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