Tutorials

Introduction

Last month I wrote about how we could take some of the new features of Silverlight 4, Webcam control,  and create a simple application that lets you store captured webcam photos to isolated storage and your file system.

In this article we will take this proof of concept and demonstrate how through the use of commanding and binding we can virtually eliminate all code behind and implement to a strong MVVM architectural pattern.

Getting Started

I think few would argue with the value of a strong separation of concerns within the design of an application.

In the previous part of this article I introduced a custom Form control I made for some real world projects. I've briefly explained the reasons why I choose to not use the Silverlight Toolkit's DataForm, just before to show how to build this control, and I've also detailed what I like of the DataForm and what I should retain in my Form control.  One of this features is the validation of the input and it is what I'm about to describe in the second part.

Download Source Code

The databinding in Silverlight directly supports the validation through a couple of attributes, that let the developer specify if the markup extension has to notify validation exceptions to the control binded to a property so it can show the errors to the user.

Introduction

Let’s imagine a scenario in which you have a series of Excel files (.xlsx) on your computer but you don’t have any Microsoft Office installed. What can we do if we want to examine the content of these files?
In this article we will describe a small Silverlight application allowing you to open and view these files and also create line series graphs. I used this exercise as laboratory to familiarize myself with some of the new features of Silverlight 4 like, for instance, drag&drop of files from local folders to the application, drag&drop between controls in the application, right click event handling, theming and so on.

Working with DataForm I found difficult to use it in many scenarios due to its design. So I've created a control where I do not generate fields but I handle automatic validation and cancel/commit commands enabling also the usage of the control in mvvm scenarios. This is a good starting point to understand about Validation, BindingExpressions and traversing the visual tree.

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The first time I've met the DataForm control - it was some days after its beta release in the Silverlight Toolkit - I was really astounded from its power. It is capable of many wonders: it generates fields detecting the properties of the binded item, it automatically validates the input values using a bunch of attributes in a way similar to ASP.NET Dynamic Data, it manages the workflow passing through Edit, ReadOnly and Insert state, and these are only a small subset of the features it exposes.

Introduction

Some years ago (pre-silverlight times) a client ask me for a weird requirement…he wanted to drag files from his local explorer and drop them on their ASP .net grid application without using any ActiveX help… I thought, umm… is that possible?

With the advent of Silverlight 2 we got the same request again, … we knew this time it was not a technology limitation, it was a sandbox security limitation, how does the Ms chaps can offer this feature without exposing a security hole? Well it seems that they have managed to “open the box” for this feature in Version 4 on a secure and very easy to use way.

The first part of the article was about getting familiar with MEF (Managed Extensibility Framework) – to get to know the basics, define its core principles and apply those to an existing Gallery application to make it configurable through themes. This part will dig deeper into the framework.

MEF as an IoC Container?

MEF is not a replacement for an IoC container - they both address different scenarios and can be used in the same application. However, MEF sure can be used for dependency injection without having to resort to a proper IoC container.

During a recent work I found some trouble working with the TreeView control in a Model-View-ViewModel scenario. As usually happen, the standard controls are designed to work in an event-driven behavior and this non always marries with a correct MVVM implementation. After some work, I found a way to change the TreeView and transform it to be lazy loadable.

Download Source Code

The Model-View-ViewModel pattern has been introduced in Silverlight by few time and this platform lacks a complete support to the pattern by the standard controls.

1. Introduction

This is the second article of my series about Silverlight web services tricks. At first time I planned to write only about WCF and that is why I called my article series “Deep dive into WCF”, but with my last experience I decided to move away from mainstream and offer some new unusual stuff. That is why I have generalized name of this series to “Deep dive into Silverlight services”.

In this article I’m going to show how you can build a super fast REST web services using ASP.NET MVC and Google Protocol Buffers library.

Whenever a new version of Silverlight is released, I start examining its features from two perspectives: how would my current (and planned) LOB applications benefit from using these new features, and what cool new things can I build to entertain my children.

This article will guide you through the process of creating a doodling application (you know, for kids ;)), while covering some of the most visible (or not) new features, coming with Silverlight 4. But this is not just about new features, it’s about how they are prepared and served.