PocketBalance Application

• Download demo project - 361 Kb
• Download source - 73 Kb

Introduction

PocketBalance is a bank balance forecasting utility. I wanted something that could tell me what my account balances would be next month, without having to put in much effort to keep it up to date.

I�d tried a few commercial money packages some years back, but my bank was a bit backward and it was a pain to integrate the two. I had to manually enter stuff and regularly reconcile things to keep it happy. In the end it was too much bother, and I had more success crawling out of debt with a simple Excel worksheet :o)

All that�s needed to keep PocketBalance happy is a list of recurring transactions (utility bills, salary etc) and an occasional snapshot of the current balance. It can:

• Manage multiple accounts (checking/current, savings, credit)
• Automatically apply recurring transactions (daily, monthly, fortnightly, annually etc)
• Automatically apply regular credit card payments (for both �pay in full� and �minimum percentage� terms, based on a previous statement balance)
• Show a balance graph you can click on to locate transactions

Of course you can throw in a whole load more detail for PocketBalance to play with if you like. The more detail it has, the more accurate its balance prediction will be.

Background / Implementation

I�d not even attempted to write a PocketPC application before. I�d done plenty with ASP.NET, loads of class libraries and some Windows Forms, but was a definite newbie here.

I knew I wanted DataSets, and wanted to get the Framework to do all the hard work for me. My plan was to throw together a nice typed dataset, bind it to a few things, add a few buttons and some calculations and I�d be done. Cake ;o)

I spent the next few evenings (real job during the day + 3 kids = little time to play) cursing Microsoft for not giving me typed datasets, XML serialization or a decent sized screen. Everything I wanted to use seemed to be missing :o( Rarely a quitter, I picked them off bit at a time:

• I drew up a schema for the data I wanted in VS.Net�s XSD designer. Overcome with giddy anticipation I gave it primary keys and relations. Victory beckoned.
• The basics of the DataSet were there, so I just loaded the XSD in (with ReadXmlSchema) and my tables were defined and looking very pleased with themselves. I roared with delight.
• I decided the screen was actually quite big if you were close to it. I�d just have to make every pixel count :o)

I created some dummy data and put it in as an embedded resource (SampleData.xml). Until I got it loading and saving stuff, it could play with this.

After that it�s a bit of a blur. I went down a couple of wrong roads and reversed best I could. I realized I didn�t know half as much as I thought I did about databinding in Windows Forms. There was a whole world of BindingContexts and things I�d never tried, so if nothing else it was good practice.

Points of Interest

Some of the nasties I battled on the way were:

• The Windows Forms controls just wrap the regular Windows CE controls, but don�t let you override very much. I wanted nice listboxes and a graph but the inbuilt controls couldn�t cut the mustard :o( I soon found it�s very easy to create new controls (probably easier than messing with the inbuilt ones) so put together a quick 2D graph viewer control (see the PocketGraph assembly).
• I wrestled with the inbuilt ListView control to display the transactions, but it beat me. It painted each row in a half-assed way, and didn�t support databinding :o( I hated it so much I wrote my own (DetailView in the PocketControls assembly). It wasn�t a complete replacement, but it did everything I needed.
• Creating forms seemed painfully slow. I put in some over-elaborate code to create them only once and it became bearable (taking some ideas from MSDN�s FormStack example).
• I wanted to use GUIDs as the row identifiers in my DataSet (to save me having to worry about uniqueness), but the PocketPC didn�t know how to make them :o( Fortunately MSDN came to the rescue with this article (posted on CodeProject), which became a new �PocketGuid� assembly.
• Sizing and positioning controls in the VS.Net designer can be fiddly, and the inbuilt ones seem inconsistent in having borders you can�t switch off etc. Creating custom controls is well worth the effort because you get the choice to forget borders if you like, and you can also implement double-buffering for flicker-free operation�

Eventually I got it doing everything I wanted (I�m sure there are a billion bugs) and set about writing an installer for it. This would have been headache-inducing (it�s not as slick as creating a regular setup project) if not for a guy called Simon Kittle who put together this very useful article.

It�s certainly not a �best practice� implementation. I�ve kept it reasonably simple, but there are places it�s a bit inconsistent (it�s largely using data binding, but there are a couple of examples of manually initialized stuff). Nothing hugely wrong with it though - I�ll just regard it as a learning exercise ;o)

Since starting this I�ve realized developing PocketPC applications is pretty satisfying. Some of the uglier moments are like having teeth pulled by enema, but once you accept the constraints it [mostly] falls nicely into place. I�ve already decided what my next PPC project will be� If it turns out OK, I�ll post it here :o)

Some screenshots

History

None yet, but lots to come!