Adding upstream version 1.2.2.upstream/1.2.2upstream

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

1 files changed, 1192 insertions, 0 deletions

diff --git a/src/ui/tools/calligraphic-tool.cpp b/src/ui/tools/calligraphic-tool.cpp
new file mode 100644
index 0000000..aced95d
--- /dev/null
+++ b/src/ui/tools/calligraphic-tool.cpp
@@ -0,0 +1,1192 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Handwriting-like drawing mode
+ *
+ * Authors:
+ *   Mitsuru Oka <oka326@parkcity.ne.jp>
+ *   Lauris Kaplinski <lauris@kaplinski.com>
+ *   bulia byak <buliabyak@users.sf.net>
+ *   MenTaLguY <mental@rydia.net>
+ *   Abhishek Sharma
+ *   Jon A. Cruz <jon@joncruz.org>
+ *
+ * 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
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#define noDYNA_DRAW_VERBOSE
+
+#include "ui/tools/calligraphic-tool.h"
+
+#include <cstring>
+#include <numeric>
+#include <string>
+
+#include <gdk/gdkkeysyms.h>
+#include <glibmm/i18n.h>
+#include <gtk/gtk.h>
+
+#include <2geom/bezier-utils.h>
+#include <2geom/circle.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 "inkscape.h"
+#include "message-context.h"
+#include "selection.h"
+
+#include "display/control/canvas-item-bpath.h"
+#include "display/control/canvas-item-drawing.h" // ctx
+#include "display/curve.h"
+#include "display/drawing.h"
+
+#include "include/macros.h"
+
+#include "livarot/Path.h"
+#include "livarot/Shape.h"
+
+#include "object/sp-shape.h"
+#include "object/sp-text.h"
+
+#include "path/path-util.h"
+
+#include "svg/svg.h"
+
+#include "ui/icon-names.h"
+#include "ui/tools/freehand-base.h"
+
+#include "util/units.h"
+
+using Inkscape::DocumentUndo;
+using Inkscape::Util::Quantity;
+using Inkscape::Util::Unit;
+using Inkscape::Util::unit_table;
+
+#define DDC_RED_RGBA 0xff0000ff
+
+#define TOLERANCE_CALLIGRAPHIC 0.1
+
+#define DYNA_EPSILON 0.5e-6
+#define DYNA_EPSILON_START 0.5e-2
+#define DYNA_VEL_START 1e-5
+
+#define DYNA_MIN_WIDTH 1.0e-6
+
+namespace Inkscape {
+namespace UI {
+namespace Tools {
+
+CalligraphicTool::CalligraphicTool(SPDesktop *desktop)
+    : DynamicBase(desktop, "/tools/calligraphic", "calligraphy.svg")
+    , keep_selected(true)
+    , hatch_spacing(0)
+    , hatch_spacing_step(0)
+    , hatch_item(nullptr)
+    , hatch_livarot_path(nullptr)
+    , hatch_last_nearest(Geom::Point(0, 0))
+    , hatch_last_pointer(Geom::Point(0, 0))
+    , hatch_escaped(false)
+    , just_started_drawing(false)
+    , trace_bg(false)
+{
+    this->vel_thin = 0.1;
+    this->flatness = -0.9;
+    this->cap_rounding = 0.0;
+    this->abs_width = false;
+
+    this->accumulated.reset(new SPCurve());
+    this->currentcurve.reset(new SPCurve());
+
+    this->cal1.reset(new SPCurve());
+    this->cal2.reset(new SPCurve());
+
+    currentshape = new Inkscape::CanvasItemBpath(desktop->getCanvasSketch());
+    currentshape->set_stroke(0x0);
+    currentshape->set_fill(DDC_RED_RGBA, SP_WIND_RULE_EVENODD);
+
+    /* fixme: Cannot we cascade it to root more clearly? */
+    currentshape->connect_event(sigc::bind(sigc::ptr_fun(sp_desktop_root_handler), desktop));
+
+    hatch_area = new Inkscape::CanvasItemBpath(desktop->getCanvasControls());
+    hatch_area->set_fill(0x0, SP_WIND_RULE_EVENODD);
+    hatch_area->set_stroke(0x0000007f);
+    hatch_area->set_pickable(false);
+    hatch_area->hide();
+
+    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, "keep_selected");
+    sp_event_context_read(this, "cap_rounding");
+
+    this->is_drawing = false;
+
+    Inkscape::Preferences *prefs = Inkscape::Preferences::get();
+    if (prefs->getBool("/tools/calligraphic/selcue")) {
+        this->enableSelectionCue();
+    }
+}
+
+CalligraphicTool::~CalligraphicTool()
+{
+    if (hatch_area) {
+        delete hatch_area;
+        hatch_area = nullptr;
+    }
+    if (currentshape) {
+        delete currentshape;
+        currentshape = nullptr;
+    }
+}
+
+void CalligraphicTool::set(const Inkscape::Preferences::Entry& val) {
+    Glib::ustring path = val.getEntryName();
+
+    if (path == "tracebackground") {
+        this->trace_bg = val.getBool();
+    } else if (path == "keep_selected") {
+        this->keep_selected = val.getBool();
+    } else {
+        //pass on up to parent class to handle common attributes.
+    	DynamicBase::set(val);
+    }
+
+    //g_print("DDC: %g %g %g %g\n", ddc->mass, ddc->drag, ddc->angle, ddc->width);
+}
+
+static double
+flerp(double f0, double f1, double p)
+{
+    return f0 + ( f1 - f0 ) * p;
+}
+
+void CalligraphicTool::reset(Geom::Point p) {
+    this->last = this->cur = this->getNormalizedPoint(p);
+
+    this->vel = Geom::Point(0,0);
+    this->vel_max = 0;
+    this->acc = Geom::Point(0,0);
+    this->ang = Geom::Point(0,0);
+    this->del = Geom::Point(0,0);
+}
+
+void CalligraphicTool::extinput(GdkEvent *event) {
+    if (gdk_event_get_axis (event, GDK_AXIS_PRESSURE, &this->pressure)) {
+        this->pressure = CLAMP (this->pressure, DDC_MIN_PRESSURE, DDC_MAX_PRESSURE);
+    } else {
+        this->pressure = DDC_DEFAULT_PRESSURE;
+    }
+
+    if (gdk_event_get_axis (event, GDK_AXIS_XTILT, &this->xtilt)) {
+        this->xtilt = CLAMP (this->xtilt, DDC_MIN_TILT, DDC_MAX_TILT);
+    } else {
+        this->xtilt = DDC_DEFAULT_TILT;
+    }
+
+    if (gdk_event_get_axis (event, GDK_AXIS_YTILT, &this->ytilt)) {
+        this->ytilt = CLAMP (this->ytilt, DDC_MIN_TILT, DDC_MAX_TILT);
+    } else {
+        this->ytilt = DDC_DEFAULT_TILT;
+    }
+}
+
+
+bool CalligraphicTool::apply(Geom::Point p) {
+    Geom::Point n = this->getNormalizedPoint(p);
+
+    /* Calculate mass and drag */
+    double const mass = flerp(1.0, 160.0, this->mass);
+    double const drag = flerp(0.0, 0.5, this->drag * this->drag);
+
+    /* Calculate force and acceleration */
+    Geom::Point force = n - this->cur;
+
+    // If force is below the absolute threshold DYNA_EPSILON,
+    // or we haven't yet reached DYNA_VEL_START (i.e. at the beginning of stroke)
+    // _and_ the force is below the (higher) DYNA_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) < DYNA_EPSILON || (this->vel_max < DYNA_VEL_START && Geom::L2(force) < DYNA_EPSILON_START)) {
+        return FALSE;
+    }
+
+    this->acc = force / mass;
+
+    /* Calculate new velocity */
+    this->vel += this->acc;
+
+    if (Geom::L2(this->vel) > this->vel_max)
+        this->vel_max = Geom::L2(this->vel);
+
+    /* Calculate angle of drawing tool */
+
+    double a1;
+    if (this->usetilt) {
+        // 1a. calculate nib angle from input device tilt:
+        if (this->xtilt == 0 && this->ytilt == 0) {
+            // to be sure that atan2 in the computation below
+            // would not crash or return NaN.
+            a1 = 0;
+        } else {
+            Geom::Point dir(-this->xtilt, this->ytilt);
+            a1 = atan2(dir);
+        }
+    }
+    else {
+        // 1b. fixed dc->angle (absolutely flat nib):
+        a1 = ( this->angle / 180.0 ) * M_PI;
+    }
+    a1 *= -_desktop->yaxisdir();
+    if (this->flatness < 0.0) {
+        // flips direction. Useful when this->usetilt
+        // allows simulating both pen and calligraphic brush
+        a1 *= -1;
+    }
+    a1 = fmod(a1, M_PI);
+    if (a1 > 0.5*M_PI) {
+        a1 -= M_PI;
+    } else if (a1 <= -0.5*M_PI) {
+        a1 += M_PI;
+    }
+
+    // 2. perpendicular to dc->vel (absolutely non-flat nib):
+    gdouble const mag_vel = Geom::L2(this->vel);
+    if ( mag_vel < DYNA_EPSILON ) {
+        return FALSE;
+    }
+    Geom::Point ang2 = Geom::rot90(this->vel) / mag_vel;
+
+    // 3. Average them using flatness parameter:
+    // calculate angles
+    double a2 = atan2(ang2);
+    // flip a2 to force it to be in the same half-circle as a1
+    bool flipped = false;
+    if (fabs (a2-a1) > 0.5*M_PI) {
+        a2 += M_PI;
+        flipped = true;
+    }
+    // normalize a2
+    if (a2 > M_PI)
+        a2 -= 2*M_PI;
+    if (a2 < -M_PI)
+        a2 += 2*M_PI;
+    // find the flatness-weighted bisector angle, unflip if a2 was flipped
+    // FIXME: when dc->vel is oscillating around the fixed angle, the new_ang flips back and forth. How to avoid this?
+    double new_ang = a1 + (1 - fabs(this->flatness)) * (a2 - a1) - (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)) - this->ang);
+    if ( angle_delta / Geom::L2(this->vel) > 4000 ) {
+        return FALSE;
+    }
+
+    // convert to point
+    this->ang = Geom::Point (cos (new_ang), sin (new_ang));
+
+//    g_print ("force %g  acc %g  vel_max %g  vel %g  a1 %g  a2 %g  new_ang %g\n", Geom::L2(force), Geom::L2(dc->acc), dc->vel_max, Geom::L2(dc->vel), a1, a2, new_ang);
+
+    /* Apply drag */
+    this->vel *= 1.0 - drag;
+
+    /* Update position */
+    this->last = this->cur;
+    this->cur += this->vel;
+
+    return TRUE;
+}
+
+void CalligraphicTool::brush() {
+    g_assert( this->npoints >= 0 && this->npoints < SAMPLING_SIZE );
+
+    // How much velocity thins strokestyle
+    double vel_thin = flerp (0, 160, this->vel_thin);
+
+    // Influence of pressure on thickness
+    double pressure_thick = (this->usepressure ? this->pressure : 1.0);
+
+    // get the real brush point, not the same as pointer (affected by hatch tracking and/or mass
+    // drag)
+    Geom::Point brush = getViewPoint(this->cur);
+    Geom::Point brush_w = _desktop->d2w(brush);
+
+    double trace_thick = 1;
+    if (this->trace_bg) {
+        // Trace background, use single pixel under brush.
+        Geom::IntRect area = Geom::IntRect::from_xywh(brush_w.floor(), Geom::IntPoint(1, 1));
+
+        Inkscape::CanvasItemDrawing *canvas_item_drawing = _desktop->getCanvasDrawing();
+        Inkscape::Drawing *drawing = canvas_item_drawing->get_drawing();
+
+        // Ensure drawing up-to-date. (Is this really necessary?)
+        drawing->update();
+
+        // Get average color.
+        double R, G, B, A;
+        drawing->average_color(area, R, G, B, A);
+
+        // Convert to thickness.
+        double max = MAX (MAX (R, G), B);
+        double min = MIN (MIN (R, G), B);
+        double L = A * (max + min)/2 + (1 - A); // blend with white bg
+        trace_thick = 1 - L;
+        //g_print ("L %g thick %g\n", L, trace_thick);
+    }
+
+    double width = (pressure_thick * trace_thick - vel_thin * Geom::L2(this->vel)) * this->width;
+
+    double tremble_left = 0, tremble_right = 0;
+    if (this->tremor > 0) {
+        // obtain two normally distributed random variables, using polar Box-Muller transform
+        double x1, x2, w, y1, y2;
+        do {
+            x1 = 2.0 * g_random_double_range(0,1) - 1.0;
+            x2 = 2.0 * g_random_double_range(0,1) - 1.0;
+            w = x1 * x1 + x2 * x2;
+        } while ( w >= 1.0 );
+        w = sqrt( (-2.0 * log( w ) ) / w );
+        y1 = x1 * w;
+        y2 = x2 * w;
+
+        // deflect both left and right edges randomly and independently, so that:
+        // (1) dc->tremor=1 corresponds to sigma=1, decreasing dc->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
+        tremble_left  = (y1)*this->tremor * (0.15 + 0.8*width) * (0.35 + 14*Geom::L2(this->vel));
+        tremble_right = (y2)*this->tremor * (0.15 + 0.8*width) * (0.35 + 14*Geom::L2(this->vel));
+    }
+
+    if ( width < 0.02 * this->width ) {
+        width = 0.02 * this->width;
+    }
+
+    double dezoomify_factor = 0.05 * 1000;
+    if (!this->abs_width) {
+        dezoomify_factor /= _desktop->current_zoom();
+    }
+
+    Geom::Point del_left = dezoomify_factor * (width + tremble_left) * this->ang;
+    Geom::Point del_right = dezoomify_factor * (width + tremble_right) * this->ang;
+
+    this->point1[this->npoints] = brush + del_left;
+    this->point2[this->npoints] = brush - del_right;
+
+    this->del = 0.5*(del_left + del_right);
+
+    this->npoints++;
+}
+
+static void
+sp_ddc_update_toolbox (SPDesktop *desktop, const gchar *id, double value)
+{
+    desktop->setToolboxAdjustmentValue (id, value);
+}
+
+void CalligraphicTool::cancel() {
+    this->dragging = false;
+    this->is_drawing = false;
+
+    ungrabCanvasEvents();
+
+    /* Remove all temporary line segments */
+    for (auto segment :this->segments) {
+        delete segment;
+    }
+    this->segments.clear();
+
+    /* reset accumulated curve */
+    this->accumulated->reset();
+    this->clear_current();
+
+    if (this->repr) {
+        this->repr = nullptr;
+    }
+}
+
+bool CalligraphicTool::root_handler(GdkEvent* event) {
+    gint ret = FALSE;
+    Inkscape::Preferences *prefs = Inkscape::Preferences::get();
+    Unit const *unit = unit_table.getUnit(prefs->getString("/tools/calligraphic/unit"));
+
+    switch (event->type) {
+        case GDK_BUTTON_PRESS:
+            if (event->button.button == 1) {
+                if (Inkscape::have_viable_layer(_desktop, defaultMessageContext()) == false) {
+                    return TRUE;
+                }
+
+                this->accumulated->reset();
+
+                if (this->repr) {
+                    this->repr = nullptr;
+                }
+
+                /* initialize first point */
+                this->npoints = 0;
+
+                grabCanvasEvents();
+
+                ret = TRUE;
+
+                set_high_motion_precision();
+                this->is_drawing = true;
+                this->just_started_drawing = 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));
+            this->extinput(event);
+
+            this->message_context->clear();
+
+            // for hatching:
+            double hatch_dist = 0;
+            Geom::Point hatch_unit_vector(0,0);
+            Geom::Point nearest(0,0);
+            Geom::Point pointer(0,0);
+            Geom::Affine motion_to_curve(Geom::identity());
+
+            if (event->motion.state & GDK_CONTROL_MASK) { // hatching - sense the item
+
+                SPItem *selected = _desktop->getSelection()->singleItem();
+                if (selected && (SP_IS_SHAPE(selected) || SP_IS_TEXT(selected))) {
+                    // One item selected, and it's a path;
+                    // let's try to track it as a guide
+
+                    if (selected != this->hatch_item) {
+                        this->hatch_item = selected;
+                        if (this->hatch_livarot_path)
+                            delete this->hatch_livarot_path;
+                        this->hatch_livarot_path = Path_for_item (this->hatch_item, true, true);
+                        if (hatch_livarot_path) {
+                            hatch_livarot_path->ConvertWithBackData(0.01);
+                        }
+                    }
+
+                    // calculate pointer point in the guide item's coords
+                    motion_to_curve = selected->dt2i_affine() * selected->i2doc_affine();
+                    pointer = motion_dt * motion_to_curve;
+
+                    // calculate the nearest point on the guide path
+                    std::optional<Path::cut_position> position = get_nearest_position_on_Path(this->hatch_livarot_path, pointer);
+                    if (position) {
+                        nearest = get_point_on_Path(hatch_livarot_path, position->piece, position->t);
+
+                        // distance from pointer to nearest
+                        hatch_dist = Geom::L2(pointer - nearest);
+                        // unit-length vector
+                        hatch_unit_vector = (pointer - nearest) / hatch_dist;
+
+                        this->message_context->set(Inkscape::NORMAL_MESSAGE, _("<b>Guide path selected</b>; start drawing along the guide with <b>Ctrl</b>"));
+                    }
+                } else {
+                    this->message_context->set(Inkscape::NORMAL_MESSAGE, _("<b>Select a guide path</b> to track with <b>Ctrl</b>"));
+                }
+            }
+
+            if ( this->is_drawing && (event->motion.state & GDK_BUTTON1_MASK)) {
+                this->dragging = TRUE;
+
+                if (event->motion.state & GDK_CONTROL_MASK && this->hatch_item) { // hatching
+
+#define HATCH_VECTOR_ELEMENTS 12
+#define INERTIA_ELEMENTS 24
+#define SPEED_ELEMENTS 12
+#define SPEED_MIN 0.3
+#define SPEED_NORMAL 0.35
+#define INERTIA_FORCE 0.5
+
+                    // speed is the movement of the nearest point along the guide path, divided by
+                    // the movement of the pointer at the same period; it is averaged for the last
+                    // SPEED_ELEMENTS motion events.  Normally, as you track the guide path, speed
+                    // is about 1, i.e. the nearest point on the path is moved by about the same
+                    // distance as the pointer. If the speed starts to decrease, we are losing
+                    // contact with the guide; if it drops below SPEED_MIN, we are on our own and
+                    // not attracted to guide anymore. Most often this happens when you have
+                    // tracked to the end of a guide calligraphic stroke and keep moving
+                    // further. We try to handle this situation gracefully: not stick with the
+                    // guide forever but let go of it smoothly and without sharp jerks (non-zero
+                    // mass recommended; with zero mass, jerks are still quite noticeable).
+
+                    double speed = 1;
+                    if (Geom::L2(this->hatch_last_nearest) != 0) {
+                        // the distance nearest moved since the last motion event
+                        double nearest_moved = Geom::L2(nearest - this->hatch_last_nearest);
+                        // the distance pointer moved since the last motion event
+                        double pointer_moved = Geom::L2(pointer - this->hatch_last_pointer);
+                        // store them in stacks limited to SPEED_ELEMENTS
+                        this->hatch_nearest_past.push_front(nearest_moved);
+                        if (this->hatch_nearest_past.size() > SPEED_ELEMENTS)
+                            this->hatch_nearest_past.pop_back();
+                        this->hatch_pointer_past.push_front(pointer_moved);
+                        if (this->hatch_pointer_past.size() > SPEED_ELEMENTS)
+                            this->hatch_pointer_past.pop_back();
+
+                        // If the stacks are full,
+                        if (this->hatch_nearest_past.size() == SPEED_ELEMENTS) {
+                            // calculate the sums of all stored movements
+                            double nearest_sum = std::accumulate (this->hatch_nearest_past.begin(), this->hatch_nearest_past.end(), 0.0);
+                            double pointer_sum = std::accumulate (this->hatch_pointer_past.begin(), this->hatch_pointer_past.end(), 0.0);
+                            // and divide to get the speed
+                            speed = nearest_sum/pointer_sum;
+                            //g_print ("nearest sum %g  pointer_sum %g  speed %g\n", nearest_sum, pointer_sum, speed);
+                        }
+                    }
+
+                    if (   this->hatch_escaped  // already escaped, do not reattach
+                        || (speed < SPEED_MIN) // stuck; most likely reached end of traced stroke
+                        || (this->hatch_spacing > 0 && hatch_dist > 50 * this->hatch_spacing) // went too far from the guide
+                        ) {
+                        // We are NOT attracted to the guide!
+
+                        //g_print ("\nlast_nearest %g %g   nearest %g %g  pointer %g %g  pos %d %g\n", dc->last_nearest[Geom::X], dc->last_nearest[Geom::Y], nearest[Geom::X], nearest[Geom::Y], pointer[Geom::X], pointer[Geom::Y], position->piece, position->t);
+
+                        // Remember hatch_escaped so we don't get
+                        // attracted again until the end of this stroke
+                        this->hatch_escaped = true;
+
+                        if (this->inertia_vectors.size() >= INERTIA_ELEMENTS/2) { // move by inertia
+                            Geom::Point moved_past_escape = motion_dt - this->inertia_vectors.front();
+                            Geom::Point inertia = 
+                                this->inertia_vectors.front() - this->inertia_vectors.back();
+
+                            double dot = Geom::dot (moved_past_escape, inertia);
+                            dot /= Geom::L2(moved_past_escape) * Geom::L2(inertia);
+
+                            if (dot > 0) { // mouse is still moving in approx the same direction
+                                Geom::Point should_have_moved = 
+                                    (inertia) * (1/Geom::L2(inertia)) * Geom::L2(moved_past_escape);
+                                motion_dt = this->inertia_vectors.front() + 
+                                    (INERTIA_FORCE * should_have_moved + (1 - INERTIA_FORCE) * moved_past_escape);
+                            }
+                        }
+
+                    } else {
+
+                        // Calculate angle cosine of this vector-to-guide and all past vectors
+                        // summed, to detect if we accidentally flipped to the other side of the
+                        // guide
+                        Geom::Point hatch_vector_accumulated = std::accumulate 
+                            (this->hatch_vectors.begin(), this->hatch_vectors.end(), Geom::Point(0,0));
+                        double dot = Geom::dot (pointer - nearest, hatch_vector_accumulated);
+                        dot /= Geom::L2(pointer - nearest) * Geom::L2(hatch_vector_accumulated);
+
+                        if (this->hatch_spacing != 0) { // spacing was already set
+                            double target;
+                            if (speed > SPEED_NORMAL) {
+                                // all ok, strictly obey the spacing
+                                target = this->hatch_spacing;
+                            } else {
+                                // looks like we're starting to lose speed,
+                                // so _gradually_ let go attraction to prevent jerks
+                                target = (this->hatch_spacing * speed + hatch_dist * (SPEED_NORMAL - speed))/SPEED_NORMAL;
+                            }
+                            if (!std::isnan(dot) && dot < -0.5) {// flip
+                                target = -target;
+                            }
+
+                            // This is the track pointer that we will use instead of the real one
+                            Geom::Point new_pointer = nearest + target * hatch_unit_vector;
+
+                            // some limited feedback: allow persistent pulling to slightly change
+                            // the spacing
+                            this->hatch_spacing += (hatch_dist - this->hatch_spacing)/3500;
+
+                            // return it to the desktop coords
+                            motion_dt = new_pointer * motion_to_curve.inverse();
+
+                            if (speed >= SPEED_NORMAL) {
+                                this->inertia_vectors.push_front(motion_dt);
+                                if (this->inertia_vectors.size() > INERTIA_ELEMENTS)
+                                    this->inertia_vectors.pop_back();
+                            }
+
+                        } else {
+                            // this is the first motion event, set the dist
+                            this->hatch_spacing = hatch_dist;
+                        }
+
+                        // remember last points
+                        this->hatch_last_pointer = pointer;
+                        this->hatch_last_nearest = nearest;
+
+                        this->hatch_vectors.push_front(pointer - nearest);
+                        if (this->hatch_vectors.size() > HATCH_VECTOR_ELEMENTS)
+                            this->hatch_vectors.pop_back();
+                    }
+
+                    this->message_context->set(Inkscape::NORMAL_MESSAGE, this->hatch_escaped? _("Tracking: <b>connection to guide path lost!</b>") : _("<b>Tracking</b> a guide path"));
+
+                } else {
+                    this->message_context->set(Inkscape::NORMAL_MESSAGE, _("<b>Drawing</b> a calligraphic stroke"));
+                }
+
+                if (this->just_started_drawing) {
+                    this->just_started_drawing = false;
+                    this->reset(motion_dt);
+                }
+
+                if (!this->apply(motion_dt)) {
+                    ret = TRUE;
+                    break;
+                }
+
+                if ( this->cur != this->last ) {
+                    this->brush();
+                    g_assert( this->npoints > 0 );
+                    this->fit_and_split(false);
+                }
+                ret = TRUE;
+            }
+
+            Geom::PathVector path = Geom::Path(Geom::Circle(0,0,1)); // Unit circle centered at origin.
+
+            // Draw the hatching circle if necessary
+            if (event->motion.state & GDK_CONTROL_MASK) {
+                if (this->hatch_spacing == 0 && hatch_dist != 0) {
+                    // Haven't set spacing yet: gray, center free, update radius live
+
+                    Geom::Point c = _desktop->w2d(motion_w);
+                    Geom::Affine const sm (Geom::Scale(hatch_dist, hatch_dist) * Geom::Translate(c));
+                    path *= sm;
+
+                    hatch_area->set_bpath(path, true);
+                    hatch_area->set_stroke(0x7f7f7fff);
+                    hatch_area->show();
+
+                } else if (this->dragging && !this->hatch_escaped && hatch_dist != 0) {
+                    // Tracking: green, center snapped, fixed radius
+
+                    Geom::Point c = motion_dt;
+                    Geom::Affine const sm (Geom::Scale(this->hatch_spacing, this->hatch_spacing) * Geom::Translate(c));
+                    path *= sm;
+
+                    hatch_area->set_bpath(path, true);
+                    hatch_area->set_stroke(0x00FF00ff);
+                    hatch_area->show();
+
+                } else if (this->dragging && this->hatch_escaped && hatch_dist != 0) {
+                    // Tracking escaped: red, center free, fixed radius
+
+                    Geom::Point c = motion_dt;
+                    Geom::Affine const sm (Geom::Scale(this->hatch_spacing, this->hatch_spacing) * Geom::Translate(c));
+                    path *= sm;
+
+                    hatch_area->set_bpath(path, true);
+                    hatch_area->set_stroke(0xff0000ff);
+                    hatch_area->show();
+
+                } else {
+                    // Not drawing but spacing set: gray, center snapped, fixed radius
+
+                    Geom::Point c = (nearest + this->hatch_spacing * hatch_unit_vector) * motion_to_curve.inverse();
+                    if (!std::isnan(c[Geom::X]) && !std::isnan(c[Geom::Y]) && this->hatch_spacing!=0) {
+                        Geom::Affine const sm (Geom::Scale(this->hatch_spacing, this->hatch_spacing) * Geom::Translate(c));
+                        path *= sm;
+
+                        hatch_area->set_bpath(path, true);
+                        hatch_area->set_stroke(0x7f7f7fff);
+                        hatch_area->show();
+                    }
+                }
+            } else {
+                hatch_area->hide();
+            }
+        }
+        break;
+
+
+    case GDK_BUTTON_RELEASE:
+    {
+        Geom::Point const motion_w(event->button.x, event->button.y);
+        Geom::Point const motion_dt(_desktop->w2d(motion_w));
+
+        ungrabCanvasEvents();
+
+        set_high_motion_precision(false);
+        this->is_drawing = false;
+
+        if (this->dragging && event->button.button == 1) {
+            this->dragging = FALSE;
+
+            this->apply(motion_dt);
+
+            /* Remove all temporary line segments */
+            for (auto segment : this->segments) {
+                delete segment;
+            }
+            this->segments.clear();
+
+            /* Create object */
+            this->fit_and_split(true);
+            if (this->accumulate())
+                this->set_to_accumulated(event->button.state & GDK_SHIFT_MASK, event->button.state & GDK_MOD1_MASK); // performs document_done
+            else
+                g_warning ("Failed to create path: invalid data in dc->cal1 or dc->cal2");
+
+            /* reset accumulated curve */
+            this->accumulated->reset();
+
+            this->clear_current();
+            if (this->repr) {
+                this->repr = nullptr;
+            }
+
+            if (!this->hatch_pointer_past.empty()) this->hatch_pointer_past.clear();
+            if (!this->hatch_nearest_past.empty()) this->hatch_nearest_past.clear();
+            if (!this->inertia_vectors.empty()) this->inertia_vectors.clear();
+            if (!this->hatch_vectors.empty()) this->hatch_vectors.clear();
+            this->hatch_last_nearest = Geom::Point(0,0);
+            this->hatch_last_pointer = Geom::Point(0,0);
+            this->hatch_escaped = false;
+            this->hatch_item = nullptr;
+            this->hatch_livarot_path = nullptr;
+            this->just_started_drawing = false;
+
+            if (this->hatch_spacing != 0 && !this->keep_selected) {
+                // we do not select the newly drawn path, so increase spacing by step
+                if (this->hatch_spacing_step == 0) {
+                    this->hatch_spacing_step = this->hatch_spacing;
+                }
+                this->hatch_spacing += this->hatch_spacing_step;
+            }
+
+            this->message_context->clear();
+            ret = TRUE;
+        } else if (!this->dragging
+                   && event->button.button == 1
+                   && Inkscape::have_viable_layer(_desktop, defaultMessageContext()))
+        {
+            spdc_create_single_dot(this, _desktop->w2d(motion_w), "/tools/calligraphic", event->button.state);
+            ret = TRUE;
+        }
+        break;
+    }
+
+    case GDK_KEY_PRESS:
+        switch (get_latin_keyval (&event->key)) {
+        case GDK_KEY_Up:
+        case GDK_KEY_KP_Up:
+            if (!MOD__CTRL_ONLY(event)) {
+                this->angle += 5.0;
+                if (this->angle > 90.0)
+                    this->angle = 90.0;
+                sp_ddc_update_toolbox(_desktop, "calligraphy-angle", this->angle);
+                ret = TRUE;
+            }
+            break;
+        case GDK_KEY_Down:
+        case GDK_KEY_KP_Down:
+            if (!MOD__CTRL_ONLY(event)) {
+                this->angle -= 5.0;
+                if (this->angle < -90.0)
+                    this->angle = -90.0;
+                sp_ddc_update_toolbox(_desktop, "calligraphy-angle", this->angle);
+                ret = TRUE;
+            }
+            break;
+        case GDK_KEY_Right:
+        case GDK_KEY_KP_Right:
+            if (!MOD__CTRL_ONLY(event)) {
+                this->width = Quantity::convert(this->width, "px", unit) + 0.01;
+                if (this->width > 1.0)
+                    this->width = 1.0;
+                sp_ddc_update_toolbox (_desktop, "calligraphy-width", this->width * 100); // the same spinbutton is for alt+x
+                ret = TRUE;
+            }
+            break;
+        case GDK_KEY_Left:
+        case GDK_KEY_KP_Left:
+            if (!MOD__CTRL_ONLY(event)) {
+                this->width = Quantity::convert(this->width, "px", unit) - 0.01;
+                if (this->width < 0.00001)
+                    this->width = 0.00001;
+                sp_ddc_update_toolbox(_desktop, "calligraphy-width", this->width * 100);
+                ret = TRUE;
+            }
+            break;
+        case GDK_KEY_Home:
+        case GDK_KEY_KP_Home:
+            this->width = 0.00001;
+            sp_ddc_update_toolbox(_desktop, "calligraphy-width", this->width * 100);
+            ret = TRUE;
+            break;
+        case GDK_KEY_End:
+        case GDK_KEY_KP_End:
+            this->width = 1.0;
+            sp_ddc_update_toolbox(_desktop, "calligraphy-width", this->width * 100);
+            ret = TRUE;
+            break;
+        case GDK_KEY_x:
+        case GDK_KEY_X:
+            if (MOD__ALT_ONLY(event)) {
+                _desktop->setToolboxFocusTo("calligraphy-width");
+                ret = TRUE;
+            }
+            break;
+        case GDK_KEY_Escape:
+            if (this->is_drawing) {
+                // if drawing, cancel, otherwise pass it up for deselecting
+                this->cancel();
+                ret = TRUE;
+            }
+            break;
+        case GDK_KEY_z:
+        case GDK_KEY_Z:
+            if (MOD__CTRL_ONLY(event) && this->is_drawing) {
+                // if drawing, cancel, otherwise pass it up for undo
+                this->cancel();
+                ret = TRUE;
+            }
+            break;
+        default:
+            break;
+        }
+        break;
+
+    case GDK_KEY_RELEASE:
+        switch (get_latin_keyval(&event->key)) {
+            case GDK_KEY_Control_L:
+            case GDK_KEY_Control_R:
+                this->message_context->clear();
+                this->hatch_spacing = 0;
+                this->hatch_spacing_step = 0;
+                break;
+            default:
+                break;
+        }
+        break;
+
+    default:
+        break;
+    }
+
+    if (!ret) {
+//        if ((SP_EVENT_CONTEXT_CLASS(sp_dyna_draw_context_parent_class))->root_handler) {
+//            ret = (SP_EVENT_CONTEXT_CLASS(sp_dyna_draw_context_parent_class))->root_handler(event_context, event);
+//        }
+    	ret = DynamicBase::root_handler(event);
+    }
+
+    return ret;
+}
+
+
+void CalligraphicTool::clear_current() {
+    /* reset bpath */
+    this->currentshape->set_bpath(nullptr);
+
+    /* reset curve */
+    this->currentcurve->reset();
+    this->cal1->reset();
+    this->cal2->reset();
+
+    /* reset points */
+    this->npoints = 0;
+}
+
+void CalligraphicTool::set_to_accumulated(bool unionize, bool subtract) {
+    if (!this->accumulated->is_empty()) {
+        if (!this->repr) {
+            /* Create object */
+            Inkscape::XML::Document *xml_doc = _desktop->doc()->getReprDoc();
+            Inkscape::XML::Node *repr = xml_doc->createElement("svg:path");
+
+            /* Set style */
+            sp_desktop_apply_style_tool(_desktop, repr, "/tools/calligraphic", false);
+
+            this->repr = repr;
+
+            auto layer = currentLayer();
+            SPItem *item=SP_ITEM(layer->appendChildRepr(this->repr));
+            Inkscape::GC::release(this->repr);
+            item->transform = layer->i2doc_affine().inverse();
+            item->updateRepr();
+        }
+
+        Geom::PathVector pathv = this->accumulated->get_pathvector() * _desktop->dt2doc();
+        this->repr->setAttribute("d", sp_svg_write_path(pathv));
+
+        if (unionize) {
+            _desktop->getSelection()->add(this->repr);
+            _desktop->getSelection()->pathUnion(true);
+        } else if (subtract) {
+            _desktop->getSelection()->add(this->repr);
+            _desktop->getSelection()->pathDiff(true);
+        } else {
+            if (this->keep_selected) {
+                _desktop->getSelection()->set(this->repr);
+            }
+        }
+
+        // Now we need to write the transform information.
+        // First, find out whether our repr is still linked to a valid object. In this case,
+        // we need to write the transform data only for this element.
+        // Either there was no boolean op or it failed.
+        SPItem *result = SP_ITEM(_desktop->doc()->getObjectByRepr(this->repr));
+
+        if (result == nullptr) {
+            // The boolean operation succeeded.
+            // Now we fetch the single item, that has been set as selected by the boolean op.
+            // This is its result.
+            result = _desktop->getSelection()->singleItem();
+        }
+        result->doWriteTransform(result->transform, nullptr, true);
+    } else {
+        if (this->repr) {
+            sp_repr_unparent(this->repr);
+        }
+
+        this->repr = nullptr;
+    }
+
+    DocumentUndo::done(_desktop->getDocument(), _("Draw calligraphic stroke"), INKSCAPE_ICON("draw-calligraphic"));
+}
+
+static void
+add_cap(SPCurve &curve,
+        Geom::Point const &from,
+        Geom::Point const &to,
+        double rounding)
+{
+    if (Geom::L2( to - from ) > DYNA_EPSILON) {
+        Geom::Point vel = rounding * Geom::rot90( to - from ) / sqrt(2.0);
+        double mag = Geom::L2(vel);
+
+        Geom::Point v = mag * Geom::rot90( to - from ) / Geom::L2( to - from );
+        curve.curveto(from + v, to + v, to);
+    }
+}
+
+bool CalligraphicTool::accumulate() {
+	if (
+		this->cal1->is_empty() ||
+		this->cal2->is_empty() ||
+		(this->cal1->get_segment_count() <= 0) ||
+		this->cal1->first_path()->closed()
+		) {
+
+		this->cal1->reset();
+		this->cal2->reset();
+
+		return false; // failure
+	}
+
+        auto rev_cal2 = this->cal2->create_reverse();
+
+	if ((rev_cal2->get_segment_count() <= 0) || rev_cal2->first_path()->closed()) {
+		this->cal1->reset();
+		this->cal2->reset();
+
+		return false; // failure
+	}
+
+	Geom::Curve const * dc_cal1_firstseg  = this->cal1->first_segment();
+	Geom::Curve const * rev_cal2_firstseg = rev_cal2->first_segment();
+	Geom::Curve const * dc_cal1_lastseg   = this->cal1->last_segment();
+	Geom::Curve const * rev_cal2_lastseg  = rev_cal2->last_segment();
+
+	this->accumulated->reset(); /*  Is this required ?? */
+
+	this->accumulated->append(*cal1);
+
+	add_cap(*accumulated, dc_cal1_lastseg->finalPoint(), rev_cal2_firstseg->initialPoint(), cap_rounding);
+
+	this->accumulated->append(*rev_cal2, true);
+
+	add_cap(*accumulated, rev_cal2_lastseg->finalPoint(), dc_cal1_firstseg->initialPoint(), cap_rounding);
+
+	this->accumulated->closepath();
+
+	this->cal1->reset();
+	this->cal2->reset();
+
+	return true; // success
+}
+
+static double square(double const x)
+{
+    return x * x;
+}
+
+void CalligraphicTool::fit_and_split(bool release) {
+    double const tolerance_sq = square(_desktop->w2d().descrim() * TOLERANCE_CALLIGRAPHIC);
+
+#ifdef DYNA_DRAW_VERBOSE
+    g_print("[F&S:R=%c]", release?'T':'F');
+#endif
+
+    if (!( this->npoints > 0 && this->npoints < SAMPLING_SIZE )) {
+        return; // just clicked
+    }
+
+    if ( this->npoints == SAMPLING_SIZE - 1 || release ) {
+#define BEZIER_SIZE       4
+#define BEZIER_MAX_BEZIERS  8
+#define BEZIER_MAX_LENGTH ( BEZIER_SIZE * BEZIER_MAX_BEZIERS )
+
+#ifdef DYNA_DRAW_VERBOSE
+        g_print("[F&S:#] dc->npoints:%d, release:%s\n",
+                this->npoints, release ? "TRUE" : "FALSE");
+#endif
+
+        /* Current calligraphic */
+        if ( this->cal1->is_empty() || this->cal2->is_empty() ) {
+            /* dc->npoints > 0 */
+            /* g_print("calligraphics(1|2) reset\n"); */
+            this->cal1->reset();
+            this->cal2->reset();
+
+            this->cal1->moveto(this->point1[0]);
+            this->cal2->moveto(this->point2[0]);
+        }
+
+        Geom::Point b1[BEZIER_MAX_LENGTH];
+        gint const nb1 = Geom::bezier_fit_cubic_r(b1, this->point1, this->npoints,
+                                               tolerance_sq, BEZIER_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, this->point2, this->npoints,
+                                               tolerance_sq, BEZIER_MAX_BEZIERS);
+        g_assert( nb2 * BEZIER_SIZE <= gint(G_N_ELEMENTS(b2)) );
+
+        if ( nb1 != -1 && nb2 != -1 ) {
+            /* Fit and draw and reset state */
+#ifdef DYNA_DRAW_VERBOSE
+            g_print("nb1:%d nb2:%d\n", nb1, nb2);
+#endif
+            /* CanvasShape */
+            if (! release) {
+                this->currentcurve->reset();
+                this->currentcurve->moveto(b1[0]);
+                for (Geom::Point *bp1 = b1; bp1 < b1 + BEZIER_SIZE * nb1; bp1 += BEZIER_SIZE) {
+                    this->currentcurve->curveto(bp1[1], bp1[2], bp1[3]);
+                }
+                this->currentcurve->lineto(b2[BEZIER_SIZE*(nb2-1) + 3]);
+                for (Geom::Point *bp2 = b2 + BEZIER_SIZE * ( nb2 - 1 ); bp2 >= b2; bp2 -= BEZIER_SIZE) {
+                    this->currentcurve->curveto(bp2[2], bp2[1], bp2[0]);
+                }
+                // FIXME: dc->segments is always NULL at this point??
+                if (this->segments.empty()) { // first segment
+                    add_cap(*currentcurve, b2[0], b1[0], cap_rounding);
+                }
+                this->currentcurve->closepath();
+                currentshape->set_bpath(currentcurve.get(), true);
+            }
+
+            /* Current calligraphic */
+            for (Geom::Point *bp1 = b1; bp1 < b1 + BEZIER_SIZE * nb1; bp1 += BEZIER_SIZE) {
+                this->cal1->curveto(bp1[1], bp1[2], bp1[3]);
+            }
+            for (Geom::Point *bp2 = b2; bp2 < b2 + BEZIER_SIZE * nb2; bp2 += BEZIER_SIZE) {
+                this->cal2->curveto(bp2[1], bp2[2], bp2[3]);
+            }
+        } else {
+            /* fixme: ??? */
+#ifdef DYNA_DRAW_VERBOSE
+            g_print("[fit_and_split] failed to fit-cubic.\n");
+#endif
+            this->draw_temporary_box();
+
+            for (gint i = 1; i < this->npoints; i++) {
+                this->cal1->lineto(this->point1[i]);
+            }
+            for (gint i = 1; i < this->npoints; i++) {
+                this->cal2->lineto(this->point2[i]);
+            }
+        }
+
+        /* Fit and draw and copy last point */
+#ifdef DYNA_DRAW_VERBOSE
+        g_print("[%d]Yup\n", this->npoints);
+#endif
+        if (!release) {
+            g_assert(!this->currentcurve->is_empty());
+
+            guint32 fillColor = sp_desktop_get_color_tool(_desktop, "/tools/calligraphic", true);
+            double opacity = sp_desktop_get_master_opacity_tool(_desktop, "/tools/calligraphic");
+            double fillOpacity = sp_desktop_get_opacity_tool(_desktop, "/tools/calligraphic", 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, SP_WIND_RULE_EVENODD);
+            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));
+
+            this->segments.push_back(cbp);
+        }
+
+        this->point1[0] = this->point1[this->npoints - 1];
+        this->point2[0] = this->point2[this->npoints - 1];
+        this->npoints = 1;
+    } else {
+        this->draw_temporary_box();
+    }
+}
+
+void CalligraphicTool::draw_temporary_box() {
+    this->currentcurve->reset();
+
+    this->currentcurve->moveto(this->point2[this->npoints-1]);
+
+    for (gint i = this->npoints-2; i >= 0; i--) {
+        this->currentcurve->lineto(this->point2[i]);
+    }
+
+    for (gint i = 0; i < this->npoints; i++) {
+        this->currentcurve->lineto(this->point1[i]);
+    }
+
+    if (this->npoints >= 2) {
+        add_cap(*currentcurve, point1[npoints - 1], point2[npoints - 1], cap_rounding);
+    }
+
+    this->currentcurve->closepath();
+    currentshape->set_bpath(currentcurve.get(), true);
+}
+
+}
+}
+}
+
+
+/*
+  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 :