Offline cacheing map tiles in Firefox OS, using IndexedDB
I've been at the OpenStreetMap hack weekend. [Photo]. One of the things I wanted to explore was getting offline maps working on my Firefox OS phone.
Firefox OS is not like iPhone or Android - every app has to be written in pure HTML and JavaScript, which means that for full-featured phone apps / web apps we need to use the fancy extra tools that Mozilla and others are providing to beef up things beyond the usual web features. One of these is IndexedDB which allows a HTML page to store objects longish-term. So let's use that for cacheing map tiles:
- A simple demo with four tiles in a HTML page
- A Leaflet slippy map, tweaked to use IndexedDB cacheing
- Get the code on Github
The demos are just online maps, so they key thing is testing them with internet access on, and then trying again with internet access off.
I had to make a small tweak to the Leaflet slippy-map code in order to patch it to grab map tiles from my cache-or-live service. I don't know if there's a more "sustainable" way to do this...
Is this any different from standard browser cacheing? Well yes and no. It lets us have tighter control over what we, as "an app", do or do not remember. We get to say that we want to remember map tiles but we don't necessarily need to remember logo images, for example.
Syndicated 2013-12-01 11:29:53 (Updated 2013-12-01 12:53:45) from Dan Stowell