signal-desktop/ts/components/GroupTitleInput.tsx
2021-06-01 20:24:28 -04:00

102 lines
3.6 KiB
TypeScript

// Copyright 2021 Signal Messenger, LLC
// SPDX-License-Identifier: AGPL-3.0-only
import React, { forwardRef, useRef, ClipboardEvent } from 'react';
import { LocalizerType } from '../types/Util';
import { multiRef } from '../util/multiRef';
import * as grapheme from '../util/grapheme';
const MAX_GRAPHEME_COUNT = 32;
type PropsType = {
disabled?: boolean;
i18n: LocalizerType;
onChangeValue: (value: string) => void;
value: string;
};
/**
* Group titles must have fewer than MAX_GRAPHEME_COUNT glyphs. Ideally, we'd use the
* `maxLength` property on inputs, but that doesn't account for glyphs that are more than
* one UTF-16 code units. For example: `'💩💩'.length === 4`.
*
* This component effectively implements a "max grapheme length" on an input.
*
* At a high level, this component handles two methods of input:
*
* - `onChange`. *Before* the value is changed (in `onKeyDown`), we save the value and the
* cursor position. Then, in `onChange`, we see if the new value is too long. If it is,
* we revert the value and selection. Otherwise, we fire `onChangeValue`.
*
* - `onPaste`. If you're pasting something that will fit, we fall back to normal browser
* behavior, which calls `onChange`. If you're pasting something that won't fit, it's a
* noop.
*/
export const GroupTitleInput = forwardRef<HTMLInputElement, PropsType>(
({ i18n, disabled = false, onChangeValue, value }, ref) => {
const innerRef = useRef<HTMLInputElement | null>(null);
const valueOnKeydownRef = useRef<string>(value);
const selectionStartOnKeydownRef = useRef<number>(value.length);
return (
<div className="module-GroupInput--container">
<input
disabled={disabled}
className="module-GroupInput"
onKeyDown={() => {
const inputEl = innerRef.current;
if (!inputEl) {
return;
}
valueOnKeydownRef.current = inputEl.value;
selectionStartOnKeydownRef.current = inputEl.selectionStart || 0;
}}
onChange={() => {
const inputEl = innerRef.current;
if (!inputEl) {
return;
}
const newValue = inputEl.value;
if (grapheme.count(newValue) <= MAX_GRAPHEME_COUNT) {
onChangeValue(newValue);
} else {
inputEl.value = valueOnKeydownRef.current;
inputEl.selectionStart = selectionStartOnKeydownRef.current;
inputEl.selectionEnd = selectionStartOnKeydownRef.current;
}
}}
onPaste={(event: ClipboardEvent<HTMLInputElement>) => {
const inputEl = innerRef.current;
if (!inputEl) {
return;
}
const selectionStart = inputEl.selectionStart || 0;
const selectionEnd =
inputEl.selectionEnd || inputEl.selectionStart || 0;
const textBeforeSelection = value.slice(0, selectionStart);
const textAfterSelection = value.slice(selectionEnd);
const pastedText = event.clipboardData.getData('Text');
const newGraphemeCount =
grapheme.count(textBeforeSelection) +
grapheme.count(pastedText) +
grapheme.count(textAfterSelection);
if (newGraphemeCount > MAX_GRAPHEME_COUNT) {
event.preventDefault();
}
}}
placeholder={i18n('setGroupMetadata__group-name-placeholder')}
ref={multiRef<HTMLInputElement>(ref, innerRef)}
type="text"
value={value}
/>
</div>
);
}
);