frontend/src/composables/useAutoHeightTextarea.ts

72 lines
1.9 KiB
TypeScript

import {ref, unref, watch} from 'vue'
import {debouncedWatch, tryOnMounted, useWindowSize, type MaybeRef} from '@vueuse/core'
// TODO: also add related styles
// OR: replace with vueuse function
export function useAutoHeightTextarea(value: MaybeRef<string>) {
const textarea = ref<HTMLTextAreaElement | null>(null)
const minHeight = ref(0)
// adapted from https://github.com/LeaVerou/stretchy/blob/47f5f065c733029acccb755cae793009645809e2/src/stretchy.js#L34
function resize(textareaEl: HTMLTextAreaElement | null) {
if (!textareaEl) return
let empty
// the value here is the attribute value
if (!textareaEl.value && textareaEl.placeholder) {
empty = true
textareaEl.value = textareaEl.placeholder
}
const cs = getComputedStyle(textareaEl)
textareaEl.style.minHeight = ''
textareaEl.style.height = '0'
const offset = textareaEl.offsetHeight - parseFloat(cs.paddingTop) - parseFloat(cs.paddingBottom)
const height = textareaEl.scrollHeight + offset + 'px'
textareaEl.style.height = height
// calculate min-height for the first time
if (!minHeight.value) {
minHeight.value = parseFloat(height)
}
textareaEl.style.minHeight = minHeight.value.toString()
if (empty) {
textareaEl.value = ''
}
}
tryOnMounted(() => {
if (textarea.value) {
// we don't want scrollbars
textarea.value.style.overflowY = 'hidden'
}
})
const {width: windowWidth} = useWindowSize()
debouncedWatch(
windowWidth,
() => resize(textarea.value),
{debounce: 200},
)
// It is not possible to get notified of a change of the value attribute of a textarea without workarounds (setTimeout)
// So instead we watch the value that we bound to it.
watch(
() => [textarea.value, unref(value)],
() => resize(textarea.value),
{
immediate: true, // calculate initial size
flush: 'post', // resize after value change is rendered to DOM
},
)
return textarea
}