129 lines
1.9 KiB
JavaScript
129 lines
1.9 KiB
JavaScript
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class Timer {
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constructor() {
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this._previousTime = 0;
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this._currentTime = 0;
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this._startTime = now();
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this._delta = 0;
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this._elapsed = 0;
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this._timescale = 1;
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// use Page Visibility API to avoid large time delta values
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this._usePageVisibilityAPI = ( typeof document !== 'undefined' && document.hidden !== undefined );
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if ( this._usePageVisibilityAPI === true ) {
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this._pageVisibilityHandler = handleVisibilityChange.bind( this );
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document.addEventListener( 'visibilitychange', this._pageVisibilityHandler, false );
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}
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}
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getDelta() {
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return this._delta / 1000;
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}
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getElapsed() {
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return this._elapsed / 1000;
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}
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getTimescale() {
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return this._timescale;
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}
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setTimescale( timescale ) {
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this._timescale = timescale;
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return this;
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}
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reset() {
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this._currentTime = now() - this._startTime;
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return this;
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}
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dispose() {
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if ( this._usePageVisibilityAPI === true ) {
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document.removeEventListener( 'visibilitychange', this._pageVisibilityHandler );
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}
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return this;
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}
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update( timestamp ) {
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if ( this._usePageVisibilityAPI === true && document.hidden === true ) {
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this._delta = 0;
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} else {
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this._previousTime = this._currentTime;
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this._currentTime = ( timestamp !== undefined ? timestamp : now() ) - this._startTime;
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this._delta = ( this._currentTime - this._previousTime ) * this._timescale;
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this._elapsed += this._delta; // _elapsed is the accumulation of all previous deltas
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}
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return this;
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}
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}
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class FixedTimer extends Timer {
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constructor( fps = 60 ) {
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super();
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this._delta = ( 1 / fps ) * 1000;
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}
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update() {
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this._elapsed += ( this._delta * this._timescale ); // _elapsed is the accumulation of all previous deltas
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return this;
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}
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}
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function now() {
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return ( typeof performance === 'undefined' ? Date : performance ).now();
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}
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function handleVisibilityChange() {
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if ( document.hidden === false ) this.reset();
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}
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export { Timer, FixedTimer };
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