<?php
/*
** Zabbix
** Copyright (C) 2001-2025 Zabbix SIA
**
** 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 2 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, write to the Free Software
** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
**/
/**
* Helper for image related operations.
*/
class CImageHelper {
/**
* Image compare threshold.
*
* @var integer
*/
protected static $threshold = 0;
/**
* Default color used to erase regions.
*
* @var array
*/
protected static $erase_color = [255, 0, 255];
/**
* Get image resource from image data string.
*
* @param string $data image data string
*
* @return resource
*
* @throws Exception on error
*/
public static function getImageResource($data) {
$image = @imagecreatefromstring($data);
if ($image === false) {
throw new Exception('Failed to load image.');
}
return $image;
}
/**
* Get image data string from image resource.
*
* @param resource $image image resource
*
* @return string
*/
public static function getImageString($image) {
ob_start();
imagepng($image);
return ob_get_clean();
}
/**
* Set compare threshold.
*
* @param float $threshold threshold in %.
*/
public static function setThreshold($threshold) {
self::$threshold = min($threshold, 100) * 7.68;
}
/**
* Set erase color.
*
* @param mixed $color hex color #XXXXXX, integer or an array
*/
public static function setEraseColor($color) {
$components = self::getColorComponents($color);
if ($components !== null) {
self::$erase_color = $components;
}
}
/**
* Get part of an image defined by coordinates, width and height.
*
* @param string $image image string
* @param array $rect array with x, y, width and height keys
*
* @return string
*
* @throws Exception on error
*/
public static function getImageRegion($image, $rect) {
$source = self::getImageResource($image);
if (!array_key_exists('x', $rect) || !array_key_exists('y', $rect) || !array_key_exists('width', $rect)
|| !array_key_exists('height', $rect) || $rect['x'] < 0 || $rect['y'] < 0
|| ($rect['x'] + $rect['width']) >= imagesx($source)
|| ($rect['y'] + $rect['height']) >= imagesy($source)) {
throw new Exception('Requested image region is invalid.');
}
$target = imagecrop($source, $rect);
imagedestroy($source);
$result = self::getImageString($target);
imagedestroy($target);
return $result;
}
/**
* Parse color and return color component values as array.
*
* @param mixed $color hex color #XXXXXX, integer or an array
*
* @return array|null
*/
private static function getColorComponents($color) {
if (is_string($color) && preg_match('/^#[0-9a-fA-F]{6}$/', $color)) {
return sscanf($color, "#%02x%02x%02x");
}
elseif (is_int($color)) {
return [(0xff & $color), ((0xff00 & $color) >> 8), ((0xff0000 & $color) >> 16)];
}
elseif (is_array($color) && array_key_exists(0, $color) && array_key_exists(1, $color)
&& array_key_exists(2, $color)) {
return $color;
}
return null;
}
/**
* Get image with some regions covered.
* Regions are covered with magenta color if no color is specified for region.
*
* @param string $data image data
* @param array $regions regions to be covered
*
* @return string
*/
public static function getImageWithoutRegions($data, $regions = []) {
if (!$regions) {
return $data;
}
$image = self::getImageResource($data);
$default = imagecolorallocate($image, self::$erase_color[0], self::$erase_color[1], self::$erase_color[2]);
foreach ($regions as $region) {
$color = (array_key_exists('color', $region)) ? self::getColorComponents($region['color']) : null;
if ($color === null) {
$color = $default;
}
else {
$color = imagecolorallocate($image, $color[0], $color[1], $color[2]);
}
imagefilledrectangle($image, $region['x'] - 1, $region['y'] - 1, $region['x'] + $region['width'] + 2,
$region['y'] + $region['height'] + 2, $color
);
}
$result = self::getImageString($image);
imagedestroy($image);
return $result;
}
/**
* Compare two images and get result of compare.
*
* @param string $source reference image data (image is used as a reference)
* @param string $current current image data (image is compared to the reference)
*
* @return array
*/
public static function compareImages($source, $current) {
$result = [
'match' => true,
'delta' => 0,
'error' => null,
'diff' => null,
'ref' => null
];
if (md5($source) === md5($current)) {
return $result;
}
try {
$delta = 0;
$reference = self::getImageResource($source);
$target = self::getImageResource($current);
$width = imagesx($reference);
$height = imagesy($reference);
if ($width !== imagesx($target) || $height !== imagesy($target)) {
$result['ref'] = self::getImageString($reference);
$message = 'Image size ('.imagesx($target).'x'.imagesy($target).
') doesn\'t match size of reference image ('.$width.'x'.$height.')';
imagedestroy($reference);
imagedestroy($target);
throw new Exception($message);
}
$mask = imagecreatetruecolor($width, $height);
imagealphablending($mask, true);
imagecopy($mask, $reference, 0, 0, 0, 0, $width, $height);
imagefilledrectangle($mask, 0, 0, $width, $height, imagecolorallocatealpha($mask, 255, 255, 255, 64));
$red = imagecolorallocatealpha($mask, 255, 0, 0, 64);
for ($y = 0; $y < $height; $y++) {
for ($x = 0; $x < $width; $x++) {
$color1 = imagecolorat($reference, $x, $y);
$color2 = imagecolorat($target, $x, $y);
if ($color1 === $color2) {
continue;
}
if (self::$threshold === 0) {
$delta++;
imagesetpixel($mask, $x, $y, $red);
continue;
}
$diff = ($color1 ^ $color2);
if ((((0xff0000 & $diff) >> 16) + ((0xff00 & $diff) >> 8) + (0xff & $diff)) > self::$threshold) {
$delta++;
imagesetpixel($mask, $x, $y, $red);
}
}
}
imagedestroy($target);
if ($delta !== 0) {
$result['match'] = false;
$delta /= $width * $height / 100;
if ($delta < 0.01) {
$delta = 0.01;
}
$result['delta'] = round($delta, 2);
}
if ($result['match'] === false) {
$result['ref'] = self::getImageString($reference);
$result['diff'] = self::getImageString($mask);
}
imagedestroy($reference);
imagedestroy($mask);
}
catch (Exception $e) {
$result['match'] = false;
$result['error'] = $e->getMessage();
}
return $result;
}
}