<?php
/**
* SeekQuarry/Yioop --
* Open Source Pure PHP Search Engine, Crawler, and Indexer
*
* Copyright (C) 2009 - 2026 Chris Pollett chris@pollett.org
*
* LICENSE:
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*
* END LICENSE
*
* @author Chris Pollett chris@pollett.org
* @license https://www.gnu.org/licenses/ GPL3
* @link https://www.seekquarry.com/
* @copyright 2009 - 2026
* @filesource
*/
namespace seekquarry\yioop\library\processors;
use seekquarry\yioop\configs as C;
use seekquarry\yioop\library as L;
/**
* Base abstract class common to all processors used to create crawl summary
* information from images
*
* @author Chris Pollett
*/
class ImageProcessor extends PageProcessor
{
/**
* Extract summary data from the image provided in $page together the url
* in $url where it was downloaded from
*
* ImageProcessor class defers a proper implementation of this method to
* subclasses
*
* @param string $page the image represented as a character string
* @param string $url the url where the image was downloaded from
* @return array summary information including a thumbnail and a
* description (where the description is just the url)
*/
public function process($page, $url)
{
return null;
}
/**
* Used to save a temporary file with the data downloaded for a url
* while carrying out image processing
*
* @param string $page contains data about an image that one needs to save
* @param string $url where $page data came from
* @param string $file_extension to be associated with the $page data
* @return mixed temporary filesystem path the image was written to;
* null when the temp directory could not be created
*/
public function saveTempFile($page, $url, $file_extension)
{
static $call_count = 0;
$temp_dir = C\TEMP_DIR . "/";
if (!file_exists($temp_dir)) {
mkdir($temp_dir);
}
if (!file_exists($temp_dir)) {
return null;
}
$temp_file = $temp_dir . $call_count .
L\crawlHash($url) . "." . $file_extension;
$call_count++;
if ($call_count > 1000000000) {
/* just fixing some value to cycle back to 0 rather than
rely on OS wrapping.
*/
$call_count = 0;
}
file_put_contents($temp_file, $page);
return $temp_file;
}
/**
* Given an $image_string determines if possible its width and height
* then assigns the values into the CrawlConstants:WIDTH,
* CrawlConstants:HEIGHT fields of $summary
*
* @param array &$summary to write the width and height into
* @param string $image_string the image represented as a character string
* @return array summary information including a thumbnail and a
* description (where the description is just the url)
*/
public function addWidthHeightSummary(&$summary, $image_string)
{
set_error_handler(null);
$image_info = @getimagesizefromstring($image_string);
restore_error_handler();
if (!empty($image_info[0]) && !empty($image_info[1])) {
list($summary[self::WIDTH], $summary[self::HEIGHT], ) =
$image_info;
}
}
/**
* Given an image try to extract and XMP info from it.
*
* @param string $image_string the image represented as a character string
* @return array XMP data converted from XML format to an array-like format
*/
public function getXmpData($image_string)
{
$xmp_data = "";
if (function_exists("simplexml_load_string") &&
preg_match('/\<x\:xmpmeta.+\<\/x\:xmpmeta\>/s', $image_string,
$match)) {
$xml_no_ns = preg_replace("/\<\/\w+\:/", "</", $match[0]);
$xml_no_ns = preg_replace("/\<\w+\:/", "<", $xml_no_ns);
set_error_handler(null);
$xmp_xml = @simplexml_load_string($xml_no_ns);
restore_error_handler();
$xmp_array = [];
if (!empty($xmp_xml) ) {
$xmp_array = json_decode(json_encode($xmp_xml), true);
}
$xmp_data = print_r($xmp_array, true);
}
return $xmp_data;
}
/**
* Used to create a thumbnail from an image object
*
* @param object $image image object with image
* @param int $width = width in pixels of thumb if width is a negative
* value and height positive, then this dimension will be set to be
* proportional based on the input images width versus height
* @param int $height = height in pixels of thumb if height is a negative
* value and width positive, then this dimension will be set to be
* proportional based on the input images width versus height
*
* @return string of webp image if this string would have been non-blank
* empty string otherwise
*/
public static function createThumb($image, $width = C\THUMB_DIM,
$height = C\THUMB_DIM)
{
if (empty($image) || ($width == 0 && $height == 0)) {
return "";
}
$size_x = imagesx($image);
$size_y = imagesy($image);
if ($height > 0 && $width <= 0) {
$width = intval(($size_x * $height)/$size_y);
}
if ($height <= 0 && $width > 0) {
$height = intval(($size_y * $width)/$size_x);
}
$thumb = imagecreatetruecolor($width, $height);
if (empty($thumb)) {
return "";
}
imagesavealpha($thumb, true);
$trans_colour = imagecolorallocatealpha($thumb, 255, 255, 255, 127);
imagefill($thumb, 0, 0, $trans_colour);
set_error_handler(null);
@imagecopyresampled($thumb,
$image, 0, 0, 0, 0, $width, $height, $size_x, $size_y);
restore_error_handler();
if (empty($thumb)) {
return "";
}
$number_of_sample_points = 200;
$is_blank = true;
$old_color = false;
for ($i = 0; $i < $number_of_sample_points; $i++) {
$x = rand(0, $width - 1);
$y = rand(0, $height - 1);
$color = imagecolorat($thumb, $x, $y);
if (!empty($old_color) && $old_color != $color) {
$is_blank = false;
break;
}
$old_color = $color;
}
if ($is_blank) {
return "";
}
ob_start();
imagewebp($thumb);
$thumb_string = ob_get_contents();
ob_end_clean();
return $thumb_string;
}
/**
* Computes the average RGBA pixel value over an image
* by resampling the image down to a 1x1 pixel image, then
* extracting its rgba value as a vector
*
* @param GdImage $image object to calculate average color for
* @return array a 4-tuple with components [red, green, blue, alpha]
*/
public static function averageColor($image)
{
$size_x = imagesx($image);
$size_y = imagesy($image);
$pixel_image = imagecreatetruecolor(1, 1);
if (empty($pixel_image)) {
return false;
}
imagesavealpha($pixel_image, true);
$trans_colour = imagecolorallocatealpha($pixel_image,
255, 255, 255, 127);
imagefill($pixel_image, 0, 0, $trans_colour);
set_error_handler(null);
@imagecopyresampled($pixel_image,
$image, 0, 0, 0, 0, 1, 1, $size_x, $size_y);
restore_error_handler();
$color_int = imagecolorat($pixel_image, 0, 0);
$color_vector = array_values(imagecolorsforindex($pixel_image,
$color_int));
return $color_vector;
}
/**
* Checks if an image is Black and White (really gray scale) by
* sampling 200 points and check that for each point the rgb values are
* the same.
*
* @param GdImage $image object to check if black white
* @return bool true if black and white
*/
public static function isBlackAndWhite($image)
{
$size_x = imagesx($image);
$size_y = imagesy($image);
$number_of_sample_points = 200;
for ($i = 0; $i < $number_of_sample_points; $i++) {
$x = rand(0, $size_x - 1);
$y = rand(0, $size_y - 1);
$color_int = imagecolorat($image, $x, $y);
$color_vector = array_values(imagecolorsforindex($image,
$color_int));
$first_color = $color_vector[0];
for($j = 1; $j < 3; $j++) {
if ($first_color != $color_vector[$j]) {
return false;
}
}
}
return true;
}
}
(c) 2026 Seekquarry - Open Source Search Engine Software