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      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 SK_API 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     */
     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     */
     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     */
     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, SkMSec nextTime,
     71                                      const SkScalar blend[4] = nullptr);
     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 SK_API 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] = nullptr);
    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[] = nullptr) 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