ivue-material-plus/src/utils/calc-textarea-height.ts

A high quality UI components Library with Vue.js

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: Record<string, any> = {};
let hiddenTextarea;

// 获取节点样式
function calculateNodeStyling(node: any, 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;
}

// 计算Textarea高度
export const calcTextareaHeight = (
  uiTextNode: Record<string, any>,
  minRows = null,
  maxRows = null,
  useCache = false
) => {
  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 = Number.MIN_SAFE_INTEGER;
  let maxHeight = Number.MAX_SAFE_INTEGER;
  let height = hiddenTextarea.scrollHeight;
  let overflowY: string;

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