WPF 默认的 TreeView 非常好,我仍然希望它有连接每个子元素的线,就像 Windows 窗体 TreeView 一样。我在网上搜索过一些例子,但设计得不够好。
如何使用 WPF 实现它?
最佳答案
让我回答我自己的问题。
代码
您需要做的只是一个 XAML 文件和后面的代码:
首先需要绘制切换按钮:从三角形按钮到加减按钮:绘制一个带有黑色边框的矩形,然后绘制两条线,一条垂直线和一条水平线。当TreeViewItem展开时,垂直线将隐藏:
<!-- Toggle Button -->
<Style x:Key="ExpandCollapseToggleStyle" TargetType="ToggleButton">
<Setter Property="Focusable" Value="False"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ToggleButton">
<Grid Width="15" Height="13" SnapsToDevicePixels="True">
<!-- Rectangle 9x9 pixels -->
<Rectangle Width="9" Height="9" Stroke="#919191" SnapsToDevicePixels="true">
<Rectangle.Fill>
<LinearGradientBrush EndPoint="0.5,2" StartPoint="0.5,0">
<GradientStop Color="White" Offset="0"/>
<GradientStop Color="Silver" Offset="0.5"/>
<GradientStop Color="LightGray" Offset="1"/>
</LinearGradientBrush>
</Rectangle.Fill>
</Rectangle>
<!-- Vertical line inside rectangle -->
<Rectangle x:Name="ExpandPath" Width="1" Height="5" Stroke="Black" SnapsToDevicePixels="true"/>
<!-- Horizontal line inside rectangle -->
<Rectangle Width="5" Height="1" Stroke="Black" SnapsToDevicePixels="true"/>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsChecked" Value="True">
<Setter Property="Visibility" TargetName="ExpandPath" Value="Collapsed"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
在上面的代码中,您可以看到一个触发器,如果项目展开,它将使切换按钮内的垂直线隐藏,如果其子项折叠,则显示。
然后,您需要在节点之间绘制垂直和水平连接线:您需要重新设计TreeViewItem控件。添加这些连接线:
<!-- Horizontal line -->
<Rectangle x:Name="HorLn" Margin="9,1,0,0" Height="1" Stroke="#DCDCDC" SnapsToDevicePixels="True"/>
<!-- Vertical line -->
<Rectangle x:Name="VerLn" Width="1" Stroke="#DCDCDC" Margin="0,0,1,0" Grid.RowSpan="2" SnapsToDevicePixels="true" Fill="White"/>
到您的 TreeViewItem 模板,如下所示:
<!-- TreeViewItem -->
<Style x:Key="{x:Type TreeViewItem}" TargetType="{x:Type TreeViewItem}">
<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>
<!-- Connecting Lines -->
<!-- Horizontal line -->
<Rectangle x:Name="HorLn" Margin="9,1,0,0" Height="1" Stroke="#DCDCDC" SnapsToDevicePixels="True"/>
<!-- Vertical line -->
<Rectangle x:Name="VerLn" Width="1" Stroke="#DCDCDC" Margin="0,0,1,0" Grid.RowSpan="2" SnapsToDevicePixels="true" Fill="White"/>
<!-- Insert Toggle Button -->
<ToggleButton Margin="-1,0,0,0" x:Name="Expander" Style="{StaticResource ExpandCollapseToggleStyle}" IsChecked="{Binding Path=IsExpanded, RelativeSource={RelativeSource TemplatedParent}}" ClickMode="Press"/>
<Border Name="Bd" Grid.Column="1" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Padding="{TemplateBinding Padding}" SnapsToDevicePixels="True">
<ContentPresenter x:Name="PART_Header" ContentSource="Header" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" MinWidth="20"/>
</Border>
<ItemsPresenter x:Name="ItemsHost" Grid.Row="1" Grid.Column="1" Grid.ColumnSpan="2"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
然后您需要将 TreeViewLineConverter 类放入您的命名空间中。如果该项目是列表中的最后一个,则此类将更改连接线:
using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
namespace TreeViewEx
{
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
}
class TreeViewLineConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
TreeViewItem item = (TreeViewItem)value;
ItemsControl ic = ItemsControl.ItemsControlFromItemContainer(item);
return ic.ItemContainerGenerator.IndexFromContainer(item) == ic.Items.Count - 1;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
return false;
}
}
}
将命名空间插入 XAML,即:
<Window x:Class="TreeViewEx.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:TreeViewEx"/>
将此行添加到 Window.Resources:
<local:TreeViewLineConverter x:Key="LineConverter"/>
向 TreeViewItem 模板添加触发器,如果该项目是列表中的最后一个,则此触发器会更改连接线:
<!-- This trigger changes the connecting lines if the item is the last in the list -->
<DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Converter={StaticResource LineConverter}}" Value="true">
<Setter TargetName="VerLn" Property="Height" Value="9"/>
<Setter TargetName="VerLn" Property="VerticalAlignment" Value="Top"/>
</DataTrigger>
TreeView 现在将具有 WinForms 样式。如果需要,您可以添加更多触发器来控制 TreeView 的行为。完整的触发器可以在附件中找到。
待办事项
在WinForms TreeView中,连接线是虚线。要使这些线成为虚线,请更改:
<!-- Connecting Lines -->
<Rectangle x:Name="HorLn" Margin="9,1,0,0" Height="1" Stroke="#DCDCDC" SnapsToDevicePixels="True"/>
<Rectangle x:Name="VerLn" Width="1" Stroke="#DCDCDC" Margin="0,0,1,0" Grid.RowSpan="2" SnapsToDevicePixels="true" Fill="White"/>
致:
<!-- Connecting Lines -->
<Rectangle x:Name="HorLn" Margin="9,1,0,0" Height="1" Stroke="Blue" StrokeDashCap="Square" StrokeDashArray="0,2" StrokeDashOffset="1" SnapsToDevicePixels="True"/>
<Rectangle x:Name="VerLn" Width="1" Stroke="Blue" StrokeDashCap="Square" StrokeDashArray="0,2" Margin="0,0,1,0" Grid.RowSpan="2" SnapsToDevicePixels="true" Fill="White"/>
但正如你所见,它并不漂亮。由于我是 WPF 的新手,我不知道如何完美地设计这些行。
问题!
向TreeView添加TreeViewItem时出现垂直线问题:
您可能建议我更改垂直线大小,但如果您也更改字体大小,则不起作用。
源代码
您可以在这里下载我的源代码:
https://www.codeproject.com/Tips/673071/WPF-TreeView-with-WinForms-Style-Fomat
引用
这是我在编写自己的代码之前引用的代码:社交MSDN:Show TreeView nodes connected with dotted lines
关于wpf - 如何使WPF TreeView风格成为WinForms TreeView?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/19560466/