jueves, 19 de septiembre de 2013

Create a Background Slideshow for Blogger

In the previous post we saw how to make the blog's background fill the screen regardless of the resolution of the monitor. The method that we'll use now with jQuery is a plugin called BackStretch which also has the option of creating a slideshow of pictures as a blog wallpaper without losing the property of adjusting to the width and height of the screen.

slideshow for blogger, blogger widgets

What we will do in this entry is just this, try to make the blog's background to have some images that are changing, all with fade effect between each transition.
You can see an example in this demo blog.

To put this slideshow in the blog's background, just go to Template - Edit HTML and before </head> add the following code:
<script src='http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js' type='text/javascript'/>
<script>
//<![CDATA[
/*
* jQuery Backstretch
* Version 1.2.8
* http://srobbin.com/jquery-plugins/jquery-backstretch/
* Add a dynamically-resized background image to the page
* Copyright (c) 2012 Scott Robbin (srobbin.com)
* Licensed under the MIT license
* https://raw.github.com/srobbin/jquery-backstretch/master/LICENSE.txt
*/
;(function(a){a.backstretch=function(p,b,l){function s(){if(p){var b;0==c.length?c=a("<div />").attr("id","backstretch").css({left:0,top:0,position:m?"fixed":"absolute",overflow:"hidden",zIndex:-999999,margin:0,padding:0,height:"100%",width:"100%"}):c.find("img").addClass("deleteable");b=a("<img />").css({position:"absolute",display:"none",margin:0,padding:0,border:"none",zIndex:-999999,maxWidth:"none"}).bind("load",function(d){var b=a(this),e;b.css({width:"auto",height:"auto"});e=this.width||a(d.target).width();d=this.height||a(d.target).height();n=e/d;q();b.fadeIn(g.speed,function(){c.find(".deleteable").remove();"function"==typeof l&&l()})}).appendTo(c);0==a("body #backstretch").length&&(0===a(window).scrollTop()&&window.scrollTo(0,0),a("body").append(c));c.data("settings",g);b.attr("src",p);a(window).unbind("resize.backstretch").bind("resize.backstretch",function(){"onorientationchange"in window&&window.pageYOffset===0&&window.scrollTo(0,1);q()})}}function q(){try{j={left:0,top:0},rootWidth=h=o.width(),rootHeight=r?window.innerHeight:o.height(),f=h/n,f>=rootHeight?(k=(f-rootHeight)/2,g.centeredY&&(j.top="-"+k+"px")):(f=rootHeight,h=f*n,k=(h-rootWidth)/2,g.centeredX&&(j.left="-"+k+"px")),c.css({width:rootWidth,height:rootHeight}).find("img:not(.deleteable)").css({width:h,height:f}).css(j)}catch(a){}}var t={centeredX:!0,centeredY:!0,speed:0},c=a("#backstretch"),g=c.data("settings")||t;c.data("settings");var o,m,r,n,h,f,k,j;b&&"object"==typeof b&&a.extend(g,b);b&&"function"==typeof b&&(l=b);a(document).ready(function(){var b=window,d=navigator.userAgent,c=navigator.platform,e=d.match(/AppleWebKit\/([0-9]+)/),e=!!e&&e[1],f=d.match(/Fennec\/([0-9]+)/),f=!!f&&f[1],g=d.match(/Opera Mobi\/([0-9]+)/),h=!!g&&g[1],i=d.match(/MSIE ([0-9]+)/),i=!!i&&i[1];o=(m=!((-1<c.indexOf("iPhone")||-1<c.indexOf("iPad")||-1<c.indexOf("iPod"))&&e&&534>e||b.operamini&&"[object OperaMini]"==={}.toString.call(b.operamini)||g&&7458>h||-1<d.indexOf("Android")&&e&&533>e||f&&6>f||"palmGetResource"in window&&e&&534>e||-1<d.indexOf("MeeGo")&&-1<d.indexOf("NokiaBrowser/8.5.0")||i&&6>=i))?a(window):a(document);r=m&&window.innerHeight;s()});return this}})(jQuery);
//]]>
</script>
<script>
//<![CDATA[
var images = [
 "Image URL",
 "Image URL",
 "Image URL",
 "Image URL",
 "Image URL",
  ];

  $(images).each(function(){
 $('<img/>')[0].src = this;
  });
  var index = 0;
$.backstretch(images[index], {speed: 1000});
  var slideshow = setInterval(function() {
  index = (index >= images.length - 1) ? 0 : index + 1;
    $.backstretch(images[index]);
  }, 5000);
//]]>
</script>
Here add the URLs of the images that will be the background of your blog.
If you would like to add more pictures, just add after the var images = [ another line like this:
 "Image URL",
The images will be changing in the order you have added them, if you want these to appear in a random order, then change the second part of the code with this:
<script>
//<![CDATA[
var images=new Array();
images[ 1 ]="Image URL";
images[ 2 ]="Image URL";
images[ 3 ]="Image URL";
images[ 4 ]="Image URL";
images[ 5 ]="Image URL";

  Array.prototype.shuffle = function() {
  var len = this.length;
  var i = len;
  while (i--) {
  var p = parseInt(Math.random()*len);
  var t = this[i];
  this[i] = this[p];
  this[p] = t;
  }
};

  images.shuffle();
  $(images).each(function(){
 $('<img/>')[0].src = this;
  });
  var index = 0;
$.backstretch(images[index], {speed: 1000});
  var slideshow = setInterval(function() {
  index = (index >= images.length - 1) ? 0 : index + 1;
    $.backstretch(images[index]);
  }, 5000);
//]]>
</script>
You can also add more pictures by adding a line like this:
images[ 6 ]="Image URL";
But you will see that in this case there are some consecutive numbers in blue, so if you add another such as 6, then the next one should be 7, etc..

In both cases you can change the duration of each image which is in the 5000 value that is at the end of the script.
The advantage of this slideshow in the blog's background is that images are automatically resized to the size of the monitor, so that, no matter of the resolution, it should look good.

It is worth remembering that if you are using Scriptaculous, you have to make some changes, and if you already use jQuery, should leave only one version.

Author page | Backstretch
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