I am trying to make offline maps through caching (IndexedDB) in browser. I understand the concept is that I download and store the tiles of map first when connected to internet.
Then I have to load the tiles logically offline.
However, I'm not able to figure it out.
How do I store them and how to load them again logically? I'm stuck here. I am using the leaflet API for maps. How can this be implemented?
See my extensive research on this at:
Storing Image Data for offline web application (client-side storage database)
and at:
https://gis.stackexchange.com/questions/44813/database-for-offline-slippy-map-tiles
Key for what you want to do is a Functional Tile layer to get stuff from the DB:
https://github.com/ismyrnow/Leaflet.functionaltilelayer
BTW, I am just now testing out PouchDB for this, which is much cleaner that the raw IndexeDB.
Follow my results at:
https://groups.google.com/forum/?fromgroups#!topic/pouchdb/RG6wUsAi2R0
I have cache example implementation http://tbicr.github.com/OfflineMap/leaflet/index.html and code https://github.com/tbicr/OfflineMap/tree/master/leaflet_idb_sql_site.
For storage used IndexedDB and WebSQL. Storage had low performance and not tested.
I am working on a solution for the same problem. Storing tiles from a tileserver, and loading them from the db in leafletjs.
I have implemented a custom layer which loads tiles from a db (indexeddb/webdatabase) if available, and fallbacks to an tileserver (which has Access-Control-Allow-Origin header, see https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS#Access-Control-Allow-Credentials)
I implemented a control which saves the tiles currently in view in indexeddb or webdatabase.
Code is on https://github.com/allartk/leaflet.offline This is still work in progress at this time!
Related
I tried to find the best way to store data on a local persistant store but I did not find a lot of resources about this.
I found only :
Motion model
But what is the best gem/way to make a offline app. I mean, I sync with remote one time and after that, my application uses a local storage (cora data, sqlite...) to read data?
Thank you
I use MotionModel (heck, I wrote MotionModel) but I'm biased. It's supposed to be for use-cases where you don't want to set up the Core Data stack. That said, InfiniteRed has done a great job with RMQ so it's likely they did a great job with CDQ, which wraps Core Data.
I suggest you make a play app with each and decide for yourself.
I prefer the way HipByte suggests in the Locations sample.
Check the LocationsStore class, and how they use CoreData in a very simple way.
You could also use CouchbaseLite and leverage it's sync capabilities to make the data available offline. I created an CouchbaseLite RubyMotion Example which is a port of a TodoLite-iOS version of the App. I'm currently working on making the integration nicer and more ruby like, but it works as is.
I am starting to evaluate frameworks for a HTML5 app. I really like the enyo model for developing an app. However, my app needs an object-relational mapper (ORM) for local storage and some way to update the UI based on changes in the ORM data.
It looks like Ember has some great linkages for the ORM and update parts.
Has anyone used these two together? Does it makes sense or do either of them (by themselves) already address the entire problem space?
Thanks in advance,
Charlie
I've not tried to integrate them directly yet, but I think that the Enyo event model would work well here. Have the ORM live as a top-level component in your application and have it broadcast data change messages into your tree of components using enyo.waterfall() or enyo.waterfallDown().
I do something similar in a cryptogram game I'm working on where I use that mechanism to broadcast information about the player's guesses into the view tree where individual cells use them to modify their display.
I have a Windows Phone 7 app that (currently) calls an OData service to get data, and throws the data into a listbox. It is horribly slow right now. The first thing I can think of is because OData returns way more data than I actually need.
What are some suggestions/best practices for speeding up the fetching of data in a Windows Phone 7 app? Anything I could be doing in the app to speed up the retrieval of data and putting into in front of the user faster?
Sounds like you've already got some clues about what to chase.
Some basic things I'd try are:
Make your HTTP requests as small as possible - if possible, only fetch the entities and fields you absolutely need.
Consider using multiple HTTP requests to fetch the data incrementally instead of fetching everything in one go (this can, of course, actually make the app slower, but generally makes the app feel faster)
For large text transfers, make sure that the content is being zipped for transfer (this should happen at the HTTP level)
Be careful that the XAML rendering the data isn't too bloated - large XAML structure repeated in a list can cause slowness.
When optimising, never assume you know where the speed problem is - always measure first!
Be careful when inserting images into a list - the MS MarketPlace app often seems to stutter on my phone - and I think this is caused by the image fetch and render process.
In addition to Stuart's great list, also consider the format of the data that's sent.
Check out this blog post by Rob Tiffany. It discusses performance based on data formats. It was written specifically with WCF in mind but the points still apply.
As an extension to the Stuart's list:
In fact there are 3 areas - communication, parsing, UI. Measure them separately:
Do just the communication with the processing switched off.
Measure parsing of fixed ODATA-formatted string.
Whether you believe or not it can be also the UI.
For example a bad usage of ProgressBar can result in dramatical decrease of the processing speed. (In general you should not use any UI animations as explained here.)
Also, make sure that the UI processing does not block the data communication.
I have been developing a Mac Desktop app with an iOS device counterpart.
Basically I want to upload event information (music gigs etc.) from the Desktop to an online database and be able to read (only) the information whilst mobile.
I've got both apps working, using Core Data (with a sqlite database - I was going to use XML but the iOS doesn't seem to let me do that), but I'm at a loss when it comes to the Web Services part.
I've been googling and checking docs involving sqlite, XML, JSON, NSXMLParser (do I need restful services?)and umpteen other things and I'm just getting nowhere fast.
Could someone explain to me the principle involved? Do I actually need Core Data? Do I have to convert the sqlite data to XML and back again to read it via an iOS mobile device?
I feel I'm making this out to be way more complicated than it should be - or is it?
Hoping someone can put me straight. Hope I've given enough information.
What i do, and I have done many web service iOS apps. I make a webpage in JSON, call it, and then I use SBJsonParser, which parses the JSON into native objects, like a dictionary or array of dictionaries, then I display the data. It really is very simple.
The at a specific time like ViewDidLoad, I fetch the JSON file. Remember, the json document can be web service or just a text file. Whatever you need. JSON doesn't need extra code, is extremely lightweight, and parses without any interference into native objects. Less work for you.
I have a webapp from which I'd like to insert diagrams and images quickly and easily. I expect there is, somewhere out there, a webservice which will take a URL with a parameter that describes the vector graphics or diagram and returns an image.
No unlike what google charts does for graphing data.
Any resources or ideas on this?
If I had to build it myself, do you have some ideas of how I might accomplish that?
For instance, does PHP/asp/etc have a graphics library that's capable of rendering simple vector graphics?
-Adam
Check out Raphael. Done by a bloke here in Australia.
No unlike what google charts does for graphing data.
Why not just use the Google Chart API?
http://code.google.com/apis/chart/
Have you considered something like http://www.walterzorn.com/jsgraphics/jsgraphics_e.htm to produce actual vector graphics on the client side, instead of making requests to a server?
One possibility would be to generate SVG in realtime in the browser. This decreases browser compatibility, but that will decrease over time.