Adding upstream version 1.2.2.upstream/1.2.2upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1229 insertions, 0 deletions

diff --git a/src/ui/tools/eraser-tool.cpp b/src/ui/tools/eraser-tool.cpp
new file mode 100644
index 0000000..5b9cbab
--- /dev/null
+++ b/src/ui/tools/eraser-tool.cpp
@@ -0,0 +1,1229 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Eraser drawing mode
+ *
+ * Authors:
+ *   Mitsuru Oka <oka326@parkcity.ne.jp>
+ *   Lauris Kaplinski <lauris@kaplinski.com>
+ *   bulia byak <buliabyak@users.sf.net>
+ *   MenTaLguY <mental@rydia.net>
+ *   Jon A. Cruz <jon@joncruz.org>
+ *   Abhishek Sharma
+ *   Rafael Siejakowski <rs@rs-math.net>
+ *
+ * The original dynadraw code:
+ *   Paul Haeberli <paul@sgi.com>
+ *
+ * Copyright (C) 1998 The Free Software Foundation
+ * Copyright (C) 1999-2005 authors
+ * Copyright (C) 2001-2002 Ximian, Inc.
+ * Copyright (C) 2005-2007 bulia byak
+ * Copyright (C) 2006 MenTaLguY
+ * Copyright (C) 2008 Jon A. Cruz
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#define noERASER_VERBOSE
+
+#include "eraser-tool.h"
+
+#include <string>
+#include <cstring>
+#include <numeric>
+
+#include <gtk/gtk.h>
+#include <gdk/gdkkeysyms.h>
+#include <glibmm/i18n.h>
+
+#include <2geom/bezier-utils.h>
+#include <2geom/pathvector.h>
+
+#include "context-fns.h"
+#include "desktop-events.h"
+#include "desktop-style.h"
+#include "desktop.h"
+#include "document-undo.h"
+#include "document.h"
+#include "layer-manager.h"
+#include "message-context.h"
+#include "message-stack.h"
+#include "path-chemistry.h"
+#include "rubberband.h"
+#include "selection-chemistry.h"
+#include "selection.h"
+
+#include "display/curve.h"
+#include "display/control/canvas-item-bpath.h"
+
+#include "include/macros.h"
+
+#include "object/sp-clippath.h"
+#include "object/sp-image.h"
+#include "object/sp-item-group.h"
+#include "object/sp-path.h"
+#include "object/sp-rect.h"
+#include "object/sp-root.h"
+#include "object/sp-shape.h"
+#include "object/sp-text.h"
+#include "object/sp-use.h"
+
+#include "ui/icon-names.h"
+
+#include "svg/svg.h"
+
+
+using Inkscape::DocumentUndo;
+
+namespace Inkscape {
+namespace UI {
+namespace Tools {
+
+extern EraserToolMode const DEFAULT_ERASER_MODE = EraserToolMode::CUT;
+
+EraserTool::EraserTool(SPDesktop *desktop)
+    : DynamicBase(desktop, "/tools/eraser", "eraser.svg")
+{
+    accumulated.reset(new SPCurve());
+    currentcurve.reset(new SPCurve());
+
+    cal1.reset(new SPCurve());
+    cal2.reset(new SPCurve());
+
+    currentshape = new Inkscape::CanvasItemBpath(desktop->getCanvasSketch());
+    currentshape->set_stroke(0x0);
+    currentshape->set_fill(trace_color_rgba, trace_wind_rule);
+
+    /* fixme: Cannot we cascade it to root more clearly? */
+    currentshape->connect_event(sigc::bind(sigc::ptr_fun(sp_desktop_root_handler), desktop));
+
+    sp_event_context_read(this, "mass");
+    sp_event_context_read(this, "wiggle");
+    sp_event_context_read(this, "angle");
+    sp_event_context_read(this, "width");
+    sp_event_context_read(this, "thinning");
+    sp_event_context_read(this, "tremor");
+    sp_event_context_read(this, "flatness");
+    sp_event_context_read(this, "tracebackground");
+    sp_event_context_read(this, "usepressure");
+    sp_event_context_read(this, "usetilt");
+    sp_event_context_read(this, "abs_width");
+    sp_event_context_read(this, "cap_rounding");
+
+    is_drawing = false;
+    //TODO not sure why get 0.01 if slider width == 0, maybe a double/int problem
+
+    Inkscape::Preferences *prefs = Inkscape::Preferences::get();
+    if (prefs->getBool("/tools/eraser/selcue", false) != 0) {
+        enableSelectionCue();
+    }
+    _updateMode();
+
+    // TODO temp force:
+    enableSelectionCue();
+}
+
+EraserTool::~EraserTool()
+{
+    delete currentshape;
+    currentshape = nullptr;
+}
+
+/**  Reads the current Eraser mode from Preferences and sets `mode` accordingly. */
+void EraserTool::_updateMode()
+{
+    Inkscape::Preferences *prefs = Inkscape::Preferences::get();
+    if (!prefs) {
+        return;
+    }
+
+    int mode_idx = prefs->getInt("/tools/eraser/mode", 1); // Cut mode is default
+
+    // Note: the integer indices must agree with those in EraserToolbar::_modeAsInt()
+    if (mode_idx == 0) {
+        mode = EraserToolMode::DELETE;
+    } else if (mode_idx == 1) {
+        mode = EraserToolMode::CUT;
+    } else if (mode_idx == 2) {
+        mode = EraserToolMode::CLIP;
+    } else {
+        g_printerr("Error: invalid mode setting \"%d\" for Eraser tool!", mode_idx);
+        mode = DEFAULT_ERASER_MODE;
+    }
+}
+
+// TODO: After switch to C++20, replace this with std::lerp
+inline double flerp(double const f0, double const f1, double const p)
+{
+    return f0 + (f1 - f0) * p;
+}
+
+inline double square(double const x)
+{
+    return x * x;
+}
+
+void EraserTool::_reset(Geom::Point p)
+{
+    last = cur = getNormalizedPoint(p);
+    vel = Geom::Point(0, 0);
+    vel_max = 0;
+    acc = Geom::Point(0, 0);
+    ang = Geom::Point(0, 0);
+    del = Geom::Point(0, 0);
+}
+
+void EraserTool::_extinput(GdkEvent *event)
+{
+    if (gdk_event_get_axis(event, GDK_AXIS_PRESSURE, &pressure)) {
+        pressure = CLAMP(pressure, min_pressure, max_pressure);
+    } else {
+        pressure = default_pressure;
+    }
+
+    if (gdk_event_get_axis(event, GDK_AXIS_XTILT, &xtilt)) {
+        xtilt = CLAMP(xtilt, min_tilt, max_tilt);
+    } else {
+        xtilt = default_tilt;
+    }
+
+    if (gdk_event_get_axis(event, GDK_AXIS_YTILT, &ytilt)) {
+        ytilt = CLAMP(ytilt, min_tilt, max_tilt);
+    } else {
+        ytilt = default_tilt;
+    }
+}
+
+bool EraserTool::_apply(Geom::Point p)
+{
+    /* Calculate force and acceleration */
+    Geom::Point n = getNormalizedPoint(p);
+    Geom::Point force = n - cur;
+
+    // If force is below the absolute threshold `epsilon`,
+    // or we haven't yet reached `vel_start` (i.e. at the beginning of stroke)
+    // _and_ the force is below the (higher) `epsilon_start` threshold,
+    // discard this move.
+    // This prevents flips, blobs, and jerks caused by microscopic tremor of the tablet pen,
+    // especially bothersome at the start of the stroke where we don't yet have the inertia to
+    // smooth them out.
+    if (Geom::L2(force) < epsilon || (vel_max < vel_start && Geom::L2(force) < epsilon_start)) {
+        return false;
+    }
+
+    // Calculate mass
+    double const m = flerp(1.0, 160.0, mass);
+    acc = force / m;
+    vel += acc; // Calculate new velocity
+    double const speed = Geom::L2(vel);
+
+    if (speed > vel_max) {
+        vel_max = speed;
+    } else if (speed < epsilon) {
+        return false; // return early if movement is insignificant
+    }
+
+    /* Calculate angle of eraser tool */
+    double angle_fixed{0.0};
+    if (usetilt) {
+        // 1a. calculate nib angle from input device tilt:
+        Geom::Point normal{ytilt, xtilt};
+        if (!Geom::is_zero(normal)) {
+            angle_fixed = Geom::atan2(normal);
+        }
+    } else {
+        // 1b. fixed angle (absolutely flat nib):
+        angle_fixed = angle * M_PI / 180.0; // convert to radians
+    }
+    if (flatness < 0.0) {
+        // flips direction. Useful when usetilt is true
+        // allows simulating both pen/charcoal and broad-nibbed pen
+        angle_fixed *= -1;
+    }
+
+    // 2. Angle perpendicular to vel (absolutely non-flat nib):
+    double angle_dynamic = Geom::atan2(Geom::rot90(vel));
+    // flip angle_dynamic to force it to be in the same half-circle as angle_fixed
+    bool flipped = false;
+    if (fabs(angle_dynamic - angle_fixed) > M_PI_2) {
+        angle_dynamic += M_PI;
+        flipped = true;
+    }
+    // normalize angle_dynamic
+    if (angle_dynamic > M_PI) {
+        angle_dynamic -= 2 * M_PI;
+    }
+    if (angle_dynamic < -M_PI) {
+        angle_dynamic += 2 * M_PI;
+    }
+
+    // 3. Average them using flatness parameter:
+    // find the flatness-weighted bisector angle, unflip if angle_dynamic was flipped
+    // FIXME: when `vel` is oscillating around the fixed angle, the new_ang flips back and forth.
+    // How to avoid this?
+    double new_ang = flerp(angle_dynamic, angle_fixed, fabs(flatness)) - (flipped ? M_PI : 0);
+
+    // Try to detect a sudden flip when the new angle differs too much from the previous for the
+    // current velocity; in that case discard this move
+    double angle_delta = Geom::L2(Geom::Point(cos(new_ang), sin(new_ang)) - ang);
+    if (angle_delta / speed > 4000) {
+        return false;
+    }
+
+    // convert to point
+    ang = Geom::Point(cos(new_ang), sin(new_ang));
+
+    /* Apply drag */
+    double const d = flerp(0.0, 0.5, square(drag));
+    vel *= 1.0 - d;
+
+    /* Update position */
+    last = cur;
+    cur += vel;
+
+    return true;
+}
+
+void EraserTool::_brush()
+{
+    g_assert(npoints >= 0 && npoints < SAMPLING_SIZE);
+
+    // How much velocity thins strokestyle
+    double const vel_thinning = flerp(0, 160, vel_thin);
+
+    // Influence of pressure on thickness
+    double const pressure_thick = (usepressure ? pressure : 1.0);
+
+    // get the real brush point, not the same as pointer (affected by mass drag)
+    Geom::Point brush = getViewPoint(cur);
+
+    double const trace_thick = 1;
+    double const speed = Geom::L2(vel);
+    double effective_width = (pressure_thick * trace_thick - vel_thinning * speed) * width;
+
+    double tremble_left = 0, tremble_right = 0;
+    if (tremor > 0) {
+        // obtain two normally distributed random variables, using polar Box-Muller transform
+        double y1, y2;
+        _generateNormalDist2(y1, y2);
+
+        // deflect both left and right edges randomly and independently, so that:
+        // (1) tremor=1 corresponds to sigma=1, decreasing tremor narrows the bell curve;
+        // (2) deflection depends on width, but is upped for small widths for better visual uniformity across widths;
+        // (3) deflection somewhat depends on speed, to prevent fast strokes looking
+        //     comparatively smooth and slow ones excessively jittery
+        double const width_coefficient = 0.15 + 0.8 * effective_width;
+        double const speed_coefficient = 0.35 + 14 * speed;
+        double const total_coefficient = tremor * width_coefficient * speed_coefficient;
+
+        tremble_left  = y1 * total_coefficient;
+        tremble_right = y2 * total_coefficient;
+    }
+
+    double const min_width = 0.02 * width;
+    if (effective_width < min_width) {
+        effective_width = min_width;
+    }
+
+    double dezoomify_factor = 0.05 * 1000;
+    if (!abs_width) {
+        dezoomify_factor /= _desktop->current_zoom();
+    }
+
+    Geom::Point del_left  = dezoomify_factor * (effective_width + tremble_left)  * ang;
+    Geom::Point del_right = dezoomify_factor * (effective_width + tremble_right) * ang;
+
+    point1[npoints] = brush + del_left;
+    point2[npoints] = brush - del_right;
+
+    if (nowidth) {
+        point1[npoints] = Geom::middle_point(point1[npoints], point2[npoints]);
+    }
+    del = Geom::middle_point(del_left, del_right);
+
+    npoints++;
+}
+
+void EraserTool::_generateNormalDist2(double &r1, double &r2)
+{
+    // obtain two normally distributed random variables, using polar Box-Muller transform
+    double x1, x2, w;
+    do {
+        x1 = 2.0 * g_random_double_range(0, 1) - 1.0;
+        x2 = 2.0 * g_random_double_range(0, 1) - 1.0;
+        w = square(x1) + square(x2);
+    } while (w >= 1.0);
+    w = sqrt(-2.0 * log(w) / w);
+    r1 = x1 * w;
+    r2 = x2 * w;
+}
+
+void EraserTool::_cancel()
+{
+    dragging = false;
+    is_drawing = false;
+    ungrabCanvasEvents();
+
+    _removeTemporarySegments();
+
+    /* reset accumulated curve */
+    accumulated->reset();
+    _clearCurrent();
+    repr = nullptr;
+}
+
+/** Removes all temporary line segments */
+void EraserTool::_removeTemporarySegments()
+{
+    for (auto segment : segments) {
+        delete segment;
+    }
+    segments.clear();
+}
+
+bool EraserTool::root_handler(GdkEvent* event)
+{
+    bool ret = false;
+    _updateMode();
+    switch (event->type) {
+        case GDK_BUTTON_PRESS:
+            if (event->button.button == 1) {
+                if (!Inkscape::have_viable_layer(_desktop, defaultMessageContext())) {
+                    return true;
+                }
+
+                Geom::Point const button_w(event->button.x, event->button.y);
+                Geom::Point const button_dt(_desktop->w2d(button_w));
+
+                _reset(button_dt);
+                _extinput(event);
+                _apply(button_dt);
+                accumulated->reset();
+
+                repr = nullptr;
+
+                if (mode == EraserToolMode::DELETE) {
+                    auto rubberband = Inkscape::Rubberband::get(_desktop);
+                    rubberband->start(_desktop, button_dt);
+                    rubberband->setMode(RUBBERBAND_MODE_TOUCHPATH);
+                }
+                /* initialize first point */
+                npoints = 0;
+
+                grabCanvasEvents();
+                is_drawing = true;
+                ret = true;
+            }
+            break;
+
+        case GDK_MOTION_NOTIFY: {
+            Geom::Point const motion_w(event->motion.x, event->motion.y);
+            Geom::Point motion_dt(_desktop->w2d(motion_w));
+            _extinput(event);
+
+            message_context->clear();
+
+            if (is_drawing && (event->motion.state & GDK_BUTTON1_MASK)) {
+                dragging = true;
+
+                message_context->set(Inkscape::NORMAL_MESSAGE, _("<b>Drawing</b> an eraser stroke"));
+
+                if (!_apply(motion_dt)) {
+                    ret = true;
+                    break;
+                }
+
+                if (cur != last) {
+                    _brush();
+                    g_assert(npoints > 0);
+                    _fitAndSplit(false);
+                }
+
+                ret = true;
+            }
+            if (mode == EraserToolMode::DELETE) {
+                accumulated->reset();
+                Inkscape::Rubberband::get(_desktop)->move(motion_dt);
+            }
+            break;
+        }
+        case GDK_BUTTON_RELEASE: {
+            if (event->button.button != 1) {
+                break;
+            }
+
+            Geom::Point const motion_w(event->button.x, event->button.y);
+            Geom::Point const motion_dt(_desktop->w2d(motion_w));
+
+            ungrabCanvasEvents();
+
+            is_drawing = false;
+
+            if (dragging) {
+                dragging = false;
+
+                _apply(motion_dt);
+                _removeTemporarySegments();
+
+                /* Create object */
+                _fitAndSplit(true);
+                _accumulate();
+                _setToAccumulated(); // performs document_done
+
+                /* reset accumulated curve */
+                accumulated->reset();
+
+                _clearCurrent();
+                repr = nullptr;
+
+                message_context->clear();
+                ret = true;
+            }
+
+            if (mode == EraserToolMode::DELETE) {
+                auto r = Inkscape::Rubberband::get(_desktop);
+                if (r->is_started()) {
+                    r->stop();
+                }
+            }
+
+            break;
+        }
+        case GDK_KEY_PRESS:
+            ret = _handleKeypress(&event->key);
+            break;
+
+        case GDK_KEY_RELEASE:
+            switch (get_latin_keyval(&event->key)) {
+                case GDK_KEY_Control_L:
+                case GDK_KEY_Control_R:
+                    message_context->clear();
+                    break;
+
+                default:
+                    break;
+            }
+            break;
+
+        default:
+            break;
+    }
+
+    if (!ret) {
+        ret = DynamicBase::root_handler(event);
+    }
+    return ret;
+}
+
+/** Analyses and handles a key press event, returns true if processed, false if not. */
+bool EraserTool::_handleKeypress(const GdkEventKey *key)
+{
+    bool ret = false;
+    bool just_ctrl = (key->state & GDK_CONTROL_MASK)                      // Ctrl key is down
+                     && !(key->state & (GDK_MOD1_MASK | GDK_SHIFT_MASK)); // but not Alt or Shift
+
+    bool just_alt = (key->state & GDK_MOD1_MASK)                            // Alt is down
+                    && !(key->state & (GDK_CONTROL_MASK | GDK_SHIFT_MASK)); // but not Ctrl or Shift
+
+    switch (get_latin_keyval(key)) {
+        case GDK_KEY_Right:
+        case GDK_KEY_KP_Right:
+            if (!just_ctrl) {
+                width += 0.01;
+                if (width > 1.0) {
+                    width = 1.0;
+                }
+                // Alt+X sets focus to this spinbutton as well
+                _desktop->setToolboxAdjustmentValue("eraser-width", width * 100);
+                ret = true;
+            }
+            break;
+
+        case GDK_KEY_Left:
+        case GDK_KEY_KP_Left:
+            if (!just_ctrl) {
+                width -= 0.01;
+                if (width < 0.01) {
+                    width = 0.01;
+                }
+                _desktop->setToolboxAdjustmentValue("eraser-width", width * 100);
+                ret = true;
+            }
+            break;
+
+        case GDK_KEY_Home:
+        case GDK_KEY_KP_Home:
+            width = 0.01;
+            _desktop->setToolboxAdjustmentValue("eraser-width", width * 100);
+            ret = true;
+            break;
+
+        case GDK_KEY_End:
+        case GDK_KEY_KP_End:
+            width = 1.0;
+            _desktop->setToolboxAdjustmentValue("eraser-width", width * 100);
+            ret = true;
+            break;
+
+        case GDK_KEY_x:
+        case GDK_KEY_X:
+            if (just_alt) {
+                _desktop->setToolboxFocusTo("eraser-width");
+                ret = true;
+            }
+            break;
+
+        case GDK_KEY_Escape:
+            if (mode == EraserToolMode::DELETE) {
+                Inkscape::Rubberband::get(_desktop)->stop();
+            }
+            if (is_drawing) {
+                // if drawing, cancel, otherwise pass it up for deselecting
+                _cancel();
+                ret = true;
+            }
+            break;
+
+        case GDK_KEY_z:
+        case GDK_KEY_Z:
+            if (just_ctrl && is_drawing) { // Ctrl+Z pressed while drawing
+                _cancel();
+                ret = true;
+            } // if not drawing, pass it up for undo
+            break;
+
+        default:
+            break;
+    }
+    return ret;
+}
+
+void EraserTool::_clearCurrent()
+{
+    // reset bpath
+    currentshape->set_bpath(nullptr);
+
+    // reset curve
+    currentcurve->reset();
+    cal1->reset();
+    cal2->reset();
+
+    // reset points
+    npoints = 0;
+}
+
+void EraserTool::_setToAccumulated()
+{
+    bool work_done = false;
+    SPDocument *document = _desktop->doc();
+
+    if (!accumulated->is_empty()) {
+        if (!repr) {
+            /* Create object */
+            Inkscape::XML::Document *xml_doc = document->getReprDoc();
+            Inkscape::XML::Node *eraser_repr = xml_doc->createElement("svg:path");
+
+            /* Set style */
+            sp_desktop_apply_style_tool(_desktop, eraser_repr, "/tools/eraser", false);
+
+            repr = eraser_repr;
+        }
+        SPObject *top_layer = _desktop->layerManager().currentRoot();
+        SPItem *item_repr = SP_ITEM(top_layer->appendChildRepr(repr));
+        Inkscape::GC::release(repr);
+        item_repr->updateRepr();
+        Geom::PathVector pathv = accumulated->get_pathvector() * _desktop->dt2doc();
+        pathv *= item_repr->i2doc_affine().inverse();
+        repr->setAttribute("d", sp_svg_write_path(pathv));
+        Geom::OptRect eraser_bbox;
+        if (repr) {
+            bool was_selection = false;
+            Inkscape::Selection *selection = _desktop->getSelection();
+            _updateMode();
+            SPItem *acid = SP_ITEM(document->getObjectByRepr(repr));
+            eraser_bbox = acid->documentVisualBounds();
+            std::vector<SPItem *> remaining_items;
+            std::vector<SPItem *> to_work_on;
+            if (selection->isEmpty()) {
+                if (mode == EraserToolMode::CUT || mode == EraserToolMode::CLIP) {
+                    to_work_on = document->getItemsPartiallyInBox(_desktop->dkey, *eraser_bbox,
+                                                                  false, false, false, true);
+                } else {
+                    Inkscape::Rubberband *r = Inkscape::Rubberband::get(_desktop);
+                    to_work_on = document->getItemsAtPoints(_desktop->dkey, r->getPoints());
+                }
+                to_work_on.erase(std::remove(to_work_on.begin(), to_work_on.end(), acid), to_work_on.end());
+            } else {
+                if (mode == EraserToolMode::DELETE) {
+                    Inkscape::Rubberband *r = Inkscape::Rubberband::get(_desktop);
+                    auto selected_items = selection->items();
+                    std::vector<SPItem *> touched = document->getItemsAtPoints(_desktop->dkey, r->getPoints());
+                    for (auto i : selected_items) {
+                        if (std::find(touched.begin(), touched.end(), i) == touched.end()) {
+                            remaining_items.push_back(i);
+                        } else {
+                            to_work_on.push_back(i);
+                        }
+                    }
+                } else {
+                    to_work_on.insert(to_work_on.end(), selection->items().begin(), selection->items().end());
+                }
+                was_selection = true;
+            }
+
+            if (to_work_on.empty()) {
+                _clearStatusBar();
+            } else {
+                selection->clear();
+                if (mode == EraserToolMode::CUT) {
+                    Error status = ALL_GOOD;
+                    for (auto item : to_work_on) {
+                        Error retval = _cutErase(item, eraser_bbox, remaining_items);
+                        if (retval == ALL_GOOD) {
+                            work_done = true;
+                        } else {
+                            status |= retval;
+                        }
+                    }
+
+                    status &= ~(NOT_IN_BOUNDS | NON_EXISTENT); // Clear flags not handled at the moment
+                    if (status == ALL_GOOD) {
+                        _clearStatusBar();
+                    } else { // Something went wrong during the cut operation
+                        if (status & RASTER_IMAGE) {
+                            _setStatusBarMessage(_("Cannot cut out from a bitmap, use <b>Clip</b> mode "
+                                                   "instead."));
+                        } else if (status & ERROR_GROUP) {
+                            _setStatusBarMessage(_("Cannot cut out from a group, ungroup the objects "
+                                                   "first."));
+                        } else if (status & NO_AREA_PATH) {
+                            _setStatusBarMessage(_("Cannot cut out from a path with zero area, use "
+                                                   "<b>Clip</b> mode instead."));
+                        }
+                    }
+                } else if (mode == EraserToolMode::CLIP) {
+                    if (!nowidth) {
+                        for (auto item : to_work_on) {
+                            _clipErase(item, item_repr->parent, eraser_bbox);
+                        }
+                        if (was_selection) {
+                            remaining_items = to_work_on;
+                        }
+                        work_done = true;
+                    }
+                    _clearStatusBar();
+                } else if (mode == EraserToolMode::DELETE) {
+                    for (auto item : to_work_on) {
+                        item->deleteObject(true);
+                    }
+                    work_done = true;
+                    _clearStatusBar();
+                }
+
+                if (was_selection && !remaining_items.empty()) {
+                    selection->add(remaining_items.begin(), remaining_items.end());
+                }
+            }
+            // Remove the eraser stroke itself:
+            sp_repr_unparent(repr);
+            repr = nullptr;
+        }
+    } else if (repr) {
+        sp_repr_unparent(repr);
+        repr = nullptr;
+    }
+
+    if (work_done) {
+        DocumentUndo::done(document, _("Draw eraser stroke"), INKSCAPE_ICON("draw-eraser"));
+    } else {
+        DocumentUndo::cancel(document);
+    }
+}
+
+/**
+ * @brief Erases from a shape by cutting
+ * @param item - the item to be erased
+ * @param eraser_bbox - bounding box of the eraser stroke
+ * @param survivers - items that survived the erase operation will be added to this vector
+ * @return type of error encountered
+ */
+EraserTool::Error EraserTool::_cutErase(SPItem* item, Geom::OptRect const &eraser_bbox,
+                                        std::vector<SPItem *> &survivers)
+{
+    // If the item cannot be cut, preserve it
+    if (Error error = EraserTool::_uncuttableItemType(item)) {
+        survivers.push_back(item);
+        return error;
+    }
+
+    Geom::OptRect bbox = item->documentVisualBounds();
+    if (!bbox || !bbox->intersects(eraser_bbox)) {
+        survivers.push_back(item);
+        return NOT_IN_BOUNDS;
+    }
+
+    // If the item is a clone, we check if the original is cuttable before unlinking it
+    if (SPUse *use = dynamic_cast<SPUse *>(item)) {
+        int depth = use->cloneDepth();
+        if (depth < 0) {
+            survivers.push_back(item);
+            return NON_EXISTENT;
+        }
+        // We recurse into the chain of uses until we reach the original item
+        SPItem *original_item = item;
+        for (int i = 0; i < depth; ++i) {
+            SPUse *intermediate_clone = dynamic_cast<SPUse *>(original_item);
+            original_item = intermediate_clone->get_original();
+        }
+        if (Error error = EraserTool::_uncuttableItemType(original_item)) {
+            survivers.push_back(item);
+            return error;
+        }
+        item = use->unlink();
+    }
+
+    _booleanErase(item, survivers);
+    return ALL_GOOD;
+}
+
+/** Returns error flags for items that cannot be meaningfully erased in CUT mode */
+EraserTool::Error EraserTool::_uncuttableItemType(SPItem *item)
+{
+    if (!item) {
+        return NON_EXISTENT;
+    } else if (dynamic_cast<SPGroup *>(item)) {
+        return ERROR_GROUP; // TODO: handle groups in the future
+    } else if (dynamic_cast<SPImage *>(item)) {
+        return RASTER_IMAGE;
+    } else if (_isStraightSegment(item)) {
+        return NO_AREA_PATH;
+    } else {
+        return ALL_GOOD;
+    }
+}
+
+/**
+ * @brief Performs a boolean difference or cut operation which implements the CUT mode operation
+ * @param erasee - the item to be erased
+ * @param survivers - items that survived the erase operation will be added to this vector
+ */
+void EraserTool::_booleanErase(SPItem *erasee, std::vector<SPItem *> &survivers) const
+{
+    XML::Document *xml_doc = _desktop->doc()->getReprDoc();
+    XML::Node *duplicate_stroke = repr->duplicate(xml_doc);
+    repr->parent()->appendChild(duplicate_stroke);
+    GC::release(duplicate_stroke); // parent takes over
+    ObjectSet operands(_desktop);
+    operands.set(duplicate_stroke);
+    if (!nowidth) {
+        operands.pathUnion(true, true);
+    }
+    operands.add(erasee);
+    operands.removeLPESRecursive(true);
+
+    _handleStrokeStyle(erasee);
+
+    if (nowidth) {
+        operands.pathCut(true, true);
+    } else {
+        operands.pathDiff(true, true);
+    }
+
+    auto *prefs = Preferences::get();
+    bool break_apart = prefs->getBool("/tools/eraser/break_apart", false);
+    if (!break_apart) {
+        operands.combine(true, true);
+    } else if (!nowidth) {
+        operands.breakApart(true, false, true);
+    }
+    survivers.insert(survivers.end(), operands.items().begin(), operands.items().end());
+}
+
+/** Handles the "evenodd" stroke style */
+void EraserTool::_handleStrokeStyle(SPItem *item) const
+{
+    if (item->style->fill_rule.value == SP_WIND_RULE_EVENODD) {
+        SPCSSAttr *css = sp_repr_css_attr_new();
+        sp_repr_css_set_property(css, "fill-rule", "evenodd");
+        sp_desktop_set_style(_desktop, css);
+        sp_repr_css_attr_unref(css);
+        css = nullptr;
+    }
+}
+
+/** Sets an error message in the status bar */
+void EraserTool::_setStatusBarMessage(char *message)
+{
+    MessageId id = _desktop->messageStack()->flash(WARNING_MESSAGE, message);
+    _our_messages.push_back(id);
+}
+
+/** Clears all of messages sent by us to the status bar */
+void EraserTool::_clearStatusBar()
+{
+    if (!_our_messages.empty()) {
+        auto ms = _desktop->messageStack();
+        for (MessageId id : _our_messages) {
+            ms->cancel(id);
+        }
+        _our_messages.clear();
+    }
+}
+
+/** Clips through an item */
+void EraserTool::_clipErase(SPItem *item, SPObject *parent, Geom::OptRect &eraser_box)
+{
+    Inkscape::ObjectSet w_selection(_desktop);
+    Geom::OptRect bbox = item->documentVisualBounds();
+    Inkscape::XML::Document *xml_doc = _desktop->doc()->getReprDoc();
+    Inkscape::XML::Node *dup = repr->duplicate(xml_doc);
+    repr->parent()->appendChild(dup);
+    Inkscape::GC::release(dup); // parent takes over
+    w_selection.set(dup);
+    w_selection.pathUnion(true);
+    bool delete_old_clip_path = false;
+    if (bbox && bbox->intersects(*eraser_box)) {
+        SPClipPath *clip_path = item->getClipObject();
+        if (clip_path) {
+            std::vector<SPItem *> selected;
+            selected.push_back(SP_ITEM(clip_path->firstChild()));
+            std::vector<Inkscape::XML::Node *> to_select;
+            std::vector<SPItem *> items(selected);
+            sp_item_list_to_curves(items, selected, to_select);
+            Inkscape::XML::Node *clip_data = SP_ITEM(clip_path->firstChild())->getRepr();
+            if (!clip_data && !to_select.empty()) {
+                clip_data = *(to_select.begin());
+            }
+            if (clip_data) {
+                Inkscape::XML::Node *dup_clip = clip_data->duplicate(xml_doc);
+                if (dup_clip) {
+                    SPItem *dup_clip_obj = SP_ITEM(parent->appendChildRepr(dup_clip));
+                    Inkscape::GC::release(dup_clip);
+                    if (dup_clip_obj) {
+                        dup_clip_obj->transform *= item->getRelativeTransform(SP_ITEM(parent));
+                        dup_clip_obj->updateRepr();
+                        delete_old_clip_path = true;
+                        w_selection.raiseToTop(true);
+                        w_selection.add(dup_clip);
+                        w_selection.pathDiff(true, true);
+                    }
+                }
+            }
+        } else {
+            Inkscape::XML::Node *rect_repr = xml_doc->createElement("svg:rect");
+            sp_desktop_apply_style_tool(_desktop, rect_repr, "/tools/eraser", false);
+            SPRect *rect = SP_RECT(parent->appendChildRepr(rect_repr));
+            Inkscape::GC::release(rect_repr);
+            rect->setPosition(bbox->left(), bbox->top(), bbox->width(), bbox->height());
+            rect->transform = SP_ITEM(rect->parent)->i2doc_affine().inverse();
+
+            rect->updateRepr();
+            rect->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+            w_selection.raiseToTop(true);
+            w_selection.add(rect);
+            w_selection.pathDiff(true, true);
+        }
+        w_selection.raiseToTop(true);
+        w_selection.add(item);
+        w_selection.setMask(true, false, true);
+        if (delete_old_clip_path) {
+            clip_path->deleteObject(true);
+        }
+    } else {
+        SPItem *erase_clip = w_selection.singleItem();
+        if (erase_clip) {
+            erase_clip->deleteObject(true);
+        }
+    }
+}
+
+/** Detects whether the given path is a straight line segment which encloses no area
+ or consists of several such segments */
+bool EraserTool::_isStraightSegment(SPItem *path)
+{
+    SPPath *as_path = dynamic_cast<SPPath *>(path);
+    if (!as_path) {
+        return false;
+    }
+
+    auto const &curve = as_path->curve();
+    if (!curve) {
+        return false;
+    }
+    auto const &pathvector = curve->get_pathvector();
+
+    // Check if all segments are straight and collinear
+    for (auto const &path : pathvector) {
+        Geom::Point initial_tangent = path.front().unitTangentAt(0.0);
+        for (auto const &segment : path) {
+            if (!segment.isLineSegment()) {
+                return false;
+            } else {
+                Geom::Point dir = segment.unitTangentAt(0.0);
+                if (!Geom::are_near(dir, initial_tangent) && !Geom::are_near(-dir, initial_tangent)) {
+                    return false;
+                }
+            }
+        }
+    }
+    return true;
+}
+
+void EraserTool::_addCap(SPCurve &curve, Geom::Point const &pre, Geom::Point const &from, Geom::Point const &to,
+                         Geom::Point const &post, double rounding)
+{
+    Geom::Point vel = rounding * Geom::rot90(to - from) / M_SQRT2;
+    double mag = Geom::L2(vel);
+
+    Geom::Point v_in = from - pre;
+    double mag_in = Geom::L2(v_in);
+
+    if (mag_in > epsilon) {
+        v_in = mag * v_in / mag_in;
+    } else {
+        v_in = Geom::Point(0, 0);
+    }
+
+    Geom::Point v_out = to - post;
+    double mag_out = Geom::L2(v_out);
+
+    if (mag_out > epsilon) {
+        v_out = mag * v_out / mag_out;
+    } else {
+        v_out = Geom::Point(0, 0);
+    }
+
+    if (Geom::L2(v_in) > epsilon || Geom::L2(v_out) > epsilon) {
+        curve.curveto(from + v_in, to + v_out, to);
+    }
+}
+
+void EraserTool::_accumulate()
+{
+    // construct a crude outline of the eraser's path.
+    // this desperately needs to be rewritten to use the path outliner...
+    if (!cal1->get_segment_count() || !cal2->get_segment_count()) {
+        return;
+    }
+
+    auto rev_cal2 = cal2->create_reverse();
+
+    g_assert(!cal1->first_path()->closed());
+    g_assert(!rev_cal2->first_path()->closed());
+
+    Geom::BezierCurve const *dc_cal1_firstseg  = dynamic_cast<Geom::BezierCurve const *>(cal1->first_segment());
+    Geom::BezierCurve const *rev_cal2_firstseg = dynamic_cast<Geom::BezierCurve const *>(rev_cal2->first_segment());
+    Geom::BezierCurve const *dc_cal1_lastseg   = dynamic_cast<Geom::BezierCurve const *>(cal1->last_segment());
+    Geom::BezierCurve const *rev_cal2_lastseg  = dynamic_cast<Geom::BezierCurve const *>(rev_cal2->last_segment());
+
+    g_assert(dc_cal1_firstseg);
+    g_assert(rev_cal2_firstseg);
+    g_assert(dc_cal1_lastseg);
+    g_assert(rev_cal2_lastseg);
+
+    accumulated->append(*cal1);
+    if (!nowidth) {
+        _addCap(*accumulated,
+                dc_cal1_lastseg->finalPoint() - dc_cal1_lastseg->unitTangentAt(1),
+                dc_cal1_lastseg->finalPoint(),
+                rev_cal2_firstseg->initialPoint(),
+                rev_cal2_firstseg->initialPoint() + rev_cal2_firstseg->unitTangentAt(0),
+                cap_rounding);
+
+        accumulated->append(*rev_cal2, true);
+
+        _addCap(*accumulated,
+                rev_cal2_lastseg->finalPoint() - rev_cal2_lastseg->unitTangentAt(1),
+                rev_cal2_lastseg->finalPoint(),
+                dc_cal1_firstseg->initialPoint(),
+                dc_cal1_firstseg->initialPoint() + dc_cal1_firstseg->unitTangentAt(0),
+                cap_rounding);
+
+        accumulated->closepath();
+    }
+    cal1->reset();
+    cal2->reset();
+}
+
+void EraserTool::_fitAndSplit(bool releasing)
+{
+    double const tolerance_sq = square(_desktop->w2d().descrim() * tolerance);
+    Inkscape::Preferences *prefs = Inkscape::Preferences::get();
+    nowidth = (prefs->getDouble("/tools/eraser/width", 1) == 0);
+
+#ifdef ERASER_VERBOSE
+    g_print("[F&S:R=%c]", releasing ? 'T' : 'F');
+#endif
+    if (npoints >= SAMPLING_SIZE || npoints <= 0) {
+        return; // just clicked
+    }
+
+    if (npoints == SAMPLING_SIZE - 1 || releasing) {
+        _completeBezier(tolerance_sq, releasing);
+
+#ifdef ERASER_VERBOSE
+        g_print("[%d]Yup\n", npoints);
+#endif
+        if (!releasing) {
+            _fitDrawLastPoint();
+        }
+
+        // Copy last point
+        point1[0] = point1[npoints - 1];
+        point2[0] = point2[npoints - 1];
+        npoints = 1;
+    } else {
+        _drawTemporaryBox();
+    }
+}
+
+void EraserTool::_completeBezier(double tolerance_sq, bool releasing)
+{
+    /* Current eraser */
+    if (cal1->is_empty() || cal2->is_empty()) {
+        /* dc->npoints > 0 */
+        cal1->reset();
+        cal2->reset();
+
+        cal1->moveto(point1[0]);
+        cal2->moveto(point2[0]);
+    }
+#ifdef ERASER_VERBOSE
+    g_print("[F&S:#] npoints:%d, releasing:%s\n", npoints, releasing ? "TRUE" : "FALSE");
+#endif
+
+    unsigned const bezier_size = 4;
+    unsigned const max_beziers = 8;
+    size_t const bezier_max_length = bezier_size * max_beziers;
+
+    Geom::Point b1[bezier_max_length];
+    gint const nb1 = Geom::bezier_fit_cubic_r(b1, point1, npoints, tolerance_sq, max_beziers);
+    g_assert(nb1 * bezier_size <= gint(G_N_ELEMENTS(b1)));
+
+    Geom::Point b2[bezier_max_length];
+    gint const nb2 = Geom::bezier_fit_cubic_r(b2, point2, npoints, tolerance_sq, max_beziers);
+    g_assert(nb2 * bezier_size <= gint(G_N_ELEMENTS(b2)));
+
+    if (nb1 == -1 || nb2 == -1) {
+        _failedBezierFallback(); // TODO: do we ever need this?
+        return;
+    }
+
+    /* Fit and draw and reset state */
+#ifdef ERASER_VERBOSE
+    g_print("nb1:%d nb2:%d\n", nb1, nb2);
+#endif
+
+    /* CanvasShape */
+    if (!releasing) {
+        currentcurve->reset();
+        currentcurve->moveto(b1[0]);
+
+        for (Geom::Point *bp1 = b1; bp1 < b1 + bezier_size * nb1; bp1 += bezier_size) {
+            currentcurve->curveto(bp1[1], bp1[2], bp1[3]);
+        }
+
+        currentcurve->lineto(b2[bezier_size * (nb2 - 1) + 3]);
+
+        for (Geom::Point *bp2 = b2 + bezier_size * (nb2 - 1); bp2 >= b2; bp2 -= bezier_size) {
+            currentcurve->curveto(bp2[2], bp2[1], bp2[0]);
+        }
+
+        // FIXME: segments is always NULL at this point??
+        if (segments.empty()) { // first segment
+            _addCap(*currentcurve, b2[1], b2[0], b1[0], b1[1], cap_rounding);
+        }
+
+        currentcurve->closepath();
+        currentshape->set_bpath(currentcurve.get(), true);
+    }
+
+    /* Current eraser */
+    for (Geom::Point *bp1 = b1; bp1 < b1 + bezier_size * nb1; bp1 += bezier_size) {
+        cal1->curveto(bp1[1], bp1[2], bp1[3]);
+    }
+
+    for (Geom::Point *bp2 = b2; bp2 < b2 + bezier_size * nb2; bp2 += bezier_size) {
+        cal2->curveto(bp2[1], bp2[2], bp2[3]);
+    }
+}
+
+void EraserTool::_failedBezierFallback()
+{
+    /* fixme: ??? */
+#ifdef ERASER_VERBOSE
+    g_print("[_failedBezierFallback] - failed to fit cubic.\n");
+#endif
+    _drawTemporaryBox();
+
+    for (gint i = 1; i < npoints; i++) {
+        cal1->lineto(point1[i]);
+    }
+
+    for (gint i = 1; i < npoints; i++) {
+        cal2->lineto(point2[i]);
+    }
+}
+
+void EraserTool::_fitDrawLastPoint()
+{
+    g_assert(!currentcurve->is_empty());
+
+    guint32 fillColor = sp_desktop_get_color_tool(_desktop, "/tools/eraser", true);
+    double opacity = sp_desktop_get_master_opacity_tool(_desktop, "/tools/eraser");
+    double fillOpacity = sp_desktop_get_opacity_tool(_desktop, "/tools/eraser", true);
+
+    guint fill = (fillColor & 0xffffff00) | SP_COLOR_F_TO_U(opacity * fillOpacity);
+
+    auto cbp = new Inkscape::CanvasItemBpath(_desktop->getCanvasSketch(), currentcurve.get(), true);
+    cbp->set_fill(fill, trace_wind_rule);
+    cbp->set_stroke(0x0);
+
+    /* fixme: Cannot we cascade it to root more clearly? */
+    cbp->connect_event(sigc::bind(sigc::ptr_fun(sp_desktop_root_handler), _desktop));
+    segments.push_back(cbp);
+
+    if (mode == EraserToolMode::DELETE) {
+        cbp->hide();
+        currentshape->hide();
+    }
+}
+
+void EraserTool::_drawTemporaryBox()
+{
+    currentcurve->reset();
+
+    currentcurve->moveto(point1[npoints - 1]);
+
+    for (gint i = npoints - 2; i >= 0; i--) {
+        currentcurve->lineto(point1[i]);
+    }
+
+    for (gint i = 0; i < npoints; i++) {
+        currentcurve->lineto(point2[i]);
+    }
+
+    if (npoints >= 2) {
+        _addCap(*currentcurve,
+                point2[npoints - 2], point2[npoints - 1],
+                point1[npoints - 1], point1[npoints - 2], cap_rounding);
+    }
+
+    currentcurve->closepath();
+    currentshape->set_bpath(currentcurve.get(), true);
+}
+
+} // namespace Tools
+} // namespace UI
+} // namespace Inkscape
+
+/*
+  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 :