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