_N_ELEMENTS(pc->p));
 610
 611     if ( ( p != pc->p[ pc->npoints - 1 ] )
 612          && in_svg_plane(p) )
 613     {
 614         pc->p[pc->npoints++] = p;
 615         fit_and_split(pc);
 616     }
 617 }
 618
 619 static inline double
 620 square(double const x)
 621 {
 622     return x * x;
 623 }
 624
 625 static void
 626 fit_and_split(SPPencilContext *pc)
 627 {
 628     g_assert( pc->npoints > 1 );
 629
 630     double const tol = prefs_get_double_attribute_limited("tools.freehand.pencil",                                                                             "tolerance", 10.0, 1.0, 100.0);
 631     double const tolerance_sq = 0.02 * square( NR::expansion(pc->desktop->w2d()) * tol)
 632         * exp(0.2*tol - 2);
 633
 634     NR::Point b[4];
 635     g_assert(is_zero(pc->req_tangent)
 636              || is_unit_vector(pc->req_tangent));
 637     NR::Point const tHatEnd(0, 0);
 638     int const n_segs = sp_bezier_fit_cubic_full(b, NULL, pc->p, pc->npoints,
 639                                                 pc->req_tangent, tHatEnd, tolerance_sq, 1);
 640     if ( n_segs > 0
 641          && unsigned(pc->npoints) < G_N_ELEMENTS(pc->p) )
 642     {
 643         /* Fit and draw and reset state */
 644         pc->red_curve->reset();
 645         pc->red_curve->moveto(b[0]);
 646         pc->red_curve->curveto(b[1], b[2], b[3]);
 647         sp_canvas_bpath_set_bpath(SP_CANVAS_BPATH(pc->red_bpath), pc->red_curve);
 648         pc->red_curve_is_valid = true;
 649     } else {
 650         /* Fit and draw and copy last point */
 651
 652         g_assert(!pc->red_curve->is_empty());
 653
 654         /* Set up direction of next curve. */
 655         {
 656             Geom::CubicBezier const * last_seg = dynamic_cast<Geom::CubicBezier const *>(pc->red_curve->last_segment());
 657             g_assert( last_seg );      // Relevance: validity of (*last_seg)[2]
 658             pc->p[0] = last_seg->finalPoint();
 659             pc->npoints = 1;
 660             NR::Point const req_vec( pc->p[0] - (*last_seg)[2] );
 661             pc->req_tangent = ( ( NR::is_zero(req_vec) || !in_svg_plane(req_vec) )
 662                                 ? NR::Point(0, 0)
 663                                 : NR::unit_vector(req_vec) );
 664         }
 665
 666         pc->green_curve->append_continuous(pc->red_curve, 0.0625);
 667         SPCurve *curve = pc->red_curve->copy();
 668
 669         /// \todo fixme:
 670         SPCanvasItem *cshape = sp_canvas_bpath_new(sp_desktop_sketch(pc->desktop), curve);
 671         curve->unref();
 672         sp_canvas_bpath_set_stroke(SP_CANVAS_BPATH(cshape), pc->green_color, 1.0, SP_STROKE_LINEJOIN_MITER, SP_STROKE_LINECAP_BUTT);
 673
 674         pc->green_bpaths = g_slist_prepend(pc->green_bpaths, cshape);
 675
 676         pc->red_curve_is_valid = false;
 677     }
 678 }
 679
 680
 681 /*
 682   Local Variables:
 683   mode:c++
 684   c-file-style:"stroustrup"
 685   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 686   indent-tabs-mode:nil
 687   fill-column:99
 688   End:
 689 */
 690 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :