1 files changed, 138 insertions, 0 deletions
diff --git a/src/svg/svg-affine.cpp b/src/svg/svg-affine.cpp
new file mode 100644
index 0000000..336eeca
--- /dev/null
+++ b/src/svg/svg-affine.cpp
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * SVG data parser
+ *
+ * Authors:
+ *   Lauris Kaplinski <lauris@kaplinski.com>
+ *   Raph Levien <raph@acm.org>
+ *
+ * Copyright (C) 1999-2002 Lauris Kaplinski
+ * Copyright (C) 1999 Raph Levien
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#include <cstring>
+#include <string>
+#include <cstdlib>
+#include <cstdio>
+#include <glib.h>
+#include <2geom/transforms.h>
+#include "svg.h"
+#include "preferences.h"
+
+std::string
+sp_svg_transform_write(Geom::Affine const &transform)
+{
+    Inkscape::Preferences *prefs = Inkscape::Preferences::get();
+
+    // this must be a bit grater than EPSILON
+    double e = 1e-5 * transform.descrim();
+    int prec = prefs->getInt("/options/svgoutput/numericprecision", 8);
+    int min_exp = prefs->getInt("/options/svgoutput/minimumexponent", -8);
+
+    // Special case: when all fields of the affine are zero,
+    // the optimized transformation is scale(0)
+    if (transform[0] == 0 && transform[1] == 0 && transform[2] == 0 &&
+        transform[3] == 0 && transform[4] == 0 && transform[5] == 0)
+    {
+        return "scale(0)";
+    }
+
+
+    std::stringstream c(""); // string buffer
+
+    if (transform.isIdentity()) {
+        // We are more or less identity, so no transform attribute needed:
+        return {};
+    } else if (transform.isScale()) {
+        // We are more or less a uniform scale
+        c << "scale(";
+        c << sp_svg_number_write_de(transform[0], prec, min_exp);
+        if (Geom::are_near(transform[0], transform[3], e)) {
+            c << ")";
+        } else {
+            c << ",";
+            c << sp_svg_number_write_de(transform[3], prec, min_exp);
+            c << ")";
+        }
+    } else if (transform.isTranslation()) {
+        // We are more or less a pure translation
+        c  << "translate(";
+        c << sp_svg_number_write_de(transform[4], prec, min_exp);
+        if (Geom::are_near(transform[5], 0.0, e)) {
+            c << ")";
+        } else {
+            c << ",";
+            c << sp_svg_number_write_de(transform[5], prec, min_exp);
+            c << ")";
+        }
+    } else if (transform.isRotation()) {
+        // We are more or less a pure rotation
+        c << "rotate(";
+        double angle = std::atan2(transform[1], transform[0]) * (180 / M_PI);
+        c << sp_svg_number_write_de(angle, prec, min_exp);
+        c << ")";
+    } else if (transform.withoutTranslation().isRotation()) {
+        // Solution found by Johan Engelen
+        // Refer to the matrix in svg-affine-test.h
+
+        // We are a rotation about a special axis
+        c << "rotate(";
+        double angle = std::atan2(transform[1], transform[0]) * (180 / M_PI);
+        c << sp_svg_number_write_de(angle, prec, min_exp);
+        c << ",";
+
+        Geom::Affine const& m = transform;
+        double tx = (m[2]*m[5]+m[4]-m[4]*m[3]) / (1-m[3]-m[0]+m[0]*m[3]-m[2]*m[1]);
+
+        c << sp_svg_number_write_de(tx, prec, min_exp);
+        c << ",";
+
+        double ty = (m[1]*tx + m[5]) / (1 - m[3]);
+        c << sp_svg_number_write_de(ty, prec, min_exp);
+        c << ")";
+    } else if (transform.isHShear()) {
+        // We are more or less a pure skewX
+        c << "skewX(";
+        double angle = atan(transform[2]) * (180 / M_PI);
+        c << sp_svg_number_write_de(angle, prec, min_exp);
+        c << ")";
+    } else if (transform.isVShear()) {
+        // We are more or less a pure skewY
+        c << "skewY(";
+        double angle = atan(transform[1]) * (180 / M_PI);
+
+        c << sp_svg_number_write_de(angle, prec, min_exp);
+        c << ")";
+    } else {
+        c << "matrix(";
+        c << sp_svg_number_write_de(transform[0], prec, min_exp);
+        c << ",";
+        c << sp_svg_number_write_de(transform[1], prec, min_exp);
+        c << ",";
+        c << sp_svg_number_write_de(transform[2], prec, min_exp);
+        c << ",";
+        c << sp_svg_number_write_de(transform[3], prec, min_exp);
+        c << ",";
+        c << sp_svg_number_write_de(transform[4], prec, min_exp);
+        c << ",";
+        c << sp_svg_number_write_de(transform[5], prec, min_exp);
+        c << ")";
+    }
+
+    assert(c.str().length() <= 256);
+    return c.str();
+
+}
+
+/*
+  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 :