import settings from '../settings';
import { config } from '../settings'; // eslint-disable-line
import * as utils from '../utils';
import { UPDATE_PRIORITY } from '../const';
import TickerListener from './TickerListener';
/**
* A Ticker class that runs an update loop that other objects listen to.
* This class is composed around listeners meant for execution on the next requested animation frame.
* Animation frames are requested only when necessary,
* e.g. When the ticker is started and the emitter has listeners.
*
* @class
* @memberof Tiny.ticker
*/
export default class Ticker {
/**
*
*/
constructor() {
/**
* The first listener. All new listeners added are chained on this.
* @private
* @type {TickerListener}
*/
this._head = new TickerListener(null, null, Infinity);
/**
* Internal current frame request ID
* @private
*/
this._requestId = null;
/**
* Internal value managed by minFPS property setter and getter.
* This is the maximum allowed milliseconds between updates.
* @private
*/
this._maxElapsedMS = 100;
/**
* Whether or not this ticker should invoke the method {@link Tiny.ticker.Ticker#start} automatically when a listener is added.
*
* @member {boolean}
* @default false
*/
this.autoStart = false;
/**
* Scalar time value from last frame to this frame.
* This value is capped by setting {@link Tiny.ticker.Ticker#minFPS} and is scaled with {@link Tiny.ticker.Ticker#speed}.
* **Note:** The cap may be exceeded by scaling.
*
* @member {number}
* @default 1
*/
this.deltaTime = 1;
/**
* Time elapsed in milliseconds from last frame to this frame.
* Opposed to what the scalar {@link Tiny.ticker.Ticker#deltaTime} is based, this value is neither capped nor scaled.
* If the platform supports DOMHighResTimeStamp, this value will have a precision of 1 µs.
* Defaults to target frame time
*
* @member {number}
* @default 16.66
*/
this.elapsedMS = 1 / settings.TARGET_FPMS;
/**
* The last time {@link Tiny.ticker.Ticker#update} was invoked.
* This value is also reset internally outside of invoking update, but only when a new animation frame is requested.
* If the platform supports DOMHighResTimeStamp, this value will have a precision of 1 µs.
*
* @member {number}
* @default 0
*/
this.lastTime = 0;
/**
* Factor of current {@link Tiny.ticker.Ticker#deltaTime}.
* @example
* // Scales ticker.deltaTime to what would be the equivalent of approximately 120 FPS
* ticker.speed = 2;
*
* @member {number}
* @default 1
*/
this.speed = 1;
/**
* Whether or not this ticker has been started. `true` if {@link Tiny.ticker.Ticker#start} has been called. `false` if {@link Tiny.ticker.Ticker#stop} has been called.
* While `false`, this value may change to `true` in the event of {@link Tiny.ticker.Ticker#autoStart} being `true`
* and a listener is added.
*
* @member {boolean}
* @default false
*/
this.started = false;
/**
* Internal tick method bound to ticker instance.
* This is because in early 2015, Function.bind
* is still 60% slower in high performance scenarios.
* Also separating frame requests from update method
* so listeners may be called at any time and with
* any animation API, just invoke ticker.update(time).
*
* @private
* @param {number} time - Time since last tick.
*/
this._tick = (time) => {
this._requestId = null;
if (this.started) {
// Invoke listeners now
this.update(time);
// Listener side effects may have modified ticker state.
if (this.started && this._requestId === null && this._head.next) {
this._requestId = requestAnimationFrame(this._tick);
}
}
};
}
/**
* Conditionally requests a new animation frame.
* If a frame has not already been requested, and if the internal
* emitter has listeners, a new frame is requested.
*
* @private
*/
_requestIfNeeded() {
if (this._requestId === null && this._head.next) {
// ensure callbacks get correct delta
this.lastTime = performance.now();
this._requestId = requestAnimationFrame(this._tick);
}
}
/**
* Conditionally cancels a pending animation frame.
*
* @private
*/
_cancelIfNeeded() {
if (this._requestId !== null) {
cancelAnimationFrame(this._requestId);
this._requestId = null;
}
}
/**
* Conditionally requests a new animation frame.
* If the ticker has been started it checks if a frame has not already
* been requested, and if the internal emitter has listeners. If these
* conditions are met, a new frame is requested. If the ticker has not
* been started, but autoStart is `true`, then the ticker starts now,
* and continues with the previous conditions to request a new frame.
*
* @private
*/
_startIfPossible() {
if (this.started) {
this._requestIfNeeded();
} else if (this.autoStart) {
this.start();
}
}
/**
* Register a handler for tick events. Calls continuously unless
* it is removed or the ticker is stopped.
*
* @param {Function} fn - The listener function to be added for updates
* @param {Function} [context] - The listener context
* @param {number} [priority=Tiny.UPDATE_PRIORITY.NORMAL] - The priority for emitting
* @returns {Tiny.ticker.Ticker} This instance of a ticker
*/
add(fn, context, priority = UPDATE_PRIORITY.NORMAL) {
return this._addListener(new TickerListener(fn, context, priority));
}
/**
* Add a handler for the tick event which is only execute once.
*
* @param {Function} fn - The listener function to be added for one update
* @param {Function} [context] - The listener context
* @param {number} [priority=Tiny.UPDATE_PRIORITY.NORMAL] - The priority for emitting
* @returns {Tiny.ticker.Ticker} This instance of a ticker
*/
addOnce(fn, context, priority = UPDATE_PRIORITY.NORMAL) {
return this._addListener(new TickerListener(fn, context, priority, true));
}
/**
* Internally adds the event handler so that it can be sorted by priority.
* Priority allows certain handler (user, AnimatedSprite, Interaction) to be run
* before the rendering.
*
* @private
* @param {TickerListener} listener - Current listener being added.
* @returns {Tiny.ticker.Ticker} This instance of a ticker
*/
_addListener(listener) {
//@version 1.1.7 引入，用于控制所有实例化的 Ticker 的帧率
if (listener.fn !== utils.__frameDot) {
const func = listener.fn;
listener.preFn = func;
listener.fn = function (t) {
if (utils.equalsFramCount(config.fps)) {
func.call(this, t);
}
};
}
// For attaching to head
let current = this._head.next;
let previous = this._head;
// Add the first item
if (!current) {
listener.connect(previous);
} else {
// Go from highest to lowest priority
while (current) {
if (listener.priority > current.priority) {
listener.connect(previous);
break;
}
previous = current;
current = current.next;
}
// Not yet connected
if (!listener.previous) {
listener.connect(previous);
}
}
this._startIfPossible();
return this;
}
/**
* Removes any handlers matching the function and context parameters.
* If no handlers are left after removing, then it cancels the animation frame.
*
* @param {Function} fn - The listener function to be removed
* @param {Function} [context] - The listener context to be removed
* @returns {Tiny.ticker.Ticker} This instance of a ticker
*/
remove(fn, context) {
let listener = this._head.next;
while (listener) {
//@version 1.1.7 引入，_addListener 中重设后的恢复
if (listener.fn !== utils.__frameDot) {
listener.fn = listener.preFn;
}
// We found a match, lets remove it
// no break to delete all possible matches
// incase a listener was added 2+ times
if (listener.match(fn, context)) {
listener = listener.destroy();
} else {
listener = listener.next;
}
}
if (!this._head.next) {
this._cancelIfNeeded();
}
return this;
}
/**
* Starts the ticker. If the ticker has listeners
* a new animation frame is requested at this point.
*/
start() {
if (!this.started) {
this.started = true;
this._requestIfNeeded();
}
}
/**
* Stops the ticker. If the ticker has requested
* an animation frame it is canceled at this point.
*/
stop() {
if (this.started) {
this.started = false;
this._cancelIfNeeded();
}
}
/**
* Destroy the ticker and don't use after this. Calling
* this method removes all references to internal events.
*/
destroy() {
this.stop();
if (this._head) {
let listener = this._head.next;
while (listener) {
listener = listener.destroy(true);
}
this._head.destroy();
this._head = null;
}
}
/**
* 定时触发，暂不支持 stop
* 注意：该方法已不推荐使用，请直接使用 `Tiny.ticker.CountDown`
*
* @version 1.0.2
* @deprecated since version 1.1.7
* @param {object} opts
* @param {number} opts.duration - 间隔时长（单位：ms）
* @param {function} opts.callback
* @param {number} opts.times - 次数，不传即无限次
* @param {function} opts.complete - 完成后的回调
*/
countDown(opts) {
console.warn('This Function is deprecated, use Tiny.ticker.Countdown instead.');
const duration = opts.duration || 1e3;
const times = opts.times || Infinity;
const callback = opts.callback ||
function () {
};
const complete = opts.complete ||
function () {
};
let start = utils.getTime();
let count = 0;
const self = this;
const fn = function (time) {
if (count >= times) {
self.remove(fn);
complete(time);
return;
}
if (utils.getTime() - start >= duration) {
callback(time);
start += duration;
count++;
}
};
self.add(fn);
}
/**
* Triggers an update. An update entails setting the
* current {@link Tiny.ticker.Ticker#elapsedMS},
* the current {@link Tiny.ticker.Ticker#deltaTime},
* invoking all listeners with current deltaTime,
* and then finally setting {@link Tiny.ticker.Ticker#lastTime}
* with the value of currentTime that was provided.
* This method will be called automatically by animation
* frame callbacks if the ticker instance has been started
* and listeners are added.
*
* @param {number} [currentTime=performance.now()] - the current time of execution
*/
update(currentTime = performance.now()) {
let elapsedMS;
// If the difference in time is zero or negative, we ignore most of the work done here.
// If there is no valid difference, then should be no reason to let anyone know about it.
// A zero delta, is exactly that, nothing should update.
//
// The difference in time can be negative, and no this does not mean time traveling.
// This can be the result of a race condition between when an animation frame is requested
// on the current JavaScript engine event loop, and when the ticker's start method is invoked
// (which invokes the internal _requestIfNeeded method). If a frame is requested before
// _requestIfNeeded is invoked, then the callback for the animation frame the ticker requests,
// can receive a time argument that can be less than the lastTime value that was set within
// _requestIfNeeded. This difference is in microseconds, but this is enough to cause problems.
//
// This check covers this browser engine timing issue, as well as if consumers pass an invalid
// currentTime value. This may happen if consumers opt-out of the autoStart, and update themselves.
if (currentTime > this.lastTime) {
// Save uncapped elapsedMS for measurement
elapsedMS = this.elapsedMS = currentTime - this.lastTime;
// cap the milliseconds elapsed used for deltaTime
if (elapsedMS > this._maxElapsedMS) {
elapsedMS = this._maxElapsedMS;
}
this.deltaTime = elapsedMS * settings.TARGET_FPMS * this.speed;
// Cache a local reference, in-case ticker is destroyed
// during the emit, we can still check for head.next
const head = this._head;
// Invoke listeners added to internal emitter
let listener = head.next;
while (listener) {
listener = listener.emit(this.deltaTime);
}
if (!head.next) {
this._cancelIfNeeded();
}
} else {
this.deltaTime = this.elapsedMS = 0;
}
this.lastTime = currentTime;
}
/**
* The frames per second at which this ticker is running.
* The default is approximately 60 in most modern browsers.
* **Note:** This does not factor in the value of
* {@link Tiny.ticker.Ticker#speed}, which is specific
* to scaling {@link Tiny.ticker.Ticker#deltaTime}.
*
* @member {number}
* @readonly
* @private
*/
get FPS() {
return 1000 / this.elapsedMS;
}
/**
* Manages the maximum amount of milliseconds allowed to
* elapse between invoking {@link Tiny.ticker.Ticker#update}.
* This value is used to cap {@link Tiny.ticker.Ticker#deltaTime},
* but does not effect the measured value of {@link Tiny.ticker.Ticker#FPS}.
* When setting this property it is clamped to a value between
* `0` and `Tiny.settings.TARGET_FPMS * 1000`.
*
* @member {number}
* @private
* @default 10
*/
get minFPS() {
return 1000 / this._maxElapsedMS;
}
set minFPS(fps) {
// Clamp: 0 to TARGET_FPMS
const minFPMS = Math.min(Math.max(0, fps) / 1000, settings.TARGET_FPMS);
this._maxElapsedMS = 1 / minFPMS;
}
}