ant-design-vue/components/input/calculateNodeHeight.js

// Thanks to https://github.com/andreypopp/react-textarea-autosize/

/**
 * calculateNodeHeight(uiTextNode, useCache = false)
 */

const HIDDEN_TEXTAREA_STYLE = `
min-height:0 !important;
max-height:none !important;
height:0 !important;
visibility:hidden !important;
overflow:hidden !important;
position:absolute !important;
z-index:-1000 !important;
top:0 !important;
right:0 !important
`

const SIZING_STYLE = [
  'letter-spacing',
  'line-height',
  'padding-top',
  'padding-bottom',
  'font-family',
  'font-weight',
  'font-size',
  'text-rendering',
  'text-transform',
  'width',
  'text-indent',
  'padding-left',
  'padding-right',
  'border-width',
  'box-sizing',
]

const computedStyleCache = {}
let hiddenTextarea

function calculateNodeStyling (node, useCache = false) {
  const nodeRef = (
    node.getAttribute('id') ||
  node.getAttribute('data-reactid') ||
  node.getAttribute('name')
  )

  if (useCache && computedStyleCache[nodeRef]) {
    return computedStyleCache[nodeRef]
  }

  const style = window.getComputedStyle(node)

  const boxSizing = (
    style.getPropertyValue('box-sizing') ||
  style.getPropertyValue('-moz-box-sizing') ||
  style.getPropertyValue('-webkit-box-sizing')
  )

  const paddingSize = (
    parseFloat(style.getPropertyValue('padding-bottom')) +
  parseFloat(style.getPropertyValue('padding-top'))
  )

  const borderSize = (
    parseFloat(style.getPropertyValue('border-bottom-width')) +
  parseFloat(style.getPropertyValue('border-top-width'))
  )

  const sizingStyle = SIZING_STYLE
    .map(name => `${name}:${style.getPropertyValue(name)}`)
    .join(';')

  const nodeInfo = {
    sizingStyle,
    paddingSize,
    borderSize,
    boxSizing,
  }

  if (useCache && nodeRef) {
    computedStyleCache[nodeRef] = nodeInfo
  }

  return nodeInfo
}

export default function calculateNodeHeight (
  uiTextNode,
  useCache = false,
  minRows = null,
  maxRows = null,
) {
  if (!hiddenTextarea) {
    hiddenTextarea = document.createElement('textarea')
    document.body.appendChild(hiddenTextarea)
  }

  // Fix wrap="off" issue
  // https://github.com/ant-design/ant-design/issues/6577
  if (uiTextNode.getAttribute('wrap')) {
    hiddenTextarea.setAttribute('wrap', uiTextNode.getAttribute('wrap'))
  } else {
    hiddenTextarea.removeAttribute('wrap')
  }

  // Copy all CSS properties that have an impact on the height of the content in
  // the textbox
  const {
    paddingSize, borderSize,
    boxSizing, sizingStyle,
  } = calculateNodeStyling(uiTextNode, useCache)

  // Need to have the overflow attribute to hide the scrollbar otherwise
  // text-lines will not calculated properly as the shadow will technically be
  // narrower for content
  hiddenTextarea.setAttribute('style', `${sizingStyle};${HIDDEN_TEXTAREA_STYLE}`)
  hiddenTextarea.value = uiTextNode.value || uiTextNode.placeholder || ''

  let minHeight = -Infinity
  let maxHeight = Infinity
  let height = hiddenTextarea.scrollHeight
  let overflowY

  if (boxSizing === 'border-box') {
  // border-box: add border, since height = content + padding + border
    height = height + borderSize
  } else if (boxSizing === 'content-box') {
  // remove padding, since height = content
    height = height - paddingSize
  }

  if (minRows !== null || maxRows !== null) {
  // measure height of a textarea with a single row
    hiddenTextarea.value = ''
    const singleRowHeight = hiddenTextarea.scrollHeight - paddingSize
    if (minRows !== null) {
      minHeight = singleRowHeight * minRows
      if (boxSizing === 'border-box') {
        minHeight = minHeight + paddingSize + borderSize
      }
      height = Math.max(minHeight, height)
    }
    if (maxRows !== null) {
      maxHeight = singleRowHeight * maxRows
      if (boxSizing === 'border-box') {
        maxHeight = maxHeight + paddingSize + borderSize
      }
      overflowY = height > maxHeight ? '' : 'hidden'
      height = Math.min(maxHeight, height)
    }
  }
  // Remove scroll bar flash when autosize without maxRows
  if (!maxRows) {
    overflowY = 'hidden'
  }
  return { height: `${height}px`, minHeight: `${minHeight}px`, maxHeight: `${maxHeight}px`, overflowY }
}