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 "preferences.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, Geom::Point const p);
  57 static void spdc_set_endpoint(SPPencilContext *pc, Geom::Point const p);
  58 static void spdc_finish_endpoint(SPPencilContext *pc);
  59 static void spdc_add_freehand_point(SPPencilContext *pc, Geom::Point p, guint state);
  60 static void fit_and_split(SPPencilContext *pc);
  61
  62
  63 static SPDrawContextClass *pencil_parent_class;
  64 static Geom::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 = Geom::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     Inkscape::Preferences *prefs = Inkscape::Preferences::get();
 134     if (prefs->getBool("/tools/freehand/pencil/selcue")) {
 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, Geom::Point &p, guint const state)
 157 {
 158     if ((state & GDK_CONTROL_MASK)) { //CTRL enables constrained snapping
 159         spdc_endpoint_snap_rotation(pc, p, pc->p[0], state);
 160     } else {
 161         if (!(state & GDK_SHIFT_MASK)) { //SHIFT disables all snapping, except the angular snapping above
 162                                          //After all, the user explicitely asked for angular snapping by
 163                                          //pressing CTRL
 164             spdc_endpoint_snap_free(pc, p, state);
 165         }
 166     }
 167 }
 168
 169 /**
 170  * Callback for handling all pencil context events.
 171  */
 172 gint
 173 sp_pencil_context_root_handler(SPEventContext *const ec, GdkEvent *event)
 174 {
 175     SPPencilContext *const pc = SP_PENCIL_CONTEXT(ec);
 176
 177     gint ret = FALSE;
 178
 179     switch (event->type) {
 180         case GDK_BUTTON_PRESS:
 181             ret = pencil_handle_button_press(pc, event->button);
 182             break;
 183
 184         case GDK_MOTION_NOTIFY:
 185             ret = pencil_handle_motion_notify(pc, event->motion);
 186             break;
 187
 188         case GDK_BUTTON_RELEASE:
 189             ret = pencil_handle_button_release(pc, event->button);
 190             break;
 191
 192         case GDK_KEY_PRESS:
 193             ret = pencil_handle_key_press(pc, get_group0_keyval (&event->key), event->key.state);
 194             break;
 195
 196         default:
 197             break;
 198     }
 199
 200     if (!ret) {
 201         gint (*const parent_root_handler)(SPEventContext *, GdkEvent *)
 202             = ((SPEventContextClass *) pencil_parent_class)->root_handler;
 203         if (parent_root_handler) {
 204             ret = parent_root_handler(ec, event);
 205         }
 206     }
 207
 208     return ret;
 209 }
 210
 211 static gint
 212 pencil_handle_button_press(SPPencilContext *const pc, GdkEventButton const &bevent)
 213 {
 214     gint ret = FALSE;
 215     SPEventContext *event_context = SP_EVENT_CONTEXT(pc);
 216     if ( bevent.button == 1  && !event_context->space_panning) {
 217
 218         SPDrawContext *dc = SP_DRAW_CONTEXT (pc);
 219         SPDesktop *desktop = SP_EVENT_CONTEXT_DESKTOP(dc);
 220         Inkscape::Selection *selection = sp_desktop_selection(desktop);
 221
 222         if (Inkscape::have_viable_layer(desktop, dc->_message_context) == false) {
 223             return TRUE;
 224         }
 225
 226         Geom::Point const button_w(bevent.x, bevent.y);
 227
 228         /* Find desktop coordinates */
 229         Geom::Point p = pc->desktop->w2d(button_w);
 230
 231         /* Test whether we hit any anchor. */
 232         SPDrawAnchor *anchor = spdc_test_inside(pc, button_w);
 233
 234         pencil_drag_origin_w = Geom::Point(bevent.x,bevent.y);
 235         pencil_within_tolerance = true;
 236
 237         switch (pc->state) {
 238             case SP_PENCIL_CONTEXT_ADDLINE:
 239                 /* Current segment will be finished with release */
 240                 ret = TRUE;
 241                 break;
 242             default:
 243                 /* Set first point of sequence */
 244                 if (bevent.state & GDK_CONTROL_MASK) {
 245                     spdc_create_single_dot(event_context, from_2geom(p), "/tools/freehand/pencil", bevent.state);
 246                     ret = true;
 247                     break;
 248                 }
 249                 if (anchor) {
 250                     p = to_2geom(anchor->dp);
 251                     desktop->messageStack()->flash(Inkscape::NORMAL_MESSAGE, _("Continuing selected path"));
 252                 } else {
 253
 254                     if (!(bevent.state & GDK_SHIFT_MASK)) {
 255
 256                         // This is the first click of a new curve; deselect item so that
 257                         // this curve is not combined with it (unless it is drawn from its
 258                         // anchor, which is handled by the sibling branch above)
 259                         selection->clear();
 260                         desktop->messageStack()->flash(Inkscape::NORMAL_MESSAGE, _("Creating new path"));
 261                         SnapManager &m = desktop->namedview->snap_manager;
 262                         m.setup(desktop);
 263                         Inkscape::SnappedPoint const s = m.freeSnap(Inkscape::SnapPreferences::SNAPPOINT_NODE, p);
 264                         if (s.getSnapped()) {
 265                                 s.getPoint(p);
 266                                 pc->pencil_has_snapped_before = true;
 267                         } else {
 268                                 pc->pencil_has_snapped_before = false;
 269                         }
 270                     } else if (selection->singleItem() && SP_IS_PATH(selection->singleItem())) {
 271                         desktop->messageStack()->flash(Inkscape::NORMAL_MESSAGE, _("Appending to selected path"));
 272                     }
 273                 }
 274                 pc->sa = anchor;
 275                 spdc_set_startpoint(pc, from_2geom(p));
 276                 ret = TRUE;
 277                 break;
 278         }
 279
 280         pc->is_drawing = true;
 281     }
 282     return ret;
 283 }
 284
 285 static gint
 286 pencil_handle_motion_notify(SPPencilContext *const pc, GdkEventMotion const &mevent)
 287 {
 288     if ((mevent.state & GDK_CONTROL_MASK) && (mevent.state & GDK_BUTTON1_MASK)) {
 289         // mouse was accidentally moved during Ctrl+click;
 290         // ignore the motion and create a single point
 291         pc->is_drawing = false;
 292         return TRUE;
 293     }
 294     gint ret = FALSE;
 295     SPDesktop *const dt = pc->desktop;
 296
 297     SPEventContext *event_context = SP_EVENT_CONTEXT(pc);
 298     if (event_context->space_panning || mevent.state & GDK_BUTTON2_MASK || mevent.state & GDK_BUTTON3_MASK) {
 299         // allow scrolling
 300         return FALSE;
 301     }
 302
 303     if ( ( mevent.state & GDK_BUTTON1_MASK ) && !pc->grab && pc->is_drawing) {
 304         /* Grab mouse, so release will not pass unnoticed */
 305         pc->grab = SP_CANVAS_ITEM(dt->acetate);
 306         sp_canvas_item_grab(pc->grab, ( GDK_KEY_PRESS_MASK | GDK_BUTTON_PRESS_MASK   |
 307                                         GDK_BUTTON_RELEASE_MASK |
 308                                         GDK_POINTER_MOTION_MASK  ),
 309                             NULL, mevent.time);
 310     }
 311
 312     /* Find desktop coordinates */
 313     Geom::Point p = to_2geom(dt->w2d(Geom::Point(mevent.x, mevent.y)));
 314
 315     /* Test whether we hit any anchor. */
 316     SPDrawAnchor *anchor = spdc_test_inside(pc, Geom::Point(mevent.x, mevent.y));
 317
 318     if (pencil_within_tolerance) {
 319         Inkscape::Preferences *prefs = Inkscape::Preferences::get();
 320         gint const tolerance = prefs->getIntLimited("/options/dragtolerance/value", 0, 0, 100);
 321         if ( NR::LInfty( Geom::Point(mevent.x,mevent.y) - pencil_drag_origin_w ) < tolerance ) {
 322             return FALSE;   // Do not drag if we're within tolerance from origin.
 323         }
 324     }
 325
 326     // Once the user has moved farther than tolerance from the original location
 327     // (indicating they intend to move the object, not click), then always process the
 328     // motion notify coordinates as given (no snapping back to origin)
 329     pencil_within_tolerance = false;
 330
 331     switch (pc->state) {
 332         case SP_PENCIL_CONTEXT_ADDLINE:
 333             /* Set red endpoint */
 334             if (anchor) {
 335                 p = to_2geom(anchor->dp);
 336             } else {
 337                 Geom::Point ptnr = from_2geom(p);
 338                 spdc_endpoint_snap(pc, ptnr, mevent.state);
 339                 p = to_2geom(ptnr);
 340             }
 341             spdc_set_endpoint(pc, from_2geom(p));
 342             ret = TRUE;
 343             break;
 344         default:
 345             /* We may be idle or already freehand */
 346             if ( mevent.state & GDK_BUTTON1_MASK && pc->is_drawing ) {
 347                 pc->state = SP_PENCIL_CONTEXT_FREEHAND;
 348                 if ( !pc->sa && !pc->green_anchor ) {
 349                     /* Create green anchor */
 350                     pc->green_anchor = sp_draw_anchor_new(pc, pc->green_curve, TRUE, pc->p[0]);
 351                 }
 352                 /** \todo
 353                  * fixme: I am not sure whether we want to snap to anchors
 354                  * in middle of freehand (Lauris)
 355                  */
 356                 SnapManager &m = dt->namedview->snap_manager;
 357
 358                 if (anchor) {
 359                     p = to_2geom(anchor->dp);
 360                 } else if ((mevent.state & GDK_SHIFT_MASK) == 0) {
 361                     m.setup(dt);
 362                     Inkscape::SnappedPoint const s = m.freeSnap(Inkscape::SnapPreferences::SNAPPOINT_NODE, p);
 363                     if (s.getSnapped()) {
 364                         s.getPoint(p);
 365                         pc->pencil_has_snapped_before = true;
 366                     }
 367                 }
 368                 if ( pc->npoints != 0) { // buttonpress may have happened before we entered draw context!
 369                         if (!(pc->pencil_has_snapped_before && m.snapprefs.getSnapPostponedGlobally())) {
 370                             // When snapping is enabled but temporarily on hold because the mouse is moving
 371                                 // fast, then we don't want to add nodes off-grid
 372                                 spdc_add_freehand_point(pc, from_2geom(p), mevent.state);
 373                             ret = TRUE;
 374                         }
 375                 }
 376
 377                 if (anchor && !pc->anchor_statusbar) {
 378                     pc->_message_context->set(Inkscape::NORMAL_MESSAGE, _("<b>Release</b> here to close and finish the path."));
 379                     pc->anchor_statusbar = true;
 380                 } else if (!anchor && pc->anchor_statusbar) {
 381                     pc->_message_context->clear();
 382                     pc->anchor_statusbar = false;
 383                 } else if (!anchor) {
 384                     pc->_message_context->set(Inkscape::NORMAL_MESSAGE, _("Drawing a freehand path"));
 385                 }
 386
 387             } else {
 388                 if (anchor && !pc->anchor_statusbar) {
 389                     pc->_message_context->set(Inkscape::NORMAL_MESSAGE, _("<b>Drag</b> to continue the path from this point."));
 390                     pc->anchor_statusbar = true;
 391                 } else if (!anchor && pc->anchor_statusbar) {
 392                     pc->_message_context->clear();
 393                     pc->anchor_statusbar = false;
 394                 }
 395             }
 396             break;
 397     }
 398     return ret;
 399 }
 400
 401 static gint
 402 pencil_handle_button_release(SPPencilContext *const pc, GdkEventButton const &revent)
 403 {
 404     gint ret = FALSE;
 405
 406     SPEventContext *event_context = SP_EVENT_CONTEXT(pc);
 407     if ( revent.button == 1 && pc->is_drawing && !event_context->space_panning) {
 408         SPDesktop *const dt = pc->desktop;
 409
 410         pc->is_drawing = false;
 411
 412         /* Find desktop coordinates */
 413         Geom::Point p = dt->w2d(Geom::Point(revent.x, revent.y));
 414
 415         /* Test whether we hit any anchor. */
 416         SPDrawAnchor *anchor = spdc_test_inside(pc, Geom::Point(revent.x,
 417                                                               revent.y));
 418
 419         switch (pc->state) {
 420             case SP_PENCIL_CONTEXT_IDLE:
 421                 /* Releasing button in idle mode means single click */
 422                 /* We have already set up start point/anchor in button_press */
 423                 if (!(revent.state & GDK_CONTROL_MASK)) {
 424                     // Ctrl+click creates a single point so only set context in ADDLINE mode when Ctrl isn't pressed
 425                     pc->state = SP_PENCIL_CONTEXT_ADDLINE;
 426                 }
 427                 ret = TRUE;
 428                 break;
 429             case SP_PENCIL_CONTEXT_ADDLINE:
 430                 /* Finish segment now */
 431                 if (anchor) {
 432                     p = anchor->dp;
 433                 } else {
 434                     spdc_endpoint_snap(pc, p, revent.state);
 435                 }
 436                 pc->ea = anchor;
 437                 spdc_set_endpoint(pc, p);
 438                 spdc_finish_endpoint(pc);
 439                 pc->state = SP_PENCIL_CONTEXT_IDLE;
 440                 ret = TRUE;
 441                 break;
 442             case SP_PENCIL_CONTEXT_FREEHAND:
 443                 /* Finish segment now */
 444                 /// \todo fixme: Clean up what follows (Lauris)
 445                 if (anchor) {
 446                     p = anchor->dp;
 447                 }
 448                 pc->ea = anchor;
 449                 /* Write curves to object */
 450
 451                 dt->messageStack()->flash(Inkscape::NORMAL_MESSAGE, _("Finishing freehand"));
 452
 453                 spdc_concat_colors_and_flush(pc, FALSE);
 454                 pc->sa = NULL;
 455                 pc->ea = NULL;
 456                 if (pc->green_anchor) {
 457                     pc->green_anchor = sp_draw_anchor_destroy(pc->green_anchor);
 458                 }
 459                 pc->state = SP_PENCIL_CONTEXT_IDLE;
 460                 ret = TRUE;
 461                 break;
 462             default:
 463                 break;
 464         }
 465
 466         if (pc->grab) {
 467             /* Release grab now */
 468             sp_canvas_item_ungrab(pc->grab, revent.time);
 469             pc->grab = NULL;
 470         }
 471
 472         ret = TRUE;
 473     }
 474     return ret;
 475 }
 476
 477 static void
 478 pencil_cancel (SPPencilContext *const pc)
 479 {
 480     if (pc->grab) {
 481         /* Release grab now */
 482         sp_canvas_item_ungrab(pc->grab, 0);
 483         pc->grab = NULL;
 484     }
 485
 486     pc->is_drawing = false;
 487
 488     pc->state = SP_PENCIL_CONTEXT_IDLE;
 489
 490     pc->red_curve->reset();
 491     sp_canvas_bpath_set_bpath(SP_CANVAS_BPATH(pc->red_bpath), NULL);
 492     while (pc->green_bpaths) {
 493         gtk_object_destroy(GTK_OBJECT(pc->green_bpaths->data));
 494         pc->green_bpaths = g_slist_remove(pc->green_bpaths, pc->green_bpaths->data);
 495     }
 496     pc->green_curve->reset();
 497     if (pc->green_anchor) {
 498         pc->green_anchor = sp_draw_anchor_destroy(pc->green_anchor);
 499     }
 500
 501     pc->_message_context->clear();
 502     pc->_message_context->flash(Inkscape::NORMAL_MESSAGE, _("Drawing cancelled"));
 503
 504     sp_canvas_end_forced_full_redraws(pc->desktop->canvas);
 505 }
 506
 507 static gint
 508 pencil_handle_key_press(SPPencilContext *const pc, guint const keyval, guint const state)
 509 {
 510     gint ret = FALSE;
 511     switch (keyval) {
 512         case GDK_Up:
 513         case GDK_Down:
 514         case GDK_KP_Up:
 515         case GDK_KP_Down:
 516             // Prevent the zoom field from activation.
 517             if (!mod_ctrl_only(state)) {
 518                 ret = TRUE;
 519             }
 520             break;
 521         case GDK_Escape:
 522             if (pc->npoints != 0) {
 523                 // if drawing, cancel, otherwise pass it up for deselecting
 524                 if (pc->state != SP_PENCIL_CONTEXT_IDLE) {
 525                     pencil_cancel (pc);
 526                     ret = TRUE;
 527                 }
 528             }
 529             break;
 530         case GDK_z:
 531         case GDK_Z:
 532             if (mod_ctrl_only(state) && pc->npoints != 0) {
 533                 // if drawing, cancel, otherwise pass it up for undo
 534                 if (pc->state != SP_PENCIL_CONTEXT_IDLE) {
 535                     pencil_cancel (pc);
 536                     ret = TRUE;
 537                 }
 538             }
 539             break;
 540         case GDK_g:
 541         case GDK_G:
 542             if (mod_shift_only(state)) {
 543                 sp_selection_to_guides(SP_EVENT_CONTEXT(pc)->desktop);
 544                 ret = true;
 545             }
 546             break;
 547         default:
 548             break;
 549     }
 550     return ret;
 551 }
 552
 553 /**
 554  * Reset points and set new starting point.
 555  */
 556 static void
 557 spdc_set_startpoint(SPPencilContext *const pc, Geom::Point const p)
 558 {
 559     pc->npoints = 0;
 560     pc->red_curve_is_valid = false;
 561     if (in_svg_plane(p)) {
 562         pc->p[pc->npoints++] = p;
 563     }
 564 }
 565
 566 /**
 567  * Change moving endpoint position.
 568  * <ul>
 569  * <li>Ctrl constrains to moving to H/V direction, snapping in given direction.
 570  * <li>Otherwise we snap freely to whatever attractors are available.
 571  * </ul>
 572  *
 573  * Number of points is (re)set to 2 always, 2nd point is modified.
 574  * We change RED curve.
 575  */
 576 static void
 577 spdc_set_endpoint(SPPencilContext *const pc, Geom::Point const p)
 578 {
 579     if (pc->npoints == 0) {
 580         return;
 581         /* May occur if first point wasn't in SVG plane (e.g. weird w2d transform, perhaps from bad
 582          * zoom setting).
 583          */
 584     }
 585     g_return_if_fail( pc->npoints > 0 );
 586
 587     pc->red_curve->reset();
 588     if ( ( p == pc->p[0] )
 589          || !in_svg_plane(p) )
 590     {
 591         pc->npoints = 1;
 592     } else {
 593         pc->p[1] = p;
 594         pc->npoints = 2;
 595
 596         pc->red_curve->moveto(pc->p[0]);
 597         pc->red_curve->lineto(pc->p[1]);
 598         pc->red_curve_is_valid = true;
 599
 600         sp_canvas_bpath_set_bpath(SP_CANVAS_BPATH(pc->red_bpath), pc->red_curve);
 601     }
 602 }
 603
 604 /**
 605  * Finalize addline.
 606  *
 607  * \todo
 608  * fixme: I'd like remove red reset from concat colors (lauris).
 609  * Still not sure, how it will make most sense.
 610  */
 611 static void
 612 spdc_finish_endpoint(SPPencilContext *const pc)
 613 {
 614     if ( ( pc->red_curve->is_empty() )
 615          || ( *(pc->red_curve->first_point()) == *(pc->red_curve->second_point())   ) )
 616     {
 617         pc->red_curve->reset();
 618         sp_canvas_bpath_set_bpath(SP_CANVAS_BPATH(pc->red_bpath), NULL);
 619     } else {
 620         /* Write curves to object. */
 621         spdc_concat_colors_and_flush(pc, FALSE);
 622         pc->sa = NULL;
 623         pc->ea = NULL;
 624     }
 625 }
 626
 627 static void
 628 spdc_add_freehand_point(SPPencilContext *pc, Geom::Point p, guint /*state*/)
 629 {
 630     g_assert( pc->npoints > 0 );
 631     g_return_if_fail(unsigned(pc->npoints) < G_N_ELEMENTS(pc->p));
 632
 633     if ( ( p != pc->p[ pc->npoints - 1 ] )
 634          && in_svg_plane(p) )
 635     {
 636         pc->p[pc->npoints++] = p;
 637         fit_and_split(pc);
 638     }
 639 }
 640
 641 static inline double
 642 square(double const x)
 643 {
 644     return x * x;
 645 }
 646
 647 static void
 648 fit_and_split(SPPencilContext *pc)
 649 {
 650     g_assert( pc->npoints > 1 );
 651
 652     Inkscape::Preferences *prefs = Inkscape::Preferences::get();
 653     double const tol = prefs->getDoubleLimited("/tools/freehand/pencil/tolerance", 10.0, 1.0, 100.0);
 654     double const tolerance_sq = 0.02 * square( pc->desktop->w2d().descrim() * tol)
 655         * exp(0.2*tol - 2);
 656
 657     Geom::Point b[4];
 658     g_assert(is_zero(pc->req_tangent)
 659              || is_unit_vector(pc->req_tangent));
 660     Geom::Point const tHatEnd(0, 0);
 661     int const n_segs = sp_bezier_fit_cubic_full(b, NULL, pc->p, pc->npoints,
 662                                                 pc->req_tangent, tHatEnd, tolerance_sq, 1);
 663     if ( n_segs > 0
 664          && unsigned(pc->npoints) < G_N_ELEMENTS(pc->p) )
 665     {
 666         /* Fit and draw and reset state */
 667         pc->red_curve->reset();
 668         pc->red_curve->moveto(b[0]);
 669         pc->red_curve->curveto(b[1], b[2], b[3]);
 670         sp_canvas_bpath_set_bpath(SP_CANVAS_BPATH(pc->red_bpath), pc->red_curve);
 671         pc->red_curve_is_valid = true;
 672     } else {
 673         /* Fit and draw and copy last point */
 674
 675         g_assert(!pc->red_curve->is_empty());
 676
 677         /* Set up direction of next curve. */
 678         {
 679             Geom::CubicBezier const * last_seg = dynamic_cast<Geom::CubicBezier const *>(pc->red_curve->last_segment());
 680             g_assert( last_seg );      // Relevance: validity of (*last_seg)[2]
 681             pc->p[0] = last_seg->finalPoint();
 682             pc->npoints = 1;
 683             Geom::Point const req_vec( pc->p[0] - (*last_seg)[2] );
 684             pc->req_tangent = ( ( Geom::is_zero(req_vec) || !in_svg_plane(req_vec) )
 685                                 ? Geom::Point(0, 0)
 686                                 : Geom::unit_vector(req_vec) );
 687         }
 688
 689         pc->green_curve->append_continuous(pc->red_curve, 0.0625);
 690         SPCurve *curve = pc->red_curve->copy();
 691
 692         /// \todo fixme:
 693         SPCanvasItem *cshape = sp_canvas_bpath_new(sp_desktop_sketch(pc->desktop), curve);
 694         curve->unref();
 695         sp_canvas_bpath_set_stroke(SP_CANVAS_BPATH(cshape), pc->green_color, 1.0, SP_STROKE_LINEJOIN_MITER, SP_STROKE_LINECAP_BUTT);
 696
 697         pc->green_bpaths = g_slist_prepend(pc->green_bpaths, cshape);
 698
 699         pc->red_curve_is_valid = false;
 700     }
 701 }
 702
 703
 704 /*
 705   Local Variables:
 706   mode:c++
 707   c-file-style:"stroustrup"
 708   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 709   indent-tabs-mode:nil
 710   fill-column:99
 711   End:
 712 */
 713 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :