flutter_map_tile_caching 1.0.0

Plugin package for flutter_map to provide an easy way to cache and download tiles for later offline use.

flutter_map_tile_caching

A plugin for the flutter_map library. Adds full tile caching functionality and methods to download areas of tiles.

Example

To view the example, copy the main.dart file inside the example directory, and run it inside your own new project. You shouldn't need to add any extra dependencies except this package (see below).

Installation

To install this plugin, add the below code snippet to your pubspec.yaml file.

    flutter_map_tile_caching:
        git:
            url: https://github.com/JaffaKetchup/flutter_map_tile_caching

In the future, the ownership of this package may be transferred, which will result in the above URL no longer being valid. Alternatively, I hope to publish this plugin to pub.dev in the future, and then this package will be able to be imported in a cleaner way.

Usage

New Tile Provider

This plugin adds the new tile provider: StorageCachingTileProvider(...). This takes the optional cachedValidDuration Duration argument which defaults to a duration of 1 day.

When new tiles are loaded, this tile provider will cache them in a database cache. When these tiles are requested again, the tile will be taken from cache if it is younger than it's cachedValidDuration, otherwise the tile will be requested again. However, if the request fails (eg. there is no Internet connection), the tile should still be taken from cache.

New Classes, Methods & Functions

This plugin adds the new classes: StorageCachingTileProvider & TileStorageCachingManager.

StorageCachingTileProvider

You can call loadTiles(...) on StorageCachingTileProvider(...), and pass in the appropriate bounds and min/max zoom levels. This will download and precache all the tiles in the specified area for all the specified zoom levels. It can be listened to for a Tuple3<int, int, int>, with the number of downloaded tiles, number of errored tiles (eg. tiles that couldn't be downloaded due to lack of Internet connection), and the total number of tiles to be downloaded, in that order. A maximum of 10000 tiles can be downloaded at once, or the maxCachedTilesAmount in total, whichever comes first. You can see an example of this in the example file.

You can call approximateTileAmount(...) on StorageCachingTileProvider, and pass in the appropriate bounds and min/max zoom levels. This will return an int which is the approximate number of tiles within the specified area.

TileStorageCachingManager

You can call cacheDbSize on TileStorageCachingManager. This will return a Future<int> which is the size of the caching database in bytes. Divide by 1024 then by 1024 to get the number of megabytes.

You can call cachedTilesAmount on TileStorageCachingManager. This will return a Future<int> which is the total number of tiles currently cached.

You can call maxCachedTilesAmount on TileStorageCachingManager. This will return a Future<int> which is the maximum number of tiles allowed to be cached at any one time.

You can call kDefaultMaxTileAmount on TileStorageCachingManager. This will return an int which is the default maximum number of tiles allowed to be cached at any one time. This might differ to maxCachedTilesAmount if changeMaxTileAmount(...) has ever been called.

You can call changeMaxTileAmount(...) on TileStorageCachingManager, and pass in the new max tile amount to change maxCachedTilesAmount.

You can call cleanCache() on TileStorageCachingManager. This will clear all the cached tiles from the database forever, without warning.

Limitations

This package currently uses flutter_map: ^0.12.0, and is therefore not null-safe. It does not support the web platform (due to the usage of dart:io), and the code has not been tested on desktop platforms.

Credits

This code was originally created by bugDim88, and improved upon by multiple people. You can see the original pull request here: pull request #564 on fleaflet/flutter_map. JaffaKetchup seperated the code into this external package on behalf of bugDim88 & other contributors to keep the base package small. All credit therefore goes to bugDim88 and the other contributors.