WPF Mouseover Trigger Effect for Child Controls

Question

Lets say I have this bit of code:

<Window>
    <Window.Resources>
        <Color x:Key="MyColor"
               A="255"
               R="152"
               G="152"
               B="152" />
        <DropShadowEffect x:Key="MyEffect" 
                          ShadowDepth="0"
                          Color="{StaticResource MyColor}"
                          BlurRadius="10" />
        <Style x:Key="MyGridStyle"
               TargetType="{x:Type Grid}">
            <Setter Property="Height"
                    Value="200" />
            <Setter Property="Width"
                    Value="200" />
            <Style.Resources>
                <Style TargetType="{x:Type TextBlock}">
                    <Setter Property="Width"
                            Value="100" />
                </Style>
                <Style TargetType="{x:Type Image}">
                    <Setter Property="Height"
                            Value="100" />
                    <Setter Property="Width"
                            Value="100" />
                </Style>
            </Style.Resources>
            <Style.Triggers>
                <Trigger Property="IsMouseOver"
                         Value="true">
                    <!-- How do I apply my effect when this grid is hovered over to Image and TextBox, but not the grid itself? -->
                </Trigger>
            </Style.Triggers>
        </Style>
    </Window.Resources>
    <Grid Style="{StaticResource MyGridStyle}">
        <Grid.RowDefinitions>
            <RowDefinition />
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition />
            <ColumnDefinition />
        </Grid.ColumnDefinitions>
        <Image Grid.Row="0"
               Grid.Column="0"
               Source="image.png" />
        <TextBlock Grid.Row="0"
                   Grid.Column="0"
                   Text="Hover Over Me" />
    </Grid>
</Window>

Basically I have a Style applied to the Grid that says any TextBlock or Image within it should be styles to a certain size.

I want to create a Trigger on the Grid that causes an effect to be applied to all TextBlocks and Images within the Grid, but not to the Grid itself.

I can apply the Trigger directly to TextBlock and/or Image, but then the effect only occurs on each element separately. I need to have the effect occur to any TextBlock and/or Image within the Grid despite which inner child element I am hovered over.

Can anyone help me with this?

Fredrik Hedblad Fredrik Hedblad · Accepted Answer · 2011-10-05T20:19:31

You can do it the other way around. That is, add DataTriggers to Image and TextBlock and make them trigger on IsMouseOver for the ancestor Grid.

Note: If you want this effect to trigger as soon as the mouse is over the Grid you will need to set Background to a value, like Transparent. By default, the Background is null and this value isn't used in hit testing.

<Style x:Key="MyGridStyle" TargetType="{x:Type Grid}">
    <!--<Setter Property="Background" Value="Transparent"/>-->
    <Setter Property="Height" Value="200" />
    <Setter Property="Width" Value="200" />
    <Style.Resources>
        <Style TargetType="{x:Type TextBlock}">
            <Setter Property="Width" Value="200" />
            <Style.Triggers>
                <DataTrigger Binding="{Binding RelativeSource={RelativeSource AncestorType=Grid},
                                               Path=IsMouseOver}" Value="True">
                    <Setter Property="Effect" Value="{StaticResource MyEffect}"/>
                </DataTrigger>
            </Style.Triggers>
        </Style>
        <Style TargetType="{x:Type Image}">
            <Setter Property="Height" Value="200" />
            <Setter Property="Width" Value="200" />
            <Style.Triggers>
                <DataTrigger Binding="{Binding RelativeSource={RelativeSource AncestorType=Grid},
                                               Path=IsMouseOver}" Value="True">
                    <Setter Property="Effect" Value="{StaticResource MyEffect}"/>
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </Style.Resources>
</Style>

WPF Mouseover Trigger Effect for Child Controls

2 Answers