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mirror of https://github.com/flarum/core.git synced 2025-07-12 04:16:24 +02:00

Extract PostStream state (#2160)

Co-authored-by: Franz Liedke <franz@develophp.org>
This commit is contained in:
Alexander Skvortsov
2020-08-08 14:45:54 -04:00
committed by GitHub
parent f9c9b5d5e4
commit 6953d93c6d
4 changed files with 595 additions and 606 deletions

View File

@ -1,8 +1,6 @@
import Component from '../../common/Component';
import ScrollListener from '../../common/utils/ScrollListener';
import PostLoading from './LoadingPost';
import anchorScroll from '../../common/utils/anchorScroll';
import evented from '../../common/utils/evented';
import ReplyPlaceholder from './ReplyPlaceholder';
import Button from '../../common/components/Button';
@ -13,183 +11,16 @@ import Button from '../../common/components/Button';
* ### Props
*
* - `discussion`
* - `includedPosts`
* - `stream`
* - `targetPost`
* - `onPositionChange`
*/
class PostStream extends Component {
export default class PostStream extends Component {
init() {
/**
* The discussion to display the post stream for.
*
* @type {Discussion}
*/
this.discussion = this.props.discussion;
/**
* Whether or not the infinite-scrolling auto-load functionality is
* disabled.
*
* @type {Boolean}
*/
this.paused = false;
this.stream = this.props.stream;
this.scrollListener = new ScrollListener(this.onscroll.bind(this));
this.loadPageTimeouts = {};
this.pagesLoading = 0;
this.show(this.props.includedPosts);
}
/**
* Load and scroll to a post with a certain number.
*
* @param {Integer|String} number The post number to go to. If 'reply', go to
* the last post and scroll the reply preview into view.
* @param {Boolean} noAnimation
* @return {Promise}
*/
goToNumber(number, noAnimation) {
// If we want to go to the reply preview, then we will go to the end of the
// discussion and then scroll to the very bottom of the page.
if (number === 'reply') {
return this.goToLast().then(() => {
$('html,body')
.stop(true)
.animate(
{
scrollTop: $(document).height() - $(window).height(),
},
'fast',
() => {
this.flashItem(this.$('.PostStream-item:last-child'));
}
);
});
}
this.paused = true;
const promise = this.loadNearNumber(number);
m.redraw(true);
return promise.then(() => {
m.redraw(true);
this.scrollToNumber(number, noAnimation).done(this.unpause.bind(this));
});
}
/**
* Load and scroll to a certain index within the discussion.
*
* @param {Integer} index
* @param {Boolean} backwards Whether or not to load backwards from the given
* index.
* @param {Boolean} noAnimation
* @return {Promise}
*/
goToIndex(index, backwards, noAnimation) {
this.paused = true;
const promise = this.loadNearIndex(index);
m.redraw(true);
return promise.then(() => {
anchorScroll(this.$('.PostStream-item:' + (backwards ? 'last' : 'first')), () => m.redraw(true));
this.scrollToIndex(index, noAnimation, backwards).done(this.unpause.bind(this));
});
}
/**
* Load and scroll up to the first post in the discussion.
*
* @return {Promise}
*/
goToFirst() {
return this.goToIndex(0);
}
/**
* Load and scroll down to the last post in the discussion.
*
* @return {Promise}
*/
goToLast() {
return this.goToIndex(this.count() - 1, true);
}
/**
* Update the stream so that it loads and includes the latest posts in the
* discussion, if the end is being viewed.
*
* @public
*/
update() {
if (!this.viewingEnd) return m.deferred().resolve().promise;
this.visibleEnd = this.count();
return this.loadRange(this.visibleStart, this.visibleEnd).then(() => m.redraw());
}
/**
* Get the total number of posts in the discussion.
*
* @return {Integer}
*/
count() {
return this.discussion.postIds().length;
}
/**
* Make sure that the given index is not outside of the possible range of
* indexes in the discussion.
*
* @param {Integer} index
* @protected
*/
sanitizeIndex(index) {
return Math.max(0, Math.min(this.count(), index));
}
/**
* Set up the stream with the given array of posts.
*
* @param {Post[]} posts
*/
show(posts) {
this.visibleStart = posts.length ? this.discussion.postIds().indexOf(posts[0].id()) : 0;
this.visibleEnd = this.visibleStart + posts.length;
}
/**
* Reset the stream so that a specific range of posts is displayed. If a range
* is not specified, the first page of posts will be displayed.
*
* @param {Integer} [start]
* @param {Integer} [end]
*/
reset(start, end) {
this.visibleStart = start || 0;
this.visibleEnd = this.sanitizeIndex(end || this.constructor.loadCount);
}
/**
* Get the visible page of posts.
*
* @return {Post[]}
*/
posts() {
return this.discussion
.postIds()
.slice(this.visibleStart, this.visibleEnd)
.map((id) => {
const post = app.store.getById('posts', id);
return post && post.discussion() && typeof post.canEdit() !== 'undefined' ? post : null;
});
}
view() {
@ -200,15 +31,13 @@ class PostStream extends Component {
let lastTime;
this.visibleEnd = this.sanitizeIndex(this.visibleEnd);
this.viewingEnd = this.visibleEnd === this.count();
const posts = this.posts();
const viewingEnd = this.stream.viewingEnd();
const posts = this.stream.posts();
const postIds = this.discussion.postIds();
const items = posts.map((post, i) => {
let content;
const attrs = { 'data-index': this.visibleStart + i };
const attrs = { 'data-index': this.stream.visibleStart + i };
if (post) {
const time = post.createdAt();
@ -238,7 +67,7 @@ class PostStream extends Component {
lastTime = time;
} else {
attrs.key = 'post' + postIds[this.visibleStart + i];
attrs.key = 'post' + postIds[this.stream.visibleStart + i];
content = PostLoading.component();
}
@ -250,10 +79,10 @@ class PostStream extends Component {
);
});
if (!this.viewingEnd && posts[this.visibleEnd - this.visibleStart - 1]) {
if (!viewingEnd && posts[this.stream.visibleEnd - this.stream.visibleStart - 1]) {
items.push(
<div className="PostStream-loadMore" key="loadMore">
<Button className="Button" onclick={this.loadNext.bind(this)}>
<Button className="Button" onclick={this.stream.loadNext.bind(this.stream)}>
{app.translator.trans('core.forum.post_stream.load_more_button')}
</Button>
</div>
@ -262,7 +91,7 @@ class PostStream extends Component {
// If we're viewing the end of the discussion, the user can reply, and
// is not already doing so, then show a 'write a reply' placeholder.
if (this.viewingEnd && (!app.session.user || this.discussion.canReply())) {
if (viewingEnd && (!app.session.user || this.discussion.canReply())) {
items.push(
<div className="PostStream-item" key="reply">
{ReplyPlaceholder.component({ discussion: this.discussion })}
@ -274,6 +103,8 @@ class PostStream extends Component {
}
config(isInitialized, context) {
this.triggerScroll();
if (isInitialized) return;
// This is wrapped in setTimeout due to the following Mithril issue:
@ -286,201 +117,135 @@ class PostStream extends Component {
};
}
/**
* Start scrolling, if appropriate, to a newly-targeted post.
*/
triggerScroll() {
if (!this.props.targetPost) return;
const oldTarget = this.prevTarget;
const newTarget = this.props.targetPost;
if (oldTarget) {
if ('number' in oldTarget && oldTarget.number === newTarget.number) return;
if ('index' in oldTarget && oldTarget.index === newTarget.index) return;
}
if ('number' in newTarget) {
this.scrollToNumber(newTarget.number, this.stream.noAnimationScroll);
} else if ('index' in newTarget) {
const backwards = newTarget.index === this.stream.count() - 1;
this.scrollToIndex(newTarget.index, this.stream.noAnimationScroll, backwards);
}
this.prevTarget = newTarget;
}
/**
* When the window is scrolled, check if either extreme of the post stream is
* in the viewport, and if so, trigger loading the next/previous page.
*
* @param {Integer} top
*/
onscroll(top) {
if (this.paused) return;
onscroll(top = window.pageYOffset) {
if (this.stream.paused) return;
const marginTop = this.getMarginTop();
const viewportHeight = $(window).height() - marginTop;
const viewportTop = top + marginTop;
const loadAheadDistance = 300;
if (this.visibleStart > 0) {
const $item = this.$('.PostStream-item[data-index=' + this.visibleStart + ']');
if (this.stream.visibleStart > 0) {
const $item = this.$('.PostStream-item[data-index=' + this.stream.visibleStart + ']');
if ($item.length && $item.offset().top > viewportTop - loadAheadDistance) {
this.loadPrevious();
this.stream.loadPrevious();
}
}
if (this.visibleEnd < this.count()) {
const $item = this.$('.PostStream-item[data-index=' + (this.visibleEnd - 1) + ']');
if (this.stream.visibleEnd < this.stream.count()) {
const $item = this.$('.PostStream-item[data-index=' + (this.stream.visibleEnd - 1) + ']');
if ($item.length && $item.offset().top + $item.outerHeight(true) < viewportTop + viewportHeight + loadAheadDistance) {
this.loadNext();
this.stream.loadNext();
}
}
// Throttle calculation of our position (start/end numbers of posts in the
// viewport) to 100ms.
clearTimeout(this.calculatePositionTimeout);
this.calculatePositionTimeout = setTimeout(this.calculatePosition.bind(this), 100);
this.calculatePositionTimeout = setTimeout(this.calculatePosition.bind(this, top), 100);
this.updateScrubber(top);
}
/**
* Load the next page of posts.
*/
loadNext() {
const start = this.visibleEnd;
const end = (this.visibleEnd = this.sanitizeIndex(this.visibleEnd + this.constructor.loadCount));
updateScrubber(top = window.pageYOffset) {
const marginTop = this.getMarginTop();
const viewportHeight = $(window).height() - marginTop;
const viewportTop = top + marginTop;
// Unload the posts which are two pages back from the page we're currently
// loading.
const twoPagesAway = start - this.constructor.loadCount * 2;
if (twoPagesAway > this.visibleStart && twoPagesAway >= 0) {
this.visibleStart = twoPagesAway + this.constructor.loadCount + 1;
// Before looping through all of the posts, we reset the scrollbar
// properties to a 'default' state. These values reflect what would be
// seen if the browser were scrolled right up to the top of the page,
// and the viewport had a height of 0.
const $items = this.$('.PostStream-item[data-index]');
let index = $items.first().data('index') || 0;
let visible = 0;
let period = '';
if (this.loadPageTimeouts[twoPagesAway]) {
clearTimeout(this.loadPageTimeouts[twoPagesAway]);
this.loadPageTimeouts[twoPagesAway] = null;
this.pagesLoading--;
// Now loop through each of the items in the discussion. An 'item' is
// either a single post or a 'gap' of one or more posts that haven't
// been loaded yet.
$items.each(function () {
const $this = $(this);
const top = $this.offset().top;
const height = $this.outerHeight(true);
// If this item is above the top of the viewport, skip to the next
// one. If it's below the bottom of the viewport, break out of the
// loop.
if (top + height < viewportTop) {
return true;
}
}
this.loadPage(start, end);
}
/**
* Load the previous page of posts.
*/
loadPrevious() {
const end = this.visibleStart;
const start = (this.visibleStart = this.sanitizeIndex(this.visibleStart - this.constructor.loadCount));
// Unload the posts which are two pages back from the page we're currently
// loading.
const twoPagesAway = start + this.constructor.loadCount * 2;
if (twoPagesAway < this.visibleEnd && twoPagesAway <= this.count()) {
this.visibleEnd = twoPagesAway;
if (this.loadPageTimeouts[twoPagesAway]) {
clearTimeout(this.loadPageTimeouts[twoPagesAway]);
this.loadPageTimeouts[twoPagesAway] = null;
this.pagesLoading--;
if (top > viewportTop + viewportHeight) {
return false;
}
}
this.loadPage(start, end, true);
}
// Work out how many pixels of this item are visible inside the viewport.
// Then add the proportion of this item's total height to the index.
const visibleTop = Math.max(0, viewportTop - top);
const visibleBottom = Math.min(height, viewportTop + viewportHeight - top);
const visiblePost = visibleBottom - visibleTop;
/**
* Load a page of posts into the stream and redraw.
*
* @param {Integer} start
* @param {Integer} end
* @param {Boolean} backwards
*/
loadPage(start, end, backwards) {
const redraw = () => {
if (start < this.visibleStart || end > this.visibleEnd) return;
if (top <= viewportTop) {
index = parseFloat($this.data('index')) + visibleTop / height;
}
const anchorIndex = backwards ? this.visibleEnd - 1 : this.visibleStart;
anchorScroll(`.PostStream-item[data-index="${anchorIndex}"]`, () => m.redraw(true));
if (visiblePost > 0) {
visible += visiblePost / height;
}
this.unpause();
};
redraw();
// If this item has a time associated with it, then set the
// scrollbar's current period to a formatted version of this time.
const time = $this.data('time');
if (time) period = time;
});
this.loadPageTimeouts[start] = setTimeout(
() => {
this.loadRange(start, end).then(() => {
redraw();
this.pagesLoading--;
});
this.loadPageTimeouts[start] = null;
},
this.pagesLoading ? 1000 : 0
);
this.pagesLoading++;
}
/**
* Load and inject the specified range of posts into the stream, without
* clearing it.
*
* @param {Integer} start
* @param {Integer} end
* @return {Promise}
*/
loadRange(start, end) {
const loadIds = [];
const loaded = [];
this.discussion
.postIds()
.slice(start, end)
.forEach((id) => {
const post = app.store.getById('posts', id);
if (post && post.discussion() && typeof post.canEdit() !== 'undefined') {
loaded.push(post);
} else {
loadIds.push(id);
}
});
return loadIds.length ? app.store.find('posts', loadIds) : m.deferred().resolve(loaded).promise;
}
/**
* Clear the stream and load posts near a certain number. Returns a promise.
* If the post with the given number is already loaded, the promise will be
* resolved immediately.
*
* @param {Integer} number
* @return {Promise}
*/
loadNearNumber(number) {
if (this.posts().some((post) => post && Number(post.number()) === Number(number))) {
return m.deferred().resolve().promise;
}
this.reset();
return app.store
.find('posts', {
filter: { discussion: this.discussion.id() },
page: { near: number },
})
.then(this.show.bind(this));
}
/**
* Clear the stream and load posts near a certain index. A page of posts
* surrounding the given index will be loaded. Returns a promise. If the given
* index is already loaded, the promise will be resolved immediately.
*
* @param {Integer} index
* @return {Promise}
*/
loadNearIndex(index) {
if (index >= this.visibleStart && index <= this.visibleEnd) {
return m.deferred().resolve().promise;
}
const start = this.sanitizeIndex(index - this.constructor.loadCount / 2);
const end = start + this.constructor.loadCount;
this.reset(start, end);
return this.loadRange(start, end).then(this.show.bind(this));
this.stream.index = index + 1;
this.stream.visible = visible;
if (period) this.stream.description = dayjs(period).format('MMMM YYYY');
}
/**
* Work out which posts (by number) are currently visible in the viewport, and
* fire an event with the information.
*/
calculatePosition() {
calculatePosition(top = window.pageYOffset) {
const marginTop = this.getMarginTop();
const $window = $(window);
const viewportHeight = $window.height() - marginTop;
const scrollTop = $window.scrollTop() + marginTop;
const viewportTop = top + marginTop;
let startNumber;
let endNumber;
@ -488,12 +253,15 @@ class PostStream extends Component {
const $item = $(this);
const top = $item.offset().top;
const height = $item.outerHeight(true);
const visibleTop = Math.max(0, viewportTop - top);
const threeQuartersVisible = visibleTop / height < 0.75;
const coversQuarterOfViewport = (height - visibleTop) / viewportHeight > 0.25;
if (startNumber === undefined && (threeQuartersVisible || coversQuarterOfViewport)) {
startNumber = $item.data('number');
}
if (top + height > scrollTop) {
if (!startNumber) {
startNumber = endNumber = $item.data('number');
}
if (top + height < scrollTop + viewportHeight) {
if ($item.data('number')) {
endNumber = $item.data('number');
@ -503,7 +271,7 @@ class PostStream extends Component {
});
if (startNumber) {
this.trigger('positionChanged', startNumber || 1, endNumber);
this.props.onPositionChange(startNumber || 1, endNumber, startNumber);
}
}
@ -521,42 +289,46 @@ class PostStream extends Component {
* Scroll down to a certain post by number and 'flash' it.
*
* @param {Integer} number
* @param {Boolean} noAnimation
* @param {Boolean} animate
* @return {jQuery.Deferred}
*/
scrollToNumber(number, noAnimation) {
scrollToNumber(number, animate) {
const $item = this.$(`.PostStream-item[data-number=${number}]`);
return this.scrollToItem($item, noAnimation).done(this.flashItem.bind(this, $item));
return this.scrollToItem($item, animate).then(this.flashItem.bind(this, $item));
}
/**
* Scroll down to a certain post by index.
*
* @param {Integer} index
* @param {Boolean} noAnimation
* @param {Boolean} animate
* @param {Boolean} bottom Whether or not to scroll to the bottom of the post
* at the given index, instead of the top of it.
* @return {jQuery.Deferred}
*/
scrollToIndex(index, noAnimation, bottom) {
scrollToIndex(index, animate, bottom) {
const $item = this.$(`.PostStream-item[data-index=${index}]`);
return this.scrollToItem($item, noAnimation, true, bottom);
return this.scrollToItem($item, animate, true, bottom).then(() => {
if (index == this.stream.count() - 1) {
this.flashItem(this.$('.PostStream-item:last-child'));
}
});
}
/**
* Scroll down to the given post.
*
* @param {jQuery} $item
* @param {Boolean} noAnimation
* @param {Boolean} animate
* @param {Boolean} force Whether or not to force scrolling to the item, even
* if it is already in the viewport.
* @param {Boolean} bottom Whether or not to scroll to the bottom of the post
* at the given index, instead of the top of it.
* @return {jQuery.Deferred}
*/
scrollToItem($item, noAnimation, force, bottom) {
scrollToItem($item, animate, force, bottom) {
const $container = $('html, body').stop(true);
if ($item.length) {
@ -571,7 +343,7 @@ class PostStream extends Component {
if (force || itemTop < scrollTop || itemBottom > scrollBottom) {
const top = bottom ? itemBottom - $(window).height() + app.composer.computedHeight() : $item.is(':first-child') ? 0 : itemTop;
if (noAnimation) {
if (!animate) {
$container.scrollTop(top);
} else if (top !== scrollTop) {
$container.animate({ scrollTop: top }, 'fast');
@ -579,7 +351,15 @@ class PostStream extends Component {
}
}
return $container.promise();
return Promise.all([$container.promise(), this.stream.loadPromise]).then(() => {
this.updateScrubber();
const index = $item.data('index');
m.redraw(true);
const scroll = index == 0 ? 0 : $(`.PostStream-item[data-index=${$item.data('index')}]`).offset().top - this.getMarginTop();
$(window).scrollTop(scroll);
this.calculatePosition();
this.stream.paused = false;
});
}
/**
@ -590,24 +370,4 @@ class PostStream extends Component {
flashItem($item) {
$item.addClass('flash').one('animationend webkitAnimationEnd', () => $item.removeClass('flash'));
}
/**
* Resume the stream's ability to auto-load posts on scroll.
*/
unpause() {
this.paused = false;
this.scrollListener.update();
this.trigger('unpaused');
}
}
/**
* The number of posts to load per page.
*
* @type {Integer}
*/
PostStream.loadCount = 20;
Object.assign(PostStream.prototype, evented);
export default PostStream;