1. 技术文章
  2. Transparent text cut out of background

Transparent text cut out of background

由 天涯浪子 提交于 2019-11-25 23:16:27

问题


Is there any way to make a transparent text cut out of a background effect like the one in the following image, with CSS?
It would be sad to lose all precious SEO because of images replacing text.

\"Transparent

I first thought of shadows but I can\'t figure anything out...

The image is the site background, an absolute positioned <img> tag


回答1:


It's possible with css3 but it's not supported in all browsers

With background-clip: text; you can use a background for the text, but you will have to align it with the background of the page

body {
    background: url(http://www.color-hex.com/palettes/26323.png) repeat;
    margin:10px;
}
h1 { 
    background-color:#fff;
    overflow:hidden;
    display:inline-block; 
    padding:10px; 
    font-weight:bold;
    font-family:arial;
    color:transparent;
    font-size:200px;
}span { 
    background: url(http://www.color-hex.com/palettes/26323.png) -20px -20px repeat;
    -webkit-text-fill-color: transparent;
    -webkit-background-clip: text;
    display:block;
}
<h1><span>ABCDEFGHIKJ</span></h1>

http://jsfiddle.net/JGPuZ/1337/

Automatic alignment

with a little javascript you can align the background automatic:

$(document).ready(function(){
  var position = $("h1").position(); //Position of the header in the webpage
  var padding = 10; //Padding set to the header
  var left = position.left + padding;
  var top = position.top + padding;
  $("h1").find("span").css("background-position","-"+left+"px -"+top+"px"); 
});
body {
    background: url(http://www.color-hex.com/palettes/26323.png) repeat;
    margin:10px;
}
h1 { 
    background-color:#fff;
    overflow:hidden;
    display:inline-block; 
    padding:10px; 
    font-weight:bold;
    font-family:arial;
    color:transparent;
    font-size:200px;
}span { 
    background: url(http://www.color-hex.com/palettes/26323.png) -20px -20px repeat;
    -webkit-text-fill-color: transparent;
    -webkit-background-clip: text;
    display:block;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<h1><span>ABCDEFGHIKJ</span></h1>
​ http://jsfiddle.net/JGPuZ/1336/


回答2:


Although this is possible with CSS, a better approach would be to use an inline SVG with SVG masking. This approach has some advantages over CSS :

  • Much better browser support: IE10+, chrome, Firefox, safari...
  • This doesn't impact SEO as spiders can crawl SVG content (google indexes SVG content since 2010)

CodePen Demo : SVG text mask

body,html{height:100%;margin:0;padding:0;}
body{
  background:url('https://farm9.staticflickr.com/8760/17195790401_94fcf60556_c.jpg');
  background-size:cover;
  background-attachment:fixed;
}
svg{width:100%;}
<svg viewbox="0 0 100 60">
  <defs>
    <mask id="mask" x="0" y="0" width="100" height="50">
      <rect x="0" y="0" width="100" height="40" fill="#fff"/>
      <text text-anchor="middle" x="50" y="18" dy="1">SVG</text>
      <text text-anchor="middle" x="50" y="30" dy="1">Text mask</text>
    </mask>
  </defs>
  <rect x="5" y="5" width="90" height="30" mask="url(#mask)" fill-opacity="0.5"/>    
</svg>

If you aim on making the text selectable and searchable, you need to include it outside the <defs> tag. The following example shows a way to do that keeping the transparent text with the <use> tag:

body,html{height:100%;margin:0;padding:0;}
body{
  background:url('https://farm9.staticflickr.com/8760/17195790401_94fcf60556_c.jpg');
  background-size:cover;
  background-attachment:fixed;
}
svg{width:100%;}
<svg viewbox="0 0 100 60">
  <defs>
    <g id="text">
      <text text-anchor="middle" x="50" y="18" dy="1">SVG</text>
      <text text-anchor="middle" x="50" y="30" dy="1">Text mask</text>
    </g>
    <mask id="mask" x="0" y="0" width="100" height="50">
      <rect x="0" y="0" width="100" height="40" fill="#fff"/>
      <use xlink:href="#text" />
    </mask>
  </defs>
  <rect x="5" y="5" width="90" height="30" mask="url(#mask)" fill-opacity="0.5"/>
  <use xlink:href="#text" mask="url(#mask)" />
</svg>



