Development Journal – Smsr Update 001

I’d like to think that I started working on a rough draft with Smsr and then it evolved into something else.

This “rough draft” had a bit of code in it encapsulated in an entity called ConversationThread. A function of this class in particular was really nasty since what it did was take all of the SMS messages on the device and effectively organize them in a cohesive manner that didn’t rely on querying sub-providers like Sms.Inbox or Sms.Sent. The reasoning behind this was that when I would query some of the more specific Content Providers, like Sms.Conversations, the Cursor returned from that query would only contain three fields regardless of the applied projection. In other words, despite the fact that the contract class inherited from base interfaces that gave it the additional fields you’d want, this inheritance doesn’t apply to what’s returned from queries against the provider because these columns are missing from the Cursor. So it wouldn’t contain things like ADDRESS or _ID. And because these Content Providers weren’t designed with the ability to perform SQL Joins via queries (despite the fact that the documentation would lead you to believe so), the only other alternative, really, is to perform several separate queries against several different Content Providers and join them using either MatrixCursor or CursorJoiner. The issue there is (A) how to do this without blocking on the UI thread and (B) because subsequent queries would rely specifically on information that was contained in previous queries, how then to make sure that the queries had completed before attempting to use them?

I really tried to avoid the solution where multiple queries were involved because it just seemed so… lackluster. Not to mention that the idea of tossing back and forth between five or six Cursors seemed like an explosion in the works. But there was a major issue with the way I was doing it originally – real-time updates. Because the backing data was effectively abstracted into this seemingly convoluted construct that didn’t directly bind to the backing data, if something changed in the data (i.e. received a new text message), the structure would effectively have to be completely rebuilt. One pass on building that thing was expensive enough since it relied heavily on Collections. Doing it over and over again could lead to some really janky issues.

So I went back to the drawing board. And what I came out with, after struggling for a bit to understand MatrixCursor, was a solution that does in fact query multiple Content Providers which will yield several Cursors and then combines them into a MatrixCursor which is then given to my custom CursorAdapter. The result here also adds to a modified layout for the Conversation Stubs which uses a LayerDrawable to get the contact’s image (default if none) and apply a gradient over top of it that leads to the other half of the list.

Unfortunately, this change has broken the Activity that will show the Conversation Thread because the data that’s now contained in the stubs is different than what that Activity was looking for in the first place. But the stub viewer looks nice! 😀

If you want to follow along, the branch that this work is being done on is the “rewrite” branch.

https://github.com/gregfmartin/smsdemo/tree/rewrite

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