inherit style from default style

Question

In my project there is a custom style for text box. It is defined as:

<Style TargetType="TextBox"/>

So it is applied to all text box child controls by default.

I need to create another style that is based on default style. But how do I specify in the BasedOn attribute that my new style should use the default style?

Solution 1

Use the type of the control you would like to extend

BasedOn="{StaticResource {x:Type TextBox}}"

Full example:

<Style x:Key="NamedStyle" TargetType="TextBox" BasedOn="{StaticResource {x:Type TextBox}}">
    <Setter property="Opacity" value="0.5" />
</Style>

Solution 2

@Aphelion has the correct answer. I would like to add that the order in which items are defined in the ResourceDictionary matter.

If you override the default style of a slider and you want to base another slider style on that, you must declare the "based on" slider after the override style.

For example, if you do this:

<Style x:Key="BlueSlider" TargetType="{x:Type Slider}" BasedOn="{StaticResource {x:Type Slider}}">
    <Setter Property="Background" Value="Blue"/>
</Style>

<Style TargetType="{x:Type Slider}">
    <Setter Property="Foreground" Value="Yellow"/>
</Style>

BlueSlider will have a blue background with the default (white) foreground.

But if you do this:

<Style TargetType="{x:Type Slider}">
    <Setter Property="Foreground" Value="Yellow"/>
</Style>

<Style x:Key="BlueSlider" TargetType="{x:Type Slider}" BasedOn="{StaticResource {x:Type Slider}}">
    <Setter Property="Background" Value="Blue"/>
</Style>

BlueSlider will have a blue background and a yellow foreground.

Comments

[honzakuzel1989]

You needn't set x:Key if you want apply additional changes (opacity in your case) automatically (without style name).

[Myrtle]

@honzakuzel1989 that's true indeed. It depends on the use case whether you want the key to be set.

[bunkerdive]

How about in uwp, where x:Type does not exist?

[bunkerdive]

Thanks. What if the style is for some inherited control class, like MyButton : Button? The x:Type would be helpful here, but now, I'm assuming it must be done in the code-behind for the custom class?

[bunkerdive]

I'm thinking something like this can be used in the ctor: this.DefaultStyleKey = typeof(Button); And then the style can be defined per usual. I'll give it a try.