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  1. #1
    SitePoint Evangelist
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    javascript transition onclick problem

    Hi,

    I was trying to set up an effect on a clients site whereby:
    • the first image fades away to be replaced by a second image
    • the transition is triggered by the user clicking a button


    Because my understanding of Javascript is quite poor (please bear this in mind) I looked at open source ready made scripts. Unfortunately the way the script is it fades in and out all the all the time. It is also not triggered by clicking a button.

    does anyone know how i can change this script so it is triggered by a button on the index page next to the image?

    or at worst by rollover?

    I have put the javascript below. You can also find the page at: www.alphatest.co.uk

    In the head:

    /***********************************************
    * Ultimate Fade-In Slideshow (v1.51): Dynamic Drive (http://www.dynamicdrive.com)
    * This notice MUST stay intact for legal use
    * Visit http://www.dynamicdrive.com/ for this script and 100s more.
    ***********************************************/

    var fadeimages=new Array()
    //SET IMAGE PATHS. Extend or contract array as needed
    fadeimages[0]=["images/bookcover1.jpg"] //plain image syntax
    fadeimages[1]=["images/bookinside1.jpg", "http://www.cssdrive.com", ""] //image with link syntax


    var fadebgcolor="white"

    ////NO need to edit beyond here/////////////

    var fadearray=new Array() //array to cache fadeshow instances
    var fadeclear=new Array() //array to cache corresponding clearinterval pointers

    var dom=(document.getElementById) //modern dom browsers
    var iebrowser=document.all

    function fadeshow(theimages, fadewidth, fadeheight, borderwidth, delay, pause, displayorder){
    this.pausecheck=pause
    this.mouseovercheck=0
    this.delay=delay
    this.degree=10 //initial opacity degree (10%)
    this.curimageindex=0
    this.nextimageindex=1
    fadearray[fadearray.length]=this
    this.slideshowid=fadearray.length-1
    this.canvasbase="canvas"+this.slideshowid
    this.curcanvas=this.canvasbase+"_0"
    if (typeof displayorder!="undefined")
    theimages.sort(function() {return 0.5 - Math.random();}) //thanks to Mike (aka Mwinter)
    this.theimages=theimages
    this.imageborder=parseInt(borderwidth)
    this.postimages=new Array() //preload images
    for (p=0;p<theimages.length;p++){
    this.postimages[p]=new Image()
    this.postimages[p].src=theimages[p][0]
    }

    var fadewidth=fadewidth+this.imageborder*2
    var fadeheight=fadeheight+this.imageborder*2

    if (iebrowser&&dom||dom) //if IE5+ or modern browsers (ie: Firefox)
    document.write('<div id="master'+this.slideshowid+'" style="position:relative;width:'+fadewidth+'px;height:'+fadeheight+'px;overflow:hidden;"><div id="'+this.canvasbase+'_0" style="position:absolute;width:'+fadewidth+'px;height:'+fadeheight+'px;top:0;left:0;filterrogidXImageTransform.Microsoft.alpha(opacity=10);opacity:0.1;-moz-opacity:0.1;-khtml-opacity:0.1;background-color:'+fadebgcolor+'"></div><div id="'+this.canvasbase+'_1" style="position:absolute;width:'+fadewidth+'px;height:'+fadeheight+'px;top:0;left:0;filterrogidXImageTransform.Microsoft.alpha(opacity=10);opacity:0.1;-moz-opacity:0.1;-khtml-opacity:0.1;background-color:'+fadebgcolor+'"></div></div>')
    else
    document.write('<div><img name="defaultslide'+this.slideshowid+'" src="'+this.postimages[0].src+'"></div>')

    if (iebrowser&&dom||dom) //if IE5+ or modern browsers such as Firefox
    this.startit()
    else{
    this.curimageindex++
    setInterval("fadearray["+this.slideshowid+"].rotateimage()", this.delay)
    }
    }

