How to resize images proportionally / keeping the aspect ratio?

Question

I have images that will be quite big in dimension and I want to shrink them down with jQuery while keeping the proportions constrained, i.e. the same aspect ratio.

C

Answer 1

This issue can be solved by CSS.

.image{
 max-width:*px;
}

Answer 2

The resize can be achieved(maintaining aspect ratio) using CSS. This is a further simplified answer inspired by Dan Dascalescu's post.

http://jsbin.com/viqare

img{
     max-width:200px;
 /*Or define max-height*/
  }

<img src="http://e1.365dm.com/13/07/4-3/20/alastair-cook-ashes-profile_2967773.jpg"  alt="Alastair Cook" />

<img src="http://e1.365dm.com/13/07/4-3/20/usman-khawaja-australia-profile_2974601.jpg" alt="Usman Khawaja"/>

Answer 3

I think this is a really cool method:

 /**
  * Conserve aspect ratio of the original region. Useful when shrinking/enlarging
  * images to fit into a certain area.
  *
  * @param {Number} srcWidth width of source image
  * @param {Number} srcHeight height of source image
  * @param {Number} maxWidth maximum available width
  * @param {Number} maxHeight maximum available height
  * @return {Object} { width, height }
  */
function calculateAspectRatioFit(srcWidth, srcHeight, maxWidth, maxHeight) {

    var ratio = Math.min(maxWidth / srcWidth, maxHeight / srcHeight);

    return { width: srcWidth*ratio, height: srcHeight*ratio };
 }

Answer 4

There are 4 parameters to this problem

1. current image width iX
2. current image height iY
3. target viewport width cX
4. target viewport height cY

And there are 3 different conditional parameters

1. cX > cY ?
2. iX > cX ?
3. iY > cY ?

solution

1. Find the smaller side of the target view port F
2. Find the larger side of the current view port L
3. Find the factor of both F/L = factor
4. Multiply both sides of the current port with the factor ie, fX = iX * factor; fY = iY * factor

that's all you need to do.

//Pseudo code


iX;//current width of image in the client
iY;//current height of image in the client
cX;//configured width
cY;//configured height
fX;//final width
fY;//final height

1. check if iX,iY,cX,cY values are >0 and all values are not empty or not junk

2. lE = iX > iY ? iX: iY; //long edge

3. if ( cX < cY )
   then
4.      factor = cX/lE;     
   else
5.      factor = cY/lE;

6. fX = iX * factor ; fY = iY * factor ; 

This is a mature forum, I am not giving you code for that :)

Answer 5

Does <img src="/path/to/pic.jpg" style="max-width:XXXpx; max-height:YYYpx;" > help?

Browser will take care of keeping aspect ratio intact.

i.e max-width kicks in when image width is greater than height and its height will be calculated proportionally. Similarly max-height will be in effect when height is greater than width.

You don't need any jQuery or javascript for this.

Supported by ie7+ and other browsers (http://caniuse.com/minmaxwh).

Answer 6

If I understand the question correctly, you don't even need jQuery for this. Shrinking the image proportionally on the client can be done with CSS alone: just set its max-width and max-height to 100%.

<div style="height: 100px">
<img src="http://www.getdigital.de/images/produkte/t4/t4_css_sucks2.jpg"
    style="max-height: 100%; max-width: 100%">
</div>​

Here's the fiddle: http://jsfiddle.net/9EQ5c/