1 /************************************************************** 2 * 3 * Licensed to the Apache Software Foundation (ASF) under one 4 * or more contributor license agreements. See the NOTICE file 5 * distributed with this work for additional information 6 * regarding copyright ownership. The ASF licenses this file 7 * to you under the Apache License, Version 2.0 (the 8 * "License"); you may not use this file except in compliance 9 * with the License. You may obtain a copy of the License at 10 * 11 * http://www.apache.org/licenses/LICENSE-2.0 12 * 13 * Unless required by applicable law or agreed to in writing, 14 * software distributed under the License is distributed on an 15 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 16 * KIND, either express or implied. See the License for the 17 * specific language governing permissions and limitations 18 * under the License. 19 * 20 *************************************************************/ 21 22 23 24 #ifndef _BGFX_TOOLS_KEYSTOPLERP_HXX 25 #define _BGFX_TOOLS_KEYSTOPLERP_HXX 26 27 #include <basegfx/numeric/ftools.hxx> 28 #include <vector> 29 30 namespace com{ namespace sun{ namespace star{ namespace uno { 31 template<typename T> class Sequence; 32 }}}} 33 34 namespace basegfx 35 { 36 namespace tools 37 { 38 /** Lerp in a vector of key stops 39 40 This class holds a key stop vector and provides the 41 functionality to lerp inside it. Useful e.g. for 42 multi-stop gradients, or the SMIL key time activity. 43 44 For those, given a global [0,1] lerp alpha, one need to 45 find the suitable bucket index from key stop vector, and 46 then calculate the relative alpha between the two buckets 47 found. 48 */ 49 class KeyStopLerp 50 { 51 public: 52 typedef std::pair<std::ptrdiff_t,double> ResultType; 53 54 /** Create lerper with given vector of stops 55 56 @param rKeyStops 57 58 Vector of stops, must contain at least two elements 59 (though preferrably more, otherwise you probably don't 60 need key stop lerping in the first place). All 61 elements must be of monotonically increasing value. 62 */ 63 explicit KeyStopLerp( const std::vector<double>& rKeyStops ); 64 65 /** Create lerper with given sequence of stops 66 67 @param rKeyStops 68 69 Sequence of stops, must contain at least two elements 70 (though preferrably more, otherwise you probably don't 71 need key stop lerping in the first place). All 72 elements must be of monotonically increasing value. 73 */ 74 explicit KeyStopLerp( const ::com::sun::star::uno::Sequence<double>& rKeyStops ); 75 76 /** Find two nearest bucket index & interpolate 77 78 @param fAlpha 79 Find bucket index i, with keyStops[i] < fAlpha <= 80 keyStops[i+1]. Return new alpha value in [0,1), 81 proportional to fAlpha's position between keyStops[i] 82 and keyStops[i+1] 83 */ 84 ResultType lerp(double fAlpha) const; 85 86 private: 87 std::vector<double> maKeyStops; 88 mutable std::ptrdiff_t mnLastIndex; 89 }; 90 } 91 } 92 93 #endif 94