PHP Image resizing and cropping methods.

imageresizing.php

<?php
	
	/*
	 	Creates a thumbnail keeping the aspect ratio of the source image, and
	 	saves it to a destination $dest.
	 	
	 	Credits: http://davidwalsh.name/create-image-thumbnail-php
	 */
	function make_thumb($src, $dest, $desired_width) {
		$info = getimagesize($src);
	    	$imgtype = image_type_to_mime_type($info[2]);

		/* read the source image */
		switch ($imgtype) {
	        case 'image/jpeg':
	            $source_image = imagecreatefromjpeg($src);
	            break;
	        case 'image/gif':
	            $source_image = imagecreatefromgif($src);
	            break;
	        case 'image/png':
	            $source_image = imagecreatefrompng($src);
	            break;
	        default:
	            die('Invalid image type.');
	    	}

		$width = imagesx($source_image);
		$height = imagesy($source_image);
		
		/* find the "desired height" of this thumbnail, relative to the desired width  */
		$desired_height = floor($height * ($desired_width / $width));
		
		/* create a new, "virtual" image */
		$virtual_image = imagecreatetruecolor($desired_width, $desired_height);
		
		/* copy source image at a resized size */
		imagecopyresampled($virtual_image, $source_image, 0, 0, 0, 0, $desired_width, $desired_height, $width, $height);
		
		/* create the physical thumbnail image to its destination */
		imagejpeg($virtual_image, $dest);
	}

	/*
	 	Creates and returns a thumbnail, keeping the aspect ratio of the source image.
	 	
	 	Credits: http://php.net/manual/en/function.imagejpeg.php
	 */
	function create_thumb($src, $desired_width) {
		$info = getimagesize($src);
	    	$imgtype = image_type_to_mime_type($info[2]);

		/* read the source image */
		switch ($imgtype) {
	        case 'image/jpeg':
	            $source_image = imagecreatefromjpeg($src);
	            break;
	        case 'image/gif':
	            $source_image = imagecreatefromgif($src);
	            break;
	        case 'image/png':
	            $source_image = imagecreatefrompng($src);
	            break;
	        default:
	            die('Invalid image type.');
	    	}

		$width = imagesx($source_image);
		$height = imagesy($source_image);
		
		/* find the "desired height" of this thumbnail, relative to the desired width  */
		$desired_height = floor($height * ($desired_width / $width));
		
		/* create a new, "virtual" image */
		$virtual_image = imagecreatetruecolor($desired_width, $desired_height);
		
		/* copy source image at a resized size */
		imagecopyresampled($virtual_image, $source_image, 0, 0, 0, 0, $desired_width, $desired_height, $width, $height);
		
	    	/*
	     	* imageXXX() only has two options, save as a file, or send to the browser.
	     	* It does not provide you the oppurtunity to manipulate the final GIF/JPG/PNG file stream
	     	* So I start the output buffering, use imageXXX() to output the data stream to the browser, 
	     	* get the contents of the stream, and use clean to silently discard the buffered contents.
	    	*/
		ob_start();

		/* create the thumbnail image */
		imagejpeg($virtual_image, null);

		$final_image = ob_get_contents();

    		ob_end_clean();

		return $final_image;
	}

	/*
		Crops an image to the specified thumbnail size, starting the cropping from $x and $y.
		
		Credits: http://stackoverflow.com/questions/3255773/php-crop-image-to-fix-width-and-height-without-losing-dimension-ratio
	*/
	function cropImageToSquare($imgSrc, $imgDest, $thumbSize, $x = 0, $y = 0) {
		//getting the image dimensions
		list($width, $height) = getimagesize($imgSrc);
	
		//saving the image into memory (for manipulation with GD Library)
		$myImage = imagecreatefromjpeg($imgSrc);
	
		// calculating the part of the image to use for thumbnail
		$smallestSide = min($height, $width);
	
		// copying the part into thumbnail
		$thumb = imagecreatetruecolor($thumbSize, $thumbSize);
		imagecopyresampled($thumb, $myImage, 0, 0, $x, $y, $thumbSize, $thumbSize, $smallestSide, $smallestSide);
	
		//final output
		header('Content-type: image/jpeg');
		imagejpeg($thumb, $imgDest);
	}
	
	/*
		Resizes an image and puts it on top of a white, square background.
		Returns true if successful, false otherwise.
		
		Credits: http://stackoverflow.com/questions/4478223/how-do-i-fill-white-background-while-resize-image
	*/
	function resizeImage($source_image, $destination, $tn_w, $tn_h, $quality = 100) {
	    $info = getimagesize($source_image);
	    $imgtype = image_type_to_mime_type($info[2]);
	
	    #assuming the mime type is correct
	    switch ($imgtype) {
	        case 'image/jpeg':
	            $source = imagecreatefromjpeg($source_image);
	            break;
	        case 'image/gif':
	            $source = imagecreatefromgif($source_image);
	            break;
	        case 'image/png':
	            $source = imagecreatefrompng($source_image);
	            break;
	        default:
	            die('Invalid image type.');
	    }
	
	    #Figure out the dimensions of the image and the dimensions of the desired thumbnail
	    $src_w = imagesx($source);
	    $src_h = imagesy($source);
	
	    #Do some math to figure out which way we'll need to crop the image
	    #to get it proportional to the new size, then crop or adjust as needed
	
	    $x_ratio = $tn_w / $src_w;
	    $y_ratio = $tn_h / $src_h;
	
	    if (($src_w <= $tn_w) && ($src_h <= $tn_h)) {
	        $new_w = $src_w;
	        $new_h = $src_h;
	    } elseif (($x_ratio * $src_h) < $tn_h) {
	        $new_h = ceil($x_ratio * $src_h);
	        $new_w = $tn_w;
	    } else {
	        $new_w = ceil($y_ratio * $src_w);
	        $new_h = $tn_h;
	    }
	    
	    $newpic = imagecreatetruecolor(round($new_w), round($new_h));
	    imagecopyresampled($newpic, $source, 0, 0, 0, 0, $new_w, $new_h, $src_w, $src_h);
	    $final = imagecreatetruecolor($tn_w, $tn_h);
	    $backgroundColor = imagecolorallocate($final, 255, 255, 255);
	    imagefill($final, 0, 0, $backgroundColor);
	    //imagecopyresampled($final, $newpic, 0, 0, ($x_mid - ($tn_w / 2)), ($y_mid - ($tn_h / 2)), $tn_w, $tn_h, $tn_w, $tn_h);
	    imagecopy($final, $newpic, (($tn_w - $new_w)/ 2), (($tn_h - $new_h) / 2), 0, 0, $new_w, $new_h);
	
	    if (imagejpeg($final, $destination, $quality)) {
	        return true;
	    }
	
	    return false;
	}
	
?>