<?

error_reporting( 0 );
//цвет "полос" по бокам
$color = array( 255, 255, 255 );
$file_name = $_GET["src"];
list( $width, $height, $ext ) = getimagesize( $file_name );

//задаем новые ширину и высоту
$params["width"] = (int)$_GET["w"];
if( !isset( $_GET["h"] ) || 0 == (int)$_GET["h"] ){
	$params["height"] = $height * $params["width"]/$width;
} else {
	$params["height"] = (int)$_GET["h"];
}
if( 0 == $params["width"] ){
	$params["width"] = $width * $params["height"]/$height;
}

//папка с кешем изображений. Внутри img_cache/ повторяется полный путь исходного изображения
$cache_file_folder = "img_cache/" . substr( $file_name, 0, strrpos( $file_name, "/" ) );
$cache_file_name = "img_cache/" . substr( $file_name, 0, strrpos( $file_name, "." ) ) . "_" . $_GET["resize_type"] . "_" . $params["width"] . "_" . $params["height"] . substr( $file_name, strrpos( $file_name, "." ) );

//проверка наличия изображения в кеше. Если оно есть и было создано после последнего изменения исходного изображения - берем его
if( file_exists( $cache_file_name ) ){
	if( filemtime( $cache_file_name ) > filemtime( $file_name ) ){
		if( 1 == $ext ){
			header( "Content-type: " . image_type_to_mime_type( IMAGETYPE_GIF ) );
		} else if( 2 == $ext ){
			header( "Content-type: " . image_type_to_mime_type( IMAGETYPE_JPEG ) );
		} else if( 3 == $ext ){
			header( "Content-type: " . image_type_to_mime_type( IMAGETYPE_PNG ) );
		}
		//обновление времени последнего изменения. Используется, если необходима очистка давно не запрашиваемых картинок
		touch( $cache_file_name );
		echo file_get_contents( $cache_file_name );
		exit();
	}
}

//пытаемся создать папку для кеша
mkdir( $cache_file_folder, 0755, true );

//непосредственно код ресайзинга
switch( $_GET["resize_type"] ){
	case "b":
		if( 1 == $ext ){
			header( "Content-type: " . image_type_to_mime_type( IMAGETYPE_GIF ) );
			$image = imagecreatefromgif( $file_name );
		} else if( 2 == $ext ){
			header( "Content-type: " . image_type_to_mime_type( IMAGETYPE_JPEG ) );
			$image = imagecreatefromjpeg( $file_name );
		} else if( 3 == $ext ){
			header( "Content-type: " . image_type_to_mime_type( IMAGETYPE_PNG ) );
			$image = imagecreatefrompng( $file_name );
		}
		$new_width = (int)$params["width"];
		$new_height = (int)$params["height"];
		if( $new_width == 0 || $new_height == 0 || !$image || !in_array( $ext, array( 1, 2, 3 ) ) ){
			$image_new = imagecreatetruecolor( 100, 30 );
			$bgc = imagecolorallocatealpha( $image_new, $color[0], $color[1], $color[2], 127 );
			$tc = imagecolorallocate( $image_new, 0, 0, 0 );
			imagefilledrectangle( $image_new, 0, 0, 100, 30, $bgc );
			imagestring( $image_new, 1, 5, 5, "Error loading", $tc );
			if( 1 == $ext ){
				imagegif( $image_new );
				imagedestroy( $image_new );
			} else if( 2 == $ext ){
				imagejpeg( $image_new );
				imagedestroy( $image_new );
			} else if( 3 == $ext ){
				imagepng( $image_new );
				imagedestroy( $image_new );
			}
			exit();
		}
		$image_new = imagecreatetruecolor( $new_width, $new_height );
		imagealphablending( $image_new, false );
		imagesavealpha( $image_new, true );
		$bgc = imagecolorallocatealpha( $image_new, $color[0], $color[1], $color[2], 127 );
		imagefilledrectangle( $image_new, 0, 0, $new_width, $new_height, $bgc );
		if( $new_width/$new_height > $width/$height ){
			$ins = $width*($new_height/$height);
			$out = ( $new_width - $ins )/2;
			imagecopyresampled( $image_new, $image, $out, 0, 0, 0, $ins, $new_height, $width, $height );
		} else {
			$ins = $height*($new_width/$width);
			$out = ( $new_height - $ins )/2;
			imagecopyresampled( $image_new, $image, 0, $out, 0, 0, $new_width, $ins, $width, $height );
		}
		
		if( 1 == $ext ){
			imagegif( $image_new );
			imagegif( $image_new, $cache_file_name );
			imagedestroy( $image_new );
		} else if( 2 == $ext ){
			imagejpeg( $image_new );
			imagejpeg( $image_new, $cache_file_name );
			imagedestroy( $image_new );
		} else if( 3 == $ext ){
			imagepng( $image_new );
			imagepng( $image_new, $cache_file_name );
			imagedestroy( $image_new );
		}
	break;
	case "t":
		if( 1 == $ext ){
			$image = imagecreatefromgif( $file_name );
		} else if( 2 == $ext ){
			$image = imagecreatefromjpeg( $file_name );
		} else if( 3 == $ext ){
			$image = imagecreatefrompng( $file_name );
		}
		header( "Content-type: " . image_type_to_mime_type( IMAGETYPE_PNG ) );
		$new_width = (int)$params["width"];
		$new_height = (int)$params["height"];
		if( $new_width == 0 || $new_height == 0 || !$image || !in_array( $ext, array( 1, 2, 3 ) ) ){
			$image_new = imagecreatetruecolor( 100, 30 );
			$bgc = imagecolorallocatealpha( $image_new, $color[0], $color[1], $color[2], 127 );
			$tc = imagecolorallocate( $image_new, 0, 0, 0 );
			imagefilledrectangle( $image_new, 0, 0, 100, 30, $bgc );
			imagestring( $image_new, 1, 5, 5, "Error loading", $tc );
			if( 1 == $ext ){
				imagegif( $image_new );
				imagedestroy( $image_new );
			} else if( 2 == $ext ){
				imagejpeg( $image_new );
				imagedestroy( $image_new );
			} else if( 3 == $ext ){
				imagepng( $image_new );
				imagedestroy( $image_new );
			}
			exit();
		}
		$image_new = imagecreatetruecolor( $new_width, $new_height );
		imagealphablending( $image_new, false );
		imagesavealpha( $image_new, true );
		$bgc = imagecolorallocatealpha( $image_new, $color[0], $color[1], $color[2], 127 );
		imagefilledrectangle( $image_new, 0, 0, $new_width, $new_height, $bgc );
		if( $new_width/$new_height > $width/$height ){
			$ins = $width*($new_height/$height);
			$out = ( $new_width - $ins )/2;
			imagecopyresampled( $image_new, $image, $out, 0, 0, 0, $ins, $new_height, $width, $height );
		} else {
			$ins = $height*($new_width/$width);
			$out = ( $new_height - $ins )/2;
			imagecopyresampled( $image_new, $image, 0, $out, 0, 0, $new_width, $ins, $width, $height );
		}
		imagepng( $image_new );
		imagepng( $image_new, $cache_file_name );
		imagedestroy( $image_new );
	break;
	case "c":
		if( 1 == $ext ){
			header( "Content-type: " . image_type_to_mime_type( IMAGETYPE_GIF ) );
			$image = imagecreatefromgif( $file_name );
		} else if( 2 == $ext ){
			header( "Content-type: " . image_type_to_mime_type( IMAGETYPE_JPEG ) );
			$image = imagecreatefromjpeg( $file_name );
		} else if( 3 == $ext ){
			header( "Content-type: " . image_type_to_mime_type( IMAGETYPE_PNG ) );
			$image = imagecreatefrompng( $file_name );
		}
		$new_width = (int)$params["width"];
		$new_height = (int)$params["height"];
		if( $new_width == 0 || $new_height == 0 || !$image || !in_array( $ext, array( 1, 2, 3 ) ) ){
			$image_new = imagecreatetruecolor( 100, 30 );
			$bgc = imagecolorallocate( $image_new, 255, 255, 255 );
			$tc = imagecolorallocate( $image_new, 0, 0, 0 );
			imagefilledrectangle( $image_new, 0, 0, 100, 30, $bgc );
			imagestring( $image_new, 1, 5, 5, "Error loading", $tc );
			if( 1 == $ext ){
				imagegif( $image_new );
				imagedestroy( $image_new );
			} else if( 2 == $ext ){
				imagejpeg( $image_new );
				imagedestroy( $image_new );
			} else if( 3 == $ext ){
				imagepng( $image_new );
				imagedestroy( $image_new );
			}
			exit();
		}
		$image_new = imagecreatetruecolor( $new_width, $new_height );
		imagealphablending( $image_new, false );
		imagesavealpha( $image_new, true );
		$width/$new_width < $height/$new_height ? $coef = $width/$new_width : $coef = $height/$new_height;
		$start_x = ( $width - $new_width*$coef )/2;
		$start_y = ( $height - $new_height*$coef )/2;
		$end_x = $width - 2*$start_x;
		$end_y = $height - 2*$start_y;
		imagecopyresampled( $image_new, $image, 0, 0, $start_x, $start_y, $new_width, $new_height, $end_x, $end_y );
		if( 1 == $ext ){
			imagegif( $image_new );
			imagegif( $image_new, $cache_file_name );
			imagedestroy( $image_new );
		} else if( 2 == $ext ){
			imagejpeg( $image_new );
			imagejpeg( $image_new, $cache_file_name );
			imagedestroy( $image_new );
		} else if( 3 == $ext ){
			imagepng( $image_new );
			imagepng( $image_new, $cache_file_name );
			imagedestroy( $image_new );
		}
	break;
}

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /

RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^image/([a-z])/([0-9]+)/([0-9]+)/([A-z0-9-\/\.]+)$ image.php?resize_type=$1&w=$2&h=$3&src=$4 [QSA,L]

RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^image/([a-z])/([0-9]+)/([A-z0-9-\/\.]+)$ image.php?resize_type=$1&w=$2&src=$4 [QSA,L]

</IfModule>