fix: auto grow textarea

app/utils.ts

@@ -97,3 +97,51 @@ export function getCurrentVersion() {
 export function getEmojiUrl(unified: string, style: EmojiStyle) {
   return `https://cdn.staticfile.org/emoji-datasource-apple/14.0.0/img/${style}/64/${unified}.png`;
 }
+
+function getDomContentWidth(dom: HTMLElement) {
+  const style = window.getComputedStyle(dom);
+  const paddingWidth =
+    parseFloat(style.paddingLeft) + parseFloat(style.paddingRight);
+  const width = dom.clientWidth - paddingWidth;
+  return width;
+}
+
+function getOrCreateMeasureDom(id: string, init?: (dom: HTMLElement) => void) {
+  let dom = document.getElementById(id);
+
+  if (!dom) {
+    dom = document.createElement("span");
+    dom.style.position = "absolute";
+    dom.style.wordBreak = "break-word";
+    dom.style.fontSize = "14px";
+    dom.style.transform = "translateY(-200vh)";
+    dom.style.pointerEvents = "none";
+    dom.style.opacity = "0";
+    dom.id = id;
+    document.body.appendChild(dom);
+    init?.(dom);
+  }
+
+  return dom!;
+}
+
+export function autoGrowTextArea(dom: HTMLTextAreaElement) {
+  const measureDom = getOrCreateMeasureDom("__measure");
+  const singleLineDom = getOrCreateMeasureDom("__single_measure", (dom) => {
+    dom.innerText = "TEXT_FOR_MEASURE";
+  });
+
+  const width = getDomContentWidth(dom);
+  measureDom.style.width = width + "px";
+  measureDom.innerHTML = dom.value.trim().length > 0 ? dom.value : "1";
+
+  const lineWrapCount = Math.max(0, dom.value.split("\n").length - 1);
+  const height = parseFloat(window.getComputedStyle(measureDom).height);
+  const singleLineHeight = parseFloat(
+    window.getComputedStyle(singleLineDom).height,
+  );
+
+  const rows = Math.round(height / singleLineHeight) + lineWrapCount;
+
+  return rows;
+}