| // Copyright 2019 Google LLC |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef TimeUtils_DEFINED |
| #define TimeUtils_DEFINED |
| |
| #include "include/core/SkTypes.h" |
| |
| #include <cmath> |
| |
| namespace TimeUtils { |
| // Returns 0 if the timer is stopped. Behavior is undefined if the timer |
| // has been running longer than SK_MSecMax. |
| static inline SkMSec NanosToMSec(double nanos) { |
| const double msec = nanos * 1e-6; |
| SkASSERT(SK_MSecMax >= msec); |
| return static_cast<SkMSec>(msec); |
| } |
| |
| static inline double NanosToSeconds(double nanos) { |
| return nanos * 1e-9; |
| } |
| |
| // Return the time scaled by "speed" and (if not zero) mod by period. |
| static inline float Scaled(float time, float speed, float period = 0) { |
| double value = time * speed; |
| if (period) { |
| value = ::fmod(value, (double)(period)); |
| } |
| return (float)value; |
| } |
| |
| // Transitions from ends->mid->ends linearly over period time. The phase |
| // specifies a phase shift in time units. |
| static inline float PingPong(double time, |
| float period, |
| float phase, |
| float ends, |
| float mid) { |
| double value = ::fmod(time + phase, period); |
| double half = period / 2.0; |
| double diff = ::fabs(value - half); |
| return (float)(ends + (1.0 - diff / half) * (mid - ends)); |
| } |
| } // namespace TimeUtils |
| #endif |