AbstractResource.php

<?php
namespace GdWrapper\Image\Resource;

use GdWrapper\Image\Resource\Exceptions\InvalidRawResourceException;
use GdWrapper\Image\Resource\Exceptions\InvalidFilePathException;

abstract class AbstractResource {
	const IMAGE_QUALITY_MAX = 100;
	const IMAGE_QUALITY_HIGH = 90;
	const IMAGE_QUALITY_MED = 75;
	const IMAGE_QUALITY_LOW = 50;
	const IMAGE_QUALITY_DRAFT = 30;

	private $rawResource;

	public function __construct($resource) 
	{
		if (is_string($resource)) {
			$this->createResource($resource);
		} else {
			$this->setRawResource($resource);	
		}
	}

	final public function __destruct() {
		if (is_resource($this->rawResource)) {
			imagedestroy($this->rawResource);
		}
	}

	final public function __clone() 
	{
		$this->rawResource = $this->cloneResource();
	}

	private function cloneResource() {
		ob_start();
		imagegd2($this->rawResource);
		return imagecreatefromstring(ob_get_clean());
	}


	public function setRawResource($resource) 
	{
		if (!is_resource($resource)) {
			throw new InvalidRawResourceException(
				'Invalid resource passed to ' . get_class($this)
			);
		}
		$this->rawResource = $resource;
	}

	public function raw($copy = false) 
	{
		if($copy) {
			return $this->cloneResource();
		}
		return $this->rawResource;
	}

	private function createResource($filepath) {
		if (! (new \SplFileInfo($filepath))->isFile()) {
			throw new InvalidFilePathException(
				"Invalid filepath location: ${filepath}"
			);
		}

		$this->setRawResource($this->doCreateResource($filepath));
	}

	abstract protected function doCreateResource($filepath);

	abstract public function output(
		$filename = null, 
		$quality = self::IMAGE_QUALITY_MAX,
		$additionalParameters = null
	);

	public static function factory($path) {
		$type = pathinfo($path, PATHINFO_EXTENSION);
		$className = __NAMESPACE__ . '\\' . ucfirst(strtolower($type)) . 'Resource';
		try {
			return (new \ReflectionClass($className))->newInstance($path);
		} catch(\ReflectionException $e) {
			throw new UnsupportedFileExtensionException("Extension ${path} not supported!");
		}
	}

	public static function copy(AbstractResource $orig, $newType = null) {
		if ($newType === null) {
			return clone $orig;
		} else {
			$className = __NAMESPACE__ . '\\' . ucfirst(strtolower($newType)) . 'Resource';
			try {
				return (new \ReflectionClass($className))->newInstance($orig->raw(true));
			} catch(\ReflectionException $e) {
				throw new UnsupportedFileExtensionException("Extension ${fileType} not supported!");
			}
		}
	}
}

JpegResource.php

<?php
namespace GdWrapper\Image\Resource;

/**
 * 
 **/
class JpegResource extends AbstractResource
{
	final protected function doCreateResource($filepath) 
	{
		return imagecreatefromjpeg($filepath);
	}

	final public function output(
		$filename = null, 
		$quality = self::IMAGE_QUALITY_MAX,
		$additionalParameters = null
	) {
		if(strpos($filename, '.') === false) {
			$filename = null;
		}
		$args = array_merge(array($this->raw()), func_get_args());
		return call_user_func_array('imagejpeg', $args);
	}
}

PngResource.php

<?php
namespace GdWrapper\Image\Resource;

/**
 * 
 **/
class PngResource extends AbstractResource
{
	final protected function doCreateResource($filepath) 
	{
		return imagecreatefrompng($filepath);
	}

	final public function output(
		$filename = null, 
		$quality = self::IMAGE_QUALITY_MAX,
		$additionalParameters = array()
	) {
		$funcArgs = func_get_args();
		if(count($funcArgs) > 2) {
			$additionalParameters = array_slice($funcArgs, 2);
		}

		if(strpos($filename, '.') === false) {
			$filename = null;
		}

		if($filename === null) {
			$quality = 100;
		}

		if($quality !== null) {
			$quality = floor((100 - $quality) / (100/9));
		}

		$args = array_merge([$this->raw(), $filename, $quality], $additionalParameters);
		return call_user_func_array('imagepng', $args);
	}
}

test.php

<?php
require 'autoload.php';

use GdWrapper\Image\Resource\AbstractResource;
use GdWrapper\Image\Resource\JpegResource;
use GdWrapper\Image\Resource\PngResource;

$ext = 'jpeg';

$res = AbstractResource::factory("file.{$ext}");

$png = AbstractResource::copy($res, 'png');
$png->output('teste2.png');