Resizing an image in PHP and maintaining its aspect ratio

[sujal]

Hi all some tutorials are here..


A question that has been asked many times is how to resize an image in PHP while maintaining the aspect ration of the original image.

The function below does just that, it takes an image resource and the new dimensions for the image in pixels and returns the resized image.
Code:

/**
* Resize and image while maintaining its aspect ratio.
*
* @param resource $src The image to resize.
* @param int $w The target width.
* @param int $h The target height.
* @return resource The resized image or the original image if it did not need to be scaled.
*/
function resizeImage($src, $w, $h) {

// Get the current size
$width = ImageSx($src);
$height = ImageSy($src);

// If one dimension is right then nothing to do
if($width == $w || $height == $h)
return($src);

// Calculate new size
if(($w - $width) > ($h - $height)) { // use height
$s = $h / $height;
$nw = round($width * $s);
$nh = round($height * $s);
}
else { // Use width
$s = $w / $width;
$nw = round($width * $s);
$nh = round($height * $s);
}

// Resize to correct size
$im = ImageCreateTrueColor($nw, $nh);
ImageCopyResampled($im, $src, 0, 0, 0, 0, $nw, $nh, $width, $height);

// Return the new image
return($im);
}
A simple example to load, resize and send an image to the browser would be:
Code:
$image = ImageCreateFromJPEG('images.jpg');
$image = resizeImage($image, 400, 400);
header("Content-Type: image/jpeg");
ImageJPEG($image, '', 80);

thanks