Font size auto adjust to fit

Question

I\'m trying to do what the title says. I\'ve seen that font-size can be a percentage. So my guess was that font-size: 100%; would do it, but no.

Answer 1

A bit late but this is how I approach this problem:

document.body.setScaledFont = function() {
    var f = 0.35, s = this.offsetWidth, fs = s * f;
    this.style.fontSize = fs + '%';
    return this
}
document.body.setScaledFont();

The base document font is now set.

For the rest of your elements in the dom set font sizes as % or em and they will scale proportionately.

Answer 2

This question might help you out but I warn you though this solves it through jQuery:

Auto-size dynamic text to fill fixed size container

Good luck.

The OP of that question made a plugin, here is the link to it (& download)

BTW I'm suggesting jQuery because as Gaby pointed out this can't be done though CSS only and you said you were willing to use js...

Answer 3

I was looking into this for work and I liked tnt-rox's answer, but I couldn't help but notice that it had some extra overhead that could be cut out.

document.body.setScaledFont = function(){
    this.style.fontSize = (this.offsetWidth*0.35)+'%';
    return this;
}
document.body.setScaledFont();

Cutting out the overhead makes it run a little bit quicker if you add it to an onresize event.

If you are only looking to have the font inside a specific element set to resize to fit, you could also do something like the following

window.onload = function(){
    var scaledFont = function(el){
            if(el.style !== undefined){
                el.style.fontSize = (el.offsetWidth*0.35)+'%';
            }
            return el;
        }
        navs = document.querySelectorAll('.container>nav'),
        i;
    window.onresize = function(){
        for(i in navs){
            scaledFont(navs[i]);
        }
    };
    window.onresize();
};

---

I just noticed nicolaas' answer also had some extra overhead. I've cleaned it up a bit. From a performance perspective, I'm not really a fan of using a while loop and slowly moving down the size until you find one that fits.

function setPageHeaderFontSize(selector) {
    var $ = jQuery;
    $(selector).each(function(i, el) {
        var text = $(el).text();
        if(text.length) {
            var span = $("<span>").css({
                    visibility: 'hidden',
                    width: '100%',
                    position: 'absolute',
                    'line-height': '300px',
                    top: 0,
                    left: 0,
                    overflow: 'visible',
                    display: 'table-cell'
                }).text(text),
                height = 301,
                fontSize = 200;
            $(el).append(span);
            while(height > 300 && fontSize > 10) {
                height = span.css("font-size", fontSize).height();
                fontSize--;
            }
            span.remove();
            $(el).css("font-size", fontSize+"px");
        }
    });
}
setPageHeaderFontSize("#MyDiv");

And here is an example of my earlier code using jquery.

$(function(){
    var scaledFont = function(el){
            if(el.style !== undefined){
                el.style.fontSize = (el.offsetWidth*0.35)+'%';
            }
            return el;
        };
    $(window).resize(function(){
        $('.container>nav').each(scaledFont);
    }).resize();
});

Answer 4

here I have a mootools solution:

Element.implement("fitText", function() {
                var e = this.getParent();
                var maxWidth = e.getSize().x;
                var maxHeight = e.getSize().y;
                console.log(maxWidth);
                var sizeX = this.getSize().x;
                var sizeY = this.getSize().y;
                if (sizeY <= maxHeight && sizeX <= maxWidth)
                    return;

                var fontSize = this.getStyle("font-size").toInt();
                while( (sizeX > maxWidth || sizeY > maxHeight) && fontSize > 4 ) {
                    fontSize -= .5;
                    this.setStyle("font-size", fontSize + "px");
                    sizeX = this.getSize().x;
                    sizeY = this.getSize().y;
                }
                return this;
            });

            $$("span").fitText();

Answer 5

Can't be done with CSS.

100% is in relation to the computed font-size of the parent element.

reference: http://www.w3.org/TR/CSS2/fonts.html#font-size-props

For a jQuery solution look at Auto-size dynamic text to fill fixed size container

Answer 6

Here is another jQuery solution ...

/**
 * Resizes page header font-size for the text to fit.
 * basically we add a hidden span into the header,
 * put the text into it and then keep reducing the super large font-size
 * for as long as the height of the span exceeds the super
 * tall line-height set for the test (indicating there is more than one line needed
 * to show the text).
 */
function setPageHeaderFontSize(selectorString) {
    jQuery(selectorString).each(
        function(i, el) {
            var text = jQuery(el).text();
            var length = text.length;
            if(length) {
                var id = "TestToSeeLengthOfElement_" + i;
                jQuery(el).append("<span style='visibility: hidden; width: 100%; position: absolute; line-height: 300px; top: 0; left: 0; overflow: visible; display: table-cell;' id='"+id+"'>"+text+"</span>");
                var innerEl = jQuery("#"+id);
                var height = 301;
                var fontSize = 200;
                while(height > 300 && fontSize > 10) {
                    height = jQuery(innerEl).css("font-size", fontSize).height();
                    fontSize--;
                }
                jQuery(innerEl).remove();
                jQuery(el).css("font-size", fontSize+"px");
            }
        }
    );
}

//you can run it like this... using any jQuery enabled selector string (e.g. h1.pageHeaders works fine). 
setPageHeaderFontSize("#MyDiv");