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View Full Version : Javascript: Animated Image Height Changer



Aksparks04
12-25-2010, 08:03 AM
Hi there.

I'm relatively new to coding in javascript, so I'm hoping that some kind souls could help me out! I'm trying to make an animated image height changer (example: changing an image's height from 50px to 500px). I'm working on a new web site using HTML5 and want to add some Flash-like animation to my page using javascript and <canvas>.

The animation would only need to "play" one time once the web page has loaded. No looping is required and no user interaction (ie mouseovers, etc) is needed. Any help would be greatly appreciated. If anyone knows of similar examples online please send me a link. If you're interested in helping, please let me know if more information is needed.

Thanks.

vwphillips
12-25-2010, 09:25 AM
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">

<head>
<title></title>
<script type="text/javascript">
// Animate (11-January-2010)
// by Vic Phillips http://www.vicsjavascripts.org.uk

// To progressively change the Left, Top, Width, Height or Opacity of an element over a specified period of time.
// With the ability to scale the effect time on specified minimum/maximum values
// and with three types of progression 'sin' and 'cos' and liner.

// **** Application Notes

// **** The HTML Code
//
// when moving an element the inline or class rule style position of the element should be assigned as
// 'position:relative;' or 'position:absolute;'
//
// The element would normally be assigned a unique ID name.
//

// **** Initialising the Script.
//
// The script is initialised by assigning an instance of the script to a variable.
// e.g A = new zxcAnimate('left','id1')
// where:
// A = a global variable (variable)
// parameter 0 = the mode(see Note 1). (string)
// parameter 1 = the unique ID name or element object. (string or element object)
// parameter 1 = the initial value. (digits, default = 0)

// **** Executing the Effect
//
// The effect is executed by an event call to function 'A.animate(10,800 ,5000,[10,800]);'
// where:
// A = the global referencing the script instance. (variable)
// parameter 0 = the start value. (digits, for opacity minimum 0, maximum 100)
// parameter 1 = the finish value. (digits, for opacity minimum 0, maximum 100)
// parameter 2 = period of time between the start and finish of the effect in milliseconds. (digits or defaults to previous or 0(on first call) milliSeconds)
// parameter 3 = (optional) to scale the effect time on a specified minimum/maximum. (array, see Note 3)
// field 0 the minimum value. (digits)
// field 1 the maximum value. (digits)
// parameter 3 = (optional) the type of progression, 'sin', 'cos' or 'liner'. (string, default = 'liner')
// 'sin' progression starts fast and ends slow.
// 'cos' progression starts slow and ends fast.
//
// Note 1: Examples modes: 'left', 'top', 'width', 'height', 'opacity.
// Note 2: The default units(excepting opacity) are 'px'.
// For hyphenated modes, the first character after the hyphen must be upper case, all others lower case.
// Note 3: The scale is of particular use when re-calling the effect
// in mid progression to retain an constant rate of progression.
// Note 4: The current effect value is recorded in A.data[0].
// Note 5: A function may be called on completion of the effect by assigning the function
// to the animator intance property .Complete.
// e.g. [instance].Complete=function(){ alert(this.data[0]); };
//



// **** Functional Code(1.52K) - NO NEED to Change

function zxcAnimate(mde,obj,srt){
this.to=null;
this.obj=typeof(obj)=='object'?obj:document.getElementById(obj);
this.mde=mde.replace(/\W/g,'');
this.data=[srt||0];
return this;
}

zxcAnimate.prototype={

animate:function(srt,fin,ms,scale,c){
clearTimeout(this.to);
this.time=ms||this.time||0;
this.neg=srt<0||fin<0;
this.data=[srt,srt,fin];
this.mS=this.time*(!scale?1:Math.abs((fin-srt)/(scale[1]-scale[0])));
this.c=typeof(c)=='string'?c.charAt(0).toLowerCase():this.c?this.c:'';
this.inc=Math.PI/(2*this.mS);
this.srttime=new Date().getTime();
this.cng();
},

cng:function(){
var oop=this,ms=new Date().getTime()-this.srttime;
this.data[0]=Math.floor(this.c=='s'?(this.data[2]-this.data[1])*Math.sin(this.inc*ms)+this.data[1]:this.c=='c'?this.data[2]-(this.data[2]-this.data[1])*Math.cos(this.inc*ms):(this.data[2]-this.data[1])/this.mS*ms+this.data[1]);
this.apply();
if (ms<this.mS) this.to=setTimeout(function(){oop.cng()},10);
else {
this.data[0]=this.data[2];
this.apply();
if (this.Complete) this.Complete(this);
}
},

apply:function(){
if (isFinite(this.data[0])){
if (this.data[0]<0&&!this.neg) this.data[0]=0;
if (this.mde!='opacity') this.obj.style[this.mde]=this.data[0]+'px';
else zxcOpacity(this.obj,this.data[0]);
}
}

}

function zxcOpacity(obj,opc){
if (opc<0||opc>100) return;
obj.style.filter='alpha(opacity='+opc+')';
obj.style.opacity=obj.style.MozOpacity=obj.style.WebkitOpacity=obj.style.KhtmlOpacity=opc/100-.001;
}


</script>

</head>

<body>
<img id="tst" src="http://www.vicsjavascripts.org.uk/StdImages/Egypt5.jpg" alt="Img" height="50" />

<script type="text/javascript">
/*<![CDATA[*/

var oop=new zxcAnimate('height','tst');
oop.animate(50,500,2000);
/*]]>*/
</script>
</body>

</html>

Aksparks04
12-26-2010, 01:25 AM
Thanks for the speedy reply! This is awesome. One question though: how would I modify this to make only an image's height stretch? Example:


Moving from this:
http://img510.imageshack.us/img510/9508/scale.png


To this:
http://img254.imageshack.us/img254/952/scale2.png

vwphillips
12-26-2010, 09:28 AM
<img id="tst" src="http://www.vicsjavascripts.org.uk/StdImages/Egypt5.jpg" alt="Img" height="50" width="200" />

DJCMBear
12-26-2010, 03:17 PM
It looks like the OP wants to make the image longer not wider so change the height from 50 to 200 not the width.



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