Question

I have several elements and all of them should look the same if “X”. The problem is, “X” is different for each element, so I can’t easily use a shared style for them. But in all cases, the setters are the same, so I would like to have them all in one place. How can I achieve that?

More concretely, I have this code:

<TextBlock Name="text1">
    <TextBlock.Style>
        <Style TargetType="TextBlock">
            <Style.Triggers>
                <DataTrigger Binding="{Binding SelectedMonth, Converter={conv:IsNullConverter}}"
                             Value="False">
                    <Setter Property="Background" Value="RoyalBlue" />
                    <!-- possibly other setters -->
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </TextBlock.Style>
</TextBlock>
<TextBlock Name="text2">
    <TextBlock.Style>
        <Style TargetType="TextBlock">
            <Style.Triggers>
                <DataTrigger Binding="{Binding IsSelected}" Value="True">
                    <Setter Property="Background" Value="RoyalBlue" />
                    <!-- possibly other setters, same ones as above -->
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </TextBlock.Style>
</TextBlock>

Here, I would like to put the two Setters to some common place, so that I wouldn’t have to always change them one by one. Is there some way to do that?

I tried putting a collection of Setter together and then using something like DataTrigger.Setters="{StaticResource SharedSetters}". This doesn’t work, but if it did, it would be exactly what I want.

Answer 1

First of all, you could have a common style which would be the base (BasedOn attribute) for all the other styles. This style would contain a normal Trigger which is controlled by a custom boolean attached property, and the setters you want to reuse. Then, in the other styles, which are based on the base style, your DataTriggers would only set the attached property, and let the base style set all the other properties.

Assuming you have created the attached property IsSelected on the type Foo, the base style would look something like:

<Style x:Key="IsSelectedStyle" TargetType="TextBlock">
    <Style.Triggers>
        <Trigger Property="local:Foo.IsSelected" Value="True">
            <Setter Property="Background" Value="RoyalBlue" />
            <!-- possibly other setters -->
        </Trigger>
    </Style.Triggers>
</Style>

And then you would use it like this:

<TextBlock>
    <TextBlock.Style>
        <Style TargetType="TextBlock" BasedOn="{StaticResource IsSelectedStyle}">
            <Style.Triggers>
                <DataTrigger Binding="{Binding IsSelected}" Value="True">
                    <Setter Property="local:Foo.IsSelected" Value="True" />
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </TextBlock.Style>
</TextBlock>