WPF：没有下拉按钮的组合框
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时间：2020-09-08 20:56:58 来源:igfitidea点击:
WPF: ComboBox without dropdown button
提问by codymanix
I want a ComboBox which has no dropdown button but can still be opened when I click on the text in the combobox. Is this possible with a WPF combobox?
我想要一个没有下拉按钮但仍然可以在我点击组合框中的文本时打开的组合框。使用 WPF 组合框可以实现吗？
回答by Kent Boogaart
It's possible, but you would need to retemplate it to achieve perfection. You can get most of the way there by overriding a system parameter as follows:
这是可能的，但您需要重新考虑它以达到完美。您可以通过如下覆盖系统参数来获得大部分方法：
<ComboBox xmlns:sys="clr-namespace:System;assembly=mscorlib">
<ComboBox.Resources>
<sys:Double x:Key="{x:Static SystemParameters.VerticalScrollBarWidthKey}">0</sys:Double>
</ComboBox.Resources>
<ComboBoxItem>One</ComboBoxItem>
<ComboBoxItem>Two</ComboBoxItem>
<ComboBoxItem>Three</ComboBoxItem>
</ComboBox>
However, it isn't perfect because the focus rectangle still assumes there is a drop-down button present.
但是，它并不完美，因为焦点矩形仍然假定存在下拉按钮。
回答by AndyM
All WPF controls are "lookless," so you can completely redefine their appearance. However, it's not simple and even less so for ComboBox. ComboBox uses one of two templates, depending on whether it's editable. The non-editable version uses the ToggleButton for the control appearance, so you can just remove the arrow drawing (see below). The editable version uses a TextBox and a ToggleButton, and if you have no ToggleButton, it doesn't open. So here's