I am currently implementing SemanticZoom for a Windows UWP app. As you may know, items will be grouped into different section (e.g. Group A, Group B, etc.)
The Group name will be the header.
I have changed the default style for SemanticZoom Group Header. Too bad I still can't figure out how to change the height of the header.
Screenshot:
The height of the header is too high for my taste
The Code for the custom SemanticZoom Style
<Style TargetType="GridViewHeaderItem">
<Setter Property="FontFamily" Value="Segoe UI" />
<Setter Property="Background" Value="#ff00fe"/>
<Setter Property="HorizontalContentAlignment" Value="Left" />
<Setter Property="VerticalContentAlignment" Value="Top" />
<Setter Property="Height" Value="10"/>
<Setter Property="UseSystemFocusVisuals" Value="True" />
<Setter Property="Margin" Value="0 10 10 0"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="GridViewHeaderItem">
<StackPanel Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}">
<ContentPresenter x:Name="ContentPresenter"
Margin="{TemplateBinding Padding}"
Content="{TemplateBinding Content}"
ContentTemplate="{TemplateBinding ContentTemplate}"
ContentTransitions="{TemplateBinding ContentTransitions}"
HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"/>
</StackPanel>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
XAML Code for the SemanticZoom
<SemanticZoom >
<SemanticZoom.ZoomedOutView>
<GridView>
...
</GridView>
</SemanticZoom.ZoomedOutView>
<SemanticZoom.ZoomedInView>
<GridView>
<GridView.ItemTemplate>
....
</GridView.ItemTemplate>
<GridView.GroupStyle>
<GroupStyle>
<GroupStyle.HeaderTemplate>
<DataTemplate>
<StackPanel Orientation="Vertical">
<TextBlock Text='{Binding Key}' Foreground="Black" FontSize="38" />
</StackPanel>
</DataTemplate>
</GroupStyle.HeaderTemplate>
</GroupStyle>
</GridView.GroupStyle>
</GridView>
</SemanticZoom.ZoomedInView>
</SemanticZoom>
Looking forward to your help.


There's couple properties you should set for your custom template: MinHeight and Padding.
The default GridViewHeaderItem template can be found from C:\Program Files (x86)\Windows Kits\10\DesignTime\CommonConfiguration\Neutral\UAP\10.0.10240.0\Generic
From there you can find the things you should change:
Here's the full default style for GridViewHeaderItem.