Function to dynamically resize images using jQuery

Nov 08

Adeel EjazjQuery Image Resize Plugin 19 Comments

UPDATE: I have created a jQuery plugin that dynamically resizes the images. It is faster and is optimized better (minified).

I have noticed that there has been quite a bit of interest in my post about dynamically resizing images using jQuery. I have created a function to do this job better. Not only it makes the code cleaner but it also makes it a lot easier to use it.

First, for those people looking for a quick lookup of solution, here is the optimized version of the function followed by a couple of examples to use it:

$.fn.resize=function(a){var d=Math.ceil;if(a==null)a=200;var e=a,f=a;$(this).each(function(){var b=$(this).height(),c=$(this).width();if(b>c)f=d(c/b*a);else e=d(b/c*a);$(this).css({height:e,width:f})})};

$("img").resize(200);
$("#thumbs img").resize(150);

And now the explanation.. The function takes one argument, a number, which is the maximum height and/or the width of the image. The function automatically decides what is the best way to resize the image as its all calculated from the proportions of the original image.

What follows below is an expanded (non-optimized) version of the function and explanation on what each statement does:

NOTE: I do highly recommend using the optimized version of the function above

$.fn.resize = function(max_size) {
m = Math.ceil;
if (max_size == undefined) {
max_size = 200;
}
h=w= max_size;
$(this).each(function() {
image_h = $(this).height();
image_w = $(this).width();
if (image_h > image_w) {
w = m(image_w / image_h * max_size);
} else {
h = m(image_h / image_w * max_size);
}
$(this).css({height:h,width:w});
})
};

Line 1 declares the function “resize” and accepts a variable for maximum height/width.
Line 2 stores the Math.ceil function to a single letter variable for calling up later by m(). It is same as calling Math.ceil() and is done this way for reducing the size of the script (called minifying).
Lines 3 to 5 check if a maximum height/width was specified, if not, the script defaults to a maximum size of 200px.
Line 6 sets two variables ‘h’ for height and ‘w’ for width to the maximum size. One of these variables will be changed depending up the proportions of the image being resized.
Line 7 starts the jQuery.each function that iterates over each image one by one.
Line 8 stores the image’s height to a variable and is for reducing the size of the script.
Line 9 stores the image’s width to a variable and is for reducing the size of the script.
Line 10 checks if the image height is greater than the image width.
Line 11 only executes when the image’s height is bigger than the width. It calculates the image’s new width with proportion to its original size (which would be less than the height).
Line 12 is basic else statement.
Line 13 only executes when the image’s width is bigger than the height. It calculates the image’s new height with proportion it its original size (which would be less than the width).
Line 15 uses the jQuery’s built-in CSS function to set the new height and width for the image.

Resize images using jQuery

Jun 13

Adeel EjazjQuery Image Resize Plugin 26 Comments

UPDATE: I have created a plugin that dynamically resizes the images using jQuery. It basically does the same job but is really easy to use and is optimized better (minified).

Recently I needed a script to resize images on the page. I did not want to lose the actual resolution but just wanted to create thumbnails on the go.

I spent some time searching but could not find anything suitable. The options I found were just too much while I needed something simple. At the end, I ended up writing some own code (I’m a coder after all :P ).
var max_size = 200;
$("img").each(function(i) {
if ($(this).height() > $(this).width()) {
var h = max_size;
var w = Math.ceil($(this).width() / $(this).height() * max_size);
} else {
var w = max_size;
var h = Math.ceil($(this).height() / $(this).width() * max_size);
}
$(this).css({ height: h, width: w });
});
The script resizes the images without distorting the proportions. First of all, a variable is declared called max_size that is set to the maximum height or width that the picture needs to be resized to. Then using jQuery we match all img elements and using the each function, we go through each one of them resizing them as necessary. The if statement checks which side of the image needs to be kept to the maximum and the other one is calculated proportionally.

In the final line, the new height and width values are assigned using CSS. Neat eh ;)

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