回答3:


One way that works on most modern browsers (except ie, edge), although only with a black background, is to use

background: black;
color: white;
mix-blend-mode: multiply;

in your text element and then put whatever background you want behind that. Multiply basically maps the 0-255 color code to 0-1 and then multiplies that by whatever is behind it, so black stays black and white multiplies by 1 and effectively becomes transparent. http://codepen.io/nic_klaassen/full/adKqWX/




回答4:


It is possible, but so far only with Webkit based browsers (Chrome, Safari, Rockmelt, anything based on the Chromium project.)

The trick is to have an element within the white one that has the same background as the body, then use -webkit- background-clip: text; on the inner element which basically means "don't extend the background beyond the text" and use transparent text.

section
{
    background: url(http://norcaleasygreen.com/wp-content/uploads/2012/11/turf-grass1.jpg);
    width: 100%;
    height: 300px;
}

div
{
    background: rgba(255, 255, 255, 1);
    color: rgba(255, 255, 255, 0);

    width: 60%;
    heighT: 80%;
    margin: 0 auto;
    font-size: 60px;
    text-align: center;
}

p
{
    background: url(http://norcaleasygreen.com/wp-content/uploads/2012/11/turf-grass1.jpg);
    -webkit-background-clip: text;
}
​

http://jsfiddle.net/BWRsA/




回答5:


I guess you could achieve something like that using background-clip, but I haven't tested that yet.

See this example:
http://www.css3.info/wp-content/uploads/2008/03/webkit-backgroundcliptext_color.html
(Webkit only, I don't know yet how to change the black background to a white one)




回答6:


I just discovered a new way to do this while messing around, I'm not entirely sure how it works ( if someone else wants to explain please do ).

It seems to work very well, and requires no double backgrounds or JavaScript.

Here's the code: JSFIDDLE 

body {
  padding: 0;
  margin: 0;
}

div {
  background: url(http://www.color-hex.com/palettes/26323.png) repeat;
  width: 100vw;
  height: 100vh;
}

body::before {
  content: '$ALPHABET';
  left: 0;
  top: 0;
  position: absolute;
  color: #222;
  background-color: #fff;
  padding: 1rem;
  font-family: Arial;
  z-index: 1;
  mix-blend-mode: screen;
  font-weight: 800;
  font-size: 3rem;
  letter-spacing: 1rem;
}
<div></div>



回答7:


You can use an inverted / negative / reverse font and apply it with the font-face="…" CSS rule. You might have to play with letter spacing to avoid small white gaps between letters.

If you do not require a specific font, it's simple. Download a likeable one, for example from this collection of inverted fonts.

If you require a specific font (say, "Open Sans"), it's difficult. You have to convert your existing font into an inverted version. This is possible manually with Font Creator, FontForge etc., but of course we want an automated solution. I could not find instructions for that yet, but some hints:

  • How to convert a bitmap font into a TrueType font (plus yet another way to do that). One would first use ImageMagick commands to render the font glyphs into high-resolution raster images and to invert them, then convert them back to a TrueType font with the above instructions.
  • Is it possible to invert a font with FontForge or another PGM?
  • Creating a reverse (white on black) font



回答8:


You can use myadzel's Patternizer jQuery plugin to achieve this effect across browsers. At this time, there is no cross-browser way to do this with just CSS.

You use Patternizer by adding class="background-clip" to HTML elements where you want the text to be painted as an image pattern, and specify the image in an additional data-pattern="…" attribute. See the source of the demo. Patternizer will create an SVG image with pattern-filled text and underlay it to the transparently rendered HTML element.

If, as in the question's example image, the text fill pattern should be a part of a background image extending beyond the "patternized" element, I see two options (untested, my favourite first):

  • Use masking instead of a background image in the SVG. As in web-tiki's answer, to which using Patternizer will still add automatic generation of the SVG and an invisible HTML element on top that allows text selection and copying.
  • Or use automatic alignment of the pattern image. Can be done with JavaScript code similar to the one in Gijs's answer.



回答9:


just put that css

    .banner-sale-1 .title-box .title-overlay {
      font-weight: 900;
      overflow: hidden;
      margin: 0;
      padding-right: 10%;
      padding-left: 10%;
      text-transform: uppercase;
      color: #080404;
      background-color: rgba(255, 255, 255, .85);

      /* that css is the main think (mix-blend-mode: lighten;)*/
      mix-blend-mode: lighten;

    }



回答10:


I needed to make text that looked exactly like it does in the original post, but I couldn't just fake it by lining up backgrounds, because there's some animation behind the element. Nobody seems to have suggested this yet, so here's what I did: (Tried to make it as easy to read as possible.)

var el = document.body; //Parent Element. Text is centered inside.
var mainText = "THIS IS THE FIRST LINE"; //Header Text.
var subText = "THIS TEXT HAS A KNOCKOUT EFFECT"; //Knockout Text.
var fontF = "Roboto, Arial"; //Font to use.
var mSize = 42; //Text size.

//Centered text display:
var tBox = centeredDiv(el), txtMain = mkDiv(tBox, mainText), txtSub = mkDiv(tBox),
ts = tBox.style, stLen = textWidth(subText, fontF, mSize)+5; ts.color = "#fff";
ts.font = mSize+"pt "+fontF; ts.fontWeight = 100; txtSub.style.fontWeight = 400;

//Generate subtext SVG for knockout effect:
txtSub.innerHTML =
"<svg xmlns='http://www.w3.org/2000/svg' width='"+stLen+"px' height='"+(mSize+11)+"px' viewBox='0 0 "+stLen+" "+(mSize+11)+"'>"+
    "<rect x='0' y='0' width='100%' height='100%' fill='#fff' rx='4px' ry='4px' mask='url(#txtSubMask)'></rect>"+
    "<mask id='txtSubMask'>"+
        "<rect x='0' y='0' width='100%' height='100%' fill='#fff'></rect>"+
        "<text x='"+(stLen/2)+"' y='"+(mSize+6)+"' font='"+mSize+"pt "+fontF+"' text-anchor='middle' fill='#000'>"+subText+"</text>"+
    "</mask>"+
"</svg>";

//Relevant Helper Functions:
function centeredDiv(parent) {
    //Container:
    var d = document.createElement('div'), s = d.style;
    s.display = "table"; s.position = "relative"; s.zIndex = 999;
    s.top = s.left = 0; s.width = s.height = "100%";
    //Content Box:
    var k = document.createElement('div'), j = k.style;
    j.display = "table-cell"; j.verticalAlign = "middle";
    j.textAlign = "center"; d.appendChild(k);
    parent.appendChild(d); return k;
}
function mkDiv(parent, tCont) {
    var d = document.createElement('div');
    if(tCont) d.textContent = tCont;
    parent.appendChild(d); return d;
}
function textWidth(text, font, size) {
    var canvas = window.textWidthCanvas || (window.textWidthCanvas = document.createElement("canvas")),
    context = canvas.getContext("2d"); context.font = size+(typeof size=="string"?" ":"pt ")+font;
    return context.measureText(text).width;
}

Just throw that in your window.onload, set the body's background to your image, and watch the magic happen!




回答11:


Not possible with CSS just now I'm afraid.

Your best bet is to simply use an image (probably a PNG) and and place good alt/title text on it.

Alternatively you could use a SPAN or a DIV and have the image as a background to that with your text you want for SEO purposes inside it but text-indent it off screen.



来源：https://stackoverflow.com/questions/13932946/transparent-text-cut-out-of-background

标签
css
css3
svg
fonts
css-shapes
易学教程内所有资源均来自网络或用户发布的内容，如有违反法律规定的内容欢迎反馈！
该文章没有解决你所遇到的问题?点击提问,说说你的问题,让更多的人一起探讨吧!