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php-flarum/js/src/forum/components/ComposerPostPreview.js
David Sevilla Martín 71f3379fcc Mithril 2 update (#2255)
* Update frontend to Mithril 2

- Update Mithril version to v2.0.4
- Add Typescript typings for Mithril
- Rename "props" to "attrs"; "initProps" to "initAttrs"; "m.prop" to "m.stream"; "m.withAttr" to "utils/withAttr".
- Use Mithril 2's new lifecycle hooks
- SubtreeRetainer has been rewritten to be more useful for the new system
- Utils for forcing page re-initializations have been added (force attr in links, setRouteWithForcedRefresh util)
- Other mechanical changes, following the upgrade guide
- Remove some of the custom stuff in our Component base class
- Introduce "fragments" for non-components that control their own DOM
- Remove Mithril patches, introduce a few new ones (route attrs in <a>; 
- Redesign AlertManagerState `show` with 3 overloads: `show(children)`, `show(attrs, children)`, `show(componentClass, attrs, children)`
- The `affixedSidebar` util has been replaced with an `AffixedSidebar` component

Challenges:
- `children` and `tag` are now reserved, and can not be used as attr names
- Behavior of links to current page changed in Mithril. If moving to a page that is handled by the same component, the page component WILL NOT be re-initialized by default. Additional code to keep track of the current url is needed (See IndexPage, DiscussionPage, and UserPage for examples)
- Native Promise rejections are shown on console when not handled
- Instances of components can no longer be stored. The state pattern should be used instead.

Refs #1821.

Co-authored-by: Alexander Skvortsov <sasha.skvortsov109@gmail.com>
Co-authored-by: Matthew Kilgore <tankerkiller125@gmail.com>
Co-authored-by: Franz Liedke <franz@develophp.org>
2020-09-23 22:40:37 -04:00

55 lines
1.6 KiB
JavaScript

/*global s9e*/
import Component from '../../common/Component';
/**
* The `ComposerPostPreview` component renders Markdown as HTML using the
* TextFormatter library, polling a data source for changes every 50ms. This is
* done to prevent expensive redraws on e.g. every single keystroke, while
* still retaining the perception of live updates for the user.
*
* ### Attrs
*
* - `composer` The state of the composer controlling this preview.
* - `className` A CSS class for the element surrounding the preview.
* - `surround` A callback that can execute code before and after re-render, e.g. for scroll anchoring.
*/
export default class ComposerPostPreview extends Component {
static initAttrs(attrs) {
attrs.className = attrs.className || '';
attrs.surround = attrs.surround || ((preview) => preview());
}
view() {
return <div className={this.attrs.className} />;
}
oncreate(vnode) {
super.oncreate(vnode);
// Every 50ms, if the composer content has changed, then update the post's
// body with a preview.
let preview;
const updatePreview = () => {
// Since we're polling, the composer may have been closed in the meantime,
// so we bail in that case.
if (!this.attrs.composer.isVisible()) return;
const content = this.attrs.composer.fields.content();
if (preview === content) return;
preview = content;
this.attrs.surround(() => s9e.TextFormatter.preview(preview || '', vnode.dom));
};
updatePreview();
this.updateInterval = setInterval(updatePreview, 50);
}
onremove() {
clearInterval(this.updateInterval);
}
}