This commit is contained in:
syuilo 2020-02-12 06:01:59 +09:00
parent 3f749c6540
commit 5e7be93980

View file

@ -1,15 +1,45 @@
import Vue from 'vue';
function getScrollContainer(el: Element | null): Element | null {
if (el == null || el.tagName === 'BODY') return null;
const style = window.getComputedStyle(el);
if (style.getPropertyValue('overflow') === 'auto') {
return el;
} else {
return getScrollContainer(el.parentElement);
}
}
function getScrollPosition(el: Element | null): number {
const container = getScrollContainer(el);
return container == null ? window.scrollY : container.scrollTop;
}
function onScrollTop(el, cb) {
const container = getScrollContainer(el) || window;
const onScroll = ev => {
if (!document.body.contains(el)) return;
const pos = getScrollPosition(el);
if (pos === 0) {
cb();
container.removeEventListener('scroll', onscroll);
}
};
container.addEventListener('scroll', onScroll, { passive: true });
}
export default (opts) => ({
data() {
return {
items: [],
queue: [],
offset: 0,
fetching: true,
moreFetching: false,
inited: false,
more: false,
backed: false,
isBackTop: false,
};
},
@ -32,13 +62,17 @@ export default (opts) => ({
created() {
opts.displayLimit = opts.displayLimit || 30;
this.init();
this.$on('hook:activated', () => {
this.isBackTop = false;
});
this.$on('hook:deactivated', () => {
this.isBackTop = window.scrollY === 0;
});
},
methods: {
isScrollTop() {
return window.scrollY <= 8;
},
updateItem(i, item) {
Vue.set((this as any).items, i, item);
},
@ -107,21 +141,26 @@ export default (opts) => ({
});
},
prepend(item, silent = false) {
if (opts.onPrepend) {
const cancel = opts.onPrepend(this, item, silent);
if (cancel) return;
}
prepend(item) {
const isTop = this.isBackTop || (document.body.contains(this.$el) && (getScrollPosition(this.$el) === 0));
if (isTop) {
// Prepend the item
this.items.unshift(item);
if (this.isScrollTop()) {
// オーバーフローしたら古いアイテムは捨てる
if (this.items.length >= opts.displayLimit) {
this.items = this.items.slice(0, opts.displayLimit);
this.more = true;
}
} else {
this.queue.push(item);
onScrollTop(this.$el, () => {
for (const item of this.queue) {
this.prepend(item);
}
this.queue = [];
});
}
},