plugin/openlayersmap/StaticMap.php

<?php

/*
 * Copyright (c) 2012-2023 Mark C. Prins <mprins@users.sf.net>
 *
 * In part based on staticMapLite 0.03 available at http://staticmaplite.svn.sourceforge.net/viewvc/staticmaplite/
 *
 * Copyright (c) 2009 Gerhard Koch <gerhard.koch AT ymail.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
namespace dokuwiki\plugin\openlayersmap;

use Exception;
use geoPHP\Geometry\Geometry;
use geoPHP\Geometry\GeometryCollection;
use geoPHP\Geometry\LineString;
use geoPHP\Geometry\Point;
use geoPHP\Geometry\Polygon;
use geoPHP\geoPHP;
use dokuwiki\Logger;

/**
 *
 * @author Mark C. Prins <mprins@users.sf.net>
 * @author Gerhard Koch <gerhard.koch AT ymail.com>
 *
 */
class StaticMap
{
    // the final output
    private int $tileSize = 256;
    private array $tileInfo = [
        // OSM sources
        'openstreetmap' => ['txt' => '(c) OpenStreetMap data/ODbL', 'logo' => 'osm_logo.png', 'url' => 'https://tile.openstreetmap.org/{Z}/{X}/{Y}.png'],
        // OpenTopoMap sources
        'opentopomap' => ['txt' => '(c) OpenStreetMap data/ODbL, SRTM | style: (c) OpenTopoMap', 'logo' => 'osm_logo.png', 'url' => 'https://tile.opentopomap.org/{Z}/{X}/{Y}.png'],
        // OCM sources
        'cycle' => ['txt' => '(c) Thunderforest maps', 'logo' => 'tf_logo.png', 'url' => 'https://tile.thunderforest.com/cycle/{Z}/{X}/{Y}.png'],
        'transport' => ['txt' => '(c) Thunderforest maps', 'logo' => 'tf_logo.png', 'url' => 'https://tile.thunderforest.com/transport/{Z}/{X}/{Y}.png'],
        'landscape' => ['txt' => '(c) Thunderforest maps', 'logo' => 'tf_logo.png', 'url' => 'https://tile.thunderforest.com/landscape/{Z}/{X}/{Y}.png'],
        'outdoors' => ['txt' => '(c) Thunderforest maps', 'logo' => 'tf_logo.png', 'url' => 'https://tile.thunderforest.com/outdoors/{Z}/{X}/{Y}.png'],
        'toner' => ['txt' => '(c) Stadia Maps;Stamen Design;OpenStreetMap contributors', 'logo' => 'stamen.png', 'url' => 'https://tiles-eu.stadiamaps.com/tiles/stamen_toner/{Z}/{X}/{Y}.png'],
        'terrain' => ['txt' => '(c) Stadia Maps;Stamen Design;OpenStreetMap contributors', 'logo' => 'stamen.png', 'url' => 'https://tiles-eu.stadiamaps.com/tiles/stamen_terrain/{Z}/{X}/{Y}.png'],
    ];
    private string $tileDefaultSrc = 'openstreetmap';

    // set up markers
    private array $markerPrototypes = [
        // found at http://www.mapito.net/map-marker-icons.html
        // these are 17x19 px with a pointer at the bottom left
        'lightblue' => ['regex' => '/^lightblue(\d+)$/', 'extension' => '.png', 'shadow' => false, 'offsetImage' => '0,-19', 'offsetShadow' => false],
        // openlayers std markers are 21x25px with shadow
        'ol-marker' => ['regex' => '/^marker(|-blue|-gold|-green|-red)+$/', 'extension' => '.png', 'shadow' => 'marker_shadow.png', 'offsetImage' => '-10,-25', 'offsetShadow' => '-1,-13'],
        // these are 16x16 px
        'ww_icon' => ['regex' => '/ww_\S+$/', 'extension' => '.png', 'shadow' => false, 'offsetImage' => '-8,-8', 'offsetShadow' => false],
        // assume these are 16x16 px
        'rest' => ['regex' => '/^(?!lightblue(\d+)$)(?!(ww_\S+$))(?!marker(|-blue|-gold|-green|-red)+$)(.*)/', 'extension' => '.png', 'shadow' => 'marker_shadow.png', 'offsetImage' => '-8,-8', 'offsetShadow' => '-1,-1'],
    ];
    // note even though $centerX, $centerY, $offsetX and $offsetY are defined as float,
    //   these are actually integer numbers, but the php floor()/ceil() functions return a float
    private float $centerX;
    private float $centerY;
    private float $offsetX;
    private float $offsetY;
    private $image;
    private int $zoom;
    private float $lat;
    private float $lon;
    private int $width;
    private int $height;
    private array $markers;
    private string $maptype;
    private string $kmlFileName;
    private string $gpxFileName;
    private string $geojsonFileName;
    private bool $autoZoomExtent;
    private string $apikey;
    private string $tileCacheBaseDir;
    private string $mapCacheBaseDir;
    private string $mediaBaseDir;
    private bool $useTileCache;
    private string $mapCacheID = '';
    private string $mapCacheFile = '';
    private string $mapCacheExtension = 'png';

    /**
     * Constructor.
     *
     * @param float  $lat
     *            Latitude (x) of center of map
     * @param float  $lon
     *            Longitude (y) of center of map
     * @param int    $zoom
     *            Zoomlevel
     * @param int    $width
     *            Width in pixels
     * @param int    $height
     *            Height in pixels
     * @param string $maptype
     *            Name of the map
     * @param array  $markers
     *            array of markers
     * @param string $gpx
     *            GPX filename
     * @param string $kml
     *            KML filename
     * @param string $geojson
     * @param string $mediaDir
     *            Directory to store/cache maps
     * @param string $tileCacheBaseDir
     *            Directory to cache map tiles
     * @param bool   $autoZoomExtent
     *            Wheter or not to override zoom/lat/lon and zoom to the extent of gpx/kml and markers
     * @param string $apikey
     */
    public function __construct(
        float $lat,
        float $lon,
        int $zoom,
        int $width,
        int $height,
        string $maptype,
        array $markers,
        string $gpx,
        string $kml,
        string $geojson,
        string $mediaDir,
        string $tileCacheBaseDir,
        bool $autoZoomExtent = true,
        string $apikey = ''
    ) {
        $this->zoom   = $zoom;
        $this->lat    = $lat;
        $this->lon    = $lon;
        $this->width  = $width;
        $this->height = $height;
        // validate + set maptype
        $this->maptype = $this->tileDefaultSrc;
        if (array_key_exists($maptype, $this->tileInfo)) {
            $this->maptype = $maptype;
        }
        $this->markers          = $markers;
        $this->kmlFileName      = $kml;
        $this->gpxFileName      = $gpx;
        $this->geojsonFileName  = $geojson;
        $this->mediaBaseDir     = $mediaDir;
        $this->tileCacheBaseDir = $tileCacheBaseDir . '/olmaptiles';
        $this->useTileCache     = $this->tileCacheBaseDir !== '';
        $this->mapCacheBaseDir  = $mediaDir . '/olmapmaps';
        $this->autoZoomExtent   = $autoZoomExtent;
        $this->apikey           = $apikey;
    }

    /**
     * get the map, this may return a reference to a cached copy.
     *
     * @return string url relative to media dir
     */
    public function getMap(): string
    {
        try {
            if ($this->autoZoomExtent) {
                $this->autoZoom();
            }
        } catch (Exception $e) {
            Logger::debug($e);
        }

        // use map cache, so check cache for map
        if (!$this->checkMapCache()) {
            // map is not in cache, needs to be build
            $this->makeMap();
            $this->mkdirRecursive(dirname($this->mapCacheIDToFilename()), 0777);
            imagepng($this->image, $this->mapCacheIDToFilename(), 9);
        }
        $doc = $this->mapCacheIDToFilename();
        // make url relative to media dir
        return str_replace($this->mediaBaseDir, '', $doc);
    }

    /**
     * Calculate the lat/lon/zoom values to make sure that all of the markers and gpx/kml are on the map.
     *
     * @param float $paddingFactor
     *            buffer constant to enlarge (>1.0) the zoom level
     * @throws Exception if non-geometries are found in the collection
     */
    private function autoZoom(float $paddingFactor = 1.0): void
    {
        $geoms    = [];
        $geoms [] = new Point($this->lon, $this->lat);
        if ($this->markers !== []) {
            foreach ($this->markers as $marker) {
                $geoms [] = new Point($marker ['lon'], $marker ['lat']);
            }
        }
        if (file_exists($this->kmlFileName)) {
            $g = geoPHP::load(file_get_contents($this->kmlFileName), 'kml');
            if ($g !== false) {
                $geoms [] = $g;
            }
        }
        if (file_exists($this->gpxFileName)) {
            $g = geoPHP::load(file_get_contents($this->gpxFileName), 'gpx');
            if ($g !== false) {
                $geoms [] = $g;
            }
        }
        if (file_exists($this->geojsonFileName)) {
            $g = geoPHP::load(file_get_contents($this->geojsonFileName), 'geojson');
            if ($g !== false) {
                $geoms [] = $g;
            }
        }

        if (count($geoms) <= 1) {
            Logger::debug("StaticMap::autoZoom: Skip setting autozoom options", $geoms);
            return;
        }

        $geom     = new GeometryCollection($geoms);
        $centroid = $geom->centroid();
        $bbox     = $geom->getBBox();

        // determine vertical resolution, this depends on the distance from the equator
        // $vy00 = log(tan(M_PI*(0.25 + $centroid->getY()/360)));
        $vy0 = log(tan(M_PI * (0.25 + $bbox ['miny'] / 360)));
        $vy1 = log(tan(M_PI * (0.25 + $bbox ['maxy'] / 360)));
        Logger::debug("StaticMap::autoZoom: vertical resolution: $vy0, $vy1");
        if ($vy1 - $vy0 === 0.0) {
            $resolutionVertical = 0;
            Logger::debug("StaticMap::autoZoom: using $resolutionVertical");
        } else {
            $zoomFactorPowered  = ($this->height / 2) / (40.7436654315252 * ($vy1 - $vy0));
            $resolutionVertical = 360 / ($zoomFactorPowered * $this->tileSize);
        }
        // determine horizontal resolution
        $resolutionHorizontal = ($bbox ['maxx'] - $bbox ['minx']) / $this->width;
        Logger::debug("StaticMap::autoZoom: using $resolutionHorizontal");
        $resolution           = max($resolutionHorizontal, $resolutionVertical) * $paddingFactor;
        $zoom                 = $this->zoom;
        if ($resolution > 0) {
            $zoom             = log(360 / ($resolution * $this->tileSize), 2);
        }

        if (is_finite($zoom) && $zoom < 15 && $zoom > 2) {
            $this->zoom = floor($zoom);
        }
        $this->lon = $centroid->getX();
        $this->lat = $centroid->getY();
        Logger::debug("StaticMap::autoZoom: Set autozoom options to: z: $this->zoom, lon: $this->lon, lat: $this->lat");
    }

    public function checkMapCache(): bool
    {
        // side effect: set the mapCacheID
        $this->mapCacheID = md5($this->serializeParams());
        $filename         = $this->mapCacheIDToFilename();
        return file_exists($filename);
    }

    public function serializeParams(): string
    {
        return implode(
            "&",
            [
                $this->zoom,
                $this->lat,
                $this->lon,
                $this->width,
                $this->height,
                serialize($this->markers),
                $this->maptype,
                $this->kmlFileName,
                $this->gpxFileName,
                $this->geojsonFileName
            ]
        );
    }

    public function mapCacheIDToFilename(): string
    {
        if (!$this->mapCacheFile) {
            $this->mapCacheFile = $this->mapCacheBaseDir . "/" . $this->maptype . "/" . $this->zoom . "/cache_"
                . substr($this->mapCacheID, 0, 2) . "/" . substr($this->mapCacheID, 2, 2)
                . "/" . substr($this->mapCacheID, 4);
        }
        return $this->mapCacheFile . "." . $this->mapCacheExtension;
    }

    /**
     * make the map.
     */
    public function makeMap(): void
    {
        $this->initCoords();
        $this->createBaseMap();
        if ($this->markers !== []) {
            $this->placeMarkers();
        }
        if (file_exists($this->kmlFileName)) {
            try {
                $this->drawKML();
            } catch (exception $e) {
                Logger::error('failed to load KML file', $e);
            }
        }
        if (file_exists($this->gpxFileName)) {
            try {
                $this->drawGPX();
            } catch (exception $e) {
                Logger::error('failed to load GPX file', $e);
            }
        }
        if (file_exists($this->geojsonFileName)) {
            try {
                $this->drawGeojson();
            } catch (exception $e) {
                Logger::error('failed to load GeoJSON file', $e);
            }
        }

        $this->drawCopyright();
    }

    /**
     */
    public function initCoords(): void
    {
        $this->centerX = $this->lonToTile($this->lon, $this->zoom);
        $this->centerY = $this->latToTile($this->lat, $this->zoom);
        $this->offsetX = floor((floor($this->centerX) - $this->centerX) * $this->tileSize);
        $this->offsetY = floor((floor($this->centerY) - $this->centerY) * $this->tileSize);
    }

    /**
     *
     * @param float $long
     * @param int   $zoom
     * @return float
     */
    public function lonToTile(float $long, int $zoom): float
    {
        return (($long + 180) / 360) * 2 ** $zoom;
    }

    /**
     *
     * @param float $lat
     * @param int   $zoom
     * @return float
     */
    public function latToTile(float $lat, int $zoom): float
    {
        return (1 - log(tan($lat * M_PI / 180) + 1 / cos($lat * M_PI / 180)) / M_PI) / 2 * 2 ** $zoom;
    }

    /**
     * make basemap image.
     */
    public function createBaseMap(): void
    {
        $this->image   = imagecreatetruecolor($this->width, $this->height);
        $startX        = floor($this->centerX - ($this->width / $this->tileSize) / 2);
        $startY        = floor($this->centerY - ($this->height / $this->tileSize) / 2);
        $endX          = ceil($this->centerX + ($this->width / $this->tileSize) / 2);
        $endY          = ceil($this->centerY + ($this->height / $this->tileSize) / 2);
        $this->offsetX = -floor(($this->centerX - floor($this->centerX)) * $this->tileSize);
        $this->offsetY = -floor(($this->centerY - floor($this->centerY)) * $this->tileSize);
        $this->offsetX += floor($this->width / 2);
        $this->offsetY += floor($this->height / 2);
        $this->offsetX += floor($startX - floor($this->centerX)) * $this->tileSize;
        $this->offsetY += floor($startY - floor($this->centerY)) * $this->tileSize;

        for ($x = $startX; $x <= $endX; $x++) {
            for ($y = $startY; $y <= $endY; $y++) {
                $url = str_replace(
                    ['{Z}', '{X}', '{Y}'],
                    [$this->zoom, $x, $y],
                    $this->tileInfo [$this->maptype] ['url']
                );

                $tileData = $this->fetchTile($url);
                if ($tileData) {
                    $tileImage = imagecreatefromstring($tileData);
                }
                if (!$tileData || $tileImage === false || !$tileImage instanceof \GdImage) {
                    $tileImage = imagecreate($this->tileSize, $this->tileSize);
                    $color     = imagecolorallocate($tileImage, 255, 255, 255);
                    @imagestring($tileImage, 1, 127, 127, 'err', $color);
                }
                $destX = (int) ($x - $startX) * $this->tileSize + $this->offsetX;
                $destY = (int) ($y - $startY) * $this->tileSize + $this->offsetY;
                Logger::debug("imagecopy tile into image: $destX, $destY", $this->tileSize);
                imagecopy(
                    $this->image,
                    $tileImage,
                    $destX,
                    $destY,
                    0,
                    0,
                    $this->tileSize,
                    $this->tileSize
                );
            }
        }
    }

    /**
     * Fetch a tile (from the source or from the cache) and optionally store it in the cache,
     * returns false if the tile is not a valid image.
     * @param string $url
     * @return bool|string
     * @todo refactor this to use dokuwiki\HTTP\HTTPClient or dokuwiki\HTTP\DokuHTTPClient
     *          for better proxy handling...
     */
    public function fetchTile(string $url): bool|string
    {
        if ($this->useTileCache) {
            $cached = $this->checkTileCache($url);
            if ($cached) {
                return $cached;
            }
        }

        $_UA = 'Mozilla/4.0 (compatible; DokuWikiSpatial HTTP Client; ' . PHP_OS . ')';
        if (function_exists("curl_init")) {
            // use cUrl
            $ch = curl_init();
            curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
            curl_setopt($ch, CURLOPT_USERAGENT, $_UA);
            curl_setopt($ch, CURLOPT_REFERER, DOKU_URL);
            curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10);
            curl_setopt($ch, CURLOPT_URL, $url . $this->apikey);
            Logger::debug("fetchTile: getting: $url using curl_exec");
            $tile = curl_exec($ch);
            curl_close($ch);
        } else {
            // use file_get_contents
            global $conf;
            $opts = ['http' => [
                'method' => "GET",
                'header' => "Accept-language: en\r\n" . "User-Agent: $_UA\r\n" . "accept: image/png\r\n" . "Referer: " . DOKU_URL . "\r\n",
                'request_fulluri' => true
            ]];
            if (
                isset($conf['proxy']['host'], $conf['proxy']['port'])
                && $conf['proxy']['host'] !== ''
                && $conf['proxy']['port'] !== ''
            ) {
                $opts['http'] += ['proxy' => "tcp://" . $conf['proxy']['host'] . ":" . $conf['proxy']['port']];
            }

            $context = stream_context_create($opts);
            Logger::debug("fetchTile: getting: $url . $this->apikey using file_get_contents and options", $opts);
            $tile = file_get_contents($url . $this->apikey, false, $context);
        }

        // check if we retrieved a valid image
        if (@imagecreatefromstring($tile) !== false) {
            if ($tile && $this->useTileCache) {
                $this->writeTileToCache($url, $tile);
            }
            return $tile;
        }
        return false;
    }

    /**
     *
     * @param string $url
     * @return string|false
     */
    public function checkTileCache(string $url): string|false
    {
        $filename = $this->tileUrlToFilename($url);
        if (file_exists($filename)) {
            return file_get_contents($filename);
        }
        return false;
    }

    /**
     * @param string $url
     * @return string
     */
    public function tileUrlToFilename(string $url): string
    {
        return $this->tileCacheBaseDir . "/" . substr($url, strpos($url, '/') + 1);
    }

    /**
     * Write a tile into the cache.
     *
     * @param string $url
     * @param mixed  $data
     */
    public function writeTileToCache(string $url, mixed $data): void
    {
        $filename = $this->tileUrlToFilename($url);
        $this->mkdirRecursive(dirname($filename), 0777);
        file_put_contents($filename, $data);
    }

    /**
     * Recursively create the directory.
     *
     * @param string $pathname
     *            The directory path.
     * @param int    $mode
     *            File access mode. For more information on modes, read the details on the chmod manpage.
     */
    public function mkdirRecursive(string $pathname, int $mode): bool
    {
        if (!is_dir(dirname($pathname))) {
            $this->mkdirRecursive(dirname($pathname), $mode);
        }
        return is_dir($pathname) || mkdir($pathname, $mode) || is_dir($pathname);
    }

    /**
     * Place markers on the map and number them in the same order as they are listed in the html.
     */
    public function placeMarkers(): void
    {
        $count         = 0;
        $color         = imagecolorallocate($this->image, 0, 0, 0);
        $bgcolor       = imagecolorallocate($this->image, 200, 200, 200);
        $markerBaseDir = __DIR__ . '/icons';
        $markerImageOffsetX  = 0;
        $markerImageOffsetY  = 0;
        $markerShadowOffsetX = 0;
        $markerShadowOffsetY = 0;
        $markerShadowImg     = null;
        // loop thru marker array
        foreach ($this->markers as $marker) {
            // set some local variables
            $markerLat  = $marker ['lat'];
            $markerLon  = $marker ['lon'];
            $markerType = $marker ['type'];
            // clear variables from previous loops
            $markerFilename = '';
            $markerShadow   = '';
            $matches        = false;
            // check for marker type, get settings from markerPrototypes
            if ($markerType) {
                foreach ($this->markerPrototypes as $markerPrototype) {
                    if (preg_match($markerPrototype ['regex'], $markerType, $matches)) {
                        $markerFilename = $matches [0] . $markerPrototype ['extension'];
                        if ($markerPrototype ['offsetImage']) {
                            [$markerImageOffsetX, $markerImageOffsetY] = explode(
                                ",",
                                $markerPrototype ['offsetImage']
                            );
                        }
                        $markerShadow = $markerPrototype ['shadow'];
                        if ($markerShadow) {
                            [$markerShadowOffsetX, $markerShadowOffsetY] = explode(
                                ",",
                                $markerPrototype ['offsetShadow']
                            );
                        }
                    }
                }
            }
            // create img resource
            if (file_exists($markerBaseDir . '/' . $markerFilename)) {
                $markerImg = imagecreatefrompng($markerBaseDir . '/' . $markerFilename);
            } else {
                $markerImg = imagecreatefrompng($markerBaseDir . '/marker.png');
            }
            // check for shadow + create shadow recource
            if ($markerShadow && file_exists($markerBaseDir . '/' . $markerShadow)) {
                $markerShadowImg = imagecreatefrompng($markerBaseDir . '/' . $markerShadow);
            }
            // calc position
            $destX = (int) floor(
                ($this->width / 2) -
                $this->tileSize * ($this->centerX - $this->lonToTile($markerLon, $this->zoom))
            );
            $destY = (int) floor(
                ($this->height / 2) -
                $this->tileSize * ($this->centerY - $this->latToTile($markerLat, $this->zoom))
            );
            // copy shadow on basemap
            if ($markerShadow && $markerShadowImg) {
                imagecopy(
                    $this->image,
                    $markerShadowImg,
                    $destX + (int) $markerShadowOffsetX,
                    $destY + (int) $markerShadowOffsetY,
                    0,
                    0,
                    imagesx($markerShadowImg),
                    imagesy($markerShadowImg)
                );
            }
            // copy marker on basemap above shadow
            imagecopy(
                $this->image,
                $markerImg,
                $destX + (int) $markerImageOffsetX,
                $destY + (int) $markerImageOffsetY,
                0,
                0,
                imagesx($markerImg),
                imagesy($markerImg)
            );
            // add label
            imagestring(
                $this->image,
                3,
                $destX - imagesx($markerImg) + 1,
                $destY + (int) $markerImageOffsetY + 1,
                ++$count,
                $bgcolor
            );
            imagestring(
                $this->image,
                3,
                $destX - imagesx($markerImg),
                $destY + (int) $markerImageOffsetY,
                $count,
                $color
            );
        }
    }

    /**
     * Draw kml trace on the map.
     * @throws Exception when loading the KML fails
     */
    public function drawKML(): void
    {
        // TODO get colour from kml node (not currently supported in geoPHP)
        $col     = imagecolorallocatealpha($this->image, 255, 0, 0, .4 * 127);
        $kmlgeom = geoPHP::load(file_get_contents($this->kmlFileName), 'kml');
        $this->drawGeometry($kmlgeom, $col);
    }

    /**
     * Draw geometry or geometry collection on the map.
     *
     * @param Geometry $geom
     * @param int      $colour
     *            drawing colour
     */
    private function drawGeometry(Geometry $geom, int $colour): void
    {
        if (empty($geom)) {
            return;
        }

        switch ($geom->geometryType()) {
            case 'GeometryCollection':
                // recursively draw part of the collection
                for ($i = 1; $i < $geom->numGeometries() + 1; $i++) {
                    $_geom = $geom->geometryN($i);
                    $this->drawGeometry($_geom, $colour);
                }
                break;
            case 'Polygon':
                $this->drawPolygon($geom, $colour);
                break;
            case 'LineString':
                $this->drawLineString($geom, $colour);
                break;
            case 'Point':
                $this->drawPoint($geom, $colour);
                break;
            // TODO implement / do nothing
            case 'MultiPolygon':
            case 'MultiLineString':
            case 'MultiPoint':
            default:
                // draw nothing
                break;
        }
    }

    /**
     * Draw a polygon on the map.
     *
     * @param Polygon $polygon
     * @param int     $colour
     *            drawing colour
     */
    private function drawPolygon(Polygon $polygon, int $colour): void
    {
        // TODO implementation of drawing holes,
        // maybe draw the polygon to an in-memory image and use imagecopy, draw polygon in col., draw holes in bgcol?

        // print_r('Polygon:<br />');
        // print_r($polygon);
        $extPoints = [];
        // extRing is a linestring actually...
        $extRing = $polygon->exteriorRing();

        for ($i = 1; $i < $extRing->numGeometries(); $i++) {
            $p1           = $extRing->geometryN($i);
            $x            = floor(
                ($this->width / 2) - $this->tileSize * ($this->centerX - $this->lonToTile($p1->x(), $this->zoom))
            );
            $y            = floor(
                ($this->height / 2) - $this->tileSize * ($this->centerY - $this->latToTile($p1->y(), $this->zoom))
            );
            $extPoints [] = $x;
            $extPoints [] = $y;
        }
        // print_r('points:('.($i-1).')<br />');
        // print_r($extPoints);
        // imagepolygon ($this->image, $extPoints, $i-1, $colour );
        imagefilledpolygon($this->image, $extPoints, $i - 1, $colour);
    }

    /**
     * Draw a line on the map.
     *
     * @param LineString $line
     * @param int $colour
     *            drawing colour
     */
    private function drawLineString(LineString $line, int $colour): void
    {
        imagesetthickness($this->image, 2);
        for ($p = 1; $p < $line->numGeometries(); $p++) {
            // get first pair of points
            $p1 = $line->geometryN($p);
            $p2 = $line->geometryN($p + 1);
            // translate to paper space
            $x1 = floor(
                ($this->width / 2) - $this->tileSize * ($this->centerX - $this->lonToTile($p1->x(), $this->zoom))
            );
            $y1 = floor(
                ($this->height / 2) - $this->tileSize * ($this->centerY - $this->latToTile($p1->y(), $this->zoom))
            );
            $x2 = floor(
                ($this->width / 2) - $this->tileSize * ($this->centerX - $this->lonToTile($p2->x(), $this->zoom))
            );
            $y2 = floor(
                ($this->height / 2) - $this->tileSize * ($this->centerY - $this->latToTile($p2->y(), $this->zoom))
            );
            // draw to image
            imageline($this->image, $x1, $y1, $x2, $y2, $colour);
        }
        imagesetthickness($this->image, 1);
    }

    /**
     * Draw a point on the map.
     *
     * @param Point $point
     * @param int $colour
     *            drawing colour
     */
    private function drawPoint(Point $point, int $colour): void
    {
        imagesetthickness($this->image, 2);
        // translate to paper space
        $cx = floor(
            ($this->width / 2) - $this->tileSize * ($this->centerX - $this->lonToTile($point->x(), $this->zoom))
        );
        $cy = floor(
            ($this->height / 2) - $this->tileSize * ($this->centerY - $this->latToTile($point->y(), $this->zoom))
        );
        $r  = 5;
        // draw to image
        // imageellipse($this->image, $cx, $cy,$r, $r, $colour);
        imagefilledellipse($this->image, $cx, $cy, $r, $r, $colour);
        // don't use imageellipse because the imagesetthickness function has
        // no effect. So the better workaround is to use imagearc.
        imagearc($this->image, $cx, $cy, $r, $r, 0, 359, $colour);
        imagesetthickness($this->image, 1);
    }

    /**
     * Draw gpx trace on the map.
     * @throws Exception when loading the GPX fails
     */
    public function drawGPX(): void
    {
        $col     = imagecolorallocatealpha($this->image, 0, 0, 255, .4 * 127);
        $gpxgeom = geoPHP::load(file_get_contents($this->gpxFileName), 'gpx');
        $this->drawGeometry($gpxgeom, $col);
    }

    /**
     * Draw geojson on the map.
     * @throws Exception when loading the JSON fails
     */
    public function drawGeojson(): void
    {
        $col     = imagecolorallocatealpha($this->image, 255, 0, 255, .4 * 127);
        $gpxgeom = geoPHP::load(file_get_contents($this->geojsonFileName), 'json');
        $this->drawGeometry($gpxgeom, $col);
    }

    /**
     * add copyright and origin notice and icons to the map.
     */
    public function drawCopyright(): void
    {
        $logoBaseDir = __DIR__ . '/' . 'logo/';
        $logoImg     = imagecreatefrompng($logoBaseDir . $this->tileInfo ['openstreetmap'] ['logo']);
        $textcolor   = imagecolorallocate($this->image, 0, 0, 0);
        $bgcolor     = imagecolorallocate($this->image, 200, 200, 200);

        imagecopy(
            $this->image,
            $logoImg,
            0,
            imagesy($this->image) - imagesy($logoImg),
            0,
            0,
            imagesx($logoImg),
            imagesy($logoImg)
        );
        imagestring(
            $this->image,
            1,
            imagesx($logoImg) + 2,
            imagesy($this->image) - imagesy($logoImg) + 1,
            $this->tileInfo ['openstreetmap'] ['txt'],
            $bgcolor
        );
        imagestring(
            $this->image,
            1,
            imagesx($logoImg) + 1,
            imagesy($this->image) - imagesy($logoImg),
            $this->tileInfo ['openstreetmap'] ['txt'],
            $textcolor
        );

        // additional tile source info, ie. who created/hosted the tiles
        $xIconOffset = 0;
        if ($this->maptype === 'openstreetmap') {
            $mapAuthor = "(c) OpenStreetMap maps/CC BY-SA";
        } else {
            $mapAuthor   = $this->tileInfo [$this->maptype] ['txt'];
            $iconImg     = imagecreatefrompng($logoBaseDir . $this->tileInfo [$this->maptype] ['logo']);
            $xIconOffset = imagesx($iconImg);
            imagecopy(
                $this->image,
                $iconImg,
                imagesx($logoImg) + 1,
                imagesy($this->image) - imagesy($iconImg),
                0,
                0,
                imagesx($iconImg),
                imagesy($iconImg)
            );
        }
        imagestring(
            $this->image,
            1,
            imagesx($logoImg) + $xIconOffset + 4,
            imagesy($this->image) - ceil(imagesy($logoImg) / 2) + 1,
            $mapAuthor,
            $bgcolor
        );
        imagestring(
            $this->image,
            1,
            imagesx($logoImg) + $xIconOffset + 3,
            imagesy($this->image) - ceil(imagesy($logoImg) / 2),
            $mapAuthor,
            $textcolor
        );
    }
}