1 /* 2 * Copyright 2015 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #include "SkTime.h" 9 10 #ifndef SkAnimTimer_DEFINED 11 #define SkAnimTimer_DEFINED 12 13 /** 14 * Class to track a "timer". It supports 3 states: stopped, paused, running. 15 * 16 * The caller must call updateTime() to resync with the clock (typically just before 17 * using the timer). Forcing the caller to do this ensures that the timer's return values 18 * are consistent if called repeatedly, as they only reflect the time since the last 19 * calle to updateTimer(). 20 */ 21 class SkAnimTimer { 22 public: 23 enum State { 24 kStopped_State, 25 kPaused_State, 26 kRunning_State 27 }; 28 29 /** 30 * Class begins in the "stopped" state. 31 */ SkAnimTimer()32 SkAnimTimer() : fBaseTime(0), fCurrTime(0), fState(kStopped_State) {} 33 isStopped()34 bool isStopped() const { return kStopped_State == fState; } isRunning()35 bool isRunning() const { return kRunning_State == fState; } isPaused()36 bool isPaused() const { return kPaused_State == fState; } 37 38 /** 39 * Stops the timer, and resets it, such that the next call to run or togglePauseResume 40 * will begin at time 0. 41 */ stop()42 void stop() { 43 this->setState(kStopped_State); 44 } 45 46 /** 47 * If the timer is paused or stopped, it will resume (or start if it was stopped). 48 */ run()49 void run() { 50 this->setState(kRunning_State); 51 } 52 53 /** 54 * If the timer is stopped, this has no effect, else it toggles between paused and running. 55 */ togglePauseResume()56 void togglePauseResume() { 57 if (kRunning_State == fState) { 58 this->setState(kPaused_State); 59 } else { 60 this->setState(kRunning_State); 61 } 62 } 63 64 /** 65 * Call this each time you want to sample the clock for the timer. This is NOT done 66 * automatically, so that repeated calls to msec() or secs() will always return the 67 * same value. 68 * 69 * This may safely be called with the timer in any state. 70 */ updateTime()71 void updateTime() { 72 if (kRunning_State == fState) { 73 fCurrTime = SkTime::GetMSecs(); 74 } 75 } 76 77 /** 78 * Return the time in milliseconds the timer has been in the running state. 79 * Returns 0 if the timer is stopped. 80 */ msec()81 SkMSec msec() const { return fCurrTime - fBaseTime; } 82 83 /** 84 * Return the time in seconds the timer has been in the running state. 85 * Returns 0 if the timer is stopped. 86 */ secs()87 double secs() const { 88 return this->msec() * 0.001; 89 } 90 91 /** 92 * Return the time in seconds the timer has been in the running state, 93 * scaled by "speed" and (if not zero) mod by period. 94 * Returns 0 if the timer is stopped. 95 */ 96 SkScalar scaled(SkScalar speed, SkScalar period = 0) const { 97 double value = this->secs() * speed; 98 if (period) { 99 value = ::fmod(value, SkScalarToDouble(period)); 100 } 101 return SkDoubleToScalar(value); 102 } 103 104 private: 105 SkMSec fBaseTime; 106 SkMSec fCurrTime; 107 State fState; 108 setState(State newState)109 void setState(State newState) { 110 switch (newState) { 111 case kStopped_State: 112 fBaseTime = fCurrTime = 0; 113 fState = kStopped_State; 114 break; 115 case kPaused_State: 116 if (kRunning_State == fState) { 117 fState = kPaused_State; 118 } // else stay stopped or paused 119 break; 120 case kRunning_State: 121 switch (fState) { 122 case kStopped_State: 123 fBaseTime = fCurrTime = SkTime::GetMSecs(); 124 break; 125 case kPaused_State: {// they want "resume" 126 SkMSec now = SkTime::GetMSecs(); 127 fBaseTime += now - fCurrTime; 128 fCurrTime = now; 129 } break; 130 case kRunning_State: 131 break; 132 } 133 fState = kRunning_State; 134 break; 135 } 136 } 137 }; 138 139 #endif 140