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      1 /*
      2  * Copyright (C) 2006 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef SkInterpolator_DEFINED
     18 #define SkInterpolator_DEFINED
     19 
     20 #include "SkScalar.h"
     21 
     22 class SkInterpolatorBase : SkNoncopyable {
     23 public:
     24     enum Result {
     25         kNormal_Result,
     26         kFreezeStart_Result,
     27         kFreezeEnd_Result
     28     };
     29 protected:
     30     SkInterpolatorBase();
     31     ~SkInterpolatorBase();
     32 public:
     33     void    reset(int elemCount, int frameCount);
     34 
     35     /** Return the start and end time for this interpolator.
     36         If there are no key frames, return false.
     37         @param startTime If not null, returns the time (in milliseconds) of the
     38                          first keyframe. If there are no keyframes, this param
     39                          is ignored (left unchanged).
     40         @param endTime If not null, returns the time (in milliseconds) of the
     41                        last keyframe. If there are no keyframes, this parameter
     42                        is ignored (left unchanged).
     43         @return True if there are key frames, or false if there are none.
     44     */
     45     bool    getDuration(SkMSec* startTime, SkMSec* endTime) const;
     46 
     47 
     48     /** Set the whether the repeat is mirrored.
     49         @param mirror If true, the odd repeats interpolate from the last key
     50                       frame and the first.
     51     */
     52     void setMirror(bool mirror) {
     53         fFlags = SkToU8((fFlags & ~kMirror) | (int)mirror);
     54     }
     55 
     56     /** Set the repeat count. The repeat count may be fractional.
     57         @param repeatCount Multiplies the total time by this scalar.
     58     */
     59     void    setRepeatCount(SkScalar repeatCount) { fRepeat = repeatCount; }
     60 
     61     /** Set the whether the repeat is mirrored.
     62         @param reset If true, the odd repeats interpolate from the last key
     63                      frame and the first.
     64     */
     65     void setReset(bool reset) {
     66         fFlags = SkToU8((fFlags & ~kReset) | (int)reset);
     67     }
     68 
     69     Result  timeToT(SkMSec time, SkScalar* T, int* index, SkBool* exact) const;
     70 
     71 protected:
     72     enum Flags {
     73         kMirror = 1,
     74         kReset = 2,
     75         kHasBlend = 4
     76     };
     77     static SkScalar ComputeRelativeT(SkMSec time, SkMSec prevTime,
     78                              SkMSec nextTime, const SkScalar blend[4] = NULL);
     79     int16_t fFrameCount;
     80     uint8_t fElemCount;
     81     uint8_t fFlags;
     82     SkScalar fRepeat;
     83     struct SkTimeCode {
     84         SkMSec  fTime;
     85         SkScalar fBlend[4];
     86     };
     87     SkTimeCode* fTimes;     // pointer into fStorage
     88     void* fStorage;
     89 #ifdef SK_DEBUG
     90     SkTimeCode(* fTimesArray)[10];
     91 #endif
     92 };
     93 
     94 class SkInterpolator : public SkInterpolatorBase {
     95 public:
     96     SkInterpolator();
     97     SkInterpolator(int elemCount, int frameCount);
     98     void    reset(int elemCount, int frameCount);
     99 
    100     /** Add or replace a key frame, copying the values[] data into the
    101         interpolator.
    102         @param index    The index of this frame (frames must be ordered by time)
    103         @param time The millisecond time for this frame
    104         @param values   The array of values [elemCount] for this frame. The data
    105                         is copied into the interpolator.
    106         @param blend    A positive scalar specifying how to blend between this
    107                         and the next key frame. [0...1) is a cubic lag/log/lag
    108                         blend (slow to change at the beginning and end)
    109                         1 is a linear blend (default)
    110     */
    111     bool setKeyFrame(int index, SkMSec time, const SkScalar values[],
    112                      const SkScalar blend[4] = NULL);
    113 
    114     /** Return the computed values given the specified time. Return whether
    115         those values are the result of pinning to either the first
    116         (kFreezeStart) or last (kFreezeEnd), or from interpolated the two
    117         nearest key values (kNormal).
    118         @param time The time to sample (in milliseconds)
    119         @param (may be null) where to write the computed values.
    120     */
    121     Result timeToValues(SkMSec time, SkScalar values[] = NULL) const;
    122 
    123     SkDEBUGCODE(static void UnitTest();)
    124 private:
    125     SkScalar* fValues;  // pointer into fStorage
    126 #ifdef SK_DEBUG
    127     SkScalar(* fScalarsArray)[10];
    128 #endif
    129     typedef SkInterpolatorBase INHERITED;
    130 };
    131 
    132 /** Given all the parameters are [0...1], apply the cubic specified by (0,0)
    133     (bx,by) (cx,cy) (1,1) to value, returning the answer, also [0...1].
    134 */
    135 SkScalar SkUnitCubicInterp(SkScalar value, SkScalar bx, SkScalar by,
    136                            SkScalar cx, SkScalar cy);
    137 
    138 #endif
    139 
    140