WPF Tutorial : Dependency Property

WPF comes with a lots of new features and alternatives that the normal windows applications do not have. As we have already discussed some of the features of WPF, its time to go a bit further to introduce other new features. After reading the previous articles of this tutorial, I hope you are more or less familiar with WPF architecture, borders, Effects, Transformation, Markup extensions etc.

So in this article I am going to introduce you with a new property system that underlay the WPF property system. We will go further to introduce how easily you can use these properties to produce custom callbacks, create attached properties, apply animations and styles etc using the all new Dependency properties.  Finally we will discuss about Binding alternatives that were left behind in the previous article to finis it totally. I hope you will like this article as well as you did for all the tutorials that I provided.

A new Property System

Well, you must have surprised to to see this title. Yes, WPF comes with a completely new technique of defining a property of a control. The unit of the new property system is a Dependency property and the wrapper class which can create a Dependency property is called a DependencyObject. We use to register a Dependency property into the property system to ensure that the object contains the property in it and we can easily get or set the value of those properties whenever we like. We even use normal CLR property to wrap around a dependency property and use GetValue and SetValue to get and set values passed within it.

This is almost same as CLR property system. So what is the advantages of the new property system. Lets see the difference between Dependency property and CLR property.

To Work with dependency property, you must derive the class from DependencyObject as the whole observer which holds the new Property System is defined within the DependencyObject.

Difference between Dependency property and CLR property

CLR property is just a wrapper around private variables. It uses Get / Set methods to retrieve and store value of a variable into it. So to be frank with you a CLR property gives you only one block in which you can write code to invoke whenever a property is get or set. Hence CLR property system is fairly straight forward.

On the other hand, the capabilities of Dependency property system is huge. The idea of Dependency property is to compute the value of the property based on the value of other external inputs. The external inputs might be styles, themes, system properties, animations etc. So, you can say a dependency property works with most of the WPF inbuilt features that were introduced.

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