使用PHP的GD2裁剪 + 缩放图片

	/**
	 * 裁剪 + 缩放图片
	 * @param array $params 包含x,y,width,height,path
	 * @return string
	 */
	public function tailer_image($params){
		//$target_width,$target_height是缩放图片的大小
		$target_width = 256;
		$target_height = 256;
		$source_x = intval($params['x']);
		$source_y = intval($params['y']);
		$cropped_width = intval($params['width']);
		$cropped_height = intval($params['height']);
		$source_path = trim($params['path']);
		$path = 'files/uploads/images/';
		list($source_width,$source_height) = getimagesize($source_path);
		//获取图片的扩展名
		$extend_name = ltrim(strrchr(strtolower($source_path),'.'),'.');
		if(!in_array($extend_name,array('jpg','jpeg','png'))){
			return array(
						array('message'=>"图片扩展名不正确，只允许'jpg','jpeg','png'"),
						400
					);
		}

		switch ($extend_name) {
			case 'jpg':
				$source_image = imagecreatefromjpeg($source_path);
				break;
			case 'jpeg':
				$source_image = imagecreatefromjpeg($source_path);
				break;
			case 'png':
				$source_image = imagecreatefrompng($source_path);
				break;
		}
		
		$target_image  = imagecreatetruecolor($target_width, $target_height);
		$cropped_image = imagecreatetruecolor($cropped_width, $cropped_height);
		// 裁剪
		imagecopy($cropped_image, $source_image, 0, 0, $source_x, $source_y, $cropped_width, $cropped_height);
		// 缩放
		imagecopyresampled($target_image, $cropped_image, 0, 0, 0, 0, $target_width, $target_height, $cropped_width, $cropped_height);
		$filename = md5(microtime()).'.'.$extend_name;
		$dst_url = $path.$filename;
		//输出图像到$dst_url文件
		imagejpeg($target_image, $dst_url);
		return $dst_url;
	}