1 2 /* 3 * Copyright 2006 The Android Open Source Project 4 * 5 * Use of this source code is governed by a BSD-style license that can be 6 * found in the LICENSE file. 7 */ 8 9 10 #ifndef SkInterpolator_DEFINED 11 #define SkInterpolator_DEFINED 12 13 #include "SkScalar.h" 14 15 class SkInterpolatorBase : SkNoncopyable { 16 public: 17 enum Result { 18 kNormal_Result, 19 kFreezeStart_Result, 20 kFreezeEnd_Result 21 }; 22 protected: 23 SkInterpolatorBase(); 24 ~SkInterpolatorBase(); 25 public: 26 void reset(int elemCount, int frameCount); 27 28 /** Return the start and end time for this interpolator. 29 If there are no key frames, return false. 30 @param startTime If not null, returns the time (in milliseconds) of the 31 first keyframe. If there are no keyframes, this param 32 is ignored (left unchanged). 33 @param endTime If not null, returns the time (in milliseconds) of the 34 last keyframe. If there are no keyframes, this parameter 35 is ignored (left unchanged). 36 @return True if there are key frames, or false if there are none. 37 */ 38 bool getDuration(SkMSec* startTime, SkMSec* endTime) const; 39 40 41 /** Set the whether the repeat is mirrored. 42 @param mirror If true, the odd repeats interpolate from the last key 43 frame and the first. 44 */ setMirror(bool mirror)45 void setMirror(bool mirror) { 46 fFlags = SkToU8((fFlags & ~kMirror) | (int)mirror); 47 } 48 49 /** Set the repeat count. The repeat count may be fractional. 50 @param repeatCount Multiplies the total time by this scalar. 51 */ setRepeatCount(SkScalar repeatCount)52 void setRepeatCount(SkScalar repeatCount) { fRepeat = repeatCount; } 53 54 /** Set the whether the repeat is mirrored. 55 @param reset If true, the odd repeats interpolate from the last key 56 frame and the first. 57 */ setReset(bool reset)58 void setReset(bool reset) { 59 fFlags = SkToU8((fFlags & ~kReset) | (int)reset); 60 } 61 62 Result timeToT(SkMSec time, SkScalar* T, int* index, bool* exact) const; 63 64 protected: 65 enum Flags { 66 kMirror = 1, 67 kReset = 2, 68 kHasBlend = 4 69 }; 70 static SkScalar ComputeRelativeT(SkMSec time, SkMSec prevTime, 71 SkMSec nextTime, const SkScalar blend[4] = NULL); 72 int16_t fFrameCount; 73 uint8_t fElemCount; 74 uint8_t fFlags; 75 SkScalar fRepeat; 76 struct SkTimeCode { 77 SkMSec fTime; 78 SkScalar fBlend[4]; 79 }; 80 SkTimeCode* fTimes; // pointer into fStorage 81 void* fStorage; 82 #ifdef SK_DEBUG 83 SkTimeCode(* fTimesArray)[10]; 84 #endif 85 }; 86 87 class SkInterpolator : public SkInterpolatorBase { 88 public: 89 SkInterpolator(); 90 SkInterpolator(int elemCount, int frameCount); 91 void reset(int elemCount, int frameCount); 92 93 /** Add or replace a key frame, copying the values[] data into the 94 interpolator. 95 @param index The index of this frame (frames must be ordered by time) 96 @param time The millisecond time for this frame 97 @param values The array of values [elemCount] for this frame. The data 98 is copied into the interpolator. 99 @param blend A positive scalar specifying how to blend between this 100 and the next key frame. [0...1) is a cubic lag/log/lag 101 blend (slow to change at the beginning and end) 102 1 is a linear blend (default) 103 */ 104 bool setKeyFrame(int index, SkMSec time, const SkScalar values[], 105 const SkScalar blend[4] = NULL); 106 107 /** Return the computed values given the specified time. Return whether 108 those values are the result of pinning to either the first 109 (kFreezeStart) or last (kFreezeEnd), or from interpolated the two 110 nearest key values (kNormal). 111 @param time The time to sample (in milliseconds) 112 @param (may be null) where to write the computed values. 113 */ 114 Result timeToValues(SkMSec time, SkScalar values[] = NULL) const; 115 116 private: 117 SkScalar* fValues; // pointer into fStorage 118 #ifdef SK_DEBUG 119 SkScalar(* fScalarsArray)[10]; 120 #endif 121 typedef SkInterpolatorBase INHERITED; 122 }; 123 124 /** Interpolate a cubic curve, typically to provide an ease-in ease-out transition. 125 All the parameters are in the range of [0...1]. 126 The input value is treated as the x-coordinate of the cubic. 127 The output value is the y-coordinate on the cubic at the x-coordinate. 128 129 @param value The x-coordinate pinned between [0..1]. 130 @param bx,by,cx,cy The cubic control points where the cubic is specified 131 as (0,0) (bx,by) (cx,cy) (1,1) 132 @return the corresponding y-coordinate value, from [0..1]. 133 */ 134 SkScalar SkUnitCubicInterp(SkScalar value, SkScalar bx, SkScalar by, 135 SkScalar cx, SkScalar cy); 136 137 #endif 138