src/event-context.cpp

   1 #define __SP_EVENT_CONTEXT_C__
   2
   3 /** \file
   4  * Main event handling, and related helper functions.
   5  *
   6  * Authors:
   7  *   Lauris Kaplinski <lauris@kaplinski.com>
   8  *   Frank Felfe <innerspace@iname.com>
   9  *   bulia byak <buliabyak@users.sf.net>
  10  *
  11  * Copyright (C) 1999-2005 authors
  12  * Copyright (C) 2001-2002 Ximian, Inc.
  13  *
  14  * Released under GNU GPL, read the file 'COPYING' for more information
  15  */
  16
  17 /** \class SPEventContext
  18  * SPEventContext is an abstract base class of all tools. As the name
  19  * indicates, event context implementations process UI events (mouse
  20  * movements and keypresses) and take actions (like creating or modifying
  21  * objects).  There is one event context implementation for each tool,
  22  * plus few abstract base classes. Writing a new tool involves
  23  * subclassing SPEventContext.
  24  */
  25
  26 #ifdef HAVE_CONFIG_H
  27 # include "config.h"
  28 #endif
  29
  30 #include "event-context.h"
  31
  32 #include <string.h>
  33 #include <gdk/gdkkeysyms.h>
  34 #include <gtk/gtkmain.h>
  35 #include <gtk/gtkmenu.h>
  36 #include <glibmm/i18n.h>
  37 #include <cstring>
  38 #include <string>
  39
  40 #include "display/sp-canvas.h"
  41 #include "xml/node-event-vector.h"
  42 #include "sp-cursor.h"
  43 #include "shortcuts.h"
  44 #include "desktop.h"
  45 #include "desktop-handles.h"
  46 #include "sp-namedview.h"
  47 #include "selection.h"
  48 #include "file.h"
  49 #include "interface.h"
  50 #include "macros.h"
  51 #include "tools-switch.h"
  52 #include "preferences.h"
  53 #include "message-context.h"
  54 #include "gradient-drag.h"
  55 #include "object-edit.h"
  56 #include "attributes.h"
  57 #include "rubberband.h"
  58 #include "selcue.h"
  59 #include "node-context.h"
  60 #include "lpe-tool-context.h"
  61
  62 static void sp_event_context_class_init(SPEventContextClass *klass);
  63 static void sp_event_context_init(SPEventContext *event_context);
  64 static void sp_event_context_dispose(GObject *object);
  65
  66 static void sp_event_context_private_setup(SPEventContext *ec);
  67 static gint sp_event_context_private_root_handler(SPEventContext *event_context, GdkEvent *event);
  68 static gint sp_event_context_private_item_handler(SPEventContext *event_context, SPItem *item, GdkEvent *event);
  69
  70 static void set_event_location(SPDesktop * desktop, GdkEvent * event);
  71
  72 static GObjectClass *parent_class;
  73
  74 // globals for temporary switching to selector by space
  75 static bool selector_toggled = FALSE;
  76 static int switch_selector_to = 0;
  77
  78 // globals for temporary switching to dropper by 'D'
  79 static bool dropper_toggled = FALSE;
  80 static int switch_dropper_to = 0;
  81
  82 static gint xp = 0, yp = 0; // where drag started
  83 static gint tolerance = 0;
  84 static bool within_tolerance = false;
  85
  86 // globals for keeping track of keyboard scroll events in order to accelerate
  87 static guint32 scroll_event_time = 0;
  88 static gdouble scroll_multiply = 1;
  89 static guint scroll_keyval = 0;
  90
  91 /**
  92  * Registers the SPEventContext class with Glib and returns its type number.
  93  */
  94 GType
  95 sp_event_context_get_type(void)
  96 {
  97     static GType type = 0;
  98     if (!type) {
  99         GTypeInfo info = {
 100             sizeof(SPEventContextClass),
 101             NULL, NULL,
 102             (GClassInitFunc) sp_event_context_class_init,
 103             NULL, NULL,
 104             sizeof(SPEventContext),
 105             4,
 106             (GInstanceInitFunc) sp_event_context_init,
 107             NULL,    /* value_table */
 108         };
 109         type = g_type_register_static(G_TYPE_OBJECT, "SPEventContext", &info, (GTypeFlags)0);
 110     }
 111     return type;
 112 }
 113
 114 /**
 115  * Callback to set up the SPEventContext vtable.
 116  */
 117 static void
 118 sp_event_context_class_init(SPEventContextClass *klass)
 119 {
 120     GObjectClass *object_class;
 121
 122     object_class = (GObjectClass *) klass;
 123
 124     parent_class = (GObjectClass*)g_type_class_peek_parent(klass);
 125
 126     object_class->dispose = sp_event_context_dispose;
 127
 128     klass->setup = sp_event_context_private_setup;
 129     klass->root_handler = sp_event_context_private_root_handler;
 130     klass->item_handler = sp_event_context_private_item_handler;
 131 }
 132
 133 /**
 134  * Clears all SPEventContext object members.
 135  */
 136 static void
 137 sp_event_context_init(SPEventContext *event_context)
 138 {
 139     event_context->desktop = NULL;
 140     event_context->cursor = NULL;
 141     event_context->_message_context = NULL;
 142     event_context->_selcue = NULL;
 143     event_context->_grdrag = NULL;
 144     event_context->space_panning = false;
 145     event_context->shape_editor = NULL;
 146     event_context->_delayed_snap_event = NULL;
 147 }
 148
 149 /**
 150  * Callback to free and null member variables of SPEventContext object.
 151  */
 152 static void
 153 sp_event_context_dispose(GObject *object)
 154 {
 155     SPEventContext *ec;
 156
 157     ec = SP_EVENT_CONTEXT(object);
 158
 159     if (ec->_message_context) {
 160         delete ec->_message_context;
 161     }
 162
 163     if (ec->cursor != NULL) {
 164         gdk_cursor_unref(ec->cursor);
 165         ec->cursor = NULL;
 166     }
 167
 168     if (ec->desktop) {
 169         ec->desktop = NULL;
 170     }
 171
 172     if (ec->pref_observer) {
 173         delete ec->pref_observer;
 174     }
 175
 176     if (ec->_delayed_snap_event) {
 177         delete ec->_delayed_snap_event;
 178     }
 179
 180     G_OBJECT_CLASS(parent_class)->dispose(object);
 181 }
 182
 183 /**
 184  * Recreates and draws cursor on desktop related to SPEventContext.
 185  */
 186 void
 187 sp_event_context_update_cursor(SPEventContext *ec)
 188 {
 189     GtkWidget *w = GTK_WIDGET(sp_desktop_canvas(ec->desktop));
 190     if (w->window) {
 191         /* fixme: */
 192         if (ec->cursor_shape) {
 193             GdkBitmap *bitmap = NULL;
 194             GdkBitmap *mask = NULL;
 195             sp_cursor_bitmap_and_mask_from_xpm(&bitmap, &mask, ec->cursor_shape);
 196             if ((bitmap != NULL) && (mask != NULL)) {
 197                 if (ec->cursor)
 198                     gdk_cursor_unref (ec->cursor);
 199                 ec->cursor = gdk_cursor_new_from_pixmap(bitmap, mask,
 200                                                         &w->style->black,
 201                                                         &w->style->white,
 202                                                         ec->hot_x, ec->hot_y);
 203                 g_object_unref (bitmap);
 204                 g_object_unref (mask);
 205             }
 206         }
 207         gdk_window_set_cursor(w->window, ec->cursor);
 208         gdk_flush();
 209     }
 210     ec->desktop->waiting_cursor = false;
 211 }
 212
 213 /**
 214  * Callback that gets called on initialization of SPEventContext object.
 215  * Redraws mouse cursor, at the moment.
 216  */
 217 static void
 218 sp_event_context_private_setup(SPEventContext *ec)
 219 {
 220     sp_event_context_update_cursor(ec);
 221 }
 222
 223 /**
 224  * \brief   Gobbles next key events on the queue with the same keyval and mask. Returns the number of events consumed.
 225  */
 226 gint gobble_key_events(guint keyval, gint mask)
 227 {
 228     GdkEvent *event_next;
 229     gint i = 0;
 230
 231     event_next = gdk_event_get();
 232     // while the next event is also a key notify with the same keyval and mask,
 233     while (event_next && (event_next->type == GDK_KEY_PRESS || event_next->type == GDK_KEY_RELEASE)
 234            && event_next->key.keyval == keyval
 235            && (!mask || (event_next->key.state & mask))) {
 236         if (event_next->type == GDK_KEY_PRESS)
 237             i ++;
 238         // kill it
 239         gdk_event_free(event_next);
 240         // get next
 241         event_next = gdk_event_get();
 242     }
 243     // otherwise, put it back onto the queue
 244     if (event_next) gdk_event_put(event_next);
 245
 246     return i;
 247 }
 248
 249 /**
 250  * \brief   Gobbles next motion notify events on the queue with the same mask. Returns the number of events consumed.
 251 */
 252 gint gobble_motion_events(gint mask)
 253 {
 254     GdkEvent *event_next;
 255     gint i = 0;
 256
 257     event_next = gdk_event_get();
 258     // while the next event is also a key notify with the same keyval and mask,
 259     while (event_next && event_next->type == GDK_MOTION_NOTIFY
 260            && (event_next->motion.state & mask)) {
 261         // kill it
 262         gdk_event_free(event_next);
 263         // get next
 264         event_next = gdk_event_get();
 265         i ++;
 266     }
 267     // otherwise, put it back onto the queue
 268     if (event_next) gdk_event_put(event_next);
 269
 270     return i;
 271 }
 272
 273 /**
 274  * Toggles current tool between active tool and selector tool.
 275  * Subroutine of sp_event_context_private_root_handler().
 276  */
 277 static void
 278 sp_toggle_selector(SPDesktop *dt)
 279 {
 280     if (!dt->event_context) return;
 281
 282     if (tools_isactive(dt, TOOLS_SELECT)) {
 283         if (selector_toggled) {
 284             if (switch_selector_to) tools_switch (dt, switch_selector_to);
 285             selector_toggled = FALSE;
 286         } else return;
 287     } else {
 288         selector_toggled = TRUE;
 289         switch_selector_to = tools_active(dt);
 290         tools_switch (dt, TOOLS_SELECT);
 291     }
 292 }
 293
 294 /**
 295  * Toggles current tool between active tool and dropper tool.
 296  * Subroutine of sp_event_context_private_root_handler().
 297  */
 298 static void
 299 sp_toggle_dropper(SPDesktop *dt)
 300 {
 301     if (!dt->event_context) return;
 302
 303     if (tools_isactive(dt, TOOLS_DROPPER)) {
 304         if (dropper_toggled) {
 305             if (switch_dropper_to) tools_switch (dt, switch_dropper_to);
 306             dropper_toggled = FALSE;
 307         } else return;
 308     } else {
 309         dropper_toggled = TRUE;
 310         switch_dropper_to = tools_active(dt);
 311         tools_switch (dt, TOOLS_DROPPER);
 312     }
 313 }
 314
 315 /**
 316  * Calculates and keeps track of scroll acceleration.
 317  * Subroutine of sp_event_context_private_root_handler().
 318  */
 319 static gdouble accelerate_scroll(GdkEvent *event, gdouble acceleration, SPCanvas */*canvas*/)
 320 {
 321     guint32 time_diff = ((GdkEventKey *) event)->time - scroll_event_time;
 322
 323     /* key pressed within 500ms ? (1/2 second) */
 324     if (time_diff > 500 || event->key.keyval != scroll_keyval) {
 325         scroll_multiply = 1; // abort acceleration
 326     } else {
 327         scroll_multiply += acceleration; // continue acceleration
 328     }
 329
 330     scroll_event_time = ((GdkEventKey *) event)->time;
 331     scroll_keyval = event->key.keyval;
 332
 333     return scroll_multiply;
 334 }
 335
 336 /**
 337  * Main event dispatch, gets called from Gdk.
 338  */
 339 static gint sp_event_context_private_root_handler(SPEventContext *event_context, GdkEvent *event)
 340 {
 341     static Geom::Point button_w;
 342     static unsigned int panning = 0;
 343     static unsigned int zoom_rb = 0;
 344
 345     SPDesktop *desktop = event_context->desktop;
 346     Inkscape::Preferences *prefs = Inkscape::Preferences::get();
 347
 348     /// @todo REmove redundant /value in preference keys
 349     tolerance = prefs->getIntLimited(
 350             "/options/dragtolerance/value", 0, 0, 100);
 351
 352     gint ret = FALSE;
 353
 354     switch (event->type) {
 355         case GDK_2BUTTON_PRESS:
 356             if (panning) {
 357                 panning = 0;
 358                 sp_canvas_item_ungrab(SP_CANVAS_ITEM(desktop->acetate),
 359                         event->button.time);
 360                 ret = TRUE;
 361             } else {
 362                 /* sp_desktop_dialog(); */
 363             }
 364             break;
 365         case GDK_BUTTON_PRESS:
 366
 367             // save drag origin
 368             xp = (gint) event->button.x;
 369             yp = (gint) event->button.y;
 370             within_tolerance = true;
 371
 372             button_w = Geom::Point(event->button.x, event->button.y);
 373
 374             switch (event->button.button) {
 375                 case 1:
 376                     if (event_context->space_panning) {
 377                         // When starting panning, make sure there are no snap events pending because these might disable the panning again
 378                         sp_event_context_discard_delayed_snap_event(event_context);
 379                         panning = 1;
 380                         sp_canvas_item_grab(SP_CANVAS_ITEM(desktop->acetate),
 381                             GDK_KEY_RELEASE_MASK | GDK_BUTTON_RELEASE_MASK | GDK_POINTER_MOTION_MASK | GDK_POINTER_MOTION_HINT_MASK,
 382                             NULL, event->button.time-1);
 383                         ret = TRUE;
 384                     }
 385                     break;
 386                 case 2:
 387                     if (event->button.state & GDK_SHIFT_MASK) {
 388                         zoom_rb = 2;
 389                     } else {
 390                         // When starting panning, make sure there are no snap events pending because these might disable the panning again
 391                                                 sp_event_context_discard_delayed_snap_event(event_context);
 392                                                 panning = 2;
 393                         sp_canvas_item_grab(SP_CANVAS_ITEM(desktop->acetate),
 394                             GDK_BUTTON_RELEASE_MASK | GDK_POINTER_MOTION_MASK | GDK_POINTER_MOTION_HINT_MASK,
 395                             NULL, event->button.time-1);
 396                     }
 397                     ret = TRUE;
 398                     break;
 399                 case 3:
 400                     if (event->button.state & GDK_SHIFT_MASK
 401                             || event->button.state & GDK_CONTROL_MASK) {
 402                         // When starting panning, make sure there are no snap events pending because these might disable the panning again
 403                                                 sp_event_context_discard_delayed_snap_event(event_context);
 404                         panning = 3;
 405                         sp_canvas_item_grab(SP_CANVAS_ITEM(desktop->acetate),
 406                                 GDK_BUTTON_RELEASE_MASK | GDK_POINTER_MOTION_MASK | GDK_POINTER_MOTION_HINT_MASK,
 407                                 NULL, event->button.time);
 408                         ret = TRUE;
 409                     } else {
 410                         sp_event_root_menu_popup(desktop, NULL, event);
 411                     }
 412                     break;
 413                 default:
 414                     break;
 415             }
 416             break;
 417         case GDK_MOTION_NOTIFY:
 418             if (panning) {
 419                 if ((panning == 2 && !(event->motion.state & GDK_BUTTON2_MASK))
 420                         || (panning == 1 && !(event->motion.state & GDK_BUTTON1_MASK))
 421                         || (panning == 3 && !(event->motion.state & GDK_BUTTON3_MASK))
 422                    ) {
 423                     /* Gdk seems to lose button release for us sometimes :-( */
 424                         panning = 0;
 425                     sp_canvas_item_ungrab(SP_CANVAS_ITEM(desktop->acetate),
 426                             event->button.time);
 427                     ret = TRUE;
 428                 } else {
 429                     if ( within_tolerance
 430                          && ( abs( (gint) event->motion.x - xp ) < tolerance )
 431                          && ( abs( (gint) event->motion.y - yp ) < tolerance ))
 432                     {
 433                         // do not drag if we're within tolerance from origin
 434                         break;
 435                     }
 436                     // Once the user has moved farther than tolerance from
 437                     // the original location (indicating they intend to move
 438                     // the object, not click), then always process the motion
 439                     // notify coordinates as given (no snapping back to origin)
 440                     within_tolerance = false;
 441
 442                     // gobble subsequent motion events to prevent "sticking"
 443                     // when scrolling is slow
 444                     gobble_motion_events(panning == 2 ?
 445                                          GDK_BUTTON2_MASK :
 446                                          (panning == 1 ? GDK_BUTTON1_MASK : GDK_BUTTON3_MASK));
 447
 448                     Geom::Point const motion_w(event->motion.x, event->motion.y);
 449                     Geom::Point const moved_w( motion_w - button_w );
 450                     event_context->desktop->scroll_world(moved_w, true); // we're still scrolling, do not redraw
 451                     ret = TRUE;
 452                 }
 453             } else if (zoom_rb) {
 454                 Geom::Point const motion_w(event->motion.x, event->motion.y);
 455                 Geom::Point const motion_dt(desktop->w2d(motion_w));
 456
 457                 if ( within_tolerance
 458                      && ( abs( (gint) event->motion.x - xp ) < tolerance )
 459                      && ( abs( (gint) event->motion.y - yp ) < tolerance ) ) {
 460                     break; // do not drag if we're within tolerance from origin
 461                 }
 462                 // Once the user has moved farther than tolerance from the original location
 463                 // (indicating they intend to move the object, not click), then always process the
 464                 // motion notify coordinates as given (no snapping back to origin)
 465                 within_tolerance = false;
 466
 467                 if (Inkscape::Rubberband::get(desktop)->is_started()) {
 468                     Inkscape::Rubberband::get(desktop)->move(motion_dt);
 469                 } else {
 470                     Inkscape::Rubberband::get(desktop)->start(desktop, motion_dt);
 471                 }
 472                 if (zoom_rb == 2)
 473                     gobble_motion_events(GDK_BUTTON2_MASK);
 474             }
 475             break;
 476         case GDK_BUTTON_RELEASE:
 477             xp = yp = 0;
 478             if (within_tolerance && (panning || zoom_rb)) {
 479                 zoom_rb = 0;
 480                 if (panning) {
 481                     panning = 0;
 482                     sp_canvas_item_ungrab(SP_CANVAS_ITEM(desktop->acetate),
 483                                       event->button.time);
 484                 }
 485                 Geom::Point const event_w(event->button.x, event->button.y);
 486                 Geom::Point const event_dt(desktop->w2d(event_w));
 487                 double const zoom_inc = prefs->getDoubleLimited("/options/zoomincrement/value", M_SQRT2, 1.01, 10);
 488                 desktop->zoom_relative_keep_point(event_dt,
 489                           (event->button.state & GDK_SHIFT_MASK) ? 1/zoom_inc : zoom_inc);
 490                 desktop->updateNow();
 491                 ret = TRUE;
 492             } else if (panning == event->button.button) {
 493                 panning = 0;
 494                 sp_canvas_item_ungrab(SP_CANVAS_ITEM(desktop->acetate),
 495                                       event->button.time);
 496
 497                 // in slow complex drawings, some of the motion events are lost;
 498                 // to make up for this, we scroll it once again to the button-up event coordinates
 499                 // (i.e. canvas will always get scrolled all the way to the mouse release point,
 500                 // even if few intermediate steps were visible)
 501                 Geom::Point const motion_w(event->button.x, event->button.y);
 502                 Geom::Point const moved_w( motion_w - button_w );
 503                 event_context->desktop->scroll_world(moved_w);
 504                 desktop->updateNow();
 505                 ret = TRUE;
 506             } else if (zoom_rb == event->button.button) {
 507                 zoom_rb = 0;
 508                 Geom::OptRect const b = Inkscape::Rubberband::get(desktop)->getRectangle();
 509                 Inkscape::Rubberband::get(desktop)->stop();
 510                 if (b && !within_tolerance) {
 511                     desktop->set_display_area(*b, 10);
 512                 }
 513                 ret = TRUE;
 514             }
 515             break;
 516         case GDK_KEY_PRESS:
 517                 {
 518                 double const acceleration = prefs->getDoubleLimited("/options/scrollingacceleration/value", 0, 0, 6);
 519                 int const key_scroll = prefs->getIntLimited("/options/keyscroll/value", 10, 0, 1000);
 520
 521                 switch (get_group0_keyval(&event->key)) {
 522                 // GDK insists on stealing these keys (F1 for no idea what, tab for cycling widgets
 523                 // in the editing window). So we resteal them back and run our regular shortcut
 524                 // invoker on them.
 525                 unsigned int shortcut;
 526                 case GDK_Tab:
 527                 case GDK_ISO_Left_Tab:
 528                 case GDK_F1:
 529                     shortcut = get_group0_keyval(&event->key);
 530                     if (event->key.state & GDK_SHIFT_MASK)
 531                         shortcut |= SP_SHORTCUT_SHIFT_MASK;
 532                     if (event->key.state & GDK_CONTROL_MASK)
 533                         shortcut |= SP_SHORTCUT_CONTROL_MASK;
 534                     if (event->key.state & GDK_MOD1_MASK)
 535                         shortcut |= SP_SHORTCUT_ALT_MASK;
 536                     ret = sp_shortcut_invoke(shortcut, desktop);
 537                     break;
 538
 539                 case GDK_D:
 540                 case GDK_d:
 541                     if (!MOD__SHIFT && !MOD__CTRL && !MOD__ALT) {
 542                         sp_toggle_dropper(desktop);
 543                         ret = TRUE;
 544                     }
 545                     break;
 546                 case GDK_Q:
 547                 case GDK_q:
 548                                         if (desktop->quick_zoomed()) {
 549                                                 ret = TRUE;
 550                                         }
 551                     if (!MOD__SHIFT && !MOD__CTRL && !MOD__ALT) {
 552                                                 desktop->zoom_quick(true);
 553                         ret = TRUE;
 554                     }
 555                     break;
 556                 case GDK_W:
 557                 case GDK_w:
 558                 case GDK_F4:
 559                     /* Close view */
 560                     if (MOD__CTRL_ONLY) {
 561                         sp_ui_close_view(NULL);
 562                         ret = TRUE;
 563                     }
 564                     break;
 565                 case GDK_Left: // Ctrl Left
 566                 case GDK_KP_Left:
 567                 case GDK_KP_4:
 568                     if (MOD__CTRL_ONLY) {
 569                         int i = (int) floor(key_scroll * accelerate_scroll(event, acceleration, sp_desktop_canvas(desktop)));
 570                         gobble_key_events(get_group0_keyval(&event->key),
 571                                 GDK_CONTROL_MASK);
 572                         event_context->desktop->scroll_world(i, 0);
 573                         ret = TRUE;
 574                     }
 575                     break;
 576                 case GDK_Up: // Ctrl Up
 577                 case GDK_KP_Up:
 578                 case GDK_KP_8:
 579                     if (MOD__CTRL_ONLY) {
 580                         int i = (int) floor(key_scroll * accelerate_scroll(event, acceleration, sp_desktop_canvas(desktop)));
 581                         gobble_key_events(get_group0_keyval(&event->key),
 582                                 GDK_CONTROL_MASK);
 583                         event_context->desktop->scroll_world(0, i);
 584                         ret = TRUE;
 585                     }
 586                     break;
 587                 case GDK_Right: // Ctrl Right
 588                 case GDK_KP_Right:
 589                 case GDK_KP_6:
 590                     if (MOD__CTRL_ONLY) {
 591                         int i = (int) floor(key_scroll * accelerate_scroll(event, acceleration, sp_desktop_canvas(desktop)));
 592                         gobble_key_events(get_group0_keyval(&event->key),
 593                                 GDK_CONTROL_MASK);
 594                         event_context->desktop->scroll_world(-i, 0);
 595                         ret = TRUE;
 596                     }
 597                     break;
 598                 case GDK_Down: // Ctrl Down
 599                 case GDK_KP_Down:
 600                 case GDK_KP_2:
 601                     if (MOD__CTRL_ONLY) {
 602                         int i = (int) floor(key_scroll * accelerate_scroll(event, acceleration, sp_desktop_canvas(desktop)));
 603                         gobble_key_events(get_group0_keyval(&event->key),
 604                                 GDK_CONTROL_MASK);
 605                         event_context->desktop->scroll_world(0, -i);
 606                         ret = TRUE;
 607                     }
 608                     break;
 609                 case GDK_F10:
 610                     if (MOD__SHIFT_ONLY) {
 611                         sp_event_root_menu_popup(desktop, NULL, event);
 612                         ret= TRUE;
 613                     }
 614                     break;
 615                 case GDK_space:
 616                     if (prefs->getBool("/options/spacepans/value")) {
 617                         event_context->space_panning = true;
 618                         event_context->_message_context->set(Inkscape::INFORMATION_MESSAGE, _("<b>Space+mouse drag</b> to pan canvas"));
 619                         ret= TRUE;
 620                     } else {
 621                         sp_toggle_selector(desktop);
 622                         ret= TRUE;
 623                     }
 624                     break;
 625                 case GDK_z:
 626                 case GDK_Z:
 627                     if (MOD__ALT_ONLY) {
 628                         desktop->zoom_grab_focus();
 629                         ret = TRUE;
 630                     }
 631                     break;
 632                 default:
 633                     break;
 634             }
 635                 }
 636             break;
 637         case GDK_KEY_RELEASE:
 638             switch (get_group0_keyval(&event->key)) {
 639                 case GDK_space:
 640                     if (event_context->space_panning) {
 641                         event_context->space_panning = false;
 642                         event_context->_message_context->clear();
 643                         if (panning == 1) {
 644                             panning = 0;
 645                             sp_canvas_item_ungrab(SP_CANVAS_ITEM(desktop->acetate),
 646                                   event->key.time);
 647                             desktop->updateNow();
 648                         }
 649                         ret= TRUE;
 650                     }
 651                     break;
 652                 case GDK_Q:
 653                 case GDK_q:
 654                                         if (desktop->quick_zoomed()) {
 655                                                 desktop->zoom_quick(false);
 656                         ret = TRUE;
 657                     }
 658                     break;
 659                 default:
 660                     break;
 661             }
 662             break;
 663         case GDK_SCROLL:
 664         {
 665             bool ctrl = (event->scroll.state & GDK_CONTROL_MASK);
 666             bool wheelzooms = prefs->getBool("/options/wheelzooms/value");
 667             int const wheel_scroll = prefs->getIntLimited("/options/wheelscroll/value", 40, 0, 1000);
 668
 669             /* shift + wheel, pan left--right */
 670             if (event->scroll.state & GDK_SHIFT_MASK) {
 671                 switch (event->scroll.direction) {
 672                     case GDK_SCROLL_UP:
 673                         desktop->scroll_world(wheel_scroll, 0);
 674                         break;
 675                     case GDK_SCROLL_DOWN:
 676                         desktop->scroll_world(-wheel_scroll, 0);
 677                         break;
 678                     default:
 679                         break;
 680                 }
 681
 682                 /* ctrl + wheel, zoom in--out */
 683             } else if ((ctrl && !wheelzooms) || (!ctrl && wheelzooms)) {
 684                 double rel_zoom;
 685                 double const zoom_inc = prefs->getDoubleLimited("/options/zoomincrement/value", M_SQRT2, 1.01, 10);
 686                 switch (event->scroll.direction) {
 687                     case GDK_SCROLL_UP:
 688                         rel_zoom = zoom_inc;
 689                         break;
 690                     case GDK_SCROLL_DOWN:
 691                         rel_zoom = 1 / zoom_inc;
 692                         break;
 693                     default:
 694                         rel_zoom = 0.0;
 695                         break;
 696                 }
 697                 if (rel_zoom != 0.0) {
 698                     Geom::Point const scroll_dt = desktop->point();
 699                     desktop->zoom_relative_keep_point(scroll_dt, rel_zoom);
 700                 }
 701
 702                 /* no modifier, pan up--down (left--right on multiwheel mice?) */
 703             } else {
 704                 switch (event->scroll.direction) {
 705                     case GDK_SCROLL_UP:
 706                         desktop->scroll_world(0, wheel_scroll);
 707                         break;
 708                     case GDK_SCROLL_DOWN:
 709                         desktop->scroll_world(0, -wheel_scroll);
 710                         break;
 711                     case GDK_SCROLL_LEFT:
 712                         desktop->scroll_world(wheel_scroll, 0);
 713                         break;
 714                     case GDK_SCROLL_RIGHT:
 715                         desktop->scroll_world(-wheel_scroll, 0);
 716                         break;
 717                 }
 718             }
 719             break;
 720         }
 721         default:
 722             break;
 723     }
 724
 725     return ret;
 726 }
 727
 728 /**
 729  * Handles item specific events. Gets called from Gdk.
 730  *
 731  * Only reacts to right mouse button at the moment.
 732  * \todo Fixme: do context sensitive popup menu on items.
 733  */
 734 gint
 735 sp_event_context_private_item_handler(SPEventContext *ec, SPItem *item, GdkEvent *event)
 736 {
 737     int ret = FALSE;
 738
 739     switch (event->type) {
 740         case GDK_BUTTON_PRESS:
 741             if ((event->button.button == 3)
 742                     && !(event->button.state & GDK_SHIFT_MASK || event->button.state & GDK_CONTROL_MASK)) {
 743                 sp_event_root_menu_popup(ec->desktop, item, event);
 744                 ret = TRUE;
 745             }
 746             break;
 747         default:
 748             break;
 749     }
 750
 751     return ret;
 752 }
 753
 754 /**
 755  * @brief An observer that relays pref changes to the derived classes
 756  */
 757 class ToolPrefObserver : public Inkscape::Preferences::Observer {
 758 public:
 759     ToolPrefObserver(Glib::ustring const &path, SPEventContext *ec) :
 760         Inkscape::Preferences::Observer(path),
 761         _ec(ec) {}
 762     virtual void notify(Inkscape::Preferences::Entry const &val)
 763     {
 764         if (((SPEventContextClass *) G_OBJECT_GET_CLASS(_ec))->set) {
 765             ((SPEventContextClass *) G_OBJECT_GET_CLASS(_ec))->set(_ec,
 766                 const_cast<Inkscape::Preferences::Entry*>(&val));
 767         }
 768     }
 769 private:
 770     SPEventContext * const _ec;
 771 };
 772
 773 /**
 774  * Creates new SPEventContext object and calls its virtual setup() function.
 775  * @todo This is bogus. pref_path should be a private property of the inheriting objects.
 776  */
 777 SPEventContext *
 778 sp_event_context_new(GType type, SPDesktop *desktop, gchar const *pref_path, unsigned int key)
 779 {
 780     g_return_val_if_fail(g_type_is_a(type, SP_TYPE_EVENT_CONTEXT), NULL);
 781     g_return_val_if_fail(desktop != NULL, NULL);
 782
 783     SPEventContext *const ec = (SPEventContext*)g_object_new(type, NULL);
 784
 785     ec->desktop = desktop;
 786     ec->_message_context = new Inkscape::MessageContext(desktop->messageStack());
 787     ec->key = key;
 788     ec->pref_observer = NULL;
 789
 790     if (pref_path) {
 791         ec->pref_observer = new ToolPrefObserver(pref_path, ec);
 792
 793         Inkscape::Preferences *prefs = Inkscape::Preferences::get();
 794         prefs->addObserver(*(ec->pref_observer));
 795     }
 796
 797     if (((SPEventContextClass *) G_OBJECT_GET_CLASS(ec))->setup)
 798         ((SPEventContextClass *) G_OBJECT_GET_CLASS(ec))->setup(ec);
 799
 800     return ec;
 801 }
 802
 803 /**
 804  * Finishes SPEventContext.
 805  */
 806 void
 807 sp_event_context_finish(SPEventContext *ec)
 808 {
 809     g_return_if_fail(ec != NULL);
 810     g_return_if_fail(SP_IS_EVENT_CONTEXT(ec));
 811
 812     ec->enableSelectionCue(false);
 813
 814     if (ec->next) {
 815         g_warning("Finishing event context with active link\n");
 816     }
 817
 818     if (((SPEventContextClass *) G_OBJECT_GET_CLASS(ec))->finish)
 819         ((SPEventContextClass *) G_OBJECT_GET_CLASS(ec))->finish(ec);
 820 }
 821
 822 //-------------------------------member functions
 823
 824 /**
 825  * Enables/disables the SPEventContext's SelCue.
 826  */
 827 void SPEventContext::enableSelectionCue(bool enable) {
 828     if (enable) {
 829         if (!_selcue) {
 830             _selcue = new Inkscape::SelCue(desktop);
 831         }
 832     } else {
 833         delete _selcue;
 834         _selcue = NULL;
 835     }
 836 }
 837
 838 /**
 839  * Enables/disables the SPEventContext's GrDrag.
 840  */
 841 void SPEventContext::enableGrDrag(bool enable) {
 842     if (enable) {
 843         if (!_grdrag) {
 844             _grdrag = new GrDrag(desktop);
 845         }
 846     } else {
 847         if (_grdrag) {
 848             delete _grdrag;
 849             _grdrag = NULL;
 850         }
 851     }
 852 }
 853
 854 /**
 855  * Calls virtual set() function of SPEventContext.
 856  */
 857 void
 858 sp_event_context_read(SPEventContext *ec, gchar const *key)
 859 {
 860     g_return_if_fail(ec != NULL);
 861     g_return_if_fail(SP_IS_EVENT_CONTEXT(ec));
 862     g_return_if_fail(key != NULL);
 863
 864     if (((SPEventContextClass *) G_OBJECT_GET_CLASS(ec))->set) {
 865         Inkscape::Preferences *prefs = Inkscape::Preferences::get();
 866         Inkscape::Preferences::Entry val = prefs->getEntry(
 867             ec->pref_observer->observed_path + '/' + key );
 868         ((SPEventContextClass *) G_OBJECT_GET_CLASS(ec))->set(ec, &val);
 869     }
 870 }
 871
 872 /**
 873  * Calls virtual activate() function of SPEventContext.
 874  */
 875 void
 876 sp_event_context_activate(SPEventContext *ec)
 877 {
 878     g_return_if_fail(ec != NULL);
 879     g_return_if_fail(SP_IS_EVENT_CONTEXT(ec));
 880
 881     // Make sure no delayed snapping events are carried over after switching contexts
 882     // (this is only an additional safety measure against sloppy coding, because each
 883     // context should take care of this by itself.
 884     sp_event_context_discard_delayed_snap_event(ec);
 885
 886     if (((SPEventContextClass *) G_OBJECT_GET_CLASS(ec))->activate)
 887         ((SPEventContextClass *) G_OBJECT_GET_CLASS(ec))->activate(ec);
 888 }
 889
 890 /**
 891  * Calls virtual deactivate() function of SPEventContext.
 892  */
 893 void
 894 sp_event_context_deactivate(SPEventContext *ec)
 895 {
 896     g_return_if_fail(ec != NULL);
 897     g_return_if_fail(SP_IS_EVENT_CONTEXT(ec));
 898
 899     if (((SPEventContextClass *) G_OBJECT_GET_CLASS(ec))->deactivate)
 900         ((SPEventContextClass *) G_OBJECT_GET_CLASS(ec))->deactivate(ec);
 901 }
 902
 903 /**
 904  * Calls virtual root_handler(), the main event handling function.
 905  */
 906 gint
 907 sp_event_context_root_handler(SPEventContext * event_context, GdkEvent * event)
 908 {
 909     switch (event->type) {
 910                 case GDK_MOTION_NOTIFY:
 911                         sp_event_context_snap_delay_handler(event_context, NULL, NULL, (GdkEventMotion *)event, DelayedSnapEvent::EVENTCONTEXT_ROOT_HANDLER);
 912                         break;
 913                 case GDK_BUTTON_RELEASE:
 914                         if (event_context->_delayed_snap_event) {
 915                                 // If we have any pending snapping action, then invoke it now
 916                                 sp_event_context_snap_watchdog_callback(event_context->_delayed_snap_event);
 917                         }
 918                         break;
 919                 case GDK_BUTTON_PRESS:
 920         case GDK_2BUTTON_PRESS:
 921         case GDK_3BUTTON_PRESS:
 922                         // Snapping will be on hold if we're moving the mouse at high speeds. When starting
 923                         // drawing a new shape we really should snap though.
 924                         event_context->desktop->namedview->snap_manager.snapprefs.setSnapPostponedGlobally(false);
 925                         break;
 926         default:
 927                 break;
 928     }
 929
 930     return sp_event_context_virtual_root_handler(event_context, event);
 931 }
 932
 933 gint
 934 sp_event_context_virtual_root_handler(SPEventContext * event_context, GdkEvent * event)
 935 {
 936         gint ret = ((SPEventContextClass *) G_OBJECT_GET_CLASS(event_context))->root_handler(event_context, event);
 937         set_event_location(event_context->desktop, event);
 938         return ret;
 939 }
 940
 941 /**
 942  * Calls virtual item_handler(), the item event handling function.
 943  */
 944 gint
 945 sp_event_context_item_handler(SPEventContext * event_context, SPItem * item, GdkEvent * event)
 946 {
 947         switch (event->type) {
 948                 case GDK_MOTION_NOTIFY:
 949                         sp_event_context_snap_delay_handler(event_context, item, NULL, (GdkEventMotion *)event, DelayedSnapEvent::EVENTCONTEXT_ITEM_HANDLER);
 950                         break;
 951                 case GDK_BUTTON_RELEASE:
 952                         if (event_context->_delayed_snap_event) {
 953                                 // If we have any pending snapping action, then invoke it now
 954                                 sp_event_context_snap_watchdog_callback(event_context->_delayed_snap_event);
 955                         }
 956                         break;
 957                 /*case GDK_BUTTON_PRESS:
 958                 case GDK_2BUTTON_PRESS:
 959                 case GDK_3BUTTON_PRESS:
 960                         // Snapping will be on hold if we're moving the mouse at high speeds. When starting
 961                         // drawing a new shape we really should snap though.
 962                         event_context->desktop->namedview->snap_manager.snapprefs.setSnapPostponedGlobally(false);
 963                         break;
 964                 */
 965                 default:
 966                         break;
 967         }
 968
 969     return sp_event_context_virtual_item_handler(event_context, item, event);
 970 }
 971
 972 gint
 973 sp_event_context_virtual_item_handler(SPEventContext * event_context, SPItem * item, GdkEvent * event)
 974 {
 975         gint ret = ((SPEventContextClass *) G_OBJECT_GET_CLASS(event_context))->item_handler(event_context, item, event);
 976
 977         if (! ret) {
 978                 ret = sp_event_context_virtual_root_handler(event_context, event);
 979         } else {
 980                 set_event_location(event_context->desktop, event);
 981         }
 982
 983         return ret;
 984 }
 985
 986 /**
 987  * Emits 'position_set' signal on desktop and shows coordinates on status bar.
 988  */
 989 static void set_event_location(SPDesktop *desktop, GdkEvent *event)
 990 {
 991     if (event->type != GDK_MOTION_NOTIFY) {
 992         return;
 993     }
 994
 995     Geom::Point const button_w(event->button.x, event->button.y);
 996     Geom::Point const button_dt(desktop->w2d(button_w));
 997     desktop->setPosition(button_dt);
 998     desktop->set_coordinate_status(button_dt);
 999 }
1000
1001 //-------------------------------------------------------------------
1002 /**
1003  * Create popup menu and tell Gtk to show it.
1004  */
1005 void
1006 sp_event_root_menu_popup(SPDesktop *desktop, SPItem *item, GdkEvent *event)
1007 {
1008     GtkWidget *menu;
1009
1010     /* fixme: This is not what I want but works for now (Lauris) */
1011     if (event->type == GDK_KEY_PRESS) {
1012         item = sp_desktop_selection(desktop)->singleItem();
1013     }
1014     menu = sp_ui_context_menu(desktop, item);
1015     gtk_widget_show(menu);
1016
1017     switch (event->type) {
1018         case GDK_BUTTON_PRESS:
1019             gtk_menu_popup(GTK_MENU(menu), NULL, NULL, 0, NULL, event->button.button, event->button.time);
1020             break;
1021         case GDK_KEY_PRESS:
1022             gtk_menu_popup(GTK_MENU(menu), NULL, NULL, 0, NULL, 0, event->key.time);
1023             break;
1024         default:
1025             break;
1026     }
1027 }
1028
1029 /**
1030  * Show tool context specific modifier tip.
1031  */
1032 void
1033 sp_event_show_modifier_tip(Inkscape::MessageContext *message_context,
1034         GdkEvent *event, gchar const *ctrl_tip, gchar const *shift_tip,
1035         gchar const *alt_tip)
1036 {
1037     guint keyval = get_group0_keyval(&event->key);
1038
1039     bool ctrl = ctrl_tip && (MOD__CTRL
1040             || (keyval == GDK_Control_L)
1041             || (keyval == GDK_Control_R));
1042     bool shift = shift_tip
1043         && (MOD__SHIFT || (keyval == GDK_Shift_L) || (keyval == GDK_Shift_R));
1044     bool alt = alt_tip
1045         && (MOD__ALT
1046                 || (keyval == GDK_Alt_L)
1047                 || (keyval == GDK_Alt_R)
1048                 || (keyval == GDK_Meta_L)
1049                 || (keyval == GDK_Meta_R));
1050
1051     gchar *tip = g_strdup_printf("%s%s%s%s%s",
1052                                  ( ctrl ? ctrl_tip : "" ),
1053                                  ( ctrl && (shift || alt) ? "; " : "" ),
1054                                  ( shift ? shift_tip : "" ),
1055                                  ( (ctrl || shift) && alt ? "; " : "" ),
1056                                  ( alt ? alt_tip : "" ));
1057
1058     if (strlen(tip) > 0) {
1059         message_context->flash(Inkscape::INFORMATION_MESSAGE, tip);
1060     }
1061
1062     g_free(tip);
1063 }
1064
1065 /**
1066  * Return the keyval corresponding to the key event in group 0, i.e.,
1067  * in the main (English) layout.
1068  *
1069  * Use this instead of simply event->keyval, so that your keyboard shortcuts
1070  * work regardless of layouts (e.g., in Cyrillic).
1071  */
1072 guint
1073 get_group0_keyval(GdkEventKey *event)
1074 {
1075     guint keyval = 0;
1076     gdk_keymap_translate_keyboard_state(
1077             gdk_keymap_get_for_display(gdk_display_get_default()),
1078             event->hardware_keycode,
1079             (GdkModifierType) event->state,
1080             0   /*event->key.group*/,
1081             &keyval, NULL, NULL, NULL);
1082     return keyval;
1083 }
1084
1085 /**
1086  * Returns item at point p in desktop.
1087  *
1088  * If state includes alt key mask, cyclically selects under; honors
1089  * into_groups.
1090  */
1091 SPItem *
1092 sp_event_context_find_item (SPDesktop *desktop, Geom::Point const &p,
1093         bool select_under, bool into_groups)
1094 {
1095     SPItem *item;
1096
1097     if (select_under) {
1098         SPItem *selected_at_point =
1099             desktop->item_from_list_at_point_bottom (desktop->selection->itemList(), p);
1100         item = desktop->item_at_point(p, into_groups, selected_at_point);
1101         if (item == NULL) { // we may have reached bottom, flip over to the top
1102             item = desktop->item_at_point(p, into_groups, NULL);
1103         }
1104     } else
1105         item = desktop->item_at_point(p, into_groups, NULL);
1106
1107     return item;
1108 }
1109
1110 /**
1111  * Returns item if it is under point p in desktop, at any depth; otherwise returns NULL.
1112  *
1113  * Honors into_groups.
1114  */
1115 SPItem *
1116 sp_event_context_over_item (SPDesktop *desktop, SPItem *item, Geom::Point const &p)
1117 {
1118     GSList *temp = NULL;
1119     temp = g_slist_prepend (temp, item);
1120     SPItem *item_at_point = desktop->item_from_list_at_point_bottom (temp, p);
1121     g_slist_free (temp);
1122
1123     return item_at_point;
1124 }
1125
1126 ShapeEditor *
1127 sp_event_context_get_shape_editor (SPEventContext *ec)
1128 {
1129     return ec->shape_editor;
1130 }
1131
1132 void
1133 event_context_print_event_info(GdkEvent *event, bool print_return) {
1134     switch (event->type) {
1135         case GDK_BUTTON_PRESS:
1136             g_print ("GDK_BUTTON_PRESS");
1137             break;
1138         case GDK_2BUTTON_PRESS:
1139             g_print ("GDK_2BUTTON_PRESS");
1140             break;
1141         case GDK_3BUTTON_PRESS:
1142             g_print ("GDK_3BUTTON_PRESS");
1143             break;
1144
1145         case GDK_MOTION_NOTIFY:
1146             g_print ("GDK_MOTION_NOTIFY");
1147             break;
1148         case GDK_ENTER_NOTIFY:
1149             g_print ("GDK_ENTER_NOTIFY");
1150             break;
1151
1152         case GDK_LEAVE_NOTIFY:
1153             g_print ("GDK_LEAVE_NOTIFY");
1154             break;
1155         case GDK_BUTTON_RELEASE:
1156             g_print ("GDK_BUTTON_RELEASE");
1157             break;
1158
1159         case GDK_KEY_PRESS:
1160             g_print ("GDK_KEY_PRESS: %d", get_group0_keyval(&event->key));
1161             break;
1162         case GDK_KEY_RELEASE:
1163             g_print ("GDK_KEY_RELEASE: %d", get_group0_keyval(&event->key));
1164             break;
1165         default:
1166             //g_print ("even type not recognized");
1167             break;
1168     }
1169
1170     if (print_return) {
1171         g_print ("\n");
1172     }
1173 }
1174
1175 void sp_event_context_snap_delay_handler(SPEventContext *ec, SPItem* const item, SPKnot* const knot, GdkEventMotion *event, DelayedSnapEvent::DelayedSnapEventOrigin origin)
1176 {
1177         static guint32 prev_time;
1178         static boost::optional<Geom::Point> prev_pos;
1179
1180         // Snapping occurs when dragging with the left mouse button down, or when hovering e.g. in the pen tool with left mouse button up
1181     bool const c1 = event->state & GDK_BUTTON2_MASK; // We shouldn't hold back any events when other mouse buttons have been
1182     bool const c2 = event->state & GDK_BUTTON3_MASK; // pressed, e.g. when scrolling with the middle mouse button; if we do then
1183                                                                                                      // Inkscape will get stuck in an unresponsive state
1184     bool const c3 = tools_isactive(ec->desktop, TOOLS_CALLIGRAPHIC);
1185                                                      // The snap delay will repeat the last motion event, which will lead to
1186                                                      // erroneous points in the calligraphy context. And because we don't snap
1187                                                      // in this context, we might just as well disable the snap delay all together
1188
1189     if (c1 || c2 || c3) {
1190         // Make sure that we don't send any pending snap events to a context if we know in advance
1191         // that we're not going to snap any way (e.g. while scrolling with middle mouse button)
1192         // Any motion event might affect the state of the context, leading to unexpected behavior
1193         sp_event_context_discard_delayed_snap_event(ec);
1194     } else if (ec->desktop && ec->desktop->namedview->snap_manager.snapprefs.getSnapEnabledGlobally()) {
1195                 // Snap when speed drops below e.g. 0.02 px/msec, or when no motion events have occurred for some period.
1196                 // i.e. snap when we're at stand still. A speed threshold enforces snapping for tablets, which might never
1197                 // be fully at stand still and might keep spitting out motion events.
1198                 ec->desktop->namedview->snap_manager.snapprefs.setSnapPostponedGlobally(true); // put snapping on hold
1199
1200                 Geom::Point event_pos(event->x, event->y);
1201                 guint32 event_t = gdk_event_get_time ( (GdkEvent *) event );
1202
1203                 if (prev_pos) {
1204                         Geom::Coord dist = Geom::L2(event_pos - *prev_pos);
1205                         guint32 delta_t = event_t - prev_time;
1206                         gdouble speed = delta_t > 0 ? dist/delta_t : 1000;
1207                         //std::cout << "Mouse speed = " << speed << " px/msec " << std::endl;
1208                         if (speed > 0.02) { // Jitter threshold, might be needed for tablets
1209                                 // We're moving fast, so postpone any snapping until the next GDK_MOTION_NOTIFY event. We
1210                                 // will keep on postponing the snapping as long as the speed is high.
1211                                 // We must snap at some point in time though, so set a watchdog timer at some time from
1212                                 // now, just in case there's no future motion event that drops under the speed limit (when
1213                                 // stopping abruptly)
1214                                 delete ec->_delayed_snap_event;
1215                                 ec->_delayed_snap_event = new DelayedSnapEvent(ec, item, knot, event, origin); // watchdog is reset, i.e. pushed forward in time
1216                                 // If the watchdog expires before a new motion event is received, we will snap (as explained
1217                                 // above). This means however that when the timer is too short, we will always snap and that the
1218                                 // speed threshold is ineffective. In the extreme case the delay is set to zero, and snapping will
1219                                 // be immediate, as it used to be in the old days ;-).
1220                         } else { // Speed is very low, so we're virtually at stand still
1221                                 // But if we're really standing still, then we should snap now. We could use some low-pass filtering,
1222                                 // otherwise snapping occurs for each jitter movement. For this filtering we'll leave the watchdog to expire,
1223                                 // snap, and set a new watchdog again.
1224                                 if (ec->_delayed_snap_event == NULL) { // no watchdog has been set
1225                                         // it might have already expired, so we'll set a new one; the snapping frequency will be limited by this
1226                                         ec->_delayed_snap_event = new DelayedSnapEvent(ec, item, knot, event, origin);
1227                                 } // else: watchdog has been set before and we'll wait for it to expire
1228                         }
1229                 } else {
1230                         // This is the first GDK_MOTION_NOTIFY event, so postpone snapping and set the watchdog
1231                         g_assert(ec->_delayed_snap_event == NULL);
1232                         ec->_delayed_snap_event = new DelayedSnapEvent(ec, item, knot, event, origin);
1233                 }
1234
1235                 prev_pos = event_pos;
1236                 prev_time = event_t;
1237     }
1238 }
1239
1240 gboolean sp_event_context_snap_watchdog_callback(gpointer data)
1241 {
1242         // Snap NOW! For this the "postponed" flag will be reset and the last motion event will be repeated
1243         DelayedSnapEvent *dse = reinterpret_cast<DelayedSnapEvent*>(data);
1244
1245         if (dse == NULL) {
1246                 // This might occur when this method is called directly, i.e. not through the timer
1247                 // E.g. on GDK_BUTTON_RELEASE in sp_event_context_root_handler()
1248                 return FALSE;
1249         }
1250
1251         SPEventContext *ec = dse->getEventContext();
1252         if (ec == NULL || ec->desktop == NULL) {
1253                 return false;
1254         }
1255
1256         SPDesktop *dt = ec->desktop;
1257         dt->namedview->snap_manager.snapprefs.setSnapPostponedGlobally(false);
1258
1259         switch (dse->getOrigin()) {
1260                 case DelayedSnapEvent::EVENTCONTEXT_ROOT_HANDLER:
1261                         sp_event_context_virtual_root_handler(ec, dse->getEvent());
1262                         break;
1263                 case DelayedSnapEvent::EVENTCONTEXT_ITEM_HANDLER:
1264                         {
1265                                 SPItem* item = NULL;
1266                                 item = dse->getItem();
1267                                 if (item && SP_IS_ITEM(item)) {
1268                                         sp_event_context_virtual_item_handler(ec, item, dse->getEvent());
1269                                 }
1270                         }
1271                         break;
1272                 case DelayedSnapEvent::KNOT_HANDLER:
1273                         {
1274                                 SPKnot* knot = dse->getKnot();
1275                                 if (knot && SP_IS_KNOT(knot)) {
1276                                         sp_knot_handler_request_position(dse->getEvent(), knot);
1277                                 }
1278                         }
1279                         break;
1280                 default:
1281                         g_warning("Origin of snap-delay event has not been defined!;");
1282                         break;
1283         }
1284
1285         ec->_delayed_snap_event = NULL;
1286         delete dse;
1287
1288         return FALSE; //Kills the timer and stops it from executing this callback over and over again.
1289 }
1290
1291 void sp_event_context_discard_delayed_snap_event(SPEventContext *ec)
1292 {
1293         delete ec->_delayed_snap_event;
1294         ec->_delayed_snap_event = NULL;
1295 }
1296
1297
1298
1299 /*
1300   Local Variables:
1301   mode:c++
1302   c-file-style:"stroustrup"
1303   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
1304   indent-tabs-mode:nil
1305   fill-column:99
1306   End:
1307 */
1308 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :