3 files changed, 942 insertions, 0 deletions

diff --git a/src/trace/potrace/bitmap.h b/src/trace/potrace/bitmap.h
new file mode 100644
index 0000000..2fb07e8
--- /dev/null
+++ b/src/trace/potrace/bitmap.h
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * inline macros for accessing bitmaps
+ */
+/* Copyright (C) 2001-2015 Peter Selinger.
+   This file is part of Potrace. It is free software and it is covered
+   by the GNU General Public License. See the file COPYING for details. */
+
+#ifndef BITMAP_H
+#define BITMAP_H
+
+#include <cstring>
+#include <cstdlib>
+#include <cerrno>
+#include <cstddef>
+
+/* The bitmap type is defined in potracelib.h */
+#include "potracelib.h"
+
+/* The present file defines some convenient macros and static inline
+   functions for accessing bitmaps. Since they only produce inline
+   code, they can be conveniently shared by the library and frontends,
+   if desired */
+
+/* ---------------------------------------------------------------------- */
+/* some measurements */
+
+#define BM_WORDSIZE ((int)sizeof(potrace_word))
+#define BM_WORDBITS (8*BM_WORDSIZE)
+#define BM_HIBIT (((potrace_word)1)<<(BM_WORDBITS-1))
+#define BM_ALLBITS (~(potrace_word)0)
+
+/* macros for accessing pixel at index (x,y). U* macros omit the
+   bounds check. */
+
+#define bm_scanline(bm, y) ((bm)->map + (ptrdiff_t)(y)*(ptrdiff_t)(bm)->dy)
+#define bm_index(bm, x, y) (&bm_scanline(bm, y)[(x)/BM_WORDBITS])
+#define bm_mask(x) (BM_HIBIT >> ((x) & (BM_WORDBITS-1)))
+#define bm_range(x, a) ((int)(x) >= 0 && (int)(x) < (a))
+#define bm_safe(bm, x, y) (bm_range(x, (bm)->w) && bm_range(y, (bm)->h))
+#define BM_UGET(bm, x, y) ((*bm_index(bm, x, y) & bm_mask(x)) != 0)
+#define BM_USET(bm, x, y) (*bm_index(bm, x, y) |= bm_mask(x))
+#define BM_UCLR(bm, x, y) (*bm_index(bm, x, y) &= ~bm_mask(x))
+#define BM_UINV(bm, x, y) (*bm_index(bm, x, y) ^= bm_mask(x))
+#define BM_UPUT(bm, x, y, b) ((b) ? BM_USET(bm, x, y) : BM_UCLR(bm, x, y))
+#define BM_GET(bm, x, y) (bm_safe(bm, x, y) ? BM_UGET(bm, x, y) : 0)
+#define BM_SET(bm, x, y) (bm_safe(bm, x, y) ? BM_USET(bm, x, y) : 0)
+#define BM_CLR(bm, x, y) (bm_safe(bm, x, y) ? BM_UCLR(bm, x, y) : 0)
+#define BM_INV(bm, x, y) (bm_safe(bm, x, y) ? BM_UINV(bm, x, y) : 0)
+#define BM_PUT(bm, x, y, b) (bm_safe(bm, x, y) ? BM_UPUT(bm, x, y, b) : 0)
+
+/* free the given bitmap. Leaves errno untouched. */
+static inline void bm_free(potrace_bitmap_t *bm) {
+  if (bm) {
+    free(bm->map);
+  }
+  free(bm);
+}
+
+/* return new un-initialized bitmap. NULL with errno on error.
+   Assumes w, h >= 0. */
+static inline potrace_bitmap_t *bm_new(int w, int h) {
+  potrace_bitmap_t *bm;
+  int dy = w == 0 ? 0 : (w - 1) / BM_WORDBITS + 1;
+  ptrdiff_t size = (ptrdiff_t)dy * (ptrdiff_t)h * (ptrdiff_t)BM_WORDSIZE;
+
+  /* check for overflow error */
+  if (size < 0 || (h != 0 && dy != 0 && size / h / dy != BM_WORDSIZE)) {
+    errno = ENOMEM;
+    return nullptr;
+  }
+
+  bm = (potrace_bitmap_t *) malloc(sizeof(potrace_bitmap_t));
+  if (!bm) {
+    return nullptr;
+  }
+  bm->w = w;
+  bm->h = h;
+  bm->dy = dy;
+  bm->map = (potrace_word *) malloc(size);
+  if (!bm->map) {
+    g_warning("bm_new: can not allocate memory for bitmap (%td).", size);
+    free(bm);
+    return nullptr;
+  }
+  return bm;
+}
+
+/* clear the given bitmap. Set all bits to c. */
+static inline void bm_clear(potrace_bitmap_t *bm, int c) {
+  /* Note: if the bitmap was created with bm_new, then it is
+     guaranteed that size will fit into the ptrdiff_t type. */
+  ptrdiff_t size = (ptrdiff_t)bm->dy * (ptrdiff_t)bm->h * (ptrdiff_t)BM_WORDSIZE;
+  memset(bm->map, c ? -1 : 0, size);
+}
+
+/* duplicate the given bitmap. Return NULL on error with errno set. */
+static inline potrace_bitmap_t *bm_dup(const potrace_bitmap_t *bm) {
+  potrace_bitmap_t *bm1 = bm_new(bm->w, bm->h);
+  ptrdiff_t size = (ptrdiff_t)bm->dy * (ptrdiff_t)bm->h * (ptrdiff_t)BM_WORDSIZE;
+  if (!bm1) {
+    return nullptr;
+  }
+  memcpy(bm1->map, bm->map, size);
+  return bm1;
+}
+
+/* invert the given bitmap. */
+static inline void bm_invert(potrace_bitmap_t *bm) {
+  ptrdiff_t i;
+  ptrdiff_t size = (ptrdiff_t)bm->dy * (ptrdiff_t)bm->h;
+
+  for (i = 0; i < size; i++) {
+    bm->map[i] ^= BM_ALLBITS;
+  }
+}
+
+#endif /* BITMAP_H */
diff --git a/src/trace/potrace/inkscape-potrace.cpp b/src/trace/potrace/inkscape-potrace.cpp
new file mode 100644
index 0000000..d6e9b8f
--- /dev/null
+++ b/src/trace/potrace/inkscape-potrace.cpp
@@ -0,0 +1,679 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * This is the C++ glue between Inkscape and Potrace
+ *
+ * Authors:
+ *   Bob Jamison <rjamison@titan.com>
+ *   Stéphane Gimenez <dev@gim.name>
+ *
+ * Copyright (C) 2004-2006 Authors
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ *
+ * Potrace, the wonderful tracer located at http://potrace.sourceforge.net,
+ * is provided by the generosity of Peter Selinger, to whom we are grateful.
+ *
+ */
+
+#include "inkscape-potrace.h"
+
+#include <glibmm/i18n.h>
+#include <gtkmm/main.h>
+#include <iomanip>
+
+#include "trace/filterset.h"
+#include "trace/quantize.h"
+#include "trace/imagemap-gdk.h"
+
+#include <inkscape.h>
+#include "desktop.h"
+#include "message-stack.h"
+
+#include "object/sp-path.h"
+
+#include <svg/path-string.h>
+#include "bitmap.h"
+
+using Glib::ustring;
+
+static void updateGui()
+{
+   //## Allow the GUI to update
+   Gtk::Main::iteration(false); //at least once, non-blocking
+   while( Gtk::Main::events_pending() )
+       Gtk::Main::iteration();
+
+}
+
+
+static void potraceStatusCallback(double /*progress*/, void *userData) /* callback fn */
+{
+    updateGui();
+
+    if (!userData)
+        return;
+
+    //g_message("progress: %f\n", progress);
+
+    //Inkscape::Trace::Potrace::PotraceTracingEngine *engine =
+    //      (Inkscape::Trace::Potrace::PotraceTracingEngine *)userData;
+}
+
+
+namespace {
+ustring twohex( int value )
+{
+    return ustring::format(std::hex, std::setfill(L'0'), std::setw(2), value);
+}
+} // namespace
+
+
+//required by potrace
+namespace Inkscape {
+
+namespace Trace {
+
+namespace Potrace {
+
+
+/**
+ *
+ */
+PotraceTracingEngine::PotraceTracingEngine() :
+    keepGoing(1),
+    traceType(TRACE_BRIGHTNESS),
+    invert(false),
+    quantizationNrColors(8),
+    brightnessThreshold(0.45),
+    brightnessFloor(0),
+    cannyHighThreshold(0.65),
+    multiScanNrColors(8),
+    multiScanStack(true),
+    multiScanSmooth(false),
+    multiScanRemoveBackground(false)
+{
+    /* get default parameters */
+    potraceParams = potrace_param_default();
+    potraceParams->progress.callback = potraceStatusCallback;
+    potraceParams->progress.data = (void *)this;
+}
+
+PotraceTracingEngine::PotraceTracingEngine(TraceType traceType, bool invert, int quantizationNrColors, double brightnessThreshold, double brightnessFloor, double cannyHighThreshold, int multiScanNrColors, bool multiScanStack, bool multiScanSmooth, bool multiScanRemoveBackground) :
+  keepGoing(1), traceType(traceType), invert(invert), quantizationNrColors(quantizationNrColors), brightnessThreshold(brightnessThreshold), brightnessFloor(brightnessFloor), cannyHighThreshold(cannyHighThreshold), multiScanNrColors(multiScanNrColors) , multiScanStack(multiScanStack), multiScanSmooth(multiScanSmooth), multiScanRemoveBackground(multiScanRemoveBackground)
+{
+    potraceParams = potrace_param_default();
+    potraceParams->progress.callback = potraceStatusCallback;
+    potraceParams->progress.data = (void *)this;
+}
+
+
+PotraceTracingEngine::~PotraceTracingEngine()
+{
+    potrace_param_free(potraceParams);
+}
+
+
+
+
+struct Point
+{
+    double x;
+    double y;
+};
+
+
+/**
+ * Check a point against a list of points to see if it
+ * has already occurred.
+ */
+static bool hasPoint(std::vector<Point> &points, double x, double y)
+{
+    for (auto p : points)
+        {
+        if (p.x == x && p.y == y)
+            return true;
+        }
+    return false;
+}
+
+
+/**
+ *  Recursively descend the potrace_path_t node tree, writing paths in SVG
+ *  format into the output stream.  The Point vector is used to prevent
+ *  redundant paths.  Returns number of paths processed.
+ */
+static long writePaths(PotraceTracingEngine *engine, potrace_path_t *plist,
+           Inkscape::SVG::PathString& data, std::vector<Point> &points)
+{
+    long nodeCount = 0L;
+
+    potrace_path_t *node;
+    for (node=plist; node ; node=node->sibling)
+        {
+        potrace_curve_t *curve = &(node->curve);
+        //g_message("node->fm:%d\n", node->fm);
+        if (!curve->n)
+            continue;
+        const potrace_dpoint_t *pt = curve->c[curve->n - 1];
+        double x0 = 0.0;
+        double y0 = 0.0;
+        double x1 = 0.0;
+        double y1 = 0.0;
+        double x2 = pt[2].x;
+        double y2 = pt[2].y;
+        //Have we been here already?
+        if (hasPoint(points, x2, y2))
+            {
+            //g_message("duplicate point: (%f,%f)\n", x2, y2);
+            continue;
+            }
+        else
+            {
+            Point p;
+            p.x = x2; p.y = y2;
+            points.push_back(p);
+            }
+        data.moveTo(x2, y2);
+        nodeCount++;
+
+        for (int i=0 ; i<curve->n ; i++)
+            {
+            if (!engine->keepGoing)
+                return 0L;
+            pt = curve->c[i];
+            x0 = pt[0].x;
+            y0 = pt[0].y;
+            x1 = pt[1].x;
+            y1 = pt[1].y;
+            x2 = pt[2].x;
+            y2 = pt[2].y;
+            switch (curve->tag[i])
+                {
+                case POTRACE_CORNER:
+                    data.lineTo(x1, y1).lineTo(x2, y2);
+                break;
+                case POTRACE_CURVETO:
+                    data.curveTo(x0, y0, x1, y1, x2, y2);
+                break;
+                default:
+                break;
+                }
+            nodeCount++;
+            }
+        data.closePath();
+
+        for (potrace_path_t *child=node->childlist; child ; child=child->sibling)
+            {
+            nodeCount += writePaths(engine, child, data, points);
+            }
+        }
+
+    return nodeCount;
+
+}
+
+
+static GrayMap *filter(PotraceTracingEngine &engine, GdkPixbuf * pixbuf)
+{
+    if (!pixbuf)
+        return nullptr;
+
+    GrayMap *newGm = nullptr;
+
+    /*### Color quantization -- banding ###*/
+    if (engine.traceType == TRACE_QUANT)
+        {
+        RgbMap *rgbmap = gdkPixbufToRgbMap(pixbuf);
+        if (!rgbmap)
+            return nullptr;
+        //rgbMap->writePPM(rgbMap, "rgb.ppm");
+        newGm = quantizeBand(rgbmap,
+                            engine.quantizationNrColors);
+        rgbmap->destroy(rgbmap);
+        //return newGm;
+        }
+
+    /*### Brightness threshold ###*/
+    else if ( engine.traceType == TRACE_BRIGHTNESS ||
+              engine.traceType == TRACE_BRIGHTNESS_MULTI )
+        {
+        GrayMap *gm = gdkPixbufToGrayMap(pixbuf);
+        if (!gm)
+            return nullptr;
+
+        newGm = GrayMapCreate(gm->width, gm->height);
+        if (!newGm)
+            {
+            gm->destroy(gm);
+            return nullptr;
+            }
+        double floor =  3.0 *
+               ( engine.brightnessFloor * 256.0 );
+        double cutoff =  3.0 *
+               ( engine.brightnessThreshold * 256.0 );
+        for (int y=0 ; y<gm->height ; y++)
+            {
+            for (int x=0 ; x<gm->width ; x++)
+                {
+                double brightness = (double)gm->getPixel(gm, x, y);
+                if (brightness >= floor && brightness < cutoff)
+                    newGm->setPixel(newGm, x, y, GRAYMAP_BLACK);  //black pixel
+                else
+                    newGm->setPixel(newGm, x, y, GRAYMAP_WHITE); //white pixel
+                }
+            }
+
+        gm->destroy(gm);
+        //newGm->writePPM(newGm, "brightness.ppm");
+        //return newGm;
+        }
+
+    /*### Canny edge detection ###*/
+    else if (engine.traceType == TRACE_CANNY)
+        {
+        GrayMap *gm = gdkPixbufToGrayMap(pixbuf);
+        if (!gm)
+            return nullptr;
+        newGm = grayMapCanny(gm, 0.1, engine.cannyHighThreshold);
+        gm->destroy(gm);
+        //newGm->writePPM(newGm, "canny.ppm");
+        //return newGm;
+        }
+
+    /*### Do I invert the image? ###*/
+    if (newGm && engine.invert)
+        {
+        for (int y=0 ; y<newGm->height ; y++)
+            {
+            for (int x=0 ; x<newGm->width ; x++)
+                {
+                unsigned long brightness = newGm->getPixel(newGm, x, y);
+                brightness = 765 - brightness;
+                newGm->setPixel(newGm, x, y, brightness);
+                }
+            }
+        }
+
+    return newGm;//none of the above
+}
+
+
+static IndexedMap *filterIndexed(PotraceTracingEngine &engine, GdkPixbuf * pixbuf)
+{
+    if (!pixbuf)
+        return nullptr;
+
+    IndexedMap *newGm = nullptr;
+
+    RgbMap *gm = gdkPixbufToRgbMap(pixbuf);
+    if (!gm)
+        return nullptr;
+    if (engine.multiScanSmooth)
+        {
+        RgbMap *gaussMap = rgbMapGaussian(gm);
+        newGm = rgbMapQuantize(gaussMap, engine.multiScanNrColors);
+        gaussMap->destroy(gaussMap);
+        }
+    else
+        {
+        newGm = rgbMapQuantize(gm, engine.multiScanNrColors);
+        }
+    gm->destroy(gm);
+
+    if (newGm && (engine.traceType == TRACE_QUANT_MONO || engine.traceType == TRACE_BRIGHTNESS_MULTI))
+        {
+        //Turn to grays
+        for (int i=0 ; i<newGm->nrColors ; i++)
+            {
+            RGB rgb = newGm->clut[i];
+            int grayVal = (rgb.r + rgb.g + rgb.b) / 3;
+            rgb.r = rgb.g = rgb.b = grayVal;
+            newGm->clut[i] = rgb;
+            }
+        }
+
+    return newGm;
+}
+
+
+
+
+Glib::RefPtr<Gdk::Pixbuf> 
+PotraceTracingEngine::preview(Glib::RefPtr<Gdk::Pixbuf> thePixbuf)
+{
+    GdkPixbuf *pixbuf = thePixbuf->gobj();
+
+    if ( traceType == TRACE_QUANT_COLOR ||
+         traceType == TRACE_QUANT_MONO  ||
+         traceType == TRACE_BRIGHTNESS_MULTI) /* this is a lie: multipass doesn't use filterIndexed, but it's a better preview approx than filter() */
+    {
+        IndexedMap *gm = filterIndexed(*this, pixbuf);
+        if (!gm)
+            return Glib::RefPtr<Gdk::Pixbuf>(nullptr);
+
+        Glib::RefPtr<Gdk::Pixbuf> newBuf =
+             Glib::wrap(indexedMapToGdkPixbuf(gm), false);
+
+        gm->destroy(gm);
+
+        return newBuf;
+        }
+    else
+        {
+        GrayMap *gm = filter(*this, pixbuf);
+        if (!gm)
+            return Glib::RefPtr<Gdk::Pixbuf>(nullptr);
+
+        Glib::RefPtr<Gdk::Pixbuf> newBuf =
+            Glib::wrap(grayMapToGdkPixbuf(gm), false);
+
+        gm->destroy(gm);
+
+        return newBuf;
+        }
+}
+
+
+//*This is the core inkscape-to-potrace binding
+std::string PotraceTracingEngine::grayMapToPath(GrayMap *grayMap, long *nodeCount)
+{
+    if (!keepGoing)
+    {
+        g_warning("aborted");
+        return "";
+    }
+
+    potrace_bitmap_t *potraceBitmap = bm_new(grayMap->width, grayMap->height);
+    if (!potraceBitmap)
+    {
+        return "";
+    }
+    bm_clear(potraceBitmap, 0);
+
+    //##Read the data out of the GrayMap
+    for (int y=0 ; y<grayMap->height ; y++)
+        {
+        for (int x=0 ; x<grayMap->width ; x++)
+            {
+            BM_UPUT(potraceBitmap, x, y,
+                  grayMap->getPixel(grayMap, x, y) ? 0 : 1);
+            }
+        }
+
+    //##Debug
+    /*
+    FILE *f = fopen("poimage.pbm", "wb");
+    bm_writepbm(f, bm);
+    fclose(f);
+    */
+
+    /* trace a bitmap*/
+    potrace_state_t *potraceState = potrace_trace(potraceParams,
+                                                  potraceBitmap);
+
+    //## Free the Potrace bitmap
+    bm_free(potraceBitmap);
+
+    if (!keepGoing)
+        {
+        g_warning("aborted");
+        potrace_state_free(potraceState);
+        return "";
+        }
+
+    Inkscape::SVG::PathString data;
+
+    //## copy the path information into our d="" attribute string
+    std::vector<Point> points;
+    long thisNodeCount = writePaths(this, potraceState->plist, data, points);
+
+    /* free a potrace items */
+    potrace_state_free(potraceState);
+
+    if (!keepGoing)
+        return "";
+
+    if ( nodeCount)
+        *nodeCount = thisNodeCount;
+
+    return data.string();
+}
+
+
+
+/**
+ *  This is called for a single scan
+ */
+std::vector<TracingEngineResult> PotraceTracingEngine::traceSingle(GdkPixbuf * thePixbuf)
+{
+
+    std::vector<TracingEngineResult> results;
+
+    if (!thePixbuf)
+        return results;
+
+    brightnessFloor = 0.0; //important to set this
+
+    GrayMap *grayMap = filter(*this, thePixbuf);
+    if (!grayMap)
+        return results;
+
+    long nodeCount = 0L;
+    std::string d = grayMapToPath(grayMap, &nodeCount);
+
+    grayMap->destroy(grayMap);
+
+    char const *style = "fill:#000000";
+
+    //g_message("### GOT '%s' \n", d);
+    TracingEngineResult result(style, d, nodeCount);
+    results.push_back(result);
+
+    return results;
+}
+
+
+/**
+ *  This allows routines that already generate GrayMaps to skip image filtering,
+ *  increasing performance.
+ */
+std::vector<TracingEngineResult> PotraceTracingEngine::traceGrayMap(GrayMap *grayMap)
+{
+
+    std::vector<TracingEngineResult> results;
+
+    brightnessFloor = 0.0; //important to set this
+
+    long nodeCount = 0L;
+    std::string d = grayMapToPath(grayMap, &nodeCount);
+
+    char const *style = "fill:#000000";
+
+    //g_message("### GOT '%s' \n", d);
+    TracingEngineResult result(style, d, nodeCount);
+    results.push_back(result);
+
+    return results;
+}
+
+/**
+ *  Called for multiple-scanning algorithms
+ */
+std::vector<TracingEngineResult> PotraceTracingEngine::traceBrightnessMulti(GdkPixbuf * thePixbuf)
+{
+    std::vector<TracingEngineResult> results;
+
+    if ( thePixbuf ) {
+        double low     = 0.2; //bottom of range
+        double high    = 0.9; //top of range
+        double delta   = (high - low ) / ((double)multiScanNrColors);
+
+        brightnessFloor = 0.0; //Set bottom to black
+
+        int traceCount = 0;
+
+        for ( brightnessThreshold = low ;
+              brightnessThreshold <= high ;
+              brightnessThreshold += delta) {
+            GrayMap *grayMap = filter(*this, thePixbuf);
+            if ( grayMap ) {
+                long nodeCount = 0L;
+                std::string d = grayMapToPath(grayMap, &nodeCount);
+
+                grayMap->destroy(grayMap);
+
+                if ( !d.empty() ) {
+                    //### get style info
+                    int grayVal = (int)(256.0 * brightnessThreshold);
+                    ustring style = ustring::compose("fill-opacity:1.0;fill:#%1%2%3", twohex(grayVal), twohex(grayVal), twohex(grayVal) );
+
+                    //g_message("### GOT '%s' \n", style.c_str());
+                    TracingEngineResult result(style.raw(), d, nodeCount);
+                    results.push_back(result);
+
+                    if (!multiScanStack) {
+                        brightnessFloor = brightnessThreshold;
+                    }
+
+                    SPDesktop *desktop = SP_ACTIVE_DESKTOP;
+                    if (desktop) {
+                        ustring msg = ustring::compose(_("Trace: %1.  %2 nodes"), traceCount++, nodeCount);
+                        desktop->getMessageStack()->flash(Inkscape::NORMAL_MESSAGE, msg);
+                    }
+                }
+            }
+        }
+
+        //# Remove the bottom-most scan, if requested
+        if (results.size() > 1 && multiScanRemoveBackground) {
+            results.erase(results.end() - 1);
+        }
+    }
+
+    return results;
+}
+
+
+/**
+ *  Quantization
+ */
+std::vector<TracingEngineResult> PotraceTracingEngine::traceQuant(GdkPixbuf * thePixbuf)
+{
+    std::vector<TracingEngineResult> results;
+
+    if (thePixbuf) {
+        IndexedMap *iMap = filterIndexed(*this, thePixbuf);
+        if ( iMap ) {
+            //Create and clear a gray map
+            GrayMap *gm = GrayMapCreate(iMap->width, iMap->height);
+            for (int row=0 ; row<gm->height ; row++) {
+                for (int col=0 ; col<gm->width ; col++) {
+                    gm->setPixel(gm, col, row, GRAYMAP_WHITE);
+                }
+            }
+
+            for (int colorIndex=0 ; colorIndex<iMap->nrColors ; colorIndex++) {
+                // Make a gray map for each color index
+                for (int row=0 ; row<iMap->height ; row++) {
+                    for (int col=0 ; col<iMap->width ; col++) {
+                        int indx = (int) iMap->getPixel(iMap, col, row);
+                        if (indx == colorIndex) {
+                            gm->setPixel(gm, col, row, GRAYMAP_BLACK); //black
+                        } else if (!multiScanStack) {
+                            gm->setPixel(gm, col, row, GRAYMAP_WHITE); //white
+                        }
+                    }
+                }
+
+                //## Now we have a traceable graymap
+                long nodeCount = 0L;
+                std::string d = grayMapToPath(gm, &nodeCount);
+
+                if ( !d.empty() ) {
+                    //### get style info
+                    RGB rgb = iMap->clut[colorIndex];
+                    ustring style = ustring::compose("fill:#%1%2%3", twohex(rgb.r), twohex(rgb.g), twohex(rgb.b) );
+
+                    //g_message("### GOT '%s' \n", style.c_str());
+                    TracingEngineResult result(style.raw(), d, nodeCount);
+                    results.push_back(result);
+
+                    SPDesktop *desktop = SP_ACTIVE_DESKTOP;
+                    if (desktop) {
+                        ustring msg = ustring::compose(_("Trace: %1.  %2 nodes"), colorIndex, nodeCount);
+                        desktop->getMessageStack()->flash(Inkscape::NORMAL_MESSAGE, msg);
+                    }
+                }
+            }// for colorIndex
+
+            gm->destroy(gm);
+            iMap->destroy(iMap);
+        }
+
+        //# Remove the bottom-most scan, if requested
+        if (results.size() > 1 && multiScanRemoveBackground) {
+            results.erase(results.end() - 1);
+        }
+    }
+
+    return results;
+}
+
+
+/**
+ *  This is the working method of this interface, and all
+ *  implementing classes.  Take a GdkPixbuf, trace it, and
+ *  return the path data that is compatible with the d="" attribute
+ *  of an SVG <path> element.
+ */
+std::vector<TracingEngineResult>
+PotraceTracingEngine::trace(Glib::RefPtr<Gdk::Pixbuf> pixbuf)
+{
+
+    GdkPixbuf *thePixbuf = pixbuf->gobj();
+
+    //Set up for messages
+    keepGoing             = 1;
+
+    if ( traceType == TRACE_QUANT_COLOR ||
+         traceType == TRACE_QUANT_MONO   )
+        {
+        return traceQuant(thePixbuf);
+        }
+    else if ( traceType == TRACE_BRIGHTNESS_MULTI )
+        {
+        return traceBrightnessMulti(thePixbuf);
+        }
+    else
+        {
+        return traceSingle(thePixbuf);
+        }
+}
+
+
+/**
+ *  Abort the thread that is executing getPathDataFromPixbuf()
+ */
+void PotraceTracingEngine::abort()
+{
+    //g_message("PotraceTracingEngine::abort()\n");
+    keepGoing = 0;
+}
+
+
+
+
+}  // namespace Potrace
+}  // namespace Trace
+}  // namespace Inkscape
+
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :
diff --git a/src/trace/potrace/inkscape-potrace.h b/src/trace/potrace/inkscape-potrace.h
new file mode 100644
index 0000000..c4c7bf4
--- /dev/null
+++ b/src/trace/potrace/inkscape-potrace.h
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * This is the C++ glue between Inkscape and Potrace
+ *
+ * Authors:
+ *   Bob Jamison <rjamison@titan.com>
+ *   Stéphane Gimenez <dev@gim.name>
+ *
+ * Copyright (C) 2004-2006 Authors
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ *
+ * Potrace, the wonderful tracer located at http://potrace.sourceforge.net,
+ * is provided by the generosity of Peter Selinger, to whom we are grateful.
+ *
+ */
+
+#ifndef __INKSCAPE_POTRACE_H__
+#define __INKSCAPE_POTRACE_H__
+
+#include <trace/trace.h>
+#include <potracelib.h>
+
+struct GrayMap_def;
+typedef GrayMap_def GrayMap;
+
+namespace Inkscape {
+
+namespace Trace {
+
+namespace Potrace {
+
+enum TraceType
+    {
+    TRACE_BRIGHTNESS,
+    TRACE_BRIGHTNESS_MULTI,
+    TRACE_CANNY,
+    TRACE_QUANT,
+    TRACE_QUANT_COLOR,
+    TRACE_QUANT_MONO,
+    // Used in tradedialog.cpp
+    AUTOTRACE_SINGLE,
+    AUTOTRACE_MULTI,
+    AUTOTRACE_CENTERLINE
+    };
+
+
+class PotraceTracingEngine : public TracingEngine
+{
+
+    public:
+
+    /**
+     *
+     */
+    PotraceTracingEngine();
+    PotraceTracingEngine(TraceType traceType, bool invert, int quantizationNrColors, double brightnessThreshold, double brightnessFloor, double cannyHighThreshold, int multiScanNrColors, bool multiScanStack, bool multiScanSmooth, bool multiScanRemoveBackground);
+
+    /**
+     *
+     */
+    ~PotraceTracingEngine() override;
+
+    /**
+     *  This is the working method of this implementing class, and all
+     *  implementing classes.  Take a GdkPixbuf, trace it, and
+     *  return the path data that is compatible with the d="" attribute
+     *  of an SVG <path> element.
+     */
+    std::vector<TracingEngineResult> trace(
+                        Glib::RefPtr<Gdk::Pixbuf> pixbuf) override;
+
+    /**
+     *  Abort the thread that is executing getPathDataFromPixbuf()
+     */
+    void abort() override;
+
+    /**
+     *
+     */
+    Glib::RefPtr<Gdk::Pixbuf> preview(Glib::RefPtr<Gdk::Pixbuf> pixbuf);
+
+    /**
+     *
+     */
+    int keepGoing;
+
+    std::vector<TracingEngineResult>traceGrayMap(GrayMap *grayMap);
+
+    potrace_param_t *potraceParams;
+    TraceType traceType;
+
+    //## do I invert at the end?
+    bool invert;
+
+    //## Color-->b&w quantization
+    int quantizationNrColors;
+
+    //## brightness items
+    double brightnessThreshold;
+    double brightnessFloor; //usually 0.0
+
+    //## canny items
+    double cannyHighThreshold;
+
+    //## Color-->multiscan quantization
+    int multiScanNrColors;
+    bool multiScanStack; //do we tile or stack?
+    bool multiScanSmooth;//do we use gaussian filter?
+    bool multiScanRemoveBackground; //do we remove the bottom trace?
+    
+    private:
+    /**
+     * This is the actual wrapper of the call to Potrace.  nodeCount
+     * returns the count of nodes created.  May be NULL if ignored.
+     */
+    std::string grayMapToPath(GrayMap *gm, long *nodeCount);
+
+    std::vector<TracingEngineResult>traceBrightnessMulti(GdkPixbuf *pixbuf);
+    std::vector<TracingEngineResult>traceQuant(GdkPixbuf *pixbuf);
+    std::vector<TracingEngineResult>traceSingle(GdkPixbuf *pixbuf);
+
+
+};//class PotraceTracingEngine
+
+
+
+}  // namespace Potrace
+}  // namespace Trace
+}  // namespace Inkscape
+
+
+#endif  //__INKSCAPE_POTRACE_H__
+
+
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :