I am new to using styles, resources and templates in WPF. What I need to do is override the ToggleButton +/- in the TreeView to be an image, with a different image for each TreeViewItem root Node. For Instance, I would want an image of a car for the “Car” node, and an image of an airplane for the “Plane” node. I have a colorful and a grayscale image of each (for expanded/collapsed).
I’ve found styles to override the treeview and get the image set for the toggle button, but I am not sure the best way to style each item differently.
the style code for an item is quite long, so I’m pretty sure there’s a better way than copy/pasting the full style just to change the source property.
Could someone please point me in the right direction on the best way to do this?
Thank you.
Here’s the style I’ve been playing with, which was copied from a different post and altered for my images.
<Style x:Key="TreeViewItemFocusVisual">
<Setter Property="Control.Template">
<Setter.Value>
<ControlTemplate>
<Rectangle/>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style x:Key="ExpandCollapseToggleStyle" TargetType="{x:Type ToggleButton}">
<Setter Property="Focusable" Value="False"/>
<Setter Property="Width" Value="16"/>
<Setter Property="Height" Value="16"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ToggleButton}">
<Border Width="16" Height="16" Background="Transparent">
<Border Width="16" Height="16" SnapsToDevicePixels="true" Background="{DynamicResource {x:Static SystemColors.WindowBrushKey}}" BorderBrush="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}" BorderThickness="1">
<Image x:Name="ExpandImg" Width="16" Height="16" Source="/MyApp;component/Images/Icons/Grayscale/car.ico" />
</Border>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsChecked" Value="True">
<Setter Property="Source" TargetName="ExpandImg" Value="/MyApp;component/Images/Icons/Color/car.ico"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style x:Key="TreeViewItemStyle1" TargetType="{x:Type TreeViewItem}">
<Setter Property="Background" Value="Transparent"/>
<Setter Property="HorizontalContentAlignment" Value="{Binding HorizontalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}"/>
<Setter Property="VerticalContentAlignment" Value="{Binding VerticalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}"/>
<Setter Property="Padding" Value="1,0,0,0"/>
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}"/>
<Setter Property="FocusVisualStyle" Value="{StaticResource TreeViewItemFocusVisual}"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TreeViewItem}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition MinWidth="19" Width="Auto"/>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition/>
</Grid.RowDefinitions>
<ToggleButton x:Name="Expander" Style="{StaticResource ExpandCollapseToggleStyle}" ClickMode="Press" IsChecked="{Binding IsExpanded, RelativeSource={RelativeSource TemplatedParent}}"/>
<Border x:Name="Bd" SnapsToDevicePixels="true" Grid.Column="1" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Padding="{TemplateBinding Padding}">
<ContentPresenter x:Name="PART_Header" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" ContentSource="Header"/>
</Border>
<ItemsPresenter x:Name="ItemsHost" Grid.Column="1" Grid.ColumnSpan="2" Grid.Row="1"/>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsExpanded" Value="false">
<Setter Property="Visibility" TargetName="ItemsHost" Value="Collapsed"/>
</Trigger>
<Trigger Property="HasItems" Value="false">
<Setter Property="Visibility" TargetName="Expander" Value="Hidden"/>
</Trigger>
<Trigger Property="IsSelected" Value="true">
<Setter Property="Background" TargetName="Bd" Value="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}"/>
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.HighlightTextBrushKey}}"/>
</Trigger>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="IsSelected" Value="true"/>
<Condition Property="IsSelectionActive" Value="false"/>
</MultiTrigger.Conditions>
<Setter Property="Background" TargetName="Bd" Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}"/>
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}"/>
</MultiTrigger>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
<Trigger Property="VirtualizingStackPanel.IsVirtualizing" Value="true">
<Setter Property="ItemsPanel">
<Setter.Value>
<ItemsPanelTemplate>
<VirtualizingStackPanel/>
</ItemsPanelTemplate>
</Setter.Value>
</Setter>
</Trigger>
</Style.Triggers>
</Style>
Well, unfortunately, that’s the way WPF works. If you want to change the Style of the default controls, you’re most likely bound to work with a bunch of Style declarations (as you’ve posted above) and make some changes on it.
Using Expression Blend makes it a bit easier since you’ll have a UI designer that you can use to easily modify your styles. But behind the scenes, it still has the Style declarations. As an example, here’s what I got doing your requirements using Blend:
Anyway, I hope this helps.
EDIT:
Ok, I noticed that the code I posted is much like what you posted in your example. But I assure you, I used expression blend to make the modifications above. And I guess that just proves the point: you’re bound to work with a bunch of Style declarations, whether using Blend or not. =)
EDIT2:
Window.xaml
Code-behind:
ViewModels