Styles in WPF Introduction
We need to take care of following things while using styles –
2. Styles can be set in the following two ways which I will discuss later
- Named Style
- Targeted Style
3. Styles are decalred as resources so that they can be used by the elements below them in element tree.
Named Style
We can always declare a key for the style which can been used in the application down the element tree by specifying the key for the style. An example of the named style in the resource is shown below.
I have defined a style for the button in the window resource. As we can see in the snippet I have provided a name for the style using x:key element. Further I have defined values for number of styles using the Setter attribute. However we need to keep one point in mind while using named style is that while defining setter we need to provide the element name along with the propertyName in the property e.g. Button.Height as shown in the above code snippet. It doesn’t need to be the exact class name, it can also be the classes name from which the control derives e.g. Control.Height which in turn would help you to apply the property for any class down the Hierarchy derived from that control. If some of the properties are relevant for the target control they would be simply ignored. Now I will show how it can be used.
In the above code snippet I have used two button. One button explicitly uses the style defined in resources section of the window and other one is not at all using any style. When we run the application we can see the difference between the two buttons as shown in the figure below.
Targeted Styles
This style is designed to provide a style for some particular type of control only and is applied automatically to the elements of the type below the element tree in the declaration. Below is the code snippet for the targeted style.
The changes which we can notice from that of the names style are as following.
1. There is no x:Key.
2. We have used TargetType attribute.
3. In the setter we have removed the class name from Property attribute.
As soon as we apply this style in the resources section of the window both of the buttons which we have used in the previous section are changed as shown in the below figure, which shows that whatever elements come down in the element tree they take the style by default.
One more change I want to bring to your notice is that, if we are using targeted style in that case there is no need to use the Style attribute for the button as have used for the first button in Named Style.
Style Inheritance
Styles in WPF also supports inheritane much like the inheritance in the OOP. This can be done using the BasedOn property that must point to other style to inherit from. If there is a target type specified in the base style it must be specified in the derived style also. Please check the below code snippet to get more about the BasedOn Property.
And the output as shown in the figure below.
However it is not recommended to have more than one level of inheritance as it would be a nightmare to debug the changes if we have multiple levels.
Automatic Style
We can define a particular style for whole of the application for a single control by defining it in the App.xaml as shown below . These styles are created without key.
If we want to revert the default style for the control we need to set the style as null (x:Null in xaml) or set the style to another named style. We can also create a style based on the application style as shown below.
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