World of dualities

Using custom vector data for app bar buttons in WinRT XAML - revisited

noreply@blogger.com (Krishna) — Sat, 13 Oct 2012 14:26:00 +0000

Windows 8 store apps have this concept of an App Bar where you host buttons that allow the user to perform various actions / commands.

In my app, it looks like this:

As you can see, I have two types of buttons. On the right, I have a regular appbar button that is styled based on glyphs that come from a font. So the ' + ' is just text. On the left, I have custom vector graphics I pulled from Syncfusion’s Metro Studio. The styles are slightly different because I've not yet got around to setting the proper opacity for the buttons on the right.

Anyway, in WinRT XAML, which I used to make this app, I used a style for the buttons on the left that looks something like this:

To get it to look right and work with mouse over / click styling, I had to override the entire control template for each button - ugly! Then I saw Tim Heuer's blog post on using vector data explaining why the problem occurs and how to solve it - in a very elegant way without duplicating the entire control template for each button.

However, I was still not fully satisfied with the final result where you define buttons as follows:

I still wasn't happy enough with the part where you define the full path data in the button's content property. I prefer to keep that sort of a thing in a style resource. So, I modified it to bind the button's style to a view model property and use a value converter to return the appropriate style (which is defined as a resource in a XAML file):

- A common path based app bar button base style (basically the same thing shown in Tim's blog post)

- Binding a view model's stylekey property to a button's style property and using a value converter:

The button is bound to an object that looks like:

Finally, I have something that I'm happy with - cleanly seperated styles and working app bar buttons with custom vector-based icons. Till next time... happy coding!

Getting ItemClick and item selection to work together in the XAML GridView in Windows 8

noreply@blogger.com (Krishna) — Thu, 06 Sep 2012 14:14:00 +0000

The GridView control in the ~~Metro~~ Windows 8 XAML framework (@!#!$#@!! what's it called now?) is an interesting beast.

Most apps will use it to show collections of something.

In general, it is a pretty nifty control with lots of built-in features for various interaction modes (touch, mouse, keyboard) - but at times it can throw you a curve-ball. I was faced with such a situation when I wanted to handle the click event on an item and perform an action.
I could do something like the below.(Ok, in a serious app, I'd use something like a EventToCommand to make it more MVVM-y, testable etc, but this will suffice for showing the problem I'm describing:

But with the GridView, that doesn't work! You need to set the IsItemClickEnabled property to true to get ItemClick events:

So far so good. But now, the default item selection behaviour is lost! If item click is not enabled, the default GridView behaviour is to handle clicks / taps and select / de-select the item that was clicked/tapped.

If item click is handled then you need to handle selection yourself. To do that, just bind a property of the view model for the view to the selected item:

So there you have it! GridView with item click and selection working together.

Now, what if you want to handle multiple selections? Well, that's a post for another time :)

Happy coding...

HOWTO: Provide in-app help using HTML content in Windows 8 Metro-style apps (XAML)

noreply@blogger.com (Krishna) — Sun, 02 Sep 2012 09:46:00 +0000

In my Windows 8 XAML app, I was looking to provide some basic integrated help content. I had some simple requirements:

Provide integrated help that looks and feels like it is part of the app
Also provide help online for those who visit the apps' website to check it out
Avoid duplicating content
Be able to deliver updated help to the app after the it has been installed on a device
Always provide meaningful help content in the app even when there is no network connection available

To me, an easy choice was to create the help content using HTML, host it online - and have the app pull the content from the internet. This meant hosting a web browser control in XAML and providing some fallback in case there are connectivity problems or if the site isn't reachable for some reason.

To achieve this, I created a wrapper around the web browser control in WinRT XAML to display HTML content from my support website and fallback to local HTML resources shipped with the app. The key part of the control is to try to load a URL, and if that is not possible, try to show a local HTML file (packaged with the app).

Using the control is simple - just set the Url, and FallbackUrl:

The actual control is implemented as follows:

That's it - and you have a quick and easy way to show some simple HTML content from the web in your XAML app - which is useful for things like in-app help.

I've hosted the sample on github: https://github.com/krishna-nadiminti/code-musings/tree/master/Metro.Controls if you want to check it out.

Hosting WCF services in an Azure worker role

noreply@blogger.com (Krishna) — Wed, 02 Mar 2011 10:58:00 +0000

I've been trying to get a bunch of WCF services running inside a Azure worker role instance - and so far, had major problems getting it to work. For some reason, many of the posts/samples/discussions on the interwebz keep talking about the same types of designs:

Host a public facing WCF service in a web role (almost always a http/s based binding)
Host an internal WCF in a worker role (generally using something like a netTcpBinding)

As any fan of WCF knows, there are many more scenarios in which WCF can be used and in some cases you may want to host a public facing service in a worker role. That's where the fun starts! (for anyone used to doing WCF outside Azure)

It appears that the current version of the Azure load balancer/SDK (v.1.3 - as of Feb 2011), doesn't like public http endpoints on worker roles very much. After tweaking a lot of settings/configuration, I came across this blog post from Christian Weyer - that explains it well. Unfortunately, the scenario I want (public facing http WCF service from a worker role) is not possible today - and that post does not highlight that enough - so I wanted to publish this to make it obvious.

So folks -

With Azure SDK v.1.3, as of Feb 2011, HTTP WCF endpoints on Worker roles don't work

There - that is now obvious to anyone who stumbles across this post.

Till next time...happy coding...

Day 3 - Melbourne BizSpark Event Feb 4-6 2011

noreply@blogger.com (Krishna) — Sun, 06 Feb 2011 02:17:00 +0000

Day 3 - final day of the BizCamp - and totally action packed. I can feel the tension and excitement in the air. Tweets, coding, presentations, talk about raising funds from VCs by @jackdelosa - its all happening @ #WABizCamp.

From my side, there is some good news - got the Utilify Platform working on the dev fabric locally. Deploying to Azure causes problems still with the Manager. But now I know what the problem is - so shouldn't be hard to fix from here. But for today, I'll concentrate a bit on the presentation, perhaps give the xbox competition a final shot - but the guys who are now leading @gofurtherproj definitely win my appreciation and bonus points for thinking about an FB fan page. Quality > quantity always.

...

Just returned (2 PM) from an amazing talk on raising capital for early-stage startups. Pure gold as one of the guys put it - lots of very very pracital + valuable advice on pitching, networking, and thinking about raising capital.

Right, so @ceibner just put me in the 3.15 PM slot for the practice presentation. Hopefully I've got everything they're looking for. More likely I might be way off the mark. Atleast I'll learn something. And this should give #utilify the push it needs to get out of 1st gear!

Just realised this post has turned into a stream of my current thoughts. I think I'll keep it that way - and go back to updating the notes for the whole event again after I settle down in a few days :)

For now... looking forward (with excitement and a little nervousness) to the practice presentations and the feedback. (and hopefully a prize! :P)

----------

Back from my presentation. It went rather well. Very *very* pleased with the entire event. Just when I thought I've got everything there was from the event, the presentation, questions, and the tips were extremely useful. A great confidence building exercise!

In fact most of the presentations were very good. Some of them even had live demos! Amazing how many teams thought up and built an almost viable biz idea in 2 days!

The winners are announced! The best pitch+app for the event is...

http://www.rome2rio.com

Rome2Rio is an intelligent travel search engine that finds the best modes of transport from A to B anywhere in the world, and includes flights, trains, buses, cars...and so on. Cool UI - go check it out. Congratulations to the Rome2Rio team on a solid achievement.

Sadly no prize for me - but on the upside, I've learnt a great lot in 3 days. Overall, very happy with the event.

More details and all the noise about the camp, checkout #WABizCamp

Day 2 - Melbourne BizSpark Event Feb 4-6 2011

noreply@blogger.com (Krishna) — Sat, 05 Feb 2011 23:28:00 +0000

Day 2 started off bad for me - with the rain, train cancellations and additional drama as I tried to get to the Microsoft office in Southbank. After all that, I managed to get there by about 11.30 AM - and saw everyone heads down cranking out code, drawing designs on the white board, brainstorming whatnot - there must have been a heavy concentration of brain power used in the building on a Saturday!

The day was meant for developing a business idea into a (hopefully) working prototype - preferably using as much of Windows Azure as possible. Most of the guys set out building web apps - and I was obviously going to attempt porting the Utilify Platform to Azure.

There was also a talk by Ross Hill (from the Hive), which I attempted to summarise at the BizSpark_AU Startup Camps group page.

Anyway, after that my 'port to Azure'

It turned out to be much much more difficult than expected (what with me getting distracted with Twitter) and I was getting frustrated with WCF and Azure -technologies I thought I knew reasonably well! (atleast the WCF and networking parts of Azure). It turns out there's a few tweaks that need to be done to self-hosted (and IIS hosted - I think) WCF services to make them run and actually talk through the load balancer. I'll write up a more detailed post later on with what I learnt and the how I went through the process. For now, just wanted to record that it was an absolute nightmare (mainly because I didn't understand why things were failing ;)

With Steve's (@snagi) help though, I managed to eventually spot the problem and got things working *on my machine* ;) by 1.30 AM (yep - AM).

There were a whole bunch of interesting attempts to make more noise on twitter -including an automated tweet web app (part of a larger app) that one of the guys built on Azure! Cheeky! Well, I guess the XBox is calling. (That's the prize on day 3 for those who make the most noise).
So far I seem to be doing well. Will I land an XBox? Stay tuned to find out...

Day 1 - Melbourne BizSpark Event Feb 4-6 2011

noreply@blogger.com (Krishna) — Sat, 05 Feb 2011 06:45:00 +0000

Microsoft Australia is conducting a 3-day event for budding techonology entrepreneurs at their office in Melbourne between Feb 4 and 6, 2011. More details of the event at http://blogs.msdn.com/b/ceibner/archive/2011/01/25/melbourne-azure-bizspark-startup-camp-final-agenda-announced.aspx .

Here's what happened on Day 1 - from my eyes:

Graham (@grahamelliott) and Mitch (@MitchDenny) went through a *lot* of Azure platform and SDK stuff in good detail. (Luckily for me, I studied a good part of that for the Azure beta exam a few months ago).
Things like table storage design strategies, blobs and queues went discussed
The RDBMS guys in the audience were pretty shocked at suggestions to denormalise data, and let go of column indices!
I was hoping to find out if Microsoft were going to offer an API / feature in Azure to allow service providers to automatically measure resource usage by their customers and bill them for it (like Amazon's DevPay) - and surprise surprise! They will have a simple bill-on-behalf type feature provided via the Azure Marketplace. (No word on timelines, feature details though)
Graham mentioned Zuora (zuora.com) and Metanga (metanga.com) as potential services that ISVs and SaaS providers could use to measure bill their customers' Azure usage. Eager to check them out. (Utilify could easily use something like that - DevPay has been a pain to setup - providers have to be US-based -hello 1990!)
The tweet-fest begins in earnest ;) : after all there's an XBox to win!

Overall a very technical and satisfactory day of training. (Side note: no vegetarian food for lunch :/ - but the pasta in the restaurant next to the Microsoft building was good :)

More thoughts may emerge as I recollect what else happened on the day.