Simple answer is… it is just like a regular collection except that it implements a couple of pretty interesting interfaces, INotifyCollectionChanged and INotifyPropertyChanged. Let's dive in. Take a look below.   What is so special about the ObservableCollection then? When would you use it? The reason why you would use it, is the magic word called DataBinding, which is a lifesaver, especially when you are using Silverlight/WPF applications. To bind to any variable/class is easy. Th... [More]

The concept of dependency property is fascinating. I have seen a lot of confusion around it, and here is my take on it. Without further ado, let me take you to XAML, and its output. XAML <UserControl x:Class="Dependency_Sample.MainPage" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="h... [More]

There are a few ways in which you can easily create Trial applications for Windows Phone 7 marketplace. Here is what I prefer to do it fairly quickly.     Create a new Project or use an existing project. Select Configuration Manager     From the Active Solution Configuration drop down list, select New…     Name it Release_Trial, and copy the settings from Release.     Now, you will three options… Debug, Release a... [More]

Finally I was able to get Windows Marketplace account. Although the initial experience with the marketplace was a bit "hiccupy", I liked the creation piece of small utilities for my kid, Anika… whom I fondly call nikkul. I have hosted those utilities on Windows Phone 7 Marketplace, and you can find more details on www.nikkul.com… If you are a parent with young kids, you should check these out. Memory match is a game, where as the second one is a tool with which you can teach time ... [More]

So you have a XAML page, and in the code behind you have a couple of variables. How do you bind the elements with the local variables?     To begin with, you will need the property with which you can bind the XAML element.     Implement the following interface… INotifyPropertyChanged public event PropertyChangedEventHandler PropertyChanged; private void NotifyPropertyChanged(String info) { if (PropertyChanged != n... [More]

Windows Phone 7 doesn't support multiple MediaElement. In order to play multiple sounds in the same page, you may use the following approach.     Add a reference to Microsoft.Xna.Framework     Add the following using statements… using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Audio;     Add the sound files and ensure that Copy to Output directory is set to Content     Add the follow... [More]

Let's say you have an image like the following… Fig 1 And you want to clip it using a hexagon [see Fig 2]. Or may be a rectangle with rounded edges. Clipping an image using a Geometry makes it really easy for you. You can use Expression Blend and easily do the clipping. The problem arises if you have to do the same thing in code. Fig 2 In this post, you will see how easily it can be done in code. The code is annotated with comments, and I hope you will find it useful. using System; us... [More]

You’re invited to a very special event on December 2nd, 2010 Learn about the future of Silverlight from Corporate Vice President, Scott Guthrie and other experts, direct from Microsoft’s HQ. Hear about our plans for the next version of Silverlight, the latest developments as well as in-depth sessions on building applications with Silverlight. Registration is free – take part in-person or online. ... [More]

Check out the following XAML and notice the difference in Fill of the following three rectangles. <StackPanel> <Rectangle Stroke="Black" StrokeThickness="3" Width="100" Height="100" Margin="5" MouseLeftButtonUp="rect_MouseLeftButtonUp" Fill="Transparent" /> <Rectangle Stroke="Black" StrokeThickness="3" Width="100" Height="1... [More]

In the previous post, we discussed about how to use Application Library Caching and its benefits. Although it sounds beneficial, you need to keep in mind that the benefits are more from a re-visit perspective. Sometimes, your application will have a bunch of pages, may be nested… and hence you may not require some part of functionality right away. In that case, it might not be considered wise to create the structure in such a way that each and everything is loaded right from the word, Go! This ... [More]