php class Zend_Image const TYPE_JPG jpg const TYPE_GIF gif const TYPE_

<?php

class Zend_Image
{

const TYPE_JPG = 'jpg';
const TYPE_GIF = 'gif';
const TYPE_PNG = 'png';

    public function filenameToMime ($filename)
    {
        $types = array(
	        'jpg' => self::TYPE_JPG,
	        'gif' => self::TYPE_GIF,
	        'png' => self::TYPE_PNG
        );

        foreach ($types as $extension => $mime)
        {
	        if (preg_match('/\.'.$extension.'$/', $filename))
	        {
		        return $mime;
	        }
        }


        throw new Zend_Exception('Unknown image type.');
    }
    /**
     * Returns a PHP image resource
     */

    public function readImage ($filename, $type = NULL)
    {
        if ($type === NULL)
        {
	        $type = $this->filenameToMime($filename);
        }

        switch ($type)
        {
	        case self::TYPE_JPG:
		        return imagecreatefromjpeg($filename);
		        break;

	        case self::TYPE_GIF:
		        return imagecreatefromgif($filename);
		        break;

	        case self::TYPE_PNG:
		        return imagecreatefrompng($filename);
		        break;

	        default:
		        break;
        }
    }

    /**
     * Doesn't return anything
     */

    public function writeImage ($image, $type = NULL, $filename = NULL)
    {
        if ($type === NULL)
        {
	        $type = $this->filenameToMime($filename);
        }

        switch ($type)
        {
	        case self::TYPE_JPG:
		        imagejpeg($image, $filename);
		        break;

	        case self::TYPE_GIF:
		        imagegif($image, $filename);
		        break;

	        case self::TYPE_PNG:
		        imagepng($image, $filename);
		        break;

	        default:
		        break;
        }
    }

    public function resize ($image, $width = NULL, $height = NULL, $fit = NULL)
    {
        $fit = (bool) $fit;

        // if no bounding box supplied, then return the original image

        if ($width === NULL && $height === NULL)
        {
	        return $image;
        }

        $origX = $newX = imagesx($image);
        $origY = $newY = imagesy($image);
        $origR = $origY / $origX;

        // if height only was specified

        if ($width === NULL && $height !== NULL)
        {
	        if ($origY >= $height || $fit == true) 
	        {
		        $newY = $height;
		        $newX = $newY / $origY * $origX;
	        }
        }

        // if width only was specified

        if ($width !== NULL && $height === NULL)
        {
	        if ($origX >= $width || $fit == true)
	        {
		        $newX = $width;
		        $newY = $newX / $origX * $origY;
	        }
        }

        // if width and height specified

        if ($width !== NULL && $height !== NULL)
        {
	        // if the image fits and $fit is off, just return the original
	        // image (since it fits in the bounding box)

	        if ($origX < $width && $origY < $height && $fit == false)
	        {
		        return $image;
	        }

	        $newR = $height / $width;

	        // we now need to work out whether to restrain by width or by height
	
	        if ($origR > $newR)
	        {
		        $newY = $height;
		        $newX = $newY / $origY * $origX;
	        }
	        else
	        {
		        $newX = $width;
		        $newY = $newX / $origX * $origY;
	        }		
        }

        // now we know the new image's dimensions

        $new = imagecreatetruecolor($newX, $newY);
        imagecopyresampled($new, $image, 0, 0, 0, 0, $newX, $newY, $origX, $origY);

        return $new;
    }
}