1 files changed, 116 insertions, 0 deletions
diff --git a/vcl/inc/ResampleKernel.hxx b/vcl/inc/ResampleKernel.hxx
new file mode 100644
index 000000000..ca54213f5
--- /dev/null
+++ b/vcl/inc/ResampleKernel.hxx
@@ -0,0 +1,116 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   Licensed to the Apache Software Foundation (ASF) under one or more
+ *   contributor license agreements. See the NOTICE file distributed
+ *   with this work for additional information regarding copyright
+ *   ownership. The ASF licenses this file to you under the Apache
+ *   License, Version 2.0 (the "License"); you may not use this file
+ *   except in compliance with the License. You may obtain a copy of
+ *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+
+#ifndef INCLUDED_VCL_RESAMPLEKERNEL_HXX
+#define INCLUDED_VCL_RESAMPLEKERNEL_HXX
+
+#include <boost/math/special_functions/sinc.hpp>
+
+namespace vcl {
+
+// Resample kernels
+
+class Kernel
+{
+public:
+             Kernel() {}
+    virtual ~Kernel() {}
+
+    virtual double  GetWidth() const = 0;
+    virtual double  Calculate( double x ) const = 0;
+};
+
+class Lanczos3Kernel final : public Kernel
+{
+public:
+    Lanczos3Kernel() : Kernel () {}
+
+    virtual double  GetWidth() const override { return 3.0; }
+    virtual double  Calculate (double x) const override
+    {
+        return (-3.0 <= x && x < 3.0) ? SincFilter(x) * SincFilter( x / 3.0 ) : 0.0;
+    }
+
+    static double SincFilter(double x)
+    {
+        if (x == 0.0)
+        {
+            return 1.0;
+        }
+        x = x * M_PI;
+        return boost::math::sinc_pi(x, SincPolicy());
+    }
+
+private:
+    typedef boost::math::policies::policy<
+        boost::math::policies::promote_double<false> > SincPolicy;
+};
+
+class BicubicKernel final : public Kernel
+{
+public:
+    BicubicKernel() : Kernel () {}
+
+private:
+    virtual double  GetWidth() const override { return 2.0; }
+    virtual double  Calculate (double x) const override
+    {
+        if (x < 0.0)
+        {
+            x = -x;
+        }
+
+        if (x <= 1.0)
+        {
+            return (1.5 * x - 2.5) * x * x + 1.0;
+        }
+        else if (x < 2.0)
+        {
+            return ((-0.5 * x + 2.5) * x - 4) * x + 2;
+        }
+        return 0.0;
+    }
+};
+
+class BilinearKernel final : public Kernel
+{
+public:
+    BilinearKernel() : Kernel () {}
+
+private:
+    virtual double  GetWidth() const override { return 1.0; }
+    virtual double  Calculate (double x) const override
+    {
+        if (x < 0.0)
+        {
+            x = -x;
+        }
+        if (x < 1.0)
+        {
+            return 1.0-x;
+        }
+        return 0.0;
+    }
+};
+
+} // namespace vcl
+
+#endif // INCLUDED_VCL_RESAMPLEKERNEL_HXX
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */