WPF - 使用样式为每个 TreeViewItem 根节点设置不同的 ToggleButton 图像

Question

我不熟悉在 WPF 中使用样式、资源和模板。我需要做的是将 TreeView 中的 ToggleButton +/- 覆盖为图像，每个 TreeViewItem 根节点使用不同的图像。例如，我想要一张汽车图像作为“汽车”节点，一张飞机图像作为“飞机”节点。我有每个图像的彩色图像和灰度图像（用于展开/折叠）。

我找到了覆盖树视图并获取切换按钮的图像集的样式，但我不确定以不同方式设置每个项目的最佳方式。

项目的样式代码相当长，所以我很确定有比复制/粘贴完整样式更好的方法来更改源属性。

有人可以为我指明正确的方向吗？

谢谢。

这是我一直在使用的风格，它是从另一篇文章复制的，并针对我的图像进行了更改。

    <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>

Answer 1

不幸的是，这就是 WPF 的工作方式。如果您想更改默认控件的样式，您很可能必须使用一堆样式声明（如您上面发布的）并对其进行一些更改。

使用 Expression Blend 会让事情变得更容易一些，因为您将拥有一个 UI 设计器，您可以使用它来轻松修改样式。但在幕后，它仍然有样式声明。作为一个例子，这是我使用 Blend 满足您的要求的结果：

<Window
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    x:Class="WpfApplication1.MainWindow"
    x:Name="Window"
    Title="MainWindow"
    Width="640" Height="480">
    <Window.Resources>
        <Style x:Key="TreeViewItemFocusVisual">
            <Setter Property="Control.Template">
                <Setter.Value>
                    <ControlTemplate>
                        <Rectangle/>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
        <PathGeometry x:Key="TreeArrow" Figures="M0,0 L0,6 L6,0 z"/>
        <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 Background="Transparent" Height="16" Padding="5,5,5,5" Width="16">
                            <Image x:Name="PART_Image" Source="Image1.jpg"/>
                        </Border>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsChecked" Value="False"/>
                            <Trigger Property="IsMouseOver" Value="True"/>
                            <Trigger Property="IsChecked" Value="True">
                                <Setter Property="Source" TargetName="PART_Image" Value="Image2.jpg"/>
                            </Trigger>
                        </ControlTemplate.Triggers>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
        <Style 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" ClickMode="Press" IsChecked="{Binding IsExpanded, RelativeSource={RelativeSource TemplatedParent}}" Style="{StaticResource ExpandCollapseToggleStyle}"/>
                            <Border x:Name="Bd" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.Column="1" Padding="{TemplateBinding Padding}" SnapsToDevicePixels="true">
                                <ContentPresenter x:Name="PART_Header" ContentSource="Header" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                            </Border>
                            <ItemsPresenter x:Name="ItemsHost" Grid.ColumnSpan="2" Grid.Column="1" 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>
    </Window.Resources>

    <Grid x:Name="LayoutRoot">
        <TreeView HorizontalAlignment="Left" Margin="8,8,0,105" Width="196">
            <TreeViewItem Header="Item1">
                <TreeViewItem Header="Item2"/>
            </TreeViewItem>
        </TreeView>
    </Grid>
</Window>

无论如何，我希望这会有所帮助。

编辑：

好的，我注意到我发布的代码与您在示例中发布的代码非常相似。但我向你保证，我使用了表达式混合来进行上述修改。我想这正好证明了这一点：无论是否使用 Blend，您都必须使用一堆 Style 声明。 =)

EDIT2:

Window.xaml

<Window x:Class="WpfApplication2.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:WpfApplication2"
        xmlns:sys="clr-namespace:System;assembly=mscorlib"
        Title="MainWindow" Height="300" Width="300">
    <Window.Resources>

        <HierarchicalDataTemplate x:Key="treeTemplate" 
                                  ItemsSource="{Binding SubItems}">
            <TextBlock Text="{Binding Name}"/>

            <HierarchicalDataTemplate.ItemTemplate>
                <DataTemplate>
                    <TextBlock Text="{Binding}"/>
                </DataTemplate>
            </HierarchicalDataTemplate.ItemTemplate>
        </HierarchicalDataTemplate>

        <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 Background="Transparent" Height="16"  Width="16">
                            <Image x:Name="PART_Image" Source="{Binding ImageSource}"/>
                        </Border>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>

        <Style x:Key="customTreeItemStyle" TargetType="{x:Type TreeViewItem}">
            <Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}"/>
            <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" ClickMode="Press" IsChecked="{Binding IsExpanded, RelativeSource={RelativeSource TemplatedParent}}" Style="{StaticResource ExpandCollapseToggleStyle}"/>
                            <Border x:Name="Bd" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.Column="1" Padding="{TemplateBinding Padding}" SnapsToDevicePixels="true">
                                <ContentPresenter x:Name="PART_Header" ContentSource="Header" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                            </Border>
                            <ItemsPresenter x:Name="ItemsHost" Grid.ColumnSpan="2" Grid.Column="1" 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>
    </Window.Resources>

    <TreeView x:Name="tree" 
              ItemTemplate="{StaticResource treeTemplate}"
              ItemContainerStyle="{StaticResource customTreeItemStyle}"/>

</Window>

代码隐藏：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace WpfApplication2
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        private List<ViewModel> items = new List<ViewModel>();

        public MainWindow()
        {
            InitializeComponent();

            ViewModelImpl1 vm1 = new ViewModelImpl1() { Name = "VM1" };
            vm1.SubItems.Add("SubItem1");
            vm1.SubItems.Add("SubItem2");
            vm1.SubItems.Add("SubItem3");

            ViewModelImpl1 vm2 = new ViewModelImpl1() { Name = "VM2" };
            vm2.SubItems.Add("SubItem1");
            vm2.SubItems.Add("SubItem2");
            vm2.SubItems.Add("SubItem3");
            vm2.SubItems.Add("SubItem4");

            ViewModelImpl2 vm3 = new ViewModelImpl2() { Name = "VM3" };
            vm3.SubItems.Add("SubItem1");

            items.Add(vm1);
            items.Add(vm2);
            items.Add(vm3);

            tree.ItemsSource = items;
        }
    }

}

ViewModels

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ComponentModel;

namespace WpfApplication2
{
    public abstract class ViewModel : INotifyPropertyChanged
    {
        private List<string> subItems = new List<string>();
        public List<string> SubItems
        {
            get { return this.subItems; }
        }

        private string name;
        public string Name
        {
            get { return this.name; }
            set
            {
                this.name = value;
                this.OnPropertyChanged("Name");
            }
        }

        private bool isExpanded;
        public bool IsExpanded
        {
            get { return this.isExpanded; }
            set
            {
                this.isExpanded = value;
                this.OnPropertyChanged("IsExpanded");

                UpdateImageSource();
            }
        }

        private string imageSource;
        public string ImageSource
        {
            get 
            {
                if (this.imageSource == null)
                    UpdateImageSource();

                return this.imageSource; 
            }
            protected set
            {
                this.imageSource = value;
                this.OnPropertyChanged("ImageSource");
            }
        }

        protected abstract void UpdateImageSource();

        #region INotifyPropertyChanged Members

        public event PropertyChangedEventHandler PropertyChanged;
        private void OnPropertyChanged(string propName)
        {
            if (this.PropertyChanged != null)
            {
                this.PropertyChanged(this, new PropertyChangedEventArgs(propName));
            }
        }

        #endregion 
    }

    public class ViewModelImpl1 : ViewModel
    {
        protected override void UpdateImageSource()
        {
            if (this.IsExpanded)
                this.ImageSource = "pack://application:,,,/Images/bell1.png";
            else
                this.ImageSource = "pack://application:,,,/Images/bell2.png";
        }
    }

    public class ViewModelImpl2 : ViewModel
    {
        protected override void UpdateImageSource()
        {
            if (this.IsExpanded)
                this.ImageSource = "pack://application:,,,/Images/star1.png";
            else
                this.ImageSource = "pack://application:,,,/Images/star2.png";
        }
    }
}