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// <coinos-text>: a plain-text field built on contenteditable, standing in
// for <textarea> in the composers.
//
// Why: Android keyboards (Gboard's GIFs, stickers, image suggestions) only
// offer pictures to a field that says it accepts them, and Chrome says so
// for contenteditable — never for <textarea>, where the GIF key sits greyed
// out with "This app does not support images here". So the field is
// editable HTML that behaves, to the code around it, like a textarea:
// `value`, `selectionStart`/`selectionEnd` (read and write),
// `setSelectionRange`, a `placeholder`, Enter handled by the page. Text
// stays plain — pasted formatting is dropped — and any picture that arrives
// (a keyboard GIF, a pasted or dropped image) is handed to `onmedia(file)`
// as a File, the same path as the paperclip, instead of landing in the text.
const BLOCK = new Set(['DIV', 'P', 'LI']);
// The field's text, newlines where the editor put <br> or a new block.
function textOf(root) {
let out = '';
const walk = (n) => {
for (const c of n.childNodes) {
if (c.nodeType === 3) out += c.data;
else if (c.nodeName === 'BR') out += '\n';
else if (c.nodeType === 1) {
if (BLOCK.has(c.nodeName) && out && !out.endsWith('\n')) out += '\n';
walk(c);
}
}
};
walk(root);
// an editor leaves a lone trailing <br> to hold an empty last line open
return out.endsWith('\n') && root.lastChild && root.lastChild.nodeName === 'BR' ? out.slice(0, -1) : out;
}
// Text length from the start of `root` up to (node, offset).
function offsetOf(root, node, offset) {
const r = document.createRange();
r.selectNodeContents(root);
try { r.setEnd(node, offset); } catch { return textOf(root).length; }
const frag = r.cloneContents();
const div = document.createElement('div');
div.append(frag);
let t = textOf(div);
// a <br> right at the caret counts as the newline it is
if (div.lastChild && div.lastChild.nodeName === 'BR') t += '\n';
return t.length;
}
// (node, offset) for a text position; the field is normalised to text nodes
// and <br>s, so that is all this walks.
function pointAt(root, pos) {
let left = pos;
for (const c of root.childNodes) {
if (c.nodeType === 3) {
if (left <= c.data.length) return [c, left];
left -= c.data.length;
} else if (c.nodeName === 'BR') {
if (left === 0) return [root, [...root.childNodes].indexOf(c)];
left -= 1;
}
}
return [root, root.childNodes.length];
}
const mediaOf = (dt) => [...((dt && dt.files) || [])].filter((f) => /^(image|video)\//.test(f.type));
class CoinosText extends HTMLElement {
constructor() {
super();
this._pendingValue = null;
this.addEventListener('paste', (e) => this._onPaste(e));
this.addEventListener('drop', (e) => {
const files = mediaOf(e.dataTransfer);
if (files.length) { e.preventDefault(); this._media(files); }
});
this.addEventListener('beforeinput', (e) => this._onBeforeInput(e));
this.addEventListener('input', () => this._tidy());
}
connectedCallback() {
if (!this.hasAttribute('contenteditable')) this.setAttribute('contenteditable', 'true');
this.setAttribute('role', 'textbox');
this.setAttribute('aria-multiline', 'true');
if (this.hasAttribute('placeholder')) this.setAttribute('aria-placeholder', this.getAttribute('placeholder'));
this._empty();
}
get value() { return textOf(this); }
set value(v) {
v = v == null ? '' : String(v);
if (v === this.value) return;
// text nodes and <br>s only: what pointAt walks
this.replaceChildren(...v.split('\n').flatMap((line, i) => [...(i ? [document.createElement('br')] : []), ...(line ? [document.createTextNode(line)] : [])]));
if (v.endsWith('\n')) this.append(document.createElement('br'));
this._empty();
}
get placeholder() { return this.getAttribute('placeholder') || ''; }
set placeholder(v) { this.setAttribute('placeholder', v); }
get selectionStart() { return this._sel()[0]; }
get selectionEnd() { return this._sel()[1]; }
set selectionStart(v) { const [, e] = this._sel(); this.setSelectionRange(v, Math.max(v, e)); }
set selectionEnd(v) { const [s] = this._sel(); this.setSelectionRange(Math.min(s, v), v); }
_sel() {
const sel = document.getSelection();
if (!sel || !sel.rangeCount || !this.contains(sel.anchorNode)) { const n = this.value.length; return [n, n]; }
const r = sel.getRangeAt(0);
return [offsetOf(this, r.startContainer, r.startOffset), offsetOf(this, r.endContainer, r.endOffset)];
}
setSelectionRange(start, end = start) {
this.normalize();
const sel = document.getSelection();
if (!sel) return;
const r = document.createRange();
const [sn, so] = pointAt(this, start);
const [en, eo] = pointAt(this, end);
try { r.setStart(sn, so); r.setEnd(en, eo); sel.removeAllRanges(); sel.addRange(r); } catch {}
}
// Insert text at the caret as the editor would (undo history intact).
_insert(text) {
if (!document.execCommand('insertText', false, text)) {
const s = this.selectionStart, e = this.selectionEnd, v = this.value;
this.value = v.slice(0, s) + text + v.slice(e);
this.setSelectionRange(s + text.length);
this.dispatchEvent(new Event('input', { bubbles: true }));
}
}
_media(files) {
for (const f of files) {
if (typeof this.onmedia === 'function') this.onmedia(f);
}
}
_onPaste(e) {
const dt = e.clipboardData;
const files = mediaOf(dt);
if (files.length) { e.preventDefault(); this._media(files); return; }
// plain text only: no fonts, links or colours from wherever it was copied
e.preventDefault();
const text = dt ? dt.getData('text/plain') : '';
if (text) this._insert(text.replace(/\r\n?/g, '\n'));
}
_onBeforeInput(e) {
// keyboard-inserted pictures (Android's commitContent) and drops arrive
// as insertions carrying a DataTransfer
if (e.dataTransfer) {
const files = mediaOf(e.dataTransfer);
if (files.length) { e.preventDefault(); this._media(files); return; }
if (/^insertFrom/.test(e.inputType)) {
e.preventDefault();
const text = e.dataTransfer.getData('text/plain');
if (text) this._insert(text.replace(/\r\n?/g, '\n'));
return;
}
}
// a new line is a newline, not a new <div>
if (e.inputType === 'insertParagraph') { e.preventDefault(); this._insert('\n'); return; }
if (/^format/.test(e.inputType)) e.preventDefault(); // no bold/italic shortcuts
}
// Anything that isn't text or <br> (an <img> a keyboard managed to put
// in, a styled span) is taken out; a picture goes to onmedia.
_tidy() {
for (const img of this.querySelectorAll('img')) {
const src = img.getAttribute('src');
img.remove();
if (src) fetch(src).then((r) => r.blob()).then((b) => {
if (/^(image|video)\//.test(b.type)) this._media([new File([b], 'pasted.' + (b.type.split('/')[1] || 'png'), { type: b.type })]);
}).catch(() => {});
}
if ([...this.children].some((c) => c.nodeName !== 'BR')) {
const s = this.selectionStart, v = this.value;
this.value = v;
if (document.activeElement === this) this.setSelectionRange(Math.min(s, v.length));
}
this._empty();
}
_empty() { this.toggleAttribute('data-empty', !this.value); }
}
if (typeof customElements !== 'undefined' && !customElements.get('coinos-text')) {
customElements.define('coinos-text', CoinosText);
}
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