Windows Phone 7.5 - Home button Navigation and Exit Confirmation

While developing a windows phone application, the one which involves navigation to various pages starting from something called as a homepage would quickly become annoying. You will find yourself in deeper pages and as a means on coming back to the home page, you will keep pressing the back button so many times it will exit you out of the application.

There are couple of problems associated with this. The user is forced to keep in mind how deep he has in the navigation page. The other main problem is he will not have patience to wait to go to the home page and pressing the back button on the first page will obviously throw you. This is because the navigation details are stored in a stack.

It is always nice to provide a home button to the end user on all the pages so that on click of them will take it to the home. Also, you can always have a confirmation dialogue fired while exiting the application. First problem first.

This code armed with a Home button will do the job cleanly for you.

private void Home_Click(object sender, System.Windows.RoutedEventArgs e)
{
    int depth = NavigationService.BackStack.Count();
    for (int i = 0; i < depth - 1; i++) { NavigationService.RemoveBackEntry(); }
    NavigationService.GoBack();
}

The funda here is it will empty all the stack and will call the back action of the navigation service just once making sure that the next back() will empty the stack and will make you quit.

As I told before adding this code to the MainPage.xaml.cs will show a confirmation popup while quitting the application so that user only deliberately quits but not accidentally.

protected override void OnBackKeyPress(System.ComponentModel.CancelEventArgs e)
{
    if (MessageBox.Show("Are you sure you want to exit?", "Exit?", MessageBoxButton.OKCancel) != MessageBoxResult.OK)
    {
        e.Cancel = true;
    }
}

These techniques are very simple and subtle but will improve the usability of your application by leaps and bounds.

Cheers!
Braga

Windows Phone 7.5 WebBrowserTask - Simple Yet Powerful

WebBrowserTask is one of the most simple yet powerful tasks I found in Windows Mobile development. It is amazingly simple, just two or three lines of code and super tempting to include it in your project. Lets quickly see how to use it and places where you can utilize its capability at the presentation level.

Enough intro, here is the code

WebBrowserTask pptTask = new WebBrowserTask();
pptTask.Uri = new Uri("http://www.iasted.org/conferences/formatting/presentations-tips.ppt");
pptTask.Show();

Damn simple isnt it? You could use this in places where you need to launch or open an URL in the inbuilt Internet Explorer. And the best thing about this is it will automatically detect the attachment file types (most of them) and opens them cleanly. For example, it could read ppt, pdf, xls even videos and open them cleanly. You can make the integration look rich by providing a button in the Application bar. Following is a screenshot.

Besides opening simple URLs consider using this Task to open regular attachments and make your end application look extremely rich with just one or two lines of code.

Cheers!

Braga

Windows Phone 7.5 - ShareStatusTask's Limitations

The Microsoft.Phone.Tasks namespace in Windows phone 7 is a neat way to access the default phone specific tasks. One such task is the ShareStatusTask. If you want to say share your status on facebook or twitter or to windows live account, you can do it in one shot.

The code looks very simple,

Very cool isnt it. But the usage of this kind of limited. You will have to have all the accounts configured already in your phone settings. I was looking for a direct solution to just provide a way to tweet. But it was not possible to tell the ShareStatusTask to open it only if it has Twitter. I had asked this question in Stackoverflow only to double confirm the above said point. This feature is not available in Emulator, hence posting a screenshot from a real device.

Anyways, this is one of the cool tasks available and just two to three lines will add social feature to your App, so do add it whatever be the case.

Cheers!
Braga

Windows Phone 7.5 - Rating/Review control Packages

There was a simple specification in my application that needs to have a Review feature. I started off with Google, but the irony here is the keyword "ratings" or "review" accompanied with Windows Phone 7 did not return results that I've been looking for. Instead it was returning the features and real reviews written for Windows Phone 7. The catch here was to convert my keyword to star rating control. I found some decent resources which are implementable, let me summarize them.

1) Silverlight Star Rating Control - This had most of the meat I was looking for. It was actually designed for silverlight and not really tested in Mobile or I can put it like I was not able to find snippets for Mobile implementation. However, it worked alright. The problem was that this package was not having a mechanism to NOT have the Half-Star Mechanism. Going through the source code confirmed that and I do not want to build a new dll out of it and include it in my project. So gave this up. But I would highly recommend this for web client.

2) The next one I stumbled upon was from a guy Jani Nevalainen. He has blogged it in his website and it had what I needed. But since it was not on a codeplex site/github, and due to its lack of documentation or support I had to push it down the priority list. I have not tried this, but my gut says it will surely work.

3) Another one which really looked promising was from a blogger named Matthieu. I thought it had everything and even the source on Github and the demo project worked flawlessly. I was expecting for a library file so that I could include it in my project and breathe easily. Unfortunately, that was not something already available. Yes, I can go through the code and compile a source out of it. But I was really lazy to do so. Hence dropped it. But I have to say this was a really good and careful implementation. Kudos to the Author.

4) And the winner was Coding4Fun! The most sexy and the most famous library for the Windows phone 7.5. It has everything and the forums are really great! Every week you can see builds coming and they are very much responsive to the features that you are suggesting. I could not say that this is the Open source folks' answer to Telerik, but this library is really good. I used their super slider to design my review page. I know it is not like the star mechanism, but still this did the job and it did really great for me!

Cheers!
Braga

Exception Handling in Windows Phone 7 - When all else fails

I was recently testing something with Toast Notifications with Windows Phone 7.1. Visual Studio that I use has amazing debugging features like any other IDE available IDE out there. Here was scenario. I need to send two types of Notifications Raw and Toast Notifications to my mobile and need to assert scenarios. Debugging the Raw Notification was very simple. However, I was not able to debug/step into when I launch the application after clicking the toast Notifcation.

It was really painful not to be able see any exception message. It was very annoying. Then I found a way to at least know what is happening. To do that, you can just go the App.xaml.cs file which has all the main entry and exit points to the application. To read more about this, just google life cycle of a windows phone app.

All I had to do was add a message box to the method Application_UnhandledException in the App.xaml.cs.

private void Application_UnhandledException(object sender, ApplicationUnhandledExceptionEventArgs e)
{
    MessageBox.Show(e.ExceptionObject.Message + "\n" + e.ExceptionObject.StackTrace);
    if (System.Diagnostics.Debugger.IsAttached)
    {
        // An unhandled exception has occurred; break into the debugger
        System.Diagnostics.Debugger.Break();
    }
}

Problem Solved. Now I could see the error messages/exception stack trace in a neat Message box!

Cheers!
Braga