PHP function to generate sizes or crop images

poifox_generate_size.php

<?php /** Generate a cropped version of gif, png or jpg images */
public function poifox_generateSize( $imagepath, $destWidth = 80, $cropSquare = true, $cropThreshold = 400 ) {
	
	// get original image size
	list($width, $height) = getimagesize($imagepath);
	
	// Always crop thumbs smaller than $cropThreshold
	$cropSquare = ($destWidth < $cropThreshold || $cropSquare );
	
	// Upscaling sucks
	$destWidth = ( $destWidth < $width ) ? $destWidth : $width ;
	
	// The aspect ratio of the image
	$ratio = $width / $height;
	
	// offset defines where the coordinates on the original image
	// where the cropping are starts, defaults to 0 for non cropping
	$offsetX = 0;
	$offsetY = 0;
	
	// treats height as non cropping
	$destHeight = ceil($destWidth / $ratio);
	
	// the original image is cropped up to this coordinate
	$sourceWidth = $width;
	$sourceHeight = $height;
	
	// Is the image square?
	$isSquare = ( $width == $height );
	
	// you asked for cropping and the image is not square
	// if image is square we don't even bother on calculating this
	if ( $cropSquare && ! $isSquare ) {
		$destHeight = $destWidth;
		
		if ( $width > $height ) {					// LANDSCAPE
			$offsetX = ( $width - $height ) / 2;	// X offset rules
			$sourceWidth = $sourceHeight = $height; // Adjust source to height
			
		} elseif ( $width < $height ) {				// PORTRAIT
			$offsetY = ( $height - $width ) / 2;	// Y offset rules
			$sourceWidth = $sourceHeight = $width;	// adjust source to width
		}
	}
	
	$originalImage = imagecreatefromstring(file_get_contents($imagepath));
	
	$resultImage = imagecreatetruecolor($destWidth, $destHeight);
	
	// Copy pixels
	imagecopyresampled(
		$resultImage, $originalImage, 
		0,0,						// Destiny offset 
		$offsetX, $offsetY, 		// Origin Offset 
		$destWidth, $destHeight,	// Destiny Size
		$sourceWidth, $sourceHeight	// Origin cropping
	);
	
	// free memory taken by the original image
	imagedestroy($originalImage);
	
	// Returns image resource
	// You must take care of saving the image outside of this function
	return $resultImage;
	
} ?>