scroll-view.js 19KB

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  1. (function (factory) {
  2. if (typeof module === "object" && typeof module.exports === "object") {
  3. var v = factory(require, exports);
  4. if (v !== undefined) module.exports = v;
  5. }
  6. else if (typeof define === "function" && define.amd) {
  7. define(["require", "exports", "./dom"], factory);
  8. }
  9. })(function (require, exports) {
  10. "use strict";
  11. Object.defineProperty(exports, "__esModule", { value: true });
  12. var dom_1 = require("./dom");
  13. var ScrollView = (function () {
  14. function ScrollView(_app, _plt, _dom) {
  15. this._app = _app;
  16. this._plt = _plt;
  17. this._dom = _dom;
  18. this.isScrolling = false;
  19. this.initialized = false;
  20. this._eventsEnabled = false;
  21. this._t = 0;
  22. this._l = 0;
  23. this.ev = {
  24. timeStamp: 0,
  25. scrollTop: 0,
  26. scrollLeft: 0,
  27. scrollHeight: 0,
  28. scrollWidth: 0,
  29. contentHeight: 0,
  30. contentWidth: 0,
  31. contentTop: 0,
  32. contentBottom: 0,
  33. startY: 0,
  34. startX: 0,
  35. deltaY: 0,
  36. deltaX: 0,
  37. velocityY: 0,
  38. velocityX: 0,
  39. directionY: 'down',
  40. directionX: null,
  41. domWrite: _dom.write.bind(_dom)
  42. };
  43. }
  44. ScrollView.prototype.init = function (ele, contentTop, contentBottom) {
  45. (void 0) /* assert */;
  46. this._el = ele;
  47. if (!this.initialized) {
  48. this.initialized = true;
  49. if (this._js) {
  50. this.enableJsScroll(contentTop, contentBottom);
  51. }
  52. else {
  53. this.enableNativeScrolling();
  54. }
  55. }
  56. };
  57. ScrollView.prototype.enableEvents = function () {
  58. this._eventsEnabled = true;
  59. };
  60. ScrollView.prototype.setScrolling = function (isScrolling, ev) {
  61. if (this.isScrolling) {
  62. if (isScrolling) {
  63. this.onScroll && this.onScroll(ev);
  64. }
  65. else {
  66. this.isScrolling = false;
  67. this.onScrollEnd && this.onScrollEnd(ev);
  68. }
  69. }
  70. else if (isScrolling) {
  71. this.isScrolling = true;
  72. this.onScrollStart && this.onScrollStart(ev);
  73. }
  74. };
  75. ScrollView.prototype.enableNativeScrolling = function () {
  76. (void 0) /* assert */;
  77. (void 0) /* assert */;
  78. (void 0) /* assert */;
  79. this._js = false;
  80. if (!this._el) {
  81. return;
  82. }
  83. (void 0) /* console.debug */;
  84. var self = this;
  85. var ev = self.ev;
  86. var positions = [];
  87. function scrollCallback(scrollEvent) {
  88. // remind the app that it's currently scrolling
  89. self._app.setScrolling();
  90. // if events are disabled, we do nothing
  91. if (!self._eventsEnabled) {
  92. return;
  93. }
  94. ev.timeStamp = scrollEvent.timeStamp;
  95. // Event.timeStamp is 0 in firefox
  96. if (!ev.timeStamp) {
  97. ev.timeStamp = Date.now();
  98. }
  99. // get the current scrollTop
  100. // ******** DOM READ ****************
  101. ev.scrollTop = self.getTop();
  102. // get the current scrollLeft
  103. // ******** DOM READ ****************
  104. ev.scrollLeft = self.getLeft();
  105. if (!self.isScrolling) {
  106. // remember the start positions
  107. ev.startY = ev.scrollTop;
  108. ev.startX = ev.scrollLeft;
  109. // new scroll, so do some resets
  110. ev.velocityY = ev.velocityX = 0;
  111. ev.deltaY = ev.deltaX = 0;
  112. positions.length = 0;
  113. }
  114. // actively scrolling
  115. positions.push(ev.scrollTop, ev.scrollLeft, ev.timeStamp);
  116. if (positions.length > 3) {
  117. // we've gotten at least 2 scroll events so far
  118. ev.deltaY = (ev.scrollTop - ev.startY);
  119. ev.deltaX = (ev.scrollLeft - ev.startX);
  120. var endPos = (positions.length - 1);
  121. var startPos = endPos;
  122. var timeRange = (ev.timeStamp - 100);
  123. // move pointer to position measured 100ms ago
  124. for (var i = endPos; i > 0 && positions[i] > timeRange; i -= 3) {
  125. startPos = i;
