@ionic/core
Version:
Base components for Ionic
217 lines (212 loc) • 8.43 kB
JavaScript
/*!
* (C) Ionic http://ionicframework.com - MIT License
*/
import { proxyCustomElement, HTMLElement, createEvent, writeTask, readTask, h, Host } from '@stencil/core/internal/client';
import { a as findClosestIonContent, p as printIonContentErrorMsg, g as getScrollElement } from './index8.js';
import { b as getIonMode } from './ionic-global.js';
const infiniteScrollCss = "ion-infinite-scroll{display:none;width:100%}.infinite-scroll-enabled{display:block}";
const IonInfiniteScrollStyle0 = infiniteScrollCss;
const InfiniteScroll = /*@__PURE__*/ proxyCustomElement(class InfiniteScroll extends HTMLElement {
constructor() {
super();
this.__registerHost();
this.ionInfinite = createEvent(this, "ionInfinite", 7);
this.thrPx = 0;
this.thrPc = 0;
/**
* didFire exists so that ionInfinite
* does not fire multiple times if
* users continue to scroll after
* scrolling into the infinite
* scroll threshold.
*/
this.didFire = false;
this.isBusy = false;
this.onScroll = () => {
const scrollEl = this.scrollEl;
if (!scrollEl || !this.canStart()) {
return 1;
}
const infiniteHeight = this.el.offsetHeight;
if (infiniteHeight === 0) {
// if there is no height of this element then do nothing
return 2;
}
const scrollTop = scrollEl.scrollTop;
const scrollHeight = scrollEl.scrollHeight;
const height = scrollEl.offsetHeight;
const threshold = this.thrPc !== 0 ? height * this.thrPc : this.thrPx;
const distanceFromInfinite = this.position === 'bottom'
? scrollHeight - infiniteHeight - scrollTop - threshold - height
: scrollTop - infiniteHeight - threshold;
if (distanceFromInfinite < 0) {
if (!this.didFire) {
this.isLoading = true;
this.didFire = true;
this.ionInfinite.emit();
return 3;
}
}
return 4;
};
this.isLoading = false;
this.threshold = '15%';
this.disabled = false;
this.position = 'bottom';
}
thresholdChanged() {
const val = this.threshold;
if (val.lastIndexOf('%') > -1) {
this.thrPx = 0;
this.thrPc = parseFloat(val) / 100;
}
else {
this.thrPx = parseFloat(val);
this.thrPc = 0;
}
}
disabledChanged() {
const disabled = this.disabled;
if (disabled) {
this.isLoading = false;
this.isBusy = false;
}
this.enableScrollEvents(!disabled);
}
async connectedCallback() {
const contentEl = findClosestIonContent(this.el);
if (!contentEl) {
printIonContentErrorMsg(this.el);
return;
}
this.scrollEl = await getScrollElement(contentEl);
this.thresholdChanged();
this.disabledChanged();
if (this.position === 'top') {
writeTask(() => {
if (this.scrollEl) {
this.scrollEl.scrollTop = this.scrollEl.scrollHeight - this.scrollEl.clientHeight;
}
});
}
}
disconnectedCallback() {
this.enableScrollEvents(false);
this.scrollEl = undefined;
}
/**
* Call `complete()` within the `ionInfinite` output event handler when
* your async operation has completed. For example, the `loading`
* state is while the app is performing an asynchronous operation,
* such as receiving more data from an AJAX request to add more items
* to a data list. Once the data has been received and UI updated, you
* then call this method to signify that the loading has completed.
* This method will change the infinite scroll's state from `loading`
* to `enabled`.
*/
async complete() {
const scrollEl = this.scrollEl;
if (!this.isLoading || !scrollEl) {
return;
}
this.isLoading = false;
if (this.position === 'top') {
/**
* New content is being added at the top, but the scrollTop position stays the same,
* which causes a scroll jump visually. This algorithm makes sure to prevent this.
* (Frame 1)
* - complete() is called, but the UI hasn't had time to update yet.
* - Save the current content dimensions.
* - Wait for the next frame using _dom.read, so the UI will be updated.
* (Frame 2)
* - Read the new content dimensions.
* - Calculate the height difference and the new scroll position.
* - Delay the scroll position change until other possible dom reads are done using _dom.write to be performant.
* (Still frame 2, if I'm correct)
* - Change the scroll position (= visually maintain the scroll position).
* - Change the state to re-enable the InfiniteScroll.
* - This should be after changing the scroll position, or it could
* cause the InfiniteScroll to be triggered again immediately.
* (Frame 3)
* Done.
*/
this.isBusy = true;
// ******** DOM READ ****************
// Save the current content dimensions before the UI updates
const prev = scrollEl.scrollHeight - scrollEl.scrollTop;
// ******** DOM READ ****************
requestAnimationFrame(() => {
readTask(() => {
// UI has updated, save the new content dimensions
const scrollHeight = scrollEl.scrollHeight;
// New content was added on top, so the scroll position should be changed immediately to prevent it from jumping around
const newScrollTop = scrollHeight - prev;
// ******** DOM WRITE ****************
requestAnimationFrame(() => {
writeTask(() => {
scrollEl.scrollTop = newScrollTop;
this.isBusy = false;
this.didFire = false;
});
});
});
});
}
else {
this.didFire = false;
}
}
canStart() {
return !this.disabled && !this.isBusy && !!this.scrollEl && !this.isLoading;
}
enableScrollEvents(shouldListen) {
if (this.scrollEl) {
if (shouldListen) {
this.scrollEl.addEventListener('scroll', this.onScroll);
}
else {
this.scrollEl.removeEventListener('scroll', this.onScroll);
}
}
}
render() {
const mode = getIonMode(this);
const disabled = this.disabled;
return (h(Host, { key: 'e844956795f69be33396ce4480aa7a54ad01b28c', class: {
[mode]: true,
'infinite-scroll-loading': this.isLoading,
'infinite-scroll-enabled': !disabled,
} }));
}
get el() { return this; }
static get watchers() { return {
"threshold": ["thresholdChanged"],
"disabled": ["disabledChanged"]
}; }
static get style() { return IonInfiniteScrollStyle0; }
}, [0, "ion-infinite-scroll", {
"threshold": [1],
"disabled": [4],
"position": [1],
"isLoading": [32],
"complete": [64]
}, undefined, {
"threshold": ["thresholdChanged"],
"disabled": ["disabledChanged"]
}]);
function defineCustomElement$1() {
if (typeof customElements === "undefined") {
return;
}
const components = ["ion-infinite-scroll"];
components.forEach(tagName => { switch (tagName) {
case "ion-infinite-scroll":
if (!customElements.get(tagName)) {
customElements.define(tagName, InfiniteScroll);
}
break;
} });
}
const IonInfiniteScroll = InfiniteScroll;
const defineCustomElement = defineCustomElement$1;
export { IonInfiniteScroll, defineCustomElement };