Update to trunk

(bzr r11950.1.195)

1 files changed, 1541 insertions, 0 deletions

diff --git a/src/ui/tools/tool-base.cpp b/src/ui/tools/tool-base.cpp
new file mode 100644
index 000000000..c123aec27
--- /dev/null
+++ b/src/ui/tools/tool-base.cpp
@@ -0,0 +1,1541 @@
+/*
+ * Main event handling, and related helper functions.
+ *
+ * Authors:
+ *   Lauris Kaplinski <lauris@kaplinski.com>
+ *   Frank Felfe <innerspace@iname.com>
+ *   bulia byak <buliabyak@users.sf.net>
+ *   Jon A. Cruz <jon@joncruz.org>
+ *   Kris De Gussem <Kris.DeGussem@gmail.com>
+ *
+ * Copyright (C) 1999-2012 authors
+ * Copyright (C) 2001-2002 Ximian, Inc.
+ *
+ * Released under GNU GPL, read the file 'COPYING' for more information
+ */
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#if GLIBMM_DISABLE_DEPRECATED && HAVE_GLIBMM_THREADS_H
+#include <glibmm/threads.h>
+#endif
+
+#include "shortcuts.h"
+#include "file.h"
+#include "ui/tools/tool-base.h"
+
+#include <string.h>
+#include <gdk/gdkkeysyms.h>
+#include <gtk/gtk.h>
+#include <glibmm/i18n.h>
+#include <cstring>
+#include <string>
+
+#include "display/sp-canvas.h"
+#include "xml/node-event-vector.h"
+#include "sp-cursor.h"
+#include "desktop.h"
+#include "desktop-handles.h"
+#include "desktop-events.h"
+#include "desktop-style.h"
+#include "widgets/desktop-widget.h"
+#include "sp-namedview.h"
+#include "selection.h"
+#include "interface.h"
+#include "macros.h"
+#include "tools-switch.h"
+#include "preferences.h"
+#include "message-context.h"
+#include "gradient-drag.h"
+#include "attributes.h"
+#include "rubberband.h"
+#include "selcue.h"
+#include "ui/tools/lpe-tool.h"
+#include "ui/tool/control-point.h"
+#include "shape-editor.h"
+#include "sp-guide.h"
+#include "color.h"
+
+// globals for temporary switching to selector by space
+static bool selector_toggled = FALSE;
+static int switch_selector_to = 0;
+
+// globals for temporary switching to dropper by 'D'
+static bool dropper_toggled = FALSE;
+static int switch_dropper_to = 0;
+
+//static gint xp = 0, yp = 0; // where drag started
+//static gint tolerance = 0;
+//static bool within_tolerance = false;
+
+// globals for keeping track of keyboard scroll events in order to accelerate
+static guint32 scroll_event_time = 0;
+static gdouble scroll_multiply = 1;
+static guint scroll_keyval = 0;
+
+
+namespace Inkscape {
+namespace UI {
+namespace Tools {
+
+static void set_event_location(SPDesktop * desktop, GdkEvent * event);
+
+
+void ToolBase::set(const Inkscape::Preferences::Entry& /*val*/) {
+}
+
+void ToolBase::activate() {
+}
+
+void ToolBase::deactivate() {
+}
+
+void ToolBase::finish() {
+	this->enableSelectionCue(false);
+}
+
+ToolBase::ToolBase() {
+	this->hot_y = 0;
+	this->xp = 0;
+	this->cursor_shape = 0;
+	this->pref_observer = 0;
+	this->hot_x = 0;
+	this->yp = 0;
+	this->within_tolerance = false;
+	this->tolerance = 0;
+	//this->key = 0;
+	this->item_to_select = 0;
+
+    this->desktop = NULL;
+    this->cursor = NULL;
+    this->message_context = NULL;
+    this->_selcue = NULL;
+    this->_grdrag = NULL;
+    this->space_panning = false;
+    this->shape_editor = NULL;
+    this->_delayed_snap_event = NULL;
+    this->_dse_callback_in_process = false;
+    //this->tool_url = NULL;
+}
+
+ToolBase::~ToolBase() {
+    if (this->message_context) {
+        delete this->message_context;
+    }
+
+    if (this->cursor != NULL) {
+#if GTK_CHECK_VERSION(3,0,0)
+        g_object_unref(this->cursor);
+#else
+        gdk_cursor_unref(this->cursor);
+#endif
+        this->cursor = NULL;
+    }
+
+    if (this->desktop) {
+        this->desktop = NULL;
+    }
+
+    if (this->pref_observer) {
+        delete this->pref_observer;
+    }
+
+    if (this->_delayed_snap_event) {
+        delete this->_delayed_snap_event;
+    }
+}
+
+
+/**
+ * Set the cursor to a standard GDK cursor
+ */
+static void sp_event_context_set_cursor(ToolBase *event_context, GdkCursorType cursor_type) {
+
+    GtkWidget *w = GTK_WIDGET(sp_desktop_canvas(event_context->desktop));
+    GdkDisplay *display = gdk_display_get_default();
+    GdkCursor *cursor = gdk_cursor_new_for_display(display, cursor_type);
+
+#if WITH_GTKMM_3_0
+    if (cursor) {
+          gdk_window_set_cursor (gtk_widget_get_window (w), cursor);
+          g_object_unref (cursor);
+    }
+#else
+    gdk_window_set_cursor (gtk_widget_get_window (w), cursor);
+    gdk_cursor_unref (cursor);
+#endif
+
+}
+
+/**
+ * Recreates and draws cursor on desktop related to ToolBase.
+ */
+void ToolBase::sp_event_context_update_cursor() {
+    GtkWidget *w = GTK_WIDGET(sp_desktop_canvas(this->desktop));
+    if (gtk_widget_get_window (w)) {
+    
+        GtkStyle *style = gtk_widget_get_style(w);
+
+        /* fixme: */
+        if (this->cursor_shape) {
+            GdkDisplay *display = gdk_display_get_default();
+            if (gdk_display_supports_cursor_alpha(display) && gdk_display_supports_cursor_color(display)) {
+                bool fillHasColor=false, strokeHasColor=false;
+                guint32 fillColor = sp_desktop_get_color_tool(this->desktop, this->getPrefsPath(), true, &fillHasColor);
+                guint32 strokeColor = sp_desktop_get_color_tool(this->desktop, this->getPrefsPath(), false, &strokeHasColor);
+                double fillOpacity = fillHasColor ? sp_desktop_get_opacity_tool(this->desktop, this->getPrefsPath(), true) : 0;
+                double strokeOpacity = strokeHasColor ? sp_desktop_get_opacity_tool(this->desktop, this->getPrefsPath(), false) : 0;
+
+                GdkPixbuf *pixbuf = sp_cursor_pixbuf_from_xpm(
+                    this->cursor_shape,
+                    style->black, style->white,
+                    SP_RGBA32_U_COMPOSE(SP_RGBA32_R_U(fillColor),SP_RGBA32_G_U(fillColor),SP_RGBA32_B_U(fillColor),SP_COLOR_F_TO_U(fillOpacity)),
+                    SP_RGBA32_U_COMPOSE(SP_RGBA32_R_U(strokeColor),SP_RGBA32_G_U(strokeColor),SP_RGBA32_B_U(strokeColor),SP_COLOR_F_TO_U(strokeOpacity))
+                    );
+                if (pixbuf != NULL) {
+                    if (this->cursor) {
+#if GTK_CHECK_VERSION(3,0,0)
+                        g_object_unref(this->cursor);
+#else
+                        gdk_cursor_unref(this->cursor);
+#endif
+                    }
+                    this->cursor = gdk_cursor_new_from_pixbuf(display, pixbuf, this->hot_x, this->hot_y);
+                    g_object_unref(pixbuf);
+                }
+            } else {
+            	GdkPixbuf *pixbuf = gdk_pixbuf_new_from_xpm_data((const gchar **)this->cursor_shape);
+
+                if (pixbuf) {
+                    if (this->cursor) {
+#if GTK_CHECK_VERSION(3,0,0)
+                        g_object_unref(this->cursor);
+#else
+                        gdk_cursor_unref(this->cursor);
+#endif
+                    }
+                    this->cursor = gdk_cursor_new_from_pixbuf(display,
+                    pixbuf, this->hot_x, this->hot_y);
+                    g_object_unref(pixbuf);
+                }
+            }
+        }
+        gdk_window_set_cursor(gtk_widget_get_window (w), this->cursor);
+        gdk_flush();
+    }
+    this->desktop->waiting_cursor = false;
+}
+
+/**
+ * Callback that gets called on initialization of ToolBase object.