  126. }
  127. if (startPos !== endPos) {
  128. // compute relative movement between these two points
  129. var movedTop = (positions[startPos - 2] - positions[endPos - 2]);
  130. var movedLeft = (positions[startPos - 1] - positions[endPos - 1]);
  131. var factor = FRAME_MS / (positions[endPos] - positions[startPos]);
  132. // based on XXms compute the movement to apply for each render step
  133. ev.velocityY = movedTop * factor;
  134. ev.velocityX = movedLeft * factor;
  135. // figure out which direction we're scrolling
  136. ev.directionY = (movedTop > 0 ? 'up' : 'down');
  137. ev.directionX = (movedLeft > 0 ? 'left' : 'right');
  138. }
  139. }
  140. function scrollEnd() {
  141. // reset velocity, do not reset the directions or deltas
  142. ev.velocityY = ev.velocityX = 0;
  143. // emit that the scroll has ended
  144. self.setScrolling(false, ev);
  145. self._endTmr = null;
  146. }
  147. // emit on each scroll event
  148. self.setScrolling(true, ev);
  149. // debounce for a moment after the last scroll event
  150. self._dom.cancel(self._endTmr);
  151. self._endTmr = self._dom.read(scrollEnd, SCROLL_END_DEBOUNCE_MS);
  152. }
  153. // clear out any existing listeners (just to be safe)
  154. self._lsn && self._lsn();
  155. // assign the raw scroll listener
  156. // note that it does not have a wrapping requestAnimationFrame on purpose
  157. // a scroll event callback will always be right before the raf callback
  158. // so there's little to no value of using raf here since it'll all ways immediately
  159. // call the raf if it was set within the scroll event, so this will save us some time
  160. self._lsn = self._plt.registerListener(self._el, 'scroll', scrollCallback, EVENT_OPTS);
  161. };
  162. /**
  163. * @hidden
  164. * JS Scrolling has been provided only as a temporary solution
  165. * until iOS apps can take advantage of scroll events at all times.
  166. * The goal is to eventually remove JS scrolling entirely. When we
  167. * no longer have to worry about iOS not firing scroll events during
  168. * inertia then this can be burned to the ground. iOS's more modern
  169. * WKWebView does not have this issue, only UIWebView does.
  170. */
  171. ScrollView.prototype.enableJsScroll = function (contentTop, contentBottom) {
  172. var self = this;
  173. self._js = true;
  174. var ele = self._el;
  175. if (!ele) {
  176. return;
  177. }
  178. (void 0) /* console.debug */;
  179. var ev = self.ev;
  180. var positions = [];
  181. var rafCancel;
  182. var max;
  183. function setMax() {
  184. if (!max) {
  185. // ******** DOM READ ****************
  186. max = ele.scrollHeight - ele.parentElement.offsetHeight + contentTop + contentBottom;
  187. }
  188. }
  189. function jsScrollDecelerate(timeStamp) {
  190. ev.timeStamp = timeStamp;
  191. (void 0) /* console.debug */;
  192. if (ev.velocityY) {
  193. ev.velocityY *= DECELERATION_FRICTION;
  194. // update top with updated velocity
  195. // clamp top within scroll limits
  196. // ******** DOM READ ****************
  197. setMax();
  198. self._t = Math.min(Math.max(self._t + ev.velocityY, 0), max);
  199. ev.scrollTop = self._t;
  200. // emit on each scroll event
  201. self.onScroll(ev);
  202. self._dom.write(function () {
  203. // ******** DOM WRITE ****************
  204. self.setTop(self._t);
  205. if (self._t > 0 && self._t < max && Math.abs(ev.velocityY) > MIN_VELOCITY_CONTINUE_DECELERATION) {
  206. rafCancel = self._dom.read(function (rafTimeStamp) {
  207. jsScrollDecelerate(rafTimeStamp);
  208. });
  209. }
  210. else {
  211. // haven't scrolled in a while, so it's a scrollend
  212. self.isScrolling = false;
  213. // reset velocity, do not reset the directions or deltas
  214. ev.velocityY = ev.velocityX = 0;
  215. // emit that the scroll has ended
  216. self.onScrollEnd(ev);
  217. }
  218. });
  219. }
  220. }
  221. function jsScrollTouchStart(touchEvent) {
  222. positions.length = 0;
  223. max = null;
  224. self._dom.cancel(rafCancel);
  225. positions.push(dom_1.pointerCoord(touchEvent).y, touchEvent.timeStamp);
  226. }
  227. function jsScrollTouchMove(touchEvent) {
  228. if (!positions.length) {
  229. return;
  230. }
  231. ev.timeStamp = touchEvent.timeStamp;
  232. var y = dom_1.pointerCoord(touchEvent).y;
  233. // ******** DOM READ ****************
  234. setMax();
  235. self._t -= (y - positions[positions.length - 2]);
  236. self._t = Math.min(Math.max(self._t, 0), max);
  237. positions.push(y, ev.timeStamp);
  238. if (!self.isScrolling) {
  239. // remember the start position
  240. ev.startY = self._t;
  241. // new scroll, so do some resets
  242. ev.velocityY = ev.deltaY = 0;
  243. self.isScrolling = true;
  244. // emit only on the first scroll event
  245. self.onScrollStart(ev);
  246. }
  247. self._dom.write(function () {
  248. // ******** DOM WRITE ****************
  249. self.setTop(self._t);
  250. });
  251. }
  252. function jsScrollTouchEnd(touchEvent) {
  253. // figure out what the scroll position was about 100ms ago
  254. self._dom.cancel(rafCancel);
  255. if (!positions.length && self.isScrolling) {
  256. self.isScrolling = false;
  257. ev.velocityY = ev.velocityX = 0;
  258. self.onScrollEnd(ev);
  259. return;
  260. }
  261. var y = dom_1.pointerCoord(touchEvent).y;
  262. positions.push(y, touchEvent.timeStamp);
  263. var endPos = (positions.length - 1);
  264. var startPos = endPos;
  265. var timeRange = (touchEvent.timeStamp - 100);
  266. // move pointer to position measured 100ms ago
  267. for (var i = endPos; i > 0 && positions[i] > timeRange; i -= 2) {
  268. startPos = i;
  269. }
  270. if (startPos !== endPos) {
  271. // compute relative movement between these two points
  272. var timeOffset = (positions[endPos] - positions[startPos]);
  273. var movedTop = (positions[startPos - 1] - positions[endPos - 1]);
  274. // based on XXms compute the movement to apply for each render step
  275. ev.velocityY = ((movedTop / timeOffset) * FRAME_MS);
  276. // verify that we have enough velocity to start deceleration
  277. if (Math.abs(ev.velocityY) > MIN_VELOCITY_START_DECELERATION) {
  278. // ******** DOM READ ****************
  279. setMax();
  280. rafCancel = self._dom.read(function (rafTimeStamp) {
  281. jsScrollDecelerate(rafTimeStamp);
  282. });
  283. }
  284. }
  285. else {
  286. self.isScrolling = false;
  287. ev.velocityY = 0;
  288. self.onScrollEnd(ev);
  289. }
  290. positions.length = 0;
  291. }
  292. var plt = self._plt;
  293. var unRegStart = plt.registerListener(ele, 'touchstart', jsScrollTouchStart, EVENT_OPTS);
  294. var unRegMove = plt.registerListener(ele, 'touchmove', jsScrollTouchMove, EVENT_OPTS);
  295. var unRegEnd = plt.registerListener(ele, 'touchend', jsScrollTouchEnd, EVENT_OPTS);
  296. ele.parentElement.classList.add('js-scroll');
  297. // stop listening for actual scroll events
  298. self._lsn && self._lsn();
  299. // create an unregister for all of these events
  300. self._lsn = function () {
  301. unRegStart();
  302. unRegMove();
  303. unRegEnd();
  304. ele.parentElement.classList.remove('js-scroll');
  305. };
  306. };
  307. /**
  308. * DOM READ
  309. */
  310. ScrollView.prototype.getTop = function () {
  311. if (this._js) {
  312. return this._t;
  313. }
  314. return this._t = this._el.scrollTop;
  315. };
  316. /**
  317. * DOM READ
  318. */
  319. ScrollView.prototype.getLeft = function () {
  320. if (this._js) {
  321. return 0;
  322. }
  323. return this._l = this._el.scrollLeft;
  324. };
  325. /**
  326. * DOM WRITE
  327. */
  328. ScrollView.prototype.setTop = function (top) {
  329. this._t = top;
  330. if (this._js) {
  331. this._el.style[this._plt.Css.transform] = "translate3d(" + this._l * -1 + "px," + top * -1 + "px,0px)";
  332. }
  333. else {
  334. this._el.scrollTop = top;
  335. }
  336. };
  337. /**
  338. * DOM WRITE
  339. */
  340. ScrollView.prototype.setLeft = function (left) {
  341. this._l = left;
  342. if (this._js) {
  343. this._el.style[this._plt.Css.transform] = "translate3d(" + left * -1 + "px," + this._t * -1 + "px,0px)";
  344. }
  345. else {
  346. this._el.scrollLeft = left;
  347. }
  348. };
  349. ScrollView.prototype.scrollTo = function (x, y, duration, done) {
  350. // scroll animation loop w/ easing
  351. // credit https://gist.github.com/dezinezync/5487119
  352. var promise;
  353. if (done === undefined) {
  354. // only create a promise if a done callback wasn't provided
  355. // done can be a null, which avoids any functions
  356. promise = new Promise(function (resolve) {
  357. done = resolve;
  358. });
  359. }
  360. var self = this;
  361. var el = self._el;
  362. if (!el) {
  363. // invalid element
  364. done();
  365. return promise;
  366. }
  367. if (duration < 32) {
  368. self.setTop(y);
  369. self.setLeft(x);
  370. done();
  371. return promise;
  372. }
  373. var fromY = el.scrollTop;
  374. var fromX = el.scrollLeft;
  375. var maxAttempts = (duration / 16) + 100;
  376. var transform = self._plt.Css.transform;
  377. var startTime;
  378. var attempts = 0;
  379. var stopScroll = false;
  380. // scroll loop
  381. function step(timeStamp) {
  382. attempts++;
  383. if (!self._el || stopScroll || attempts > maxAttempts) {
  384. self.setScrolling(false, null);
  385. el.style[transform] = '';
  386. done();
  387. return;
  388. }
  389. var time = Math.min(1, ((timeStamp - startTime) / duration));
  390. // where .5 would be 50% of time on a linear scale easedT gives a
  391. // fraction based on the easing method
  392. var easedT = (--time) * time * time + 1;
  393. if (fromY !== y) {
  394. self.setTop((easedT * (y - fromY)) + fromY);
  395. }
  396. if (fromX !== x) {
  397. self.setLeft(Math.floor((easedT * (x - fromX)) + fromX));
  398. }
  399. if (easedT < 1) {
  400. // do not use DomController here
  401. // must use nativeRaf in order to fire in the next frame
  402. self._plt.raf(step);
  403. }
  404. else {
  405. stopScroll = true;
  406. self.setScrolling(false, null);
  407. el.style[transform] = '';
  408. done();
  409. }
  410. }
  411. // start scroll loop
  412. self.setScrolling(true, null);
  413. self.isScrolling = true;
  414. // chill out for a frame first
  415. self._dom.write(function (timeStamp) {
  416. startTime = timeStamp;
  417. step(timeStamp);
  418. }, 16);
  419. return promise;
  420. };
  421. ScrollView.prototype.scrollToTop = function (duration) {
  422. return this.scrollTo(0, 0, duration);
  423. };
  424. ScrollView.prototype.scrollToBottom = function (duration) {
  425. var y = 0;
  426. if (this._el) {
  427. y = this._el.scrollHeight - this._el.clientHeight;
  428. }
  429. return this.scrollTo(0, y, duration);
  430. };
  431. ScrollView.prototype.stop = function () {
  432. this.setScrolling(false, null);
  433. };
  434. /**
  435. * @hidden
  436. */
  437. ScrollView.prototype.destroy = function () {
  438. this.stop();
  439. this._endTmr && this._dom.cancel(this._endTmr);
  440. this._lsn && this._lsn();
  441. var ev = this.ev;
  442. ev.domWrite = ev.contentElement = ev.fixedElement = ev.scrollElement = ev.headerElement = null;
  443. this._lsn = this._el = this._dom = this.ev = ev = null;
  444. this.onScrollStart = this.onScroll = this.onScrollEnd = null;
  445. };
  446. return ScrollView;
  447. }());
  448. exports.ScrollView = ScrollView;
  449. var SCROLL_END_DEBOUNCE_MS = 80;
  450. var MIN_VELOCITY_START_DECELERATION = 4;
  451. var MIN_VELOCITY_CONTINUE_DECELERATION = 0.12;
  452. var DECELERATION_FRICTION = 0.97;
  453. var FRAME_MS = (1000 / 60);
  454. var EVENT_OPTS = {
  455. passive: true,
  456. zone: false
  457. };
  458. });
  459. //# sourceMappingURL=scroll-view.js.map