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 "draw-anchor.h"
  25 #include "message-stack.h"
  26 #include "message-context.h"
  27 #include "modifier-fns.h"
  28 #include "sp-path.h"
  29 #include "prefs-utils.h"
  30 #include "snap.h"
  31 #include "pixmaps/cursor-pencil.xpm"
  32 #include "display/bezier-utils.h"
  33 #include "display/canvas-bpath.h"
  34 #include <glibmm/i18n.h>
  35 #include "libnr/in-svg-plane.h"
  36 #include "libnr/n-art-bpath.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
  43 static void sp_pencil_context_class_init(SPPencilContextClass *klass);
  44 static void sp_pencil_context_init(SPPencilContext *pc);
  45 static void sp_pencil_context_setup(SPEventContext *ec);
  46 static void sp_pencil_context_dispose(GObject *object);
  47
  48 static gint sp_pencil_context_root_handler(SPEventContext *event_context, GdkEvent *event);
  49 static gint pencil_handle_button_press(SPPencilContext *const pc, GdkEventButton const &bevent);
  50 static gint pencil_handle_motion_notify(SPPencilContext *const pc, GdkEventMotion const &mevent);
  51 static gint pencil_handle_button_release(SPPencilContext *const pc, GdkEventButton const &revent);
  52 static gint pencil_handle_key_press(SPPencilContext *const pc, guint const keyval, guint const state);
  53
  54 static void spdc_set_startpoint(SPPencilContext *pc, NR::Point const p);
  55 static void spdc_set_endpoint(SPPencilContext *pc, NR::Point const p);
  56 static void spdc_finish_endpoint(SPPencilContext *pc);
  57 static void spdc_add_freehand_point(SPPencilContext *pc, NR::Point p, guint state);
  58 static void fit_and_split(SPPencilContext *pc);
  59
  60
  61 static SPDrawContextClass *pencil_parent_class;
  62
  63 /**
  64  * Register SPPencilContext class with Gdk and return its type number.
  65  */
  66 GType
  67 sp_pencil_context_get_type()
  68 {
  69     static GType type = 0;
  70     if (!type) {
  71         GTypeInfo info = {
  72             sizeof(SPPencilContextClass),
  73             NULL, NULL,
  74             (GClassInitFunc) sp_pencil_context_class_init,
  75             NULL, NULL,
  76             sizeof(SPPencilContext),
  77             4,
  78             (GInstanceInitFunc) sp_pencil_context_init,
  79             NULL,   /* value_table */
  80         };
  81         type = g_type_register_static(SP_TYPE_DRAW_CONTEXT, "SPPencilContext", &info, (GTypeFlags)0);
  82     }
  83     return type;
  84 }
  85
  86 /**
  87  * Initialize SPPencilContext vtable.
  88  */
  89 static void
  90 sp_pencil_context_class_init(SPPencilContextClass *klass)
  91 {
  92     GObjectClass *object_class;
  93     SPEventContextClass *event_context_class;
  94
  95     object_class = (GObjectClass *) klass;
  96     event_context_class = (SPEventContextClass *) klass;
  97
  98     pencil_parent_class = (SPDrawContextClass*)g_type_class_peek_parent(klass);
  99
 100     object_class->dispose = sp_pencil_context_dispose;
 101
 102     event_context_class->setup = sp_pencil_context_setup;
 103     event_context_class->root_handler = sp_pencil_context_root_handler;
 104 }
 105
 106 /**
 107  * Callback to initialize SPPencilContext object.
 108  */
 109 static void
 110 sp_pencil_context_init(SPPencilContext *pc)
 111 {
 112     SPEventContext *event_context = SP_EVENT_CONTEXT(pc);
 113
 114     event_context->cursor_shape = cursor_pencil_xpm;
 115     event_context->hot_x = 4;
 116     event_context->hot_y = 4;
 117
 118     pc->npoints = 0;
 119     pc->state = SP_PENCIL_CONTEXT_IDLE;
 120     pc->req_tangent = NR::Point(0, 0);
 121 }
 122
 123 /**
 124  * Callback to setup SPPencilContext object.
 125  */
 126 static void
 127 sp_pencil_context_setup(SPEventContext *ec)
 128 {
 129     if (prefs_get_int_attribute("tools.freehand.pencil", "selcue", 0) != 0) {
 130         ec->enableSelectionCue();
 131     }
 132
 133     if (((SPEventContextClass *) pencil_parent_class)->setup) {
 134         ((SPEventContextClass *) pencil_parent_class)->setup(ec);
 135     }
 136
 137     SPPencilContext *const pc = SP_PENCIL_CONTEXT(ec);
 138     pc->is_drawing = false;
 139
 140     pc->anchor_statusbar = false;
 141 }
 142
 143 static void
 144 sp_pencil_context_dispose(GObject *object)
 145 {
 146     G_OBJECT_CLASS(pencil_parent_class)->dispose(object);
 147 }
 148
 149 /** Snaps new node relative to the previous node. */
 150 static void
 151 spdc_endpoint_snap(SPPencilContext const *pc, NR::Point &p, guint const state)
 152 {
 153     spdc_endpoint_snap_rotation(pc, p, pc->p[0], state);
 154     spdc_endpoint_snap_free(pc, p, state);
 155 }
 156
 157 /**
 158  * Callback for handling all pencil context events.
 159  */
 160 gint
 161 sp_pencil_context_root_handler(SPEventContext *const ec, GdkEvent *event)
 162 {
 163     SPPencilContext *const pc = SP_PENCIL_CONTEXT(ec);
 164
 165     gint ret = FALSE;
 166
 167     switch (event->type) {
 168         case GDK_BUTTON_PRESS:
 169             ret = pencil_handle_button_press(pc, event->button);
 170             break;
 171
 172         case GDK_MOTION_NOTIFY:
 173             ret = pencil_handle_motion_notify(pc, event->motion);
 174             break;
 175
 176         case GDK_BUTTON_RELEASE:
 177             ret = pencil_handle_button_release(pc, event->button);
 178             break;
 179
 180         case GDK_KEY_PRESS:
 181             ret = pencil_handle_key_press(pc, get_group0_keyval (&event->key), event->key.state);
 182             break;
 183
 184         default:
 185             break;
 186     }
 187
 188     if (!ret) {
 189         gint (*const parent_root_handler)(SPEventContext *, GdkEvent *)
 190             = ((SPEventContextClass *) pencil_parent_class)->root_handler;
 191         if (parent_root_handler) {
 192             ret = parent_root_handler(ec, event);
 193         }
 194     }
 195
 196     return ret;
 197 }
 198
 199 static gint
 200 pencil_handle_button_press(SPPencilContext *const pc, GdkEventButton const &bevent)
 201 {
 202     gint ret = FALSE;
 203     SPEventContext *event_context = SP_EVENT_CONTEXT(pc);
 204     if ( bevent.button == 1  && !event_context->space_panning) {
 205
 206         SPDrawContext *dc = SP_DRAW_CONTEXT (pc);
 207         SPDesktop *desktop = SP_EVENT_CONTEXT_DESKTOP(dc);
 208         Inkscape::Selection *selection = sp_desktop_selection(desktop);
 209
 210         if (Inkscape::have_viable_layer(desktop, dc->_message_context) == false) {
 211             return TRUE;
 212         }
 213
 214         NR::Point const button_w(bevent.x, bevent.y);
 215
 216         /* Find desktop coordinates */
 217         NR::Point p = pc->desktop->w2d(button_w);
 218
 219         /* Test whether we hit any anchor. */
 220         SPDrawAnchor *anchor = spdc_test_inside(pc, button_w);
 221
 222         switch (pc->state) {
 223             case SP_PENCIL_CONTEXT_ADDLINE:
 224                 /* Current segment will be finished with release */
 225                 ret = TRUE;
 226                 break;
 227             default:
 228                 /* Set first point of sequence */
 229                 if (bevent.state & GDK_CONTROL_MASK) {
 230                     /* Create object */
 231                     Inkscape::XML::Document *xml_doc = sp_document_repr_doc(desktop->doc());
 232                     Inkscape::XML::Node *repr = xml_doc->createElement("svg:path");
 233                     repr->setAttribute("sodipodi:type", "arc");
 234                     SPItem *item = SP_ITEM(desktop->currentLayer()->appendChildRepr(repr));
 235                     Inkscape::GC::release(repr);
 236                     NR::Matrix const i2d (sp_item_i2d_affine (item));
 237                     NR::Point pp = p * i2d;
 238                     sp_repr_set_svg_double (repr, "sodipodi:cx", pp[NR::X]);
 239                     sp_repr_set_svg_double (repr, "sodipodi:cy", pp[NR::Y]);
 240                     sp_repr_set_int (repr, "sodipodi:rx", 10);
 241                     sp_repr_set_int (repr, "sodipodi:ry", 10);
 242
 243                     /* Set style */
 244                     sp_desktop_apply_style_tool(desktop, repr, "tools.shapes.arc", false);
 245
 246                     item->updateRepr();
 247                     desktop->messageStack()->flash(Inkscape::NORMAL_MESSAGE, _("Creating single point"));
 248                     sp_document_done(sp_desktop_document(desktop), SP_VERB_CONTEXT_PENCIL, _("Create single point"));
 249                     ret = true;
 250                     break;
 251
 252                 }
 253                 if (anchor) {
 254                     p = anchor->dp;
 255                     desktop->messageStack()->flash(Inkscape::NORMAL_MESSAGE, _("Continuing selected path"));
 256                 } else {
 257
 258                     if (!(bevent.state & GDK_SHIFT_MASK)) {
 259
 260                         // This is the first click of a new curve; deselect item so that
 261                         // this curve is not combined with it (unless it is drawn from its
 262                         // anchor, which is handled by the sibling branch above)
 263                         selection->clear();
 264                         desktop->messageStack()->flash(Inkscape::NORMAL_MESSAGE, _("Creating new path"));
 265                         SnapManager const &m = desktop->namedview->snap_manager;
 266                         p = m.freeSnap(Inkscape::Snapper::SNAPPOINT_NODE, p, NULL).getPoint();
 267                     } else if (selection->singleItem() && SP_IS_PATH(selection->singleItem())) {
 268                         desktop->messageStack()->flash(Inkscape::NORMAL_MESSAGE, _("Appending to selected path"));
 269                     }
 270                 }
 271                 pc->sa = anchor;
 272                 spdc_set_startpoint(pc, p);
 273                 ret = TRUE;
 274                 break;
 275         }
 276
 277         pc->is_drawing = true;
 278     }
 279     return ret;
 280 }
 281
 282 static gint
 283 pencil_handle_motion_notify(SPPencilContext *const pc, GdkEventMotion const &mevent)
 284 {
 285     if (mevent.state & GDK_CONTROL_MASK) {
 286         // mouse was accidentally moved during Ctrl+click;
 287         // ignore the motion and create a single point
 288         return TRUE;
 289     }
 290     gint ret = FALSE;
 291     SPDesktop *const dt = pc->desktop;
 292
 293     SPEventContext *event_context = SP_EVENT_CONTEXT(pc);
 294     if (event_context->space_panning || mevent.state & GDK_BUTTON2_MASK || mevent.state & GDK_BUTTON3_MASK) {
 295         // allow scrolling
 296         return FALSE;
 297     }
 298
 299     if ( ( mevent.state & GDK_BUTTON1_MASK ) && !pc->grab && pc->is_drawing) {
 300         /* Grab mouse, so release will not pass unnoticed */
 301         pc->grab = SP_CANVAS_ITEM(dt->acetate);
 302         sp_canvas_item_grab(pc->grab, ( GDK_KEY_PRESS_MASK | GDK_BUTTON_PRESS_MASK   |
 303                                         GDK_BUTTON_RELEASE_MASK |
 304                                         GDK_POINTER_MOTION_MASK  ),
 305                             NULL, mevent.time);
 306     }
 307
 308     /* Find desktop coordinates */
 309     NR::Point p = dt->w2d(NR::Point(mevent.x, mevent.y));
 310
 311     /* Test whether we hit any anchor. */
 312     SPDrawAnchor *anchor = spdc_test_inside(pc, NR::Point(mevent.x, mevent.y));
 313
 314     switch (pc->state) {
 315         case SP_PENCIL_CONTEXT_ADDLINE:
 316             /* Set red endpoint */
 317             if (anchor) {
 318                 p = anchor->dp;
 319             } else {
 320                 spdc_endpoint_snap(pc, p, mevent.state);
 321             }
 322             spdc_set_endpoint(pc, p);
 323             ret = TRUE;
 324             break;
 325         default:
 326             /* We may be idle or already freehand */
 327             if ( mevent.state & GDK_BUTTON1_MASK && pc->is_drawing ) {
 328                 pc->state = SP_PENCIL_CONTEXT_FREEHAND;
 329                 if ( !pc->sa && !pc->green_anchor ) {
 330                     /* Create green anchor */
 331                     pc->green_anchor = sp_draw_anchor_new(pc, pc->green_curve, TRUE, pc->p[0]);
 332                 }
 333                 /** \todo
 334                  * fixme: I am not sure whether we want to snap to anchors
 335                  * in middle of freehand (Lauris)
 336                  */
 337                 if (anchor) {
 338                     p = anchor->dp;
 339                 } else if ((mevent.state & GDK_SHIFT_MASK) == 0) {
 340                     SnapManager const &m = dt->namedview->snap_manager;
 341                     p = m.freeSnap(Inkscape::Snapper::SNAPPOINT_NODE, p, NULL).getPoint();
 342                 }
 343                 if ( pc->npoints != 0 ) { // buttonpress may have happened before we entered draw context!
 344                     spdc_add_freehand_point(pc, p, mevent.state);
 345                     ret = TRUE;
 346                 }
 347
 348                 if (anchor && !pc->anchor_statusbar) {
 349                     pc->_message_context->set(Inkscape::NORMAL_MESSAGE, _("<b>Release</b> here to close and finish the path."));
 350                     pc->anchor_statusbar = true;
 351                 } else if (!anchor && pc->anchor_statusbar) {
 352                     pc->_message_context->clear();
 353                     pc->anchor_statusbar = false;
 354                 } else if (!anchor) {
 355                     pc->_message_context->set(Inkscape::NORMAL_MESSAGE, _("Drawing a freehand path"));
 356                 }
 357
 358             } else {
 359                 if (anchor && !pc->anchor_statusbar) {
 360                     pc->_message_context->set(Inkscape::NORMAL_MESSAGE, _("<b>Drag</b> to continue the path from this point."));
 361                     pc->anchor_statusbar = true;
 362                 } else if (!anchor && pc->anchor_statusbar) {
 363                     pc->_message_context->clear();
 364                     pc->anchor_statusbar = false;
 365                 }
 366             }
 367             break;
 368     }
 369     return ret;
 370 }
 371
 372 static gint
 373 pencil_handle_button_release(SPPencilContext *const pc, GdkEventButton const &revent)
 374 {
 375     gint ret = FALSE;
 376
 377     SPEventContext *event_context = SP_EVENT_CONTEXT(pc);
 378     if ( revent.button == 1 && pc->is_drawing && !event_context->space_panning) {
 379         SPDesktop *const dt = pc->desktop;
 380
 381         pc->is_drawing = false;
 382
 383         /* Find desktop coordinates */
 384         NR::Point p = dt->w2d(NR::Point(revent.x, revent.y));
 385
 386         /* Test whether we hit any anchor. */
 387         SPDrawAnchor *anchor = spdc_test_inside(pc, NR::Point(revent.x,
 388                                                               revent.y));
 389
 390         switch (pc->state) {
 391             case SP_PENCIL_CONTEXT_IDLE:
 392                 /* Releasing button in idle mode means single click */
 393                 /* We have already set up start point/anchor in button_press */
 394                 if (!(revent.state & GDK_CONTROL_MASK)) {
 395                     // Ctrl+click creates a single point so only set context in ADDLINE mode when Ctrl isn't pressed
 396                     pc->state = SP_PENCIL_CONTEXT_ADDLINE;
 397                 }
 398                 ret = TRUE;
 399                 break;
 400             case SP_PENCIL_CONTEXT_ADDLINE:
 401                 /* Finish segment now */
 402                 if (anchor) {
 403                     p = anchor->dp;
 404                 } else {
 405                     spdc_endpoint_snap(pc, p, revent.state);
 406                 }
 407                 pc->ea = anchor;
 408                 spdc_set_endpoint(pc, p);
 409                 spdc_finish_endpoint(pc);
 410                 pc->state = SP_PENCIL_CONTEXT_IDLE;
 411                 ret = TRUE;
 412                 break;
 413             case SP_PENCIL_CONTEXT_FREEHAND:
 414                 /* Finish segment now */
 415                 /// \todo fixme: Clean up what follows (Lauris)
 416                 if (anchor) {
 417                     p = anchor->dp;
 418                 }
 419                 pc->ea = anchor;
 420                 /* Write curves to object */
 421
 422                 dt->messageStack()->flash(Inkscape::NORMAL_MESSAGE, _("Finishing freehand"));
 423
 424                 spdc_concat_colors_and_flush(pc, FALSE);
 425                 pc->sa = NULL;
 426                 pc->ea = NULL;
 427                 if (pc->green_anchor) {
 428                     pc->green_anchor = sp_draw_anchor_destroy(pc->green_anchor);
 429                 }
 430                 pc->state = SP_PENCIL_CONTEXT_IDLE;
 431                 ret = TRUE;
 432                 break;
 433             default:
 434                 break;
 435         }
 436
 437         if (pc->grab) {
 438             /* Release grab now */
 439             sp_canvas_item_ungrab(pc->grab, revent.time);
 440             pc->grab = NULL;
 441         }
 442
 443         ret = TRUE;
 444     }
 445     return ret;
 446 }
 447
 448 static void
 449 pencil_cancel (SPPencilContext *const pc)
 450 {
 451     if (pc->grab) {
 452         /* Release grab now */
 453         sp_canvas_item_ungrab(pc->grab, 0);
 454         pc->grab = NULL;
 455     }
 456
 457     pc->is_drawing = false;
 458
 459     pc->state = SP_PENCIL_CONTEXT_IDLE;
 460
 461     sp_curve_reset(pc->red_curve);
 462     sp_canvas_bpath_set_bpath(SP_CANVAS_BPATH(pc->red_bpath), NULL);
 463     while (pc->green_bpaths) {
 464         gtk_object_destroy(GTK_OBJECT(pc->green_bpaths->data));
 465         pc->green_bpaths = g_slist_remove(pc->green_bpaths, pc->green_bpaths->data);
 466     }
 467     sp_curve_reset(pc->green_curve);
 468     if (pc->green_anchor) {
 469         pc->green_anchor = sp_draw_anchor_destroy(pc->green_anchor);
 470     }
 471
 472     pc->_message_context->clear();
 473     pc->_message_context->flash(Inkscape::NORMAL_MESSAGE, _("Drawing cancelled"));
 474
 475     sp_canvas_end_forced_full_redraws(pc->desktop->canvas);
 476 }
 477
 478
 479 static gint
 480 pencil_handle_key_press(SPPencilContext *const pc, guint const keyval, guint const state)
 481 {
 482     gint ret = FALSE;
 483     switch (keyval) {
 484         case GDK_Up:
 485         case GDK_Down:
 486         case GDK_KP_Up:
 487         case GDK_KP_Down:
 488             // Prevent the zoom field from activation.
 489             if (!mod_ctrl_only(state)) {
 490                 ret = TRUE;
 491             }
 492             break;
 493         case GDK_Escape:
 494             if (pc->npoints != 0) {
 495                 // if drawing, cancel, otherwise pass it up for deselecting
 496                 if (pc->is_drawing) {
 497                     pencil_cancel (pc);
 498                     ret = TRUE;
 499                 }
 500             }
 501             break;
 502         case GDK_z:
 503         case GDK_Z:
 504             if (mod_ctrl_only(state) && pc->npoints != 0) {
 505                 // if drawing, cancel, otherwise pass it up for undo
 506                 if (pc->is_drawing) {
 507                     pencil_cancel (pc);
 508                     ret = TRUE;
 509                 }
 510             }
 511             break;
 512         default:
 513             break;
 514     }
 515     return ret;
 516 }
 517
 518 /**
 519  * Reset points and set new starting point.
 520  */
 521 static void
 522 spdc_set_startpoint(SPPencilContext *const pc, NR::Point const p)
 523 {
 524     pc->npoints = 0;
 525     pc->red_curve_is_valid = false;
 526     if (in_svg_plane(p)) {
 527         pc->p[pc->npoints++] = p;
 528     }
 529 }
 530
 531 /**
 532  * Change moving endpoint position.
 533  * <ul>
 534  * <li>Ctrl constrains to moving to H/V direction, snapping in given direction.
 535  * <li>Otherwise we snap freely to whatever attractors are available.
 536  * </ul>
 537  *
 538  * Number of points is (re)set to 2 always, 2nd point is modified.
 539  * We change RED curve.
 540  */
 541 static void
 542 spdc_set_endpoint(SPPencilContext *const pc, NR::Point const p)
 543 {
 544     if (pc->npoints == 0) {
 545         return;
 546         /* May occur if first point wasn't in SVG plane (e.g. weird w2d transform, perhaps from bad
 547          * zoom setting).
 548          */
 549     }
 550     g_return_if_fail( pc->npoints > 0 );
 551
 552     sp_curve_reset(pc->red_curve);
 553     if ( ( p == pc->p[0] )
 554          || !in_svg_plane(p) )
 555     {
 556         pc->npoints = 1;
 557     } else {
 558         pc->p[1] = p;
 559         pc->npoints = 2;
 560
 561         sp_curve_moveto(pc->red_curve, pc->p[0]);
 562         sp_curve_lineto(pc->red_curve, pc->p[1]);
 563         pc->red_curve_is_valid = true;
 564
 565         sp_canvas_bpath_set_bpath(SP_CANVAS_BPATH(pc->red_bpath), pc->red_curve);
 566     }
 567 }
 568
 569 /**
 570  * Finalize addline.
 571  *
 572  * \todo
 573  * fixme: I'd like remove red reset from concat colors (lauris).
 574  * Still not sure, how it will make most sense.
 575  */
 576 static void
 577 spdc_finish_endpoint(SPPencilContext *const pc)
 578 {
 579     if ( ( SP_CURVE_LENGTH(pc->red_curve) != 2 )
 580          || ( SP_CURVE_SEGMENT(pc->red_curve, 0)->c(3) ==
 581               SP_CURVE_SEGMENT(pc->red_curve, 1)->c(3)   ) )
 582     {
 583         sp_curve_reset(pc->red_curve);
 584         sp_canvas_bpath_set_bpath(SP_CANVAS_BPATH(pc->red_bpath), NULL);
 585     } else {
 586         /* Write curves to object. */
 587         spdc_concat_colors_and_flush(pc, FALSE);
 588         pc->sa = NULL;
 589         pc->ea = NULL;
 590     }
 591 }
 592
 593 static void
 594 spdc_add_freehand_point(SPPencilContext *pc, NR::Point p, guint /*state*/)
 595 {
 596     g_assert( pc->npoints > 0 );
 597     g_return_if_fail(unsigned(pc->npoints) < G_N_ELEMENTS(pc->p));
 598
 599     if ( ( p != pc->p[ pc->npoints - 1 ] )
 600          && in_svg_plane(p) )
 601     {
 602         pc->p[pc->npoints++] = p;
 603         fit_and_split(pc);
 604     }
 605 }
 606
 607 static inline double
 608 square(double const x)
 609 {
 610     return x * x;
 611 }
 612
 613 static void
 614 fit_and_split(SPPencilContext *pc)
 615 {
 616     g_assert( pc->npoints > 1 );
 617
 618     double const tolerance_sq = square( NR::expansion(pc->desktop->w2d())
 619                                         * prefs_get_double_attribute_limited("tools.freehand.pencil",
 620                                                                              "tolerance", 10.0, 1.0, 100.0) );
 621
 622     NR::Point b[4];
 623     g_assert(is_zero(pc->req_tangent)
 624              || is_unit_vector(pc->req_tangent));
 625     NR::Point const tHatEnd(0, 0);
 626     int const n_segs = sp_bezier_fit_cubic_full(b, NULL, pc->p, pc->npoints,
 627                                                 pc->req_tangent, tHatEnd, tolerance_sq, 1);
 628     if ( n_segs > 0
 629          && unsigned(pc->npoints) < G_N_ELEMENTS(pc->p) )
 630     {
 631         /* Fit and draw and reset state */
 632         sp_curve_reset(pc->red_curve);
 633         sp_curve_moveto(pc->red_curve, b[0]);
 634         sp_curve_curveto(pc->red_curve, b[1], b[2], b[3]);
 635         sp_canvas_bpath_set_bpath(SP_CANVAS_BPATH(pc->red_bpath), pc->red_curve);
 636         pc->red_curve_is_valid = true;
 637     } else {
 638         /* Fit and draw and copy last point */
 639
 640         g_assert(!sp_curve_empty(pc->red_curve));
 641
 642         /* Set up direction of next curve. */
 643         {
 644             NArtBpath const &last_seg = *sp_curve_last_bpath(pc->red_curve);
 645             pc->p[0] = last_seg.c(3);
 646             pc->npoints = 1;
 647             g_assert( last_seg.code == NR_CURVETO );
 648             /* Relevance: validity of last_seg.c(2). */
 649             NR::Point const req_vec( pc->p[0] - last_seg.c(2) );
 650             pc->req_tangent = ( ( NR::is_zero(req_vec) || !in_svg_plane(req_vec) )
 651                                 ? NR::Point(0, 0)
 652                                 : NR::unit_vector(req_vec) );
 653         }
 654
 655         sp_curve_append_continuous(pc->green_curve, pc->red_curve, 0.0625);
 656         SPCurve *curve = sp_curve_copy(pc->red_curve);
 657
 658         /// \todo fixme:
 659         SPCanvasItem *cshape = sp_canvas_bpath_new(sp_desktop_sketch(pc->desktop), curve);
 660         sp_curve_unref(curve);
 661         sp_canvas_bpath_set_stroke(SP_CANVAS_BPATH(cshape), pc->green_color, 1.0, SP_STROKE_LINEJOIN_MITER, SP_STROKE_LINECAP_BUTT);
 662
 663         pc->green_bpaths = g_slist_prepend(pc->green_bpaths, cshape);
 664
 665         pc->red_curve_is_valid = false;
 666     }
 667 }
 668
 669
 670 /*
 671   Local Variables:
 672   mode:c++
 673   c-file-style:"stroustrup"
 674   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 675   indent-tabs-mode:nil
 676   fill-column:99
 677   End:
 678 */
 679 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :