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+/* -*- 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 .
+ */
+
+#include <basegfx/utils/keystoplerp.hxx>
+#include <com/sun/star/uno/Sequence.hxx>
+#include <osl/diagnose.h>
+
+#include <algorithm>
+
+static void validateInput(const std::vector<double>& rKeyStops)
+{
+#ifdef DBG_UTIL
+ OSL_ENSURE( rKeyStops.size() > 1,
+ "KeyStopLerp::KeyStopLerp(): key stop vector must have two entries or more" );
+
+ // rKeyStops must be sorted in ascending order
+ for( std::size_t i=1, len=rKeyStops.size(); i<len; ++i )
+ {
+ if( rKeyStops[i-1] > rKeyStops[i] )
+ OSL_FAIL( "KeyStopLerp::KeyStopLerp(): time vector is not sorted in ascending order!" );
+ }
+#else
+ (void)rKeyStops;
+#endif
+}
+
+namespace basegfx::utils
+{
+ KeyStopLerp::KeyStopLerp( std::vector<double>&& rKeyStops ) :
+ maKeyStops(std::move(rKeyStops)),
+ mnLastIndex(0)
+ {
+ validateInput(maKeyStops);
+ }
+
+ KeyStopLerp::KeyStopLerp( const ::css::uno::Sequence<double>& rKeyStops ) :
+ maKeyStops(rKeyStops.begin(), rKeyStops.end()),
+ mnLastIndex(0)
+ {
+ validateInput(maKeyStops);
+ }
+
+ KeyStopLerp::ResultType KeyStopLerp::lerp(double fAlpha) const
+ {
+ // cached value still okay?
+ if( maKeyStops.at(mnLastIndex) < fAlpha ||
+ maKeyStops.at(mnLastIndex+1) >= fAlpha )
+ {
+ // nope, find new index
+ mnLastIndex = std::min<std::ptrdiff_t>(
+ maKeyStops.size()-2,
+ // range is ensured by max below
+ std::max<std::ptrdiff_t>(
+ 0,
+ std::distance( maKeyStops.begin(),
+ std::lower_bound( maKeyStops.begin(),
+ maKeyStops.end(),
+ fAlpha )) - 1 ));
+ }
+
+ // lerp between stop and stop+1
+ const double fRawLerp=
+ (fAlpha-maKeyStops.at(mnLastIndex)) /
+ (maKeyStops.at(mnLastIndex+1) - maKeyStops.at(mnLastIndex));
+
+ // clamp to permissible range (input fAlpha might be
+ // everything)
+ return ResultType(
+ mnLastIndex,
+ std::clamp(fRawLerp,0.0,1.0));
+ }
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */