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This is a simple map tiles cache/proxy to use on weak computers such as RaspberryPi or NAS. The author uses it in the wi-fi router/GSM modem under OpenWRT on his sailboat Galadriel.
GaladrielCache can be used with any on-line map viewer. OruxMaps is a good choice. GaladrielMap is a good choice too.
Tiles locally stored on OSM z/x/y file structure, so you may use SD with raster maps without a server -- directly on your smartphone in the event of a disaster.

Contains:

• Features
• Compatibility
• Usage
• • OruxMaps configuration
• • GaladrielMap configuration
• • SignalK
• • OSM "slippy map" tilenames
• • MBTiles
• Install&configure
• Prepare SD card to cache
• Direct access to the cache
• • Mount SD card
• • Configure OruxMaps
• • Automated mounting in Android with 3C toolbox
• Loader
• • Using Loader to copy part of the cache
• Utilites
• • clearCache
• • checkSources
• • Coverage
• Support

1. User-defined internet map sources, with versioning, if needed.
2. Flexible and robust tile loading with proxy support.
3. Prior loading of large zoom levels.
4. Asynchronous cache freshing.
5. Separated robust loader.
6. Serves MBTiles local maps.

But no reprojection. Map projection is a client application problem.

Linux, PHP < 8. The cretinous decisions made at PHP 8 do not allow the GaladrielCache to work at PHP 8, and I do not want to follow these decisions.

tiles.php?z=Zoom&x=X_tile_num&y=Y_tile_num&r=map_Name

To use GaladrielCache with OruxMaps, add map definitions to OruxMaps onlinemapsources.xml, for example -- Yandex Sat map:

<onlinemapsource uid="1055">
<name>Yandex Sat via my proxy (SAT)</name>
<url><![CDATA[http://192.168.1.1/tileproxy/tiles.php?z={$z}&x={$x}&y={$y}&r=yasat.EPSG3395]]></url>
<minzoom>5</minzoom>
<maxzoom>19</maxzoom>
<projection>MERCATORELIPSOIDAL</projection>
<cacheable>1</cacheable>
<downloadable>0</downloadable>
</onlinemapsource>

Where: 192.168.1.1 - your server
/tileproxy/tiles.php - cache/proxy
and yasat.EPSG3395 - your custom map source name.
Try it to other maps.

ATTENTION! You MUST configure your MAP VIEWER for the use of specific projection!
(<projection>MERCATORELIPSOIDAL</projection> in the example above)
The GaladrielCache knows nothing about projections, it's store tiles only.

To use GaladrielMap with GaladrielCache -- set $tileCachePath in GaladrielMap's params.php file.

To use GaladrielCache in SignalK just configure charts-plugin to use every map available in the GaladrielCache.
For examle, for OpenTopoMap specify URL to http://you_server/tileproxy/tiles.php?z={z}&x={x}&y={y}&r=OpenTopoMap

Some applications (AvNav?) cannot use tiles other than in OSM "slippy map" tilenames format. To use the GaladrielCache with these applications, you can configure the Apache2 as follows:

<IfModule rewrite_module>
	RewriteEngine On
	RewriteRule ^tiles/(.+)/([0-9]+)/([0-9]+)/([0-9.a-z]+)$ tiles.php?r=$1&z=$2&x=$3&y=$4
</IfModule>

and refer to the cache:
tiles/map_Name/Zoom/X_tile/Y_tile
with or without extension.

The file with map on mbtiles format must have .mbtiles extension and located in $tileCacheDir directory. The map description file must have same name as map file, but with .php extension of course, and similarly to other such files be locate in mapsources/ directory.
It doesn't matter to the GaladrielCache whether vector or raster tiles are in the map file. The corresponding configuration should be in the map description file.

You must have a web server with php support. Just copy.
Paths and other settings are described in params.php Custom sources are in mapsources/* Help about map sources are in mapsources/mapsources.md

# mkfs.ext4 -O 64bit,metadata_csum -b 4096 -i 4096 /dev/sdb1

-b 4096 -i 4096 set block to 4096 bytes and increase i-nodes to max.
-O 64bit,metadata_csum needs for compability with old Android devices.
/dev/sdb1 - your SD card partition.
However, default formatting in vfat allows you to store a sufficient amount of tiles on the map for practical purposes.

If you server dead, but you have a rooted Android phone or tablet, you may use raster tiles directly:

1. remove SD card with the cache from the server
2. insert the SD card with cache to Android device on Android device with terminal:
3. Open terminal. Try:

# mount -o rw,remount /
# mkdir /data/mySDcard 
# chown 1000:1000 /data/mySDcard
# chmod 774 /data/mySDcard
# mount -o ro,remount /
# mount -rw -t ext4 /dev/block/mmcblk1p1 /data/mySDcard

This creates mount point and mounts your SD card. There to, so you have all maps on your Android device.
There:
/dev/block/mmcblk1p1 - partition wint cache on you SD card. To find it, try

$ ls /dev/block

Last mmcblk - most probably your SD card.
/data/mySDcard - mount point

Depending on how you obtain root, the command mount may be written as

# su --mount-master -c 'busybox mount -rw -t ext4 /dev/block/mmcblk1p1 /data/mySDcard' 

Modify oryxmaps/mapfiles/onlinemapsources.xml by add:

<onlinemapsource uid="1052">
<name>Navionics layer from local dir (NAV)</name>
<url><![CDATA[file://data/mySDcard/tiles/navionics_layer/{$z}/{$x}/{$y}.png]]></url> 
<minzoom>12</minzoom>
<maxzoom>18</maxzoom>
<projection>MERCATORESFERICA</projection>
<cacheable>0</cacheable>
<downloadable>0</downloadable>
</onlinemapsource>
<onlinemapsource uid="1054">
<name>OpenTopoMap from local dir (TOPO)</name>
<url><![CDATA[file://data/mySDcard/tiles/OpenTopoMap/{$z}/{$x}/{$y}.png]]></url> 
<minzoom>5</minzoom>
<maxzoom>18</maxzoom>
<projection>MERCATORESFERICA</projection>
<cacheable>0</cacheable>
<downloadable>0</downloadable>
</onlinemapsource>

and other maps by same way.
There /tiles/ - path to cache from the SD card root.

With 3C toolbox you can automate the mounting when the device boots.

1. Create file:
   01_mountExtSDcard

#!/system/bin/sh

EXT_SD_DIRECTORY=/data/mySDcard;

if [ ! -d $EXT_SD_DIRECTORY ];
then
mount -o rw,remount /
mkdir $EXT_SD_DIRECTORY;
chown 1000:1000 $EXT_SD_DIRECTORY;
chmod 774 $EXT_SD_DIRECTORY;
mount -o ro,remount /
fi
mount -rw -t ext4 /dev/block/mmcblk1p1 $EXT_SD_DIRECTORY

2. Place it in home directory by path
   Android/data/ccc71.at.free/scripts/ or
   Android/data/ccc71.at/scripts/
3. Open 3C toolbox
4. Go Tools - Script editor
5. Mark 01_mountExtSDcard as runed in boot

GaladrielCache includes a dumb tile loader. Create a csv job file with map_source_name.zoom as a name and x,y strings as content and place it in loaderjobs/ directory. Run startLoaderDaemon (or php loaderSched.php for foreground) in cli. GaladrielMap has a GUI for it.
To stop Loader run stopLoader or delete Loader job files bouth from loaderjobs/ and loaderjobs/inWork/ directories.

For example:
OpenSeaMap.9

295,145
296,145
296,144
295,144
295,143
296,143

Will be downloaded OpenSeaMap within the specified tiles from zoom 9 to $loaderMaxZoom from params.php.

Tile loader may use any number of threads to load, and use cron for robust download.
You may use a GaladrielMap for control Loader. Job files, created by GaladrielMap, saved in loaderjobs/oldjobs for backup.

Add to the first line of csv job file some copy command. In this case, Loader starts this command instead of loading tile. This first line must be started from #.
For example:
OpenSeaMap.9

# mkdir -p /mnt/mySDcard/RegionTileCache/$r/$z/$x/ && cp -Hpu $tileCacheDir/$r/$z/$x/$y /mnt/mySDcard/RegionTileCache/$r/$z/$x/
295,145
296,145
296,144
295,144
295,143
296,143

This will copy the specified tiles of OpenSeaMap up to max zoom to destination.

You can use variables from params.php, but not from mapsources/*.
Avoid creating job files that have a custom command and do not have one for one map.

Use in cli clearCache.php mapname to mapname or clearCache.php to all maps to remove from cache unwanted files, listed in $trash. This is maybe blank tiles or .tne files from SAS.Planet.
Use in cli clearCache.php mapname fresh to mapname or clearCache.php fresh to all maps to remove from cache expired tiles.

The checkSources.php is cli utility for check map source viability. If maps definition file include special tile info - checkSources.php reads this tile from source and compare loaded with stored. The result is logged. Use cron to run it periodically.

Run php checkCovers.php mapName.zoom max_zoom for calculate coverage of given region, described as Loader job file mapName.zoom. The checkCoversData/notFound/ directory contains a Loader job files with tiles that are missing from the coverage.
For display in map GaladrielCache supports calculate coverage feature. To get the transparent tile with cover map add '_COVER' to map name. This return current_zoom+8 zoom level coverage. It is clear that every pixel of this tile indicate one tile +8 zoom level. Additionally displayed coverage of loader's max zoom level.
The GaladrielMap supports this feature.

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