1 files changed, 104 insertions, 0 deletions
diff --git a/src/object/sp-paint-server.h b/src/object/sp-paint-server.h
new file mode 100644
index 0000000..a6d6f7f
--- /dev/null
+++ b/src/object/sp-paint-server.h
@@ -0,0 +1,104 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#ifndef SEEN_SP_PAINT_SERVER_H
+#define SEEN_SP_PAINT_SERVER_H
+
+/*
+ * Base class for gradients and patterns
+ *
+ * Author:
+ *   Lauris Kaplinski <lauris@kaplinski.com>
+ *   Jon A. Cruz <jon@joncruz.org>
+ *
+ * Copyright (C) 1999-2002 Lauris Kaplinski
+ * Copyright (C) 2000-2001 Ximian, Inc.
+ * Copyright (C) 2010 Authors
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#include <cairo.h>
+#include <2geom/rect.h>
+#include <sigc++/slot.h>
+#include "sp-object.h"
+
+namespace Inkscape {
+
+class Drawing;
+class DrawingPattern;
+
+}
+
+class SPPaintServer : public SPObject {
+public:
+	SPPaintServer();
+	~SPPaintServer() override;
+
+    bool isSwatch() const;
+    virtual bool isValid() const;
+
+    //There are two ways to render a paint. The simple one is to create cairo_pattern_t structure
+    //on demand by pattern_new method. It is used for gradients. The other one is to add elements
+    //representing PaintServer in NR tree. It is used by hatches and patterns.
+    //Either pattern new or all three methods show, hide, setBBox need to be implemented
+    virtual Inkscape::DrawingPattern *show(Inkscape::Drawing &drawing, unsigned int key, Geom::OptRect bbox); // TODO check passing bbox by value. Looks suspicious.
+    virtual void hide(unsigned int key);
+    virtual void setBBox(unsigned int key, Geom::OptRect const &bbox);
+
+    virtual cairo_pattern_t* pattern_new(cairo_t *ct, Geom::OptRect const &bbox, double opacity);
+
+protected:
+    bool swatch;
+};
+
+/**
+ * Returns the first of {src, src-\>ref-\>getObject(),
+ * src-\>ref-\>getObject()-\>ref-\>getObject(),...}
+ * for which \a match is true, or NULL if none found.
+ *
+ * The raison d'être of this routine is that it correctly handles cycles in the href chain (e.g., if
+ * a gradient gives itself as its href, or if each of two gradients gives the other as its href).
+ *
+ * \pre SP_IS_GRADIENT(src).
+ */
+template <class PaintServer>
+PaintServer *chase_hrefs(PaintServer *src, sigc::slot<bool, PaintServer const *> match) {
+    /* Use a pair of pointers for detecting loops: p1 advances half as fast as p2.  If there is a
+       loop, then once p1 has entered the loop, we'll detect it the next time the distance between
+       p1 and p2 is a multiple of the loop size. */
+    PaintServer *p1 = src, *p2 = src;
+    bool do1 = false;
+    for (;;) {
+        if (match(p2)) {
+            return p2;
+        }
+
+        p2 = p2->ref->getObject();
+        if (!p2) {
+            return p2;
+        }
+        if (do1) {
+            p1 = p1->ref->getObject();
+        }
+        do1 = !do1;
+
+        if ( p2 == p1 ) {
+            /* We've been here before, so return NULL to indicate that no matching gradient found
+             * in the chain. */
+            return nullptr;
+        }
+    }
+}
+
+MAKE_SP_OBJECT_TYPECHECK_FUNCTIONS(SP_IS_PAINT_SERVER, SPPaintServer)
+
+#endif // SEEN_SP_PAINT_SERVER_H
+/*
+  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 :