4

I'm using reveal.js: I'd like to display a full-screen image as a background, and once I move to a different slide I'd like to blur or dim it. Looking at Changing the background-image style in Reveal.js, I've tried this in my css: 

.html.blur .backgrounds {
  -webkit-filter: blur(5px);
 -moz-filter: blur(10px);
 -o-filter: blur(5px);
 -ms-filter: blur(5px);
 filter: blur(5px);
}

and then in my markdown document I do an html comment with

.slide: data-background="figs/background.svg" data-background-size="contain" data-state="blur"

which creates a <section> tag with data-state="blur" inside. However, the background doesn't get blurred -- what am I missing?

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Rok
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  • May depends upon browsers –  Aug 17 '15 at 16:48
  • Can you make a fiddle code –  Aug 17 '15 at 16:58
  • I borrowed the fiddle from the SO question I linked to above, and modified it: http://jsfiddle.net/k85qny9k/2/ -- the second slide should be blurred – Rok Aug 17 '15 at 17:08
  • sorry, had a typo -- here's the fixed version: http://jsfiddle.net/k85qny9k/4/ -- this seems to work, but it doesn't work in my actual slideshow... humm... – Rok Aug 17 '15 at 17:16

2 Answers2

6

just a typo: no "." in front of html...

This will work and in addition to the blurring, do some dimming and saturation change, which will make the foreground text easier to read: 

html.dim .backgrounds {
   -webkit-filter: blur(4px) saturate(.5) brightness(.8);
   -moz-filter: blur(4px) saturate(.7) brightness(.9);
   -o-filter: blur(4px) saturate(.7) brightness(.9);
   -ms-filter: blur(4px) saturate(.7) brightness(.9);
   filter: blur(4px) saturate(.7) brightness(.9);
}

and if you want it to look extra snazzy, you can add an animation: 

@-webkit-keyframes blur-animation {
  0% {
    -webkit-filter: blur(0px) ;
    -moz-filter: blur(0px);
    -o-filter: blur(0px);
    -ms-filter: blur(0px);
    filter: blur(0px);

  }
  100% {
    -webkit-filter: blur(4px) saturate(.5) brightness(.8);
    -moz-filter: blur(5px) saturate(.7) brightness(.9);
    -o-filter: blur(5px) saturate(.7) brightness(.9);
    -ms-filter: blur(5px)saturate(.7) brightness(.9);
    filter: blur(5px) saturate(.7) brightness(.9);

  }
}

html.background-blur-animation .backgrounds {
   -webkit-animation-name: blur-animation;
   -webkit-animation-duration: 1s;
   -webkit-animation-iteration-count: 1;
   -webkit-animation-direction: alternate;
   -webkit-animation-timing-function: ease-out;
   -webkit-animation-fill-mode: forwards;
   -webkit-animation-delay: 0s;
 }
Rok
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1

Please check this line in your source

 html.blur.backgrounds {     
                   //no (. sign)is required in front of .html or copy the above line and paste it.
  • Try it,please reply me if it failed –  Aug 17 '15 at 17:24
  • hi vijay, thanks for posting the answer -- the problem was that I had a "." in front of "html"... so yes, this works, thanks! – Rok Aug 19 '15 at 14:12