zent/es/utils/dom/getLineHeight.js

一套前端设计语言和基于React的实现

import createElement from './createElement';
export function getLineHeight(node, chars) {
    if (chars === void 0) { chars = ' '; }
    var lnHeightStr = computedStyle(node, 'line-height');
    var lnHeight = parseFloat(lnHeightStr);
    if (lnHeightStr === lnHeight + '') {
        var lnHeightStyle = node.style.lineHeight;
        node.style.lineHeight = lnHeightStr + 'em';
        lnHeightStr = computedStyle(node, 'line-height');
        lnHeight = parseFloat(lnHeightStr);
        if (lnHeightStyle) {
            node.style.lineHeight = lnHeightStyle;
        }
        else {
            delete node.style.lineHeight;
        }
    }
    if (lnHeightStr.indexOf('pt') !== -1) {
        lnHeight *= 4;
        lnHeight /= 3;
    }
    else if (lnHeightStr.indexOf('mm') !== -1) {
        lnHeight *= 96;
        lnHeight /= 25.4;
    }
    else if (lnHeightStr.indexOf('cm') !== -1) {
        lnHeight *= 96;
        lnHeight /= 2.54;
    }
    else if (lnHeightStr.indexOf('in') !== -1) {
        lnHeight *= 96;
    }
    else if (lnHeightStr.indexOf('pc') !== -1) {
        lnHeight *= 16;
    }
    lnHeight = Math.round(lnHeight);
    if (lnHeightStr === 'normal') {
        var nodeName = node.nodeName;
        var offScreenNode = createElement(nodeName);
        offScreenNode.innerHTML = "<span>" + chars + "</span>";
        if (nodeName.toUpperCase() === 'TEXTAREA') {
            offScreenNode.setAttribute('rows', '1');
        }
        var fontSizeStr = computedStyle(node, 'font-size');
        var style = offScreenNode.style;
        style.fontSize = fontSizeStr;
        style.padding = '0px';
        style.border = '0px';
        style.color = 'transparent';
        style.background = 'transparent';
        style.position = 'absolute';
        style.top = '-10000px';
        style.left = '-10000px';
        var body = document.body;
        body.appendChild(offScreenNode);
        var height = offScreenNode.offsetHeight;
        lnHeight = height;
        body.removeChild(offScreenNode);
    }
    return lnHeight;
}
function computedStyle(el, prop) {
    var style = getComputedStyle(el);
    return style.getPropertyValue(prop);
}