iiif-simple.php

<?php
/** @prefix : <http://purl.org/net/ns/doas#> . <> a :PHPScript;
 :title "A Simple IIIF Service";
 :created "2017-01-19";
 :creator <http://purl.org/net/who/kanzaki#masahide> ;
 :release [:revision "0.41"; :created "2017-01-25"];
 :dependencies "requires PHP GD extension" ;
 :description """A minimum IIIF service for JPEG pictures without predefined tiles. Because all tiles are generated on the fly, the performance will not be efficient as a large scale public service. Maybe useful for local testing purpose.
- define IMG_ROOT (relative path to JPEG image directory)
- prepare manifest file where service@id is set like
  "@id": "http://example.org/{path to this script}/{image path from IMG_ROOT}",
- the above manifest can be generated by the acompanying manifest-generator.php
""".
*/

// give the relative path to JPEG image directory, e.g. "../../2016/pub/images/"
define("IMG_ROOT", "images/");
$path = $_SERVER["PATH_INFO"];
if(preg_match("!^/(.*?\.jpg)(/.*)?$!", $path, $m)){
	if(!($imgwh = @getimagesize(IMG_ROOT . $m[1]))) report_error("404");
	if(!$m[2]){
		gen_image($m[1], $imgwh, array(0, 0, $imgwh[0], $imgwh[1]), $imgwh);
	}elseif($m[2] == "/info.json"){
		gen_infojson($imgwh);
	}elseif(preg_match("!^/info.json(/.*jpg)$!", $m[2], $mm)){
		gen_clipimg($m[1], $mm[1], $imgwh);
	}else{
		gen_clipimg($m[1], $m[2], $imgwh);
	}
}else{
	if(array_pop(preg_split("![/:\\\\]!", __FILE__)) == array_pop(explode("/", $_SERVER["SCRIPT_URI"]))){
		report_error("404");
	}else{
		//manifest-generator.php;
	}
}

//generates clipped and resized image as IIIF service
function gen_clipimg($imgfile, $param, $imgwh){
	$pm = explode("/", $param);
	$clip = calc_region($pm[1], $imgwh);
	$size = calc_size($pm[2], $clip, $imgwh);
	//ignores rotate and quality params
	gen_image($imgfile, $imgwh, $clip, $size);
}

//calc the clip region of the original image
function calc_region($regionp, $imgwh){
	if($regionp == "full"){
		$clip = array(0, 0, $imgwh[0], $imgwh[1]);
	}elseif(preg_match("/^(\d+),(\d+),(\d+),(\d+)$/", $regionp, $m)){
		$clip = array_slice($m, 1);
	}else{
		report_error("400", "wrong region params", $regionp);
	}
	return $clip;
}

//calc the output image size
function calc_size($sizep, $clip, $imgwh){
	if($sizep == "full" or $sizep == "max"){
		$newsize = array($clip[2], $clip[3]);
	}elseif(preg_match("/^pct:([\d\.]+)$/", $sizep, $m)){
		$newsize = array(round($clip[2] * $m[1] / 100), round($clip[3] * $m[1] / 100));
	}elseif(preg_match("/^(\d+)?,(\d+)?$/", $sizep, $m)){
		$newsize = array($m[1], $m[2]);
		if(!$newsize[0]){
			$newsize[0] = round($clip[2] * $newsize[1] / $clip[3]);
		}elseif(!$newsize[1]){
			$newsize[1] = round($clip[3] * $newsize[0] / $clip[2]);
		}
	}else{
		report_error("400", "wrong size params", $sizep);
	}
	return $newsize;
}

//generates the output image and returns with header
function gen_image($imgfile, $imgwh, $clip, $size){
	if(!($srcimg = imagecreatefromjpeg(IMG_ROOT . $imgfile))) report_error("500", "image source creation error");
	if(!($newimg = imagecreatetruecolor($size[0], $size[1]))) report_error("500", "image creation error", "($size[0], $size[1])");
	if(!(imagecopyresampled($newimg, $srcimg, 
		0, 0, //destination x, y
		$clip[0], $clip[1], //source x, y
		$size[0], $size[1], //destination w, h
		$clip[2], $clip[3] //source w, h
	))) report_error("500", "image clip error", print_r($clip, true));
	header("content-type: image/jpeg");
	imagejpeg($newimg);
}

//generates IIIF service info.json and returns with appropriate headers
function gen_infojson($imgwh){
	$service = $_SERVER["SCRIPT_URI"];
	header("Access-Control-Allow-Origin: *");
	header("content-type: application/json;charset=utf-8");
	print <<<EOF
{
  "@context" : "http://iiif.io/api/image/2/context.json",
  "@id" : "$service",
  "protocol" : "http://iiif.io/api/image",
  "width" : $imgwh[0],
  "height" : $imgwh[1],
  "tiles": [{"width" : $imgwh[0], "scaleFactors" : [1]}],
  "profile" : ["http://iiif.io/api/image/2/level1.json"]
}
EOF;
}

//error responses
function report_error($code, $msg="", $input=""){
	$errmsg = array(
		"400"=>"Bad request - invalid parameter",
		"404"=>"Not found", 
		"500"=>"Internal server error",
	);
	header("HTTP/1.0 $code");
	print $errmsg[$code].": ".(
		$msg ? $msg.($input ? " ".htmlspecialchars($input) : "") : 
		$_SERVER["REQUEST_URI"]
	) ;
	exit;
}