+ * Redraws mouse cursor, at the moment.
+ */
+
+/**
+ * When you override it, call this method first.
+ */
+void ToolBase::setup() {
+    this->pref_observer = new ToolPrefObserver(this->getPrefsPath(), this);
+    Inkscape::Preferences::get()->addObserver(*(this->pref_observer));
+
+	this->sp_event_context_update_cursor();
+}
+
+/**
+ * Gobbles next key events on the queue with the same keyval and mask. Returns the number of events consumed.
+ */
+gint gobble_key_events(guint keyval, gint mask) {
+    GdkEvent *event_next;
+    gint i = 0;
+
+    event_next = gdk_event_get();
+    // while the next event is also a key notify with the same keyval and mask,
+    while (event_next && (event_next->type == GDK_KEY_PRESS || event_next->type
+            == GDK_KEY_RELEASE) && event_next->key.keyval == keyval && (!mask
+            || (event_next->key.state & mask))) {
+        if (event_next->type == GDK_KEY_PRESS)
+            i++;
+        // kill it
+        gdk_event_free(event_next);
+        // get next
+        event_next = gdk_event_get();
+    }
+    // otherwise, put it back onto the queue
+    if (event_next)
+        gdk_event_put(event_next);
+
+    return i;
+}
+
+/**
+ * Gobbles next motion notify events on the queue with the same mask. Returns the number of events consumed.
+ */
+gint gobble_motion_events(gint mask) {
+    GdkEvent *event_next;
+    gint i = 0;
+
+    event_next = gdk_event_get();
+    // while the next event is also a key notify with the same keyval and mask,
+    while (event_next && event_next->type == GDK_MOTION_NOTIFY
+            && (event_next->motion.state & mask)) {
+        // kill it
+        gdk_event_free(event_next);
+        // get next
+        event_next = gdk_event_get();
+        i++;
+    }
+    // otherwise, put it back onto the queue
+    if (event_next)
+        gdk_event_put(event_next);
+
+    return i;
+}
+
+/**
+ * Toggles current tool between active tool and selector tool.
+ * Subroutine of sp_event_context_private_root_handler().
+ */
+static void sp_toggle_selector(SPDesktop *dt) {
+    if (!dt->event_context)
+        return;
+
+    if (tools_isactive(dt, TOOLS_SELECT)) {
+        if (selector_toggled) {
+            if (switch_selector_to)
+                tools_switch(dt, switch_selector_to);
+            selector_toggled = FALSE;
+        } else
+            return;
+    } else {
+        selector_toggled = TRUE;
+        switch_selector_to = tools_active(dt);
+        tools_switch(dt, TOOLS_SELECT);
+    }
+}
+
+/**
+ * Toggles current tool between active tool and dropper tool.
+ * Subroutine of sp_event_context_private_root_handler().
+ */
+void sp_toggle_dropper(SPDesktop *dt) {
+    if (!dt->event_context)
+        return;
+
+    if (tools_isactive(dt, TOOLS_DROPPER)) {
+        if (dropper_toggled) {
+            if (switch_dropper_to)
+                tools_switch(dt, switch_dropper_to);
+            dropper_toggled = FALSE;
+        } else
+            return;
+    } else {
+        dropper_toggled = TRUE;
+        switch_dropper_to = tools_active(dt);
+        tools_switch(dt, TOOLS_DROPPER);
+    }
+}
+
+/**
+ * Calculates and keeps track of scroll acceleration.
+ * Subroutine of sp_event_context_private_root_handler().
+ */
+static gdouble accelerate_scroll(GdkEvent *event, gdouble acceleration,
+        SPCanvas */*canvas*/) {
+    guint32 time_diff = ((GdkEventKey *) event)->time - scroll_event_time;
+
+    /* key pressed within 500ms ? (1/2 second) */
+    if (time_diff > 500 || event->key.keyval != scroll_keyval) {
+        scroll_multiply = 1; // abort acceleration
+    } else {
+        scroll_multiply += acceleration; // continue acceleration
+    }
+
+    scroll_event_time = ((GdkEventKey *) event)->time;
+    scroll_keyval = event->key.keyval;
+
+    return scroll_multiply;
+}
+
+/**
+ * Main event dispatch, gets called from Gdk.
+ */
+//static gint sp_event_context_private_root_handler(
+//        ToolBase *event_context, GdkEvent *event) {
+//
+//	return event_context->ceventcontext->root_handler(event);
+//}
+
+bool ToolBase::root_handler(GdkEvent* event) {
+    static Geom::Point button_w;
+    static unsigned int panning = 0;
+    static unsigned int panning_cursor = 0;
+    static unsigned int zoom_rb = 0;
+
+    Inkscape::Preferences *prefs = Inkscape::Preferences::get();
+
+    /// @todo REmove redundant /value in preference keys
+    tolerance = prefs->getIntLimited("/options/dragtolerance/value", 0, 0, 100);
+
+    gint ret = FALSE;
+
+    switch (event->type) {
+    case GDK_2BUTTON_PRESS:
+        if (panning) {
+            panning = 0;
+            sp_canvas_item_ungrab(SP_CANVAS_ITEM(desktop->acetate), event->button.time);
+            ret = TRUE;
+        } else {
+            /* sp_desktop_dialog(); */
+        }
+        break;
+
+    case GDK_BUTTON_PRESS:
+        // save drag origin
+        xp = (gint) event->button.x;
+        yp = (gint) event->button.y;
+        within_tolerance = true;
+
+        button_w = Geom::Point(event->button.x, event->button.y);
+
+        switch (event->button.button) {
+        case 1:
+            if (this->space_panning) {
+                // When starting panning, make sure there are no snap events pending because these might disable the panning again
+                sp_event_context_discard_delayed_snap_event(this);
+                panning = 1;
+
+                sp_canvas_item_grab(SP_CANVAS_ITEM(desktop->acetate),
+                        GDK_KEY_RELEASE_MASK | GDK_BUTTON_RELEASE_MASK
+                                | GDK_POINTER_MOTION_MASK
+                                | GDK_POINTER_MOTION_HINT_MASK, NULL,
+                        event->button.time - 1);
+
+                ret = TRUE;
+            }
+            break;
+
+        case 2:
+            if (event->button.state & GDK_SHIFT_MASK) {
+                zoom_rb = 2;
+            } else {
+                // When starting panning, make sure there are no snap events pending because these might disable the panning again
+                sp_event_context_discard_delayed_snap_event(this);
+                panning = 2;
+
+                sp_canvas_item_grab(SP_CANVAS_ITEM(desktop->acetate),
+                        GDK_BUTTON_RELEASE_MASK | GDK_POINTER_MOTION_MASK
+                                | GDK_POINTER_MOTION_HINT_MASK, NULL,
+                        event->button.time - 1);
+
+            }
+
+            ret = TRUE;
+            break;
+
+        case 3:
+            if ((event->button.state & GDK_SHIFT_MASK) || (event->button.state & GDK_CONTROL_MASK)) {
+                // When starting panning, make sure there are no snap events pending because these might disable the panning again
+                sp_event_context_discard_delayed_snap_event(this);
+                panning = 3;
+
+                sp_canvas_item_grab(SP_CANVAS_ITEM(desktop->acetate),
+                        GDK_BUTTON_RELEASE_MASK | GDK_POINTER_MOTION_MASK
+                                | GDK_POINTER_MOTION_HINT_MASK, NULL,
+                        event->button.time);
+
+                ret = TRUE;
+            } else {
+                sp_event_root_menu_popup(desktop, NULL, event);
+            }
+            break;
+
+        default:
+            break;
+        }
+        break;
+
+    case GDK_MOTION_NOTIFY:
+        if (panning) {
+            if (panning == 4 && !xp && !yp ) {
+                // <Space> + mouse panning started, save location and grab canvas
+                xp = event->motion.x;
+                yp = event->motion.y;
+                button_w = Geom::Point(event->motion.x, event->motion.y);
+
+                sp_canvas_item_grab(SP_CANVAS_ITEM(desktop->acetate),
+                        GDK_KEY_RELEASE_MASK | GDK_BUTTON_RELEASE_MASK
+                                | GDK_POINTER_MOTION_MASK
+                                | GDK_POINTER_MOTION_HINT_MASK, NULL,
+                        event->motion.time - 1);
+            }
+
+            if ((panning == 2 && !(event->motion.state & GDK_BUTTON2_MASK))
+                    || (panning == 1 && !(event->motion.state & GDK_BUTTON1_MASK))
+                    || (panning == 3 && !(event->motion.state & GDK_BUTTON3_MASK))) {
+                /* Gdk seems to lose button release for us sometimes :-( */
+                panning = 0;
+                sp_canvas_item_ungrab(SP_CANVAS_ITEM(desktop->acetate), event->button.time);
+                ret = TRUE;
+            } else {
+                if (within_tolerance && (abs((gint) event->motion.x - xp)
+                        < tolerance) && (abs((gint) event->motion.y - yp)
+                        < tolerance)) {
+                    // do not drag if we're within tolerance from origin
+                    break;
+                }
+
+                // Once the user has moved farther than tolerance from
+                // the original location (indicating they intend to move
+                // the object, not click), then always process the motion
+                // notify coordinates as given (no snapping back to origin)
+                within_tolerance = false;
+
+                // gobble subsequent motion events to prevent "sticking"
+                // when scrolling is slow
+                gobble_motion_events(panning == 2 ? GDK_BUTTON2_MASK : (panning
+                        == 1 ? GDK_BUTTON1_MASK : GDK_BUTTON3_MASK));
+
+                if (panning_cursor == 0) {
+                    panning_cursor = 1;
+                    sp_event_context_set_cursor(this, GDK_FLEUR);
+                }
+
+                Geom::Point const motion_w(event->motion.x, event->motion.y);
+                Geom::Point const moved_w(motion_w - button_w);
+                this->desktop->scroll_world(moved_w, true); // we're still scrolling, do not redraw
+                ret = TRUE;
+            }
+        } else if (zoom_rb) {
+            Geom::Point const motion_w(event->motion.x, event->motion.y);
+            Geom::Point const motion_dt(desktop->w2d(motion_w));
+
+            if (within_tolerance && (abs((gint) event->motion.x - xp)
+                    < tolerance) && (abs((gint) event->motion.y - yp)
+                    < tolerance)) {
+                break; // do not drag if we're within tolerance from origin
+            }
+
+            // Once the user has moved farther than tolerance from the original location
+            // (indicating they intend to move the object, not click), then always process the
+            // motion notify coordinates as given (no snapping back to origin)
+            within_tolerance = false;
+
+            if (Inkscape::Rubberband::get(desktop)->is_started()) {
+                Inkscape::Rubberband::get(desktop)->move(motion_dt);
+            } else {
+                Inkscape::Rubberband::get(desktop)->start(desktop, motion_dt);
+            }
+
+            if (zoom_rb == 2) {
+                gobble_motion_events(GDK_BUTTON2_MASK);
+            }
+        }
+        break;
+
+    case GDK_BUTTON_RELEASE:
+        xp = yp = 0;
+
+        if (panning_cursor == 1) {
+            panning_cursor = 0;
+            GtkWidget *w = GTK_WIDGET(sp_desktop_canvas(this->desktop));
+            gdk_window_set_cursor(gtk_widget_get_window (w), this->cursor);
+        }
+
+        if (within_tolerance && (panning || zoom_rb)) {
+            zoom_rb = 0;
+
+            if (panning) {
+                panning = 0;
+                sp_canvas_item_ungrab(SP_CANVAS_ITEM(desktop->acetate),
+                        event->button.time);
+            }
+
+            Geom::Point const event_w(event->button.x, event->button.y);
+            Geom::Point const event_dt(desktop->w2d(event_w));
+
+            double const zoom_inc = prefs->getDoubleLimited(
+                    "/options/zoomincrement/value", M_SQRT2, 1.01, 10);
+
+            desktop->zoom_relative_keep_point(event_dt, (event->button.state
+                    & GDK_SHIFT_MASK) ? 1 / zoom_inc : zoom_inc);
+
+            desktop->updateNow();
+            ret = TRUE;
+        } else if (panning == event->button.button) {
+            panning = 0;
+            sp_canvas_item_ungrab(SP_CANVAS_ITEM(desktop->acetate),
+                    event->button.time);
+
+            // in slow complex drawings, some of the motion events are lost;
+            // to make up for this, we scroll it once again to the button-up event coordinates
+            // (i.e. canvas will always get scrolled all the way to the mouse release point,
+            // even if few intermediate steps were visible)
+            Geom::Point const motion_w(event->button.x, event->button.y);
+            Geom::Point const moved_w(motion_w - button_w);
+
+            this->desktop->scroll_world(moved_w);
+            desktop->updateNow();
+            ret = TRUE;
+        } else if (zoom_rb == event->button.button) {
+            zoom_rb = 0;
+
+            Geom::OptRect const b = Inkscape::Rubberband::get(desktop)->getRectangle();
+            Inkscape::Rubberband::get(desktop)->stop();
+
+            if (b && !within_tolerance) {
+                desktop->set_display_area(*b, 10);
+            }
+
+            ret = TRUE;
+        }
+        break;
+
+    case GDK_KEY_PRESS: {
+        double const acceleration = prefs->getDoubleLimited(
+                "/options/scrollingacceleration/value", 0, 0, 6);
+
+        int const key_scroll = prefs->getIntLimited("/options/keyscroll/value",
+                10, 0, 1000);
+
+        switch (get_group0_keyval(&event->key)) {
+        // GDK insists on stealing these keys (F1 for no idea what, tab for cycling widgets
+        // in the editing window). So we resteal them back and run our regular shortcut
+        // invoker on them.
+        unsigned int shortcut;
+        case GDK_KEY_Tab:
+        case GDK_KEY_ISO_Left_Tab:
+        case GDK_KEY_F1:
+            shortcut = get_group0_keyval(&event->key);
+
+            if (event->key.state & GDK_SHIFT_MASK) {
+                shortcut |= SP_SHORTCUT_SHIFT_MASK;
+            }
+
+            if (event->key.state & GDK_CONTROL_MASK) {
+                shortcut |= SP_SHORTCUT_CONTROL_MASK;
+            }
+
+            if (event->key.state & GDK_MOD1_MASK) {
+                shortcut |= SP_SHORTCUT_ALT_MASK;
+            }
+
+            ret = sp_shortcut_invoke(shortcut, desktop);
+            break;
+
+        case GDK_KEY_Q:
+        case GDK_KEY_q:
+            if (desktop->quick_zoomed()) {
+                ret = TRUE;
+            }
+            if (!MOD__SHIFT(event) && !MOD__CTRL(event) && !MOD__ALT(event)) {
+                desktop->zoom_quick(true);
+                ret = TRUE;
+            }
+            break;
+
+        case GDK_KEY_W:
+        case GDK_KEY_w:
+        case GDK_KEY_F4:
+            /* Close view */
+            if (MOD__CTRL_ONLY(event)) {
+                sp_ui_close_view(NULL);
+                ret = TRUE;
+            }
+            break;
+
+        case GDK_KEY_Left: // Ctrl Left
+        case GDK_KEY_KP_Left:
+        case GDK_KEY_KP_4:
+            if (MOD__CTRL_ONLY(event)) {
+                int i = (int) floor(key_scroll * accelerate_scroll(event,
+                        acceleration, sp_desktop_canvas(desktop)));
+
+                gobble_key_events(get_group0_keyval(&event->key), GDK_CONTROL_MASK);
+                this->desktop->scroll_world(i, 0);
+                ret = TRUE;
+            }
+            break;
+
+        case GDK_KEY_Up: // Ctrl Up
+        case GDK_KEY_KP_Up:
+        case GDK_KEY_KP_8:
+            if (MOD__CTRL_ONLY(event)) {
+                int i = (int) floor(key_scroll * accelerate_scroll(event,
+                        acceleration, sp_desktop_canvas(desktop)));
+
+                gobble_key_events(get_group0_keyval(&event->key), GDK_CONTROL_MASK);
+                this->desktop->scroll_world(0, i);
+                ret = TRUE;
+            }
+            break;
+
+        case GDK_KEY_Right: // Ctrl Right
+        case GDK_KEY_KP_Right:
+        case GDK_KEY_KP_6:
+            if (MOD__CTRL_ONLY(event)) {
+                int i = (int) floor(key_scroll * accelerate_scroll(event,
+                        acceleration, sp_desktop_canvas(desktop)));
+
+                gobble_key_events(get_group0_keyval(&event->key), GDK_CONTROL_MASK);
+                this->desktop->scroll_world(-i, 0);
+                ret = TRUE;
+            }
+            break;
+
+        case GDK_KEY_Down: // Ctrl Down
+        case GDK_KEY_KP_Down:
+        case GDK_KEY_KP_2:
+            if (MOD__CTRL_ONLY(event)) {
+                int i = (int) floor(key_scroll * accelerate_scroll(event,
+                        acceleration, sp_desktop_canvas(desktop)));
+
+                gobble_key_events(get_group0_keyval(&event->key), GDK_CONTROL_MASK);
+                this->desktop->scroll_world(0, -i);
+                ret = TRUE;
+            }
+            break;
+
+        case GDK_KEY_F10:
+            if (MOD__SHIFT_ONLY(event)) {
+                sp_event_root_menu_popup(desktop, NULL, event);
+                ret = TRUE;
+            }
+            break;
+
+        case GDK_KEY_space:
+            xp = yp = 0;
+            within_tolerance = true;
+            panning = 4;
+
+            this->space_panning = true;
+            this->message_context->set(Inkscape::INFORMATION_MESSAGE,
+                    _("<b>Space+mouse move</b> to pan canvas"));
+
+            ret = TRUE;
+            break;
+
+        case GDK_KEY_z:
+        case GDK_KEY_Z:
+            if (MOD__ALT_ONLY(event)) {
+                desktop->zoom_grab_focus();
+                ret = TRUE;
+            }
+            break;
+
+        default:
+            break;
+            }
+        }
+        break;
+
+    case GDK_KEY_RELEASE:
+        // Stop panning on any key release
+        if (this->space_panning) {
+            this->space_panning = false;
+            this->message_context->clear();
+        }
+
+        if (panning) {
+            panning = 0;
+            xp = yp = 0;
+
+            sp_canvas_item_ungrab(SP_CANVAS_ITEM(desktop->acetate),
+                    event->key.time);
+
+            desktop->updateNow();
+        }
+
+        if (panning_cursor == 1) {
+            panning_cursor = 0;
+            GtkWidget *w = GTK_WIDGET(sp_desktop_canvas(this->desktop));
+            gdk_window_set_cursor(gtk_widget_get_window (w), this->cursor);
+        }
+
+        switch (get_group0_keyval(&event->key)) {
+        case GDK_KEY_space:
+            if (within_tolerance == true) {
+                // Space was pressed, but not panned
+                sp_toggle_selector(desktop);
+                ret = TRUE;
+            }
+
+            within_tolerance = false;
+            break;
+
+        case GDK_KEY_Q:
+        case GDK_KEY_q:
+            if (desktop->quick_zoomed()) {
+                desktop->zoom_quick(false);
+                ret = TRUE;
+            }
+            break;
+
+        default:
+            break;
+        }
+        break;
+
+    case GDK_SCROLL: {
+        bool ctrl = (event->scroll.state & GDK_CONTROL_MASK);
+        bool wheelzooms = prefs->getBool("/options/wheelzooms/value");
+
+        int const wheel_scroll = prefs->getIntLimited(
+                "/options/wheelscroll/value", 40, 0, 1000);
+
+#if GTK_CHECK_VERSION(3,0,0)
+        // Size of smooth-scrolls (only used in GTK+ 3)
+        gdouble delta_x = 0;
+        gdouble delta_y = 0;
+#endif
+
+        /* shift + wheel, pan left--right */
+        if (event->scroll.state & GDK_SHIFT_MASK) {
+            switch (event->scroll.direction) {
+            case GDK_SCROLL_UP:
+                desktop->scroll_world(wheel_scroll, 0);
+                break;
+
+            case GDK_SCROLL_DOWN:
+                desktop->scroll_world(-wheel_scroll, 0);
+                break;
+
+            default:
+                break;
+            }
+
+            /* ctrl + wheel, zoom in--out */
+        } else if ((ctrl && !wheelzooms) || (!ctrl && wheelzooms)) {
+            double rel_zoom;
+            double const zoom_inc = prefs->getDoubleLimited(
+                    "/options/zoomincrement/value", M_SQRT2, 1.01, 10);
+
+            switch (event->scroll.direction) {
+            case GDK_SCROLL_UP:
+                rel_zoom = zoom_inc;
+                break;
+
+            case GDK_SCROLL_DOWN:
+                rel_zoom = 1 / zoom_inc;
+                break;
+
+            default:
+                rel_zoom = 0.0;
+                break;
+            }
+
+            if (rel_zoom != 0.0) {
+                Geom::Point const scroll_dt = desktop->point();
+                desktop->zoom_relative_keep_point(scroll_dt, rel_zoom);
+            }
+
+            /* no modifier, pan up--down (left--right on multiwheel mice?) */
+        } else {
+            switch (event->scroll.direction) {
+            case GDK_SCROLL_UP:
+                desktop->scroll_world(0, wheel_scroll);
+                break;
+
+            case GDK_SCROLL_DOWN:
+                desktop->scroll_world(0, -wheel_scroll);
+                break;
+
+            case GDK_SCROLL_LEFT:
+                desktop->scroll_world(wheel_scroll, 0);
+                break;
+
+            case GDK_SCROLL_RIGHT:
+                desktop->scroll_world(-wheel_scroll, 0);
+                break;
+
+#if GTK_CHECK_VERSION(3,0,0)
+            case GDK_SCROLL_SMOOTH:
+                gdk_event_get_scroll_deltas(event, &delta_x, &delta_y);
+                desktop->scroll_world(delta_x, delta_y);
+                break;
+#endif
+            }
+        }
+        break;
+    }
+    default:
+        break;
+    }
+
+    return ret;
+}
+
+/**
+ * Handles item specific events. Gets called from Gdk.
+ *
+ * Only reacts to right mouse button at the moment.
+ * \todo Fixme: do context sensitive popup menu on items.
+ */
+//gint sp_event_context_private_item_handler(ToolBase *ec, SPItem *item,
+//        GdkEvent *event) {
+//
+//	return ec->ceventcontext->item_handler(item, event);
+//}
+
+bool ToolBase::item_handler(SPItem* item, GdkEvent* event) {
+    int ret = FALSE;
+
+    switch (event->type) {
+    case GDK_BUTTON_PRESS:
+        if ((event->button.button == 3) && !((event->button.state & GDK_SHIFT_MASK) || (event->button.state & GDK_CONTROL_MASK))) {
+            sp_event_root_menu_popup(this->desktop, item, event);
+            ret = TRUE;
+        }
+        break;
+
+    default:
+        break;
+    }
+
+    return ret;
+}
+
+/**
+ * Returns true if we're hovering above a knot (needed because we don't want to pre-snap in that case).
+ */
+bool sp_event_context_knot_mouseover(ToolBase *ec)
+{
+    if (ec->shape_editor) {
+        return ec->shape_editor->knot_mouseover();
+    }
+
+    return false;
+}
+
+/**
+ * Creates new ToolBase object and calls its virtual setup() function.
+ * @todo This is bogus. pref_path should be a private property of the inheriting objects.
+ */
+//ToolBase *
+//sp_event_context_new(GType type, SPDesktop *desktop, gchar const *pref_path,
+//        unsigned int key) {
+//    g_return_val_if_fail(g_type_is_a(type, SP_TYPE_EVENT_CONTEXT), NULL);
+//    g_return_val_if_fail(desktop != NULL, NULL);
+//
+//    ToolBase * const ec = static_cast<ToolBase*>(g_object_new(type, NULL));
+//
+//    ec->desktop = desktop;
+//    ec->_message_context
+//            = new Inkscape::MessageContext(desktop->messageStack());
+//    ec->key = key;
+//    ec->pref_observer = NULL;
+//
+//    if (pref_path) {
+//        ec->pref_observer = new ToolPrefObserver(pref_path, ec);
+//
+//        Inkscape::Preferences *prefs = Inkscape::Preferences::get();
+//        prefs->addObserver(*(ec->pref_observer));
+//    }
+//
+////    if ((SP_EVENT_CONTEXT_CLASS(G_OBJECT_GET_CLASS(ec)))->setup)
+////        (SP_EVENT_CONTEXT_CLASS(G_OBJECT_GET_CLASS(ec)))->setup(ec);
+//    ec->ceventcontext->setup();
+//
+//    return ec;
+//}
+
+/**
+ * Finishes ToolBase.
+ */
+//void sp_event_context_finish(ToolBase *ec) {
+//    g_return_if_fail(ec != NULL);
+//    g_return_if_fail(SP_IS_EVENT_CONTEXT(ec));
+//
+//    ec->enableSelectionCue(false);
+//
+////    if (ec->next) {
+////        g_warning("Finishing event context with active link\n");
+////    }
+//
+////    if ((SP_EVENT_CONTEXT_CLASS(G_OBJECT_GET_CLASS(ec)))->finish)
+////        (SP_EVENT_CONTEXT_CLASS(G_OBJECT_GET_CLASS(ec)))->finish(ec);
+//    ec->finish();
+//}
+
+//-------------------------------member functions
+
+/**
+ * Enables/disables the ToolBase's SelCue.
+ */
+void ToolBase::enableSelectionCue(bool enable) {
+    if (enable) {
+        if (!_selcue) {
+            _selcue = new Inkscape::SelCue(desktop);
+        }
+    } else {
+        delete _selcue;
+        _selcue = NULL;
+    }
+}
+
+/**
+ * Enables/disables the ToolBase's GrDrag.
+ */
+void ToolBase::enableGrDrag(bool enable) {
+    if (enable) {
+        if (!_grdrag) {
+            _grdrag = new GrDrag(desktop);
+        }
+    } else {
+        if (_grdrag) {
+            delete _grdrag;
+            _grdrag = NULL;
+        }
+    }
+}
+
+/**
+ * Delete a selected GrDrag point
+ */
+bool ToolBase::deleteSelectedDrag(bool just_one) {
+
+    if (_grdrag && _grdrag->selected) {
+        _grdrag->deleteSelected(just_one);
+        return TRUE;
+    }
+
+    return FALSE;
+}
+
+/**
+ * Calls virtual set() function of ToolBase.
+ */
+void sp_event_context_read(ToolBase *ec, gchar const *key) {
+    g_return_if_fail(ec != NULL);
+    g_return_if_fail(SP_IS_EVENT_CONTEXT(ec));
+    g_return_if_fail(key != NULL);
+
+//    if ((SP_EVENT_CONTEXT_CLASS(G_OBJECT_GET_CLASS(ec)))->set) {
+//        Inkscape::Preferences *prefs = Inkscape::Preferences::get();
+//        Inkscape::Preferences::Entry val = prefs->getEntry(
+//                ec->pref_observer->observed_path + '/' + key);
+//        (SP_EVENT_CONTEXT_CLASS(G_OBJECT_GET_CLASS(ec)))->set(ec, &val);
+//    }
+
+    Inkscape::Preferences *prefs = Inkscape::Preferences::get();
+    Inkscape::Preferences::Entry val = prefs->getEntry(ec->pref_observer->observed_path + '/' + key);
+    ec->set(val);
+}
+
+/**
+ * Calls virtual activate() function of ToolBase.
+ */
+void sp_event_context_activate(ToolBase *ec) {
+    g_return_if_fail(ec != NULL);
+    g_return_if_fail(SP_IS_EVENT_CONTEXT(ec));
+
+    // Make sure no delayed snapping events are carried over after switching contexts
+    // (this is only an additional safety measure against sloppy coding, because each
+    // context should take care of this by itself.
+    sp_event_context_discard_delayed_snap_event(ec);
+
+//    if ((SP_EVENT_CONTEXT_CLASS(G_OBJECT_GET_CLASS(ec)))->activate)
+//        (SP_EVENT_CONTEXT_CLASS(G_OBJECT_GET_CLASS(ec)))->activate(ec);
+    ec->activate();
+}
+
+/**
+ * Calls virtual deactivate() function of ToolBase.
+ */
+//void sp_event_context_deactivate(ToolBase *ec) {
+//    g_return_if_fail(ec != NULL);
+//    g_return_if_fail(SP_IS_EVENT_CONTEXT(ec));
+//
+////    if ((SP_EVENT_CONTEXT_CLASS(G_OBJECT_GET_CLASS(ec)))->deactivate)
+////        (SP_EVENT_CONTEXT_CLASS(G_OBJECT_GET_CLASS(ec)))->deactivate(ec);
+//    ec->deactivate();
+//}
+
+/**
+ * Calls virtual root_handler(), the main event handling function.
+ */
+gint sp_event_context_root_handler(ToolBase * event_context,
+        GdkEvent * event)
+{
+    switch (event->type) {
+    case GDK_MOTION_NOTIFY:
+        sp_event_context_snap_delay_handler(event_context, NULL, NULL,
+                (GdkEventMotion *) event,
+                DelayedSnapEvent::EVENTCONTEXT_ROOT_HANDLER);
+        break;
+    case GDK_BUTTON_RELEASE:
+        if (event_context && event_context->_delayed_snap_event) {
+            // If we have any pending snapping action, then invoke it now
+            sp_event_context_snap_watchdog_callback(
+                    event_context->_delayed_snap_event);
+        }
+        break;
+    case GDK_BUTTON_PRESS:
+    case GDK_2BUTTON_PRESS:
+    case GDK_3BUTTON_PRESS:
+        // Snapping will be on hold if we're moving the mouse at high speeds. When starting
+        // drawing a new shape we really should snap though.
+        event_context->desktop->namedview->snap_manager.snapprefs.setSnapPostponedGlobally(
+                false);
+        break;
+    default:
+        break;
+    }
+
+    return sp_event_context_virtual_root_handler(event_context, event);
+}
+
+gint sp_event_context_virtual_root_handler(ToolBase * event_context, GdkEvent * event) {
+    gint ret = false;
+    if (event_context) {    // If no event-context is available then do nothing, otherwise Inkscape would crash
+                            // (see the comment in SPDesktop::set_event_context, and bug LP #622350)
+        //ret = (SP_EVENT_CONTEXT_CLASS(G_OBJECT_GET_CLASS(event_context)))->root_handler(event_context, event);
+    	ret = event_context->root_handler(event);
+
+        set_event_location(event_context->desktop, event);
+    }
+    return ret;
+}
+
+/**
+ * Calls virtual item_handler(), the item event handling function.
+ */
+gint sp_event_context_item_handler(ToolBase * event_context,
+        SPItem * item, GdkEvent * event) {
+    switch (event->type) {
+    case GDK_MOTION_NOTIFY:
+        sp_event_context_snap_delay_handler(event_context, (gpointer) item, NULL, (GdkEventMotion *) event, DelayedSnapEvent::EVENTCONTEXT_ITEM_HANDLER);
+        break;
+    case GDK_BUTTON_RELEASE:
+        if (event_context && event_context->_delayed_snap_event) {
+            // If we have any pending snapping action, then invoke it now
+            sp_event_context_snap_watchdog_callback(event_context->_delayed_snap_event);
+        }
+        break;
+    case GDK_BUTTON_PRESS:
+    case GDK_2BUTTON_PRESS:
+    case GDK_3BUTTON_PRESS:
+        // Snapping will be on hold if we're moving the mouse at high speeds. When starting
+        // drawing a new shape we really should snap though.
+        event_context->desktop->namedview->snap_manager.snapprefs.setSnapPostponedGlobally(false);
+        break;
+    default:
+        break;
+    }
+
+    return sp_event_context_virtual_item_handler(event_context, item, event);
+}
+
+gint sp_event_context_virtual_item_handler(ToolBase * event_context, SPItem * item, GdkEvent * event) {
+    gint ret = false;
+    if (event_context) {    // If no event-context is available then do nothing, otherwise Inkscape would crash
+                            // (see the comment in SPDesktop::set_event_context, and bug LP #622350)
+        //ret = (SP_EVENT_CONTEXT_CLASS(G_OBJECT_GET_CLASS(event_context)))->item_handler(event_context, item, event);
+    	ret = event_context->item_handler(item, event);
+
+        if (!ret) {
+            ret = sp_event_context_virtual_root_handler(event_context, event);
+        } else {
+            set_event_location(event_context->desktop, event);
+        }
+    }
+
+    return ret;
+}
+
+/**
+ * Shows coordinates on status bar.
+ */
+static void set_event_location(SPDesktop *desktop, GdkEvent *event) {
+    if (event->type != GDK_MOTION_NOTIFY) {
+        return;
+    }
+
+    Geom::Point const button_w(event->button.x, event->button.y);
+    Geom::Point const button_dt(desktop->w2d(button_w));
+    desktop->set_coordinate_status(button_dt);
+}
+
+//-------------------------------------------------------------------
+/**
+ * Create popup menu and tell Gtk to show it.
+ */
+void sp_event_root_menu_popup(SPDesktop *desktop, SPItem *item, GdkEvent *event) {
+
+    // It seems the param item is the SPItem at the bottom of the z-order
+    // Using the same function call used on left click in sp_select_context_item_handler() to get top of z-order
+    // fixme: sp_canvas_arena should set the top z-order object as arena->active
+    item = sp_event_context_find_item (desktop,
+                              Geom::Point(event->button.x, event->button.y), FALSE, FALSE);
+
+    /* fixme: This is not what I want but works for now (Lauris) */
+    if (event->type == GDK_KEY_PRESS) {
+        item = sp_desktop_selection(desktop)->singleItem();
+    }
+
+    ContextMenu* CM = new ContextMenu(desktop, item);
+    CM->show();
+
+    switch (event->type) {
+    case GDK_BUTTON_PRESS:
+        CM->popup(event->button.button, event->button.time);
+        break;
+    case GDK_KEY_PRESS:
+        CM->popup(0, event->key.time);
+        break;
+    default:
+        break;
+    }
+}
+
+/**
+ * Show tool context specific modifier tip.
+ */
+void sp_event_show_modifier_tip(Inkscape::MessageContext *message_context,
+        GdkEvent *event, gchar const *ctrl_tip, gchar const *shift_tip,
+        gchar const *alt_tip) {
+    guint keyval = get_group0_keyval(&event->key);
+
+    bool ctrl = ctrl_tip && (MOD__CTRL(event) || (keyval == GDK_KEY_Control_L) || (keyval
+            == GDK_KEY_Control_R));
+    bool shift = shift_tip && (MOD__SHIFT(event) || (keyval == GDK_KEY_Shift_L) || (keyval
+            == GDK_KEY_Shift_R));
+    bool alt = alt_tip && (MOD__ALT(event) || (keyval == GDK_KEY_Alt_L) || (keyval
+            == GDK_KEY_Alt_R) || (keyval == GDK_KEY_Meta_L) || (keyval == GDK_KEY_Meta_R));
+
+    gchar *tip = g_strdup_printf("%s%s%s%s%s", (ctrl ? ctrl_tip : ""), (ctrl
+            && (shift || alt) ? "; " : ""), (shift ? shift_tip : ""), ((ctrl
+            || shift) && alt ? "; " : ""), (alt ? alt_tip : ""));
+
+    if (strlen(tip) > 0) {
+        message_context->flash(Inkscape::INFORMATION_MESSAGE, tip);
+    }
+
+    g_free(tip);
+}
+
+/**
+ * Return the keyval corresponding to the key event in group 0, i.e.,
+ * in the main (English) layout.
+ *
+ * Use this instead of simply event->keyval, so that your keyboard shortcuts
+ * work regardless of layouts (e.g., in Cyrillic).
+ */
+guint get_group0_keyval(GdkEventKey *event) {
+    guint keyval = 0;
+
+    gdk_keymap_translate_keyboard_state(gdk_keymap_get_for_display(
+            gdk_display_get_default()), event->hardware_keycode,
+            (GdkModifierType) event->state, 0 /*event->key.group*/, &keyval,
+            NULL, NULL, NULL);
+
+    return keyval;
+}
+
+/**
+ * Returns item at point p in desktop.
+ *
+ * If state includes alt key mask, cyclically selects under; honors
+ * into_groups.
+ */
+SPItem *sp_event_context_find_item(SPDesktop *desktop, Geom::Point const &p,
+                                   bool select_under, bool into_groups)
+{
+    SPItem *item = 0;
+
+    if (select_under) {
+        SPItem *selected_at_point = desktop->getItemFromListAtPointBottom(
+                desktop->selection->itemList(), p);
+        item = desktop->getItemAtPoint(p, into_groups, selected_at_point);
+        if (item == NULL) { // we may have reached bottom, flip over to the top
+            item = desktop->getItemAtPoint(p, into_groups, NULL);
+        }
+    } else {
+        item = desktop->getItemAtPoint(p, into_groups, NULL);
+    }
+
+    return item;
+}
+
+/**
+ * Returns item if it is under point p in desktop, at any depth; otherwise returns NULL.
+ *
+ * Honors into_groups.
+ */
+SPItem *
+sp_event_context_over_item(SPDesktop *desktop, SPItem *item,
+        Geom::Point const &p) {
+    GSList *temp = NULL;
+    temp = g_slist_prepend(temp, item);
+    SPItem *item_at_point = desktop->getItemFromListAtPointBottom(temp, p);
+    g_slist_free(temp);
+
+    return item_at_point;
+}
+
+ShapeEditor *
+sp_event_context_get_shape_editor(ToolBase *ec) {
+    return ec->shape_editor;
+}
+
+void event_context_print_event_info(GdkEvent *event, bool print_return) {
+    switch (event->type) {
+    case GDK_BUTTON_PRESS:
+        g_print("GDK_BUTTON_PRESS");
+        break;
+    case GDK_2BUTTON_PRESS:
+        g_print("GDK_2BUTTON_PRESS");
+        break;
+    case GDK_3BUTTON_PRESS:
+        g_print("GDK_3BUTTON_PRESS");
+        break;
+
+    case GDK_MOTION_NOTIFY:
+        g_print("GDK_MOTION_NOTIFY");
+        break;
+    case GDK_ENTER_NOTIFY:
+        g_print("GDK_ENTER_NOTIFY");
+        break;
+
+    case GDK_LEAVE_NOTIFY:
+        g_print("GDK_LEAVE_NOTIFY");
+        break;
+    case GDK_BUTTON_RELEASE:
+        g_print("GDK_BUTTON_RELEASE");
+        break;
+
+    case GDK_KEY_PRESS:
+        g_print("GDK_KEY_PRESS: %d", get_group0_keyval(&event->key));
+        break;
+    case GDK_KEY_RELEASE:
+        g_print("GDK_KEY_RELEASE: %d", get_group0_keyval(&event->key));
+        break;
+    default:
+        //g_print ("even type not recognized");
+        break;
+    }
+
+    if (print_return) {
+        g_print("\n");
+    }
+}
+
+/**
+ * Analyses the current event, calculates the mouse speed, turns snapping off (temporarily) if the
+ * mouse speed is above a threshold, and stores the current event such that it can be re-triggered when needed
+ * (re-triggering is controlled by a watchdog timer).
+ *
+ * @param ec Pointer to the event context.
+ * @param dse_item Pointer that store a reference to a canvas or to an item.
+ * @param dse_item2 Another pointer, storing a reference to a knot or controlpoint.
+ * @param event Pointer to the motion event.
+ * @param origin Identifier (enum) specifying where the delay (and the call to this method) were initiated.
+ */
+void sp_event_context_snap_delay_handler(ToolBase *ec,
+        gpointer const dse_item, gpointer const dse_item2, GdkEventMotion *event,
+        DelayedSnapEvent::DelayedSnapEventOrigin origin)
+{
+    static guint32 prev_time;
+    static boost::optional<Geom::Point> prev_pos;
+
+    if (ec->_dse_callback_in_process) {
+        return;
+    }
+
+    // Snapping occurs when dragging with the left mouse button down, or when hovering e.g. in the pen tool with left mouse button up
+    bool const c1 = event->state & GDK_BUTTON2_MASK; // We shouldn't hold back any events when other mouse buttons have been
+    bool const c2 = event->state & GDK_BUTTON3_MASK; // pressed, e.g. when scrolling with the middle mouse button; if we do then
+    // Inkscape will get stuck in an unresponsive state
+    bool const c3 = tools_isactive(ec->desktop, TOOLS_CALLIGRAPHIC);
+    // The snap delay will repeat the last motion event, which will lead to
+    // erroneous points in the calligraphy context. And because we don't snap
+    // in this context, we might just as well disable the snap delay all together
+
+    if (c1 || c2 || c3) {
+        // Make sure that we don't send any pending snap events to a context if we know in advance
+        // that we're not going to snap any way (e.g. while scrolling with middle mouse button)
+        // Any motion event might affect the state of the context, leading to unexpected behavior
+        sp_event_context_discard_delayed_snap_event(ec);
+    } else if (ec->desktop
+            && ec->desktop->namedview->snap_manager.snapprefs.getSnapEnabledGlobally()) {
+        // Snap when speed drops below e.g. 0.02 px/msec, or when no motion events have occurred for some period.
+        // i.e. snap when we're at stand still. A speed threshold enforces snapping for tablets, which might never
+        // be fully at stand still and might keep spitting out motion events.
+        ec->desktop->namedview->snap_manager.snapprefs.setSnapPostponedGlobally(true); // put snapping on hold
+
+        Geom::Point event_pos(event->x, event->y);
+        guint32 event_t = gdk_event_get_time((GdkEvent *) event);
+
+        if (prev_pos) {
+            Geom::Coord dist = Geom::L2(event_pos - *prev_pos);
+            guint32 delta_t = event_t - prev_time;
+            gdouble speed = delta_t > 0 ? dist / delta_t : 1000;
+            //std::cout << "Mouse speed = " << speed << " px/msec " << std::endl;
+            if (speed > 0.02) { // Jitter threshold, might be needed for tablets
+                // We're moving fast, so postpone any snapping until the next GDK_MOTION_NOTIFY event. We
+                // will keep on postponing the snapping as long as the speed is high.
+                // We must snap at some point in time though, so set a watchdog timer at some time from
+                // now, just in case there's no future motion event that drops under the speed limit (when
+                // stopping abruptly)
+                delete ec->_delayed_snap_event;
+                ec->_delayed_snap_event = new DelayedSnapEvent(ec, dse_item, dse_item2,
+                        event, origin); // watchdog is reset, i.e. pushed forward in time
+                // If the watchdog expires before a new motion event is received, we will snap (as explained
+                // above). This means however that when the timer is too short, we will always snap and that the
+                // speed threshold is ineffective. In the extreme case the delay is set to zero, and snapping will
+                // be immediate, as it used to be in the old days ;-).
+            } else { // Speed is very low, so we're virtually at stand still
+                // But if we're really standing still, then we should snap now. We could use some low-pass filtering,
+                // otherwise snapping occurs for each jitter movement. For this filtering we'll leave the watchdog to expire,
+                // snap, and set a new watchdog again.
+                if (ec->_delayed_snap_event == NULL) { // no watchdog has been set
+                    // it might have already expired, so we'll set a new one; the snapping frequency will be limited this way
+                    ec->_delayed_snap_event = new DelayedSnapEvent(ec, dse_item,
+                            dse_item2, event, origin);
+                } // else: watchdog has been set before and we'll wait for it to expire
+            }
+        } else {
+            // This is the first GDK_MOTION_NOTIFY event, so postpone snapping and set the watchdog
+            g_assert(ec->_delayed_snap_event == NULL);
+            ec->_delayed_snap_event = new DelayedSnapEvent(ec, dse_item, dse_item2,
+                    event, origin);
+        }
+
+        prev_pos = event_pos;
+        prev_time = event_t;
+    }
+}
+
+/**
+ * When the snap delay watchdog timer barks, this method will be called and will re-inject the last motion
+ * event in an appropriate place, with snapping being turned on again.
+ */
+gboolean sp_event_context_snap_watchdog_callback(gpointer data) {
+    // Snap NOW! For this the "postponed" flag will be reset and the last motion event will be repeated
+    DelayedSnapEvent *dse = reinterpret_cast<DelayedSnapEvent*> (data);
+
+    if (dse == NULL) {
+        // This might occur when this method is called directly, i.e. not through the timer
+        // E.g. on GDK_BUTTON_RELEASE in sp_event_context_root_handler()
+        return FALSE;
+    }
+
+    ToolBase *ec = dse->getEventContext();
+    if (ec == NULL) {
+        delete dse;
+        return false;
+    }
+    if (ec->desktop == NULL) {
+        ec->_delayed_snap_event = NULL;
+        delete dse;
+        return false;
+    }
+    
+    ec->_dse_callback_in_process = true;
+
+    SPDesktop *dt = ec->desktop;
+    dt->namedview->snap_manager.snapprefs.setSnapPostponedGlobally(false);
+
+    // Depending on where the delayed snap event originated from, we will inject it back at it's origin
+    // The switch below takes care of that and prepares the relevant parameters
+    switch (dse->getOrigin()) {
+    case DelayedSnapEvent::EVENTCONTEXT_ROOT_HANDLER:
+        sp_event_context_virtual_root_handler(ec, dse->getEvent());
+        break;
+    case DelayedSnapEvent::EVENTCONTEXT_ITEM_HANDLER: {
+        gpointer item = dse->getItem();
+        if (item && SP_IS_ITEM(item)) {
+            sp_event_context_virtual_item_handler(ec, SP_ITEM(item), dse->getEvent());
+        }
+    }
+        break;
+    case DelayedSnapEvent::KNOT_HANDLER: {
+        gpointer knot = dse->getItem2();
+        if (knot && SP_IS_KNOT(knot)) {
+            sp_knot_handler_request_position(dse->getEvent(), SP_KNOT(knot));
+        }
+    }
+        break;
+    case DelayedSnapEvent::CONTROL_POINT_HANDLER: {
+        using Inkscape::UI::ControlPoint;
+        gpointer pitem2 = dse->getItem2();
+        if (!pitem2)
+        {
+            ec->_delayed_snap_event = NULL;
+            delete dse;
+            return false;
+        }
+        ControlPoint *point = reinterpret_cast<ControlPoint*> (pitem2);
+        if (point) {
+            if (point->position().isFinite() && (dt == point->_desktop)) {            
+                point->_eventHandler(ec, dse->getEvent());
+            }
+            else {
+                //workaround:
+                //[Bug 781893] Crash after moving a Bezier node after Knot path effect?
+                // --> at some time, some point with X = 0 and Y = nan (not a number) is created ...
+                //     even so, the desktop pointer is invalid and equal to 0xff
+                g_warning ("encountered non finite point when evaluating snapping callback");
+            }
+        }
+    }
+        break;
+    case DelayedSnapEvent::GUIDE_HANDLER: {
+        gpointer item = dse->getItem();
+        gpointer item2 = dse->getItem2();
+        if (item && item2) {
+            g_assert(SP_IS_CANVAS_ITEM(item));
+            g_assert(SP_IS_GUIDE(item2));
+            sp_dt_guide_event(SP_CANVAS_ITEM(item), dse->getEvent(), item2);
+        }
+    }
+        break;
+    case DelayedSnapEvent::GUIDE_HRULER:
+    case DelayedSnapEvent::GUIDE_VRULER: {
+        gpointer item = dse->getItem();
+        gpointer item2 = dse->getItem2();
+        if (item && item2) {
+            g_assert(GTK_IS_WIDGET(item));
+            g_assert(SP_IS_DESKTOP_WIDGET(item2));
+            if (dse->getOrigin() == DelayedSnapEvent::GUIDE_HRULER) {
+                sp_dt_hruler_event(GTK_WIDGET(item), dse->getEvent(), SP_DESKTOP_WIDGET(item2));
+            } else {
+                sp_dt_vruler_event(GTK_WIDGET(item), dse->getEvent(), SP_DESKTOP_WIDGET(item2));
+            }
+        }
+    }
+        break;
+    default:
+        g_warning("Origin of snap-delay event has not been defined!;");
+        break;
+    }
+
+    ec->_delayed_snap_event = NULL;
+    delete dse;
+
+    ec->_dse_callback_in_process = false;
+
+    return FALSE; //Kills the timer and stops it from executing this callback over and over again.
+}
+
+void sp_event_context_discard_delayed_snap_event(ToolBase *ec) {
+    delete ec->_delayed_snap_event;
+    ec->_delayed_snap_event = NULL;
+    ec->desktop->namedview->snap_manager.snapprefs.setSnapPostponedGlobally(false);
+}
+
+}
+}
+}
+
+/*
+ Local Variables:
+ mode:c++
+ c-file-style:"stroustrup"
+ c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+ indent-tabs-mode:nil
+ fill-column:99
+ End:
+ */
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :