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+// SPDX-License-Identifier: GPL-2.0-or-later
+/** \file
+ * Inkscape::Extension::Internal::GimpGrad implementation
+ */
+
+/*
+ * Authors:
+ * Ted Gould <ted@gould.cx>
+ * Abhishek Sharma
+ *
+ * Copyright (C) 2004-2005 Authors
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#include <color-rgba.h>
+#include "io/sys.h"
+#include "extension/system.h"
+#include "svg/css-ostringstream.h"
+#include "svg/svg-color.h"
+
+#include "gimpgrad.h"
+#include "streq.h"
+#include "strneq.h"
+#include "document.h"
+#include "extension/extension.h"
+
+namespace Inkscape {
+namespace Extension {
+namespace Internal {
+
+/**
+ \brief A function to allocate anything -- just an example here
+ \param module Unused
+ \return Whether the load was successful
+*/
+bool GimpGrad::load (Inkscape::Extension::Extension */*module*/)
+{
+ // std::cout << "Hey, I'm loading!\n" << std::endl;
+ return TRUE;
+}
+
+/**
+ \brief A function to remove what was allocated
+ \param module Unused
+ \return None
+*/
+void GimpGrad::unload (Inkscape::Extension::Extension */*module*/)
+{
+ // std::cout << "Nooo! I'm being unloaded!" << std::endl;
+ return;
+}
+
+static void append_css_num(Glib::ustring &str, double const num)
+{
+ CSSOStringStream stream;
+ stream << num;
+ str += stream.str();
+}
+
+/**
+ \brief A function to turn a color into a gradient stop
+ \param in_color The color for the stop
+ \param location Where the stop is placed in the gradient
+ \return The text that is the stop. Full SVG containing the element.
+
+ This function encapsulates all of the translation of the ColorRGBA
+ and the location into the gradient. It is really pretty simple except
+ that the ColorRGBA is in floats that are 0 to 1 and the SVG wants
+ hex values from 0 to 255 for color. Otherwise mostly this is just
+ turning the values into strings and returning it.
+*/
+static Glib::ustring stop_svg(ColorRGBA const in_color, double const location)
+{
+ Glib::ustring ret("<stop stop-color=\"");
+
+ char stop_color_css[16];
+ sp_svg_write_color(stop_color_css, sizeof(stop_color_css), in_color.getIntValue());
+ ret += stop_color_css;
+ ret += '"';
+
+ if (in_color[3] != 1) {
+ ret += " stop-opacity=\"";
+ append_css_num(ret, in_color[3]);
+ ret += '"';
+ }
+ ret += " offset=\"";
+ append_css_num(ret, location);
+ ret += "\"/>\n";
+ return ret;
+}
+
+/**
+ \brief Actually open the gradient and turn it into an SPDocument
+ \param module The input module being used
+ \param filename The filename of the gradient to be opened
+ \return A Document with the gradient in it.
+
+ GIMP gradients are pretty simple (atleast the newer format, this
+ function does not handle the old one yet). They start out with
+ the like "GIMP Gradient", then name it, and tell how many entries
+ there are. This function currently ignores the name and the number
+ of entries just reading until it fails.
+
+ The other small piece of trickery here is that GIMP gradients define
+ a left position, right position and middle position. SVG gradients
+ have no middle position in them. In order to handle this case the
+ left and right colors are averaged in a linear manner and the middle
+ position is used for that color.
+
+ That is another point, the GIMP gradients support many different types
+ of gradients -- linear being the most simple. This plugin assumes
+ that they are all linear. Most GIMP gradients are done this way,
+ but it is possible to encounter more complex ones -- which won't be
+ handled correctly.
+
+ The one optimization that this plugin makes that if the right side
+ of the previous segment is the same color as the left side of the
+ current segment, then the second one is dropped. This is often
+ done in GIMP gradients and they are not necissary in SVG.
+
+ What this function does is build up an SVG document with a single
+ linear gradient in it with all the stops of the colors in the GIMP
+ gradient that is passed in. This document is then turned into a
+ document using the \c sp_document_from_mem. That is then returned
+ to Inkscape.
+*/
+SPDocument *
+GimpGrad::open (Inkscape::Extension::Input */*module*/, gchar const *filename)
+{
+ Inkscape::IO::dump_fopen_call(filename, "I");
+ FILE *gradient = Inkscape::IO::fopen_utf8name(filename, "r");
+ if (gradient == nullptr) {
+ return nullptr;
+ }
+
+ {
+ char tempstr[1024];
+ if (fgets(tempstr, 1024, gradient) == nullptr) {
+ // std::cout << "Seems that the read failed" << std::endl;
+ goto error;
+ }
+ if (!streq(tempstr, "GIMP Gradient\n")) {
+ // std::cout << "This doesn't appear to be a GIMP gradient" << std::endl;
+ goto error;
+ }
+
+ /* Name field. */
+ if (fgets(tempstr, 1024, gradient) == nullptr) {
+ // std::cout << "Seems that the second read failed" << std::endl;
+ goto error;
+ }
+ if (!strneq(tempstr, "Name: ", 6)) {
+ goto error;
+ }
+ /* Handle very long names. (And also handle nul bytes gracefully: don't use strlen.) */
+ while (memchr(tempstr, '\n', sizeof(tempstr) - 1) == nullptr) {
+ if (fgets(tempstr, sizeof(tempstr), gradient) == nullptr) {
+ goto error;
+ }
+ }
+
+ /* n. segments */
+ if (fgets(tempstr, 1024, gradient) == nullptr) {
+ // std::cout << "Seems that the third read failed" << std::endl;
+ goto error;
+ }
+ char *endptr = nullptr;
+ long const n_segs = strtol(tempstr, &endptr, 10);
+ if ((*endptr != '\n')
+ || n_segs < 1) {
+ /* SVG gradients are allowed to have zero stops (treated as `none'), but gimp 2.2
+ * requires at least one segment (i.e. at least two stops) (see gimp_gradient_load in
+ * gimpgradient-load.c). We try to use the same error handling as gimp, so that
+ * .ggr files that work in one program work in both programs. */
+ goto error;
+ }
+
+ ColorRGBA prev_color(-1.0, -1.0, -1.0, -1.0);
+ Glib::ustring outsvg("<svg><defs><linearGradient>\n");
+ long n_segs_found = 0;
+ double prev_right = 0.0;
+ while (fgets(tempstr, 1024, gradient) != nullptr) {
+ double dbls[3 + 4 + 4];
+ gchar *p = tempstr;
+ for (double & dbl : dbls) {
+ gchar *end = nullptr;
+ double const xi = g_ascii_strtod(p, &end);
+ if (!end || end == p || !g_ascii_isspace(*end)) {
+ goto error;
+ }
+ if (xi < 0 || 1 < xi) {
+ goto error;
+ }
+ dbl = xi;
+ p = end + 1;
+ }
+
+ double const left = dbls[0];
+ if (left != prev_right) {
+ goto error;
+ }
+ double const middle = dbls[1];
+ if (!(left <= middle)) {
+ goto error;
+ }
+ double const right = dbls[2];
+ if (!(middle <= right)) {
+ goto error;
+ }
+
+ ColorRGBA const leftcolor(dbls[3], dbls[4], dbls[5], dbls[6]);
+ ColorRGBA const rightcolor(dbls[7], dbls[8], dbls[9], dbls[10]);
+ g_assert(11 == G_N_ELEMENTS(dbls));
+
+ /* Interpolation enums: curve shape and colour space. */
+ {
+ /* TODO: Currently we silently ignore type & color, assuming linear interpolation in
+ * sRGB space (or whatever the default in SVG is). See gimp/app/core/gimpgradient.c
+ * for how gimp uses these. We could use gimp functions to sample at a few points, and
+ * add some intermediate stops to convert to the linear/sRGB interpolation */
+ int type; /* enum: linear, curved, sine, sphere increasing, sphere decreasing. */
+ int color_interpolation; /* enum: rgb, hsv anticlockwise, hsv clockwise. */
+ if (sscanf(p, "%8d %8d", &type, &color_interpolation) != 2) {
+ continue;
+ }
+ }
+
+ if (prev_color != leftcolor) {
+ outsvg += stop_svg(leftcolor, left);
+ }
+ if (fabs(middle - .5 * (left + right)) > 1e-4) {
+ outsvg += stop_svg(leftcolor.average(rightcolor), middle);
+ }
+ outsvg += stop_svg(rightcolor, right);
+
+ prev_color = rightcolor;
+ prev_right = right;
+ ++n_segs_found;
+ }
+ if (prev_right != 1.0) {
+ goto error;
+ }
+
+ if (n_segs_found != n_segs) {
+ goto error;
+ }
+
+ outsvg += "</linearGradient></defs></svg>";
+
+ // std::cout << "SVG Output: " << outsvg << std::endl;
+
+ fclose(gradient);
+
+ return SPDocument::createNewDocFromMem(outsvg.c_str(), outsvg.length(), TRUE);
+ }
+
+error:
+ fclose(gradient);
+ return nullptr;
+}
+
+#include "clear-n_.h"
+
+void GimpGrad::init ()
+{
+ // clang-format off
+ Inkscape::Extension::build_from_mem(
+ "<inkscape-extension xmlns=\"" INKSCAPE_EXTENSION_URI "\">\n"
+ "<name>" N_("GIMP Gradients") "</name>\n"
+ "<id>org.inkscape.input.gimpgrad</id>\n"
+ "<input>\n"
+ "<extension>.ggr</extension>\n"
+ "<mimetype>application/x-gimp-gradient</mimetype>\n"
+ "<filetypename>" N_("GIMP Gradient (*.ggr)") "</filetypename>\n"
+ "<filetypetooltip>" N_("Gradients used in GIMP") "</filetypetooltip>\n"
+ "</input>\n"
+ "</inkscape-extension>\n", new GimpGrad());
+ // clang-format on
+ return;
+}
+
+} } } /* namespace Internal; Extension; 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 :
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