Added new kb article adjusting-treeview-row-height-expand-button-margin

Author: KB Bot

knowledge-base/adjusting-treeview-row-height-expand-button-margin.md

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+---
+title: Adjusting TreeView Row Height and Expand Button Margin
+description: Learn how to set the row height and adjust the margin of the expand button in the TreeView for UI for .NET MAUI.
+type: how-to
+page_title: Setting Row Height and Customizing Expand Button Margin in TreeView
+meta_title: Setting Row Height and Customizing Expand Button Margin in TreeView
+slug: adjusting-treeview-row-height-expand-button-margin
+tags: treeview, .net maui, row height, expand button, styling
+res_type: kb
+---
+
+## Environment
+
+| Version | Product | Author | 
+| --- | --- | ---- | 
+| 11.1.0 | Telerik UI for .NET MAUI TreeView | [Dobrinka Yordanova](https://www.telerik.com/blogs/author/dobrinka-yordanova) | 
+
+## Description
+
+I want to limit the row height in the [TreeView](https://www.telerik.com/maui-ui/documentation/controls/treeview/overview) and adjust the margin of the expand button.
+
+This knowledge base article also answers the following questions:
+- How to set a definitive row height in TreeView?
+- How to customize the margin of the expand button in TreeView?
+- How to apply styles to TreeView items and buttons?
+
+## Solution
+
+To set a definitive height for rows and adjust the margin of the expand button in TreeView, apply custom styles using `ItemStyle`. Follow these steps:
+
+1. Define a style for the TreeView item button (`TreeViewItemButton_Style`) to customize properties such as margin, padding, height, and width.
+
+```xaml
+<Style x:Key="TreeViewItemButton_Style"
+       TargetType="telerik:TreeViewItemButton">
+    <Setter Property="BackgroundColor" Value="Transparent" />
+    <Setter Property="Margin" Value="5" />
+    <Setter Property="WidthRequest" Value="{OnPlatform Android=48, iOS=44, MacCatalyst=24, WinUI=26}" />
+    <Setter Property="HeightRequest" Value="{OnPlatform Android=48, iOS=44, MacCatalyst=24, WinUI=26}" />
+</Style>
+```
+
+2. Create a style for the expand button (`TreeViewItemExpandButton_Style`) based on the button style. Customize the appearance of the expand button.
+
+```xaml
+<Style x:Key="TreeViewItemExpandButton_Style"
+       TargetType="telerik:TreeViewItemExpandButton"
+       BasedOn="{StaticResource TreeViewItemButton_Style}">
+    <Setter Property="Text" Value="{x:Static telerik:TelerikFont.IconEmpty}" />
+    <Setter Property="VisualStateManager.VisualStateGroups">
+        <VisualStateGroupList>
+            <VisualStateGroup Name="ExpandStates">
+                <VisualState Name="Expanded">
+                    <VisualState.Setters>
+                        <Setter Property="Text" Value="{x:Static telerik:TelerikFont.IconDownArrow}" />
+                    </VisualState.Setters>
+                </VisualState>
+                <VisualState Name="Collapsed">
+                    <VisualState.Setters>
+                        <Setter Property="Text" Value="{x:Static telerik:TelerikFont.IconRightArrow}" />
+                    </VisualState.Setters>
+                </VisualState>
+            </VisualStateGroup>
+        </VisualStateGroupList>
+    </Setter>
+</Style>
+```
+
+3. Define a style for the TreeView item view (`TreeViewStyle`) to set row height and apply the custom expand button style.
+
+```xaml
+<Style x:Key="TreeViewStyle" TargetType="telerik:TreeViewItemView">
+    <Setter Property="Margin" Value="10,0" />
+    <Setter Property="HeightRequest" Value="60" />
+    <Setter Property="ExpandButtonStyle" Value="{StaticResource TreeViewItemExpandButton_Style}" />
+</Style>
+```
+
+4. Apply the styles to the RadTreeView definition.
+
+```xaml
+<telerik:RadTreeView x:Name="treeView" Grid.Row="1"
+                     AutomationId="treeView" ItemStyle="{StaticResource TreeViewStyle}"
+                     ItemsSource="{Binding TreeData}">
+    <telerik:TreeViewDescriptor DisplayMemberPath="Name"
+                                ItemsSourcePath="Children"
+                                TargetType="{x:Type local:TreeDataItem}" />
+    <telerik:RadTreeView.BindingContext>
+        <local:MainPageViewModel/>
+    </telerik:RadTreeView.BindingContext>
+</telerik:RadTreeView>
+```
+
+## See Also
+
+- [TreeView Overview](https://www.telerik.com/maui-ui/documentation/controls/treeview/overview)
+- [TreeView Styling Documentation](https://www.telerik.com/maui-ui/documentation/controls/treeview/styling/item-style)