我想使用JavaScript来计算字符串的宽度。如果不使用单行字体,这可能吗?
如果它不是内置的,我唯一的想法是为每个字符创建一个宽度表,但这是非常不合理的,特别是支持Unicode和不同的类型大小(以及所有浏览器)。
我想使用JavaScript来计算字符串的宽度。如果不使用单行字体,这可能吗?
如果它不是内置的,我唯一的想法是为每个字符创建一个宽度表,但这是非常不合理的,特别是支持Unicode和不同的类型大小(以及所有浏览器)。
当前回答
根据Deepak Nadar的回答,我修改了函数参数,以接受文本和字体样式。您不需要引用元素。此外,fontOptions有默认值,所以您不需要提供所有的选项。
(function($) { $.format = function(format) { return (function(format, args) { return format.replace(/{(\d+)}/g, function(val, pos) { return typeof args[pos] !== 'undefined' ? args[pos] : val; }); }(format, [].slice.call(arguments, 1))); }; $.measureText = function(html, fontOptions) { fontOptions = $.extend({ fontSize: '1em', fontStyle: 'normal', fontWeight: 'normal', fontFamily: 'arial' }, fontOptions); var $el = $('<div>', { html: html, css: { position: 'absolute', left: -1000, top: -1000, display: 'none' } }).appendTo('body'); $(fontOptions).each(function(index, option) { $el.css(option, fontOptions[option]); }); var h = $el.outerHeight(), w = $el.outerWidth(); $el.remove(); return { height: h, width: w }; }; }(jQuery)); var dimensions = $.measureText("Hello World!", { fontWeight: 'bold', fontFamily: 'arial' }); // Font Dimensions: 94px x 18px $('body').append('<p>').text($.format('Font Dimensions: {0}px x {1}px', dimensions.width, dimensions.height)); <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
其他回答
jQuery:
(function($) {
$.textMetrics = function(el) {
var h = 0, w = 0;
var div = document.createElement('div');
document.body.appendChild(div);
$(div).css({
position: 'absolute',
left: -1000,
top: -1000,
display: 'none'
});
$(div).html($(el).html());
var styles = ['font-size','font-style', 'font-weight', 'font-family','line-height', 'text-transform', 'letter-spacing'];
$(styles).each(function() {
var s = this.toString();
$(div).css(s, $(el).css(s));
});
h = $(div).outerHeight();
w = $(div).outerWidth();
$(div).remove();
var ret = {
height: h,
width: w
};
return ret;
}
})(jQuery);
ExtJS javascript库中有一个很棒的类,叫做Ext.util.TextMetrics,它“为文本块提供精确的像素测量,这样你就可以准确地确定给定文本块的高和宽(以像素为单位)”。您可以直接使用它,也可以查看它的源代码以了解如何完成此操作。
http://docs.sencha.com/extjs/6.5.3/modern/Ext.util.TextMetrics.html
var textWidth = (function (el) {
el.style.position = 'absolute';
el.style.top = '-1000px';
document.body.appendChild(el);
return function (text) {
el.innerHTML = text;
return el.clientWidth;
};
})(document.createElement('div'));
我为此写了一个小工具。也许对某些人有用。它不需要jQuery也能工作。
https://github.com/schickling/calculate-size
用法:
var size = calculateSize("Hello world!", {
font: 'Arial',
fontSize: '12px'
});
console.log(size.width); // 65
console.log(size.height); // 14
小提琴:http://jsfiddle.net/PEvL8/
我喜欢你的“唯一的想法”只是做一个静态字符宽度地图!它实际上很适合我的目的。有时,出于性能原因,或者因为不容易访问DOM,您可能只想要一个快速的、独立的、校准为单一字体的计算器。这是一个用Helvetica字体校准的;传递一个字符串和字体大小:
const widths = [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0.2796875,0.2765625,0.3546875,0.5546875,0.5546875,0.8890625,0.665625,0.190625,0.3328125,0.3328125,0.3890625,0.5828125,0.2765625,0.3328125,0.2765625,0.3015625,0.5546875,0.5546875,0.5546875,0.5546875,0.5546875,0.5546875,0.5546875,0.5546875,0.5546875,0.5546875,0.2765625,0.2765625,0.584375,0.5828125,0.584375,0.5546875,1.0140625,0.665625,0.665625,0.721875,0.721875,0.665625,0.609375,0.7765625,0.721875,0.2765625,0.5,0.665625,0.5546875,0.8328125,0.721875,0.7765625,0.665625,0.7765625,0.721875,0.665625,0.609375,0.721875,0.665625,0.94375,0.665625,0.665625,0.609375,0.2765625,0.3546875,0.2765625,0.4765625,0.5546875,0.3328125,0.5546875,0.5546875,0.5,0.5546875,0.5546875,0.2765625,0.5546875,0.5546875,0.221875,0.240625,0.5,0.221875,0.8328125,0.5546875,0.5546875,0.5546875,0.5546875,0.3328125,0.5,0.2765625,0.5546875,0.5,0.721875,0.5,0.5,0.5,0.3546875,0.259375,0.353125,0.5890625]
const avg = 0.5279276315789471
function measureText(str, fontSize) {
return Array.from(str).reduce(
(acc, cur) => acc + (widths[cur.charCodeAt(0)] ?? avg), 0
) * fontSize
}
这个巨大的丑陋数组是由字符代码索引的ASCII字符宽度。所以这只支持ASCII(否则它假设平均字符宽度)。幸运的是,宽度基本上是随字体大小线性缩放的,所以它在任何字体大小下都能很好地工作。它明显缺乏对字距或结扎之类的意识。
为了“校准”,我只是在svg上渲染了charCode 126(强大的波浪号)的每个字符,并获得了边界框并将其保存到这个数组中;这里有更多的代码、解释和演示。