    function fadepic(obj){
    if (obj.degree<100){
    obj.degree+=10
    if (obj.tempobj.filters&&obj.tempobj.filters[0]){
    if (typeof obj.tempobj.filters[0].opacity=="number") //if IE6+
    obj.tempobj.filters[0].opacity=obj.degree
    else //else if IE5.5-
    obj.tempobj.style.filter="alpha(opacity="+obj.degree+")"
    }
    else if (obj.tempobj.style.MozOpacity)
    obj.tempobj.style.MozOpacity=obj.degree/101
    else if (obj.tempobj.style.KhtmlOpacity)
    obj.tempobj.style.KhtmlOpacity=obj.degree/100
    else if (obj.tempobj.style.opacity&&!obj.tempobj.filters)
    obj.tempobj.style.opacity=obj.degree/101
    }
    else{
    clearInterval(fadeclear[obj.slideshowid])
    obj.nextcanvas=(obj.curcanvas==obj.canvasbase+"_0")? obj.canvasbase+"_0" : obj.canvasbase+"_1"
    obj.tempobj=iebrowser? iebrowser[obj.nextcanvas] : document.getElementById(obj.nextcanvas)
    obj.populateslide(obj.tempobj, obj.nextimageindex)
    obj.nextimageindex=(obj.nextimageindex<obj.postimages.length-1)? obj.nextimageindex+1 : 0
    setTimeout("fadearray["+obj.slideshowid+"].rotateimage()", obj.delay)
    }
    }

    fadeshow.prototype.populateslide=function(picobj, picindex){
    var slideHTML=""
    if (this.theimages[picindex][1]!="") //if associated link exists for image
    slideHTML='<a href="'+this.theimages[picindex][1]+'" target="'+this.theimages[picindex][2]+'">'
    slideHTML+='<img src="'+this.postimages[picindex].src+'" border="'+this.imageborder+'px">'
    if (this.theimages[picindex][1]!="") //if associated link exists for image
    slideHTML+='</a>'
    picobj.innerHTML=slideHTML
    }


    fadeshow.prototype.rotateimage=function(){
    if (this.pausecheck==1) //if pause onMouseover enabled, cache object
    var cacheobj=this
    if (this.mouseovercheck==1)
    setTimeout(function(){cacheobj.rotateimage()}, 100)
    else if (iebrowser&&dom||dom){
    this.resetit()
    var crossobj=this.tempobj=iebrowser? iebrowser[this.curcanvas] : document.getElementById(this.curcanvas)
    crossobj.style.zIndex++
    fadeclear[this.slideshowid]=setInterval("fadepic(fadearray["+this.slideshowid+"])",50)
    this.curcanvas=(this.curcanvas==this.canvasbase+"_0")? this.canvasbase+"_1" : this.canvasbase+"_0"
    }
    else{
    var ns4imgobj=document.images['defaultslide'+this.slideshowid]
    ns4imgobj.src=this.postimages[this.curimageindex].src
    }
    this.curimageindex=(this.curimageindex<this.postimages.length-1)? this.curimageindex+1 : 0
    }

    fadeshow.prototype.resetit=function(){
    this.degree=10
    var crossobj=iebrowser? iebrowser[this.curcanvas] : document.getElementById(this.curcanvas)
    if (crossobj.filters&&crossobj.filters[0]){
    if (typeof crossobj.filters[0].opacity=="number") //if IE6+
    crossobj.filters(0).opacity=this.degree
    else //else if IE5.5-
    crossobj.style.filter="alpha(opacity="+this.degree+")"
    }
    else if (crossobj.style.MozOpacity)
    crossobj.style.MozOpacity=this.degree/101
    else if (crossobj.style.KhtmlOpacity)
    crossobj.style.KhtmlOpacity=this.degree/100
    else if (crossobj.style.opacity&&!crossobj.filters)
    crossobj.style.opacity=this.degree/101
    }


    fadeshow.prototype.startit=function(){
    var crossobj=iebrowser? iebrowser[this.curcanvas] : document.getElementById(this.curcanvas)
    this.populateslide(crossobj, this.curimageindex)
    if (this.pausecheck==1){ //IF SLIDESHOW SHOULD PAUSE ONMOUSEOVER
    var cacheobj=this
    var crossobjcontainer=iebrowser? iebrowser["master"+this.slideshowid] : document.getElementById("master"+this.slideshowid)
    crossobjcontainer.onmouseover=function(){cacheobj.mouseovercheck=0}
    crossobjcontainer.onmouseout=function(){cacheobj.mouseovercheck=1}
    }
    this.rotateimage()
    }

    </script>
    <style type="text/css">
    <!--
    #Layer1 {
    position:absolute;
    width:129px;
    height:115px;
    z-index:1;
    left: 751px;
    top: 239px;
    }
    .style1 {font-size: 10px}
    -->
    </style>
    </head>

    In the body:
    <div id="pics"><script type="text/javascript">
    //new fadeshow(fadeimages, slideshow_width, slideshow_height, borderwidth, delay, pause (0=no, 1=yes), optionalRandomOrder)
    new fadeshow(fadeimages, 357, 215, 0, 18000, 1)


    </script></div>

    thanks for your time,

  2. #2
    SitePoint Evangelist
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    So does that mean Icant change this script (or add html) so it is triggered by the user clicking a link or mouseover?

  3. #3
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    I rather suspect that it means nobody wants to mess about with the pile of code above, so without testing it, here is how I would adjust it to meet your requirements.

    Throughout this I've tidied up the formatting, but for the sake of consistency with the existing code I haven't added some things that should be, such as semicolons.

    For the repeating images, here are the lines in the fadepic function that prepares the next image to be used.

    Code Javascript:
    obj.nextimageindex = (obj.nextimageindex < obj.postimages.length - 1)? obj.nextimageindex + 1 : 0
    setTimeout("fadearray[" + obj.slideshowid + "].rotateimage()", obj.delay)

    We could change the 0 to this.curimageindex+1 and make both conditions the same, but that then makes the ternary operator redundant, and it will still repeatedly fade on the last image as well. Instead of doing that let's simplify things so that the increment and the next image will happen only if there's another image to be done.

    Code Javascript:
    if (obj.nextimageindex < obj.postimages.length - 1) {
        obj.nextimageindex = obj.nextimageindex + 1
        setTimeout("fadearray[" + obj.slideshowid + "].rotateimage()", obj.delay)
    }

    So now when it gets to the end it won't carry on with any more images.

    This next piece is the one that starts the slideshow. I find interesting the (iebrowser && dom || dom) because it gives the same results as just (dom).

    Code Javascript:
    if (iebrowser && dom || dom) { // if IE5+ or modern browsers such as Firefox
        this.startit()
    } else {
        this.curimageindex++
        setInterval("fadearray[" + this.slideshowid + "].rotateimage()", this.delay)
    }

    The above code runs automatically from the fadeshow function, so it needs to be cut out and placed into its own function.

    Code Javascript:
    fadeshow.prototype.start=function () {
        if (dom) { // if IE5+ or modern browsers such as Firefox
            this.startit()
        } else {
            this.curimageindex++
            setInterval("fadearray[" + this.slideshowid + "].rotateimage()", this.delay)
        }
    }

    Now we just need to gain access to it from the constructor.

    Code Javascript:
    var myFadeShow = new fadeshow(fadeimages, 357, 215, 0, 18000, 1)

    So now you can start the slideshow whenever you desire

    Code HTML4Strict:
    <a href="#" onclick="myFadeShow.start()>Start show</a>
    Last edited by paul_wilkins; Jan 9, 2008 at 17:15. Reason: code formatting

  4. #4
    SitePoint Evangelist
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    Yes, Iguess your right, it was a lot top ask. so thanks for spending a lot of time on iyt and pointing me in the right direction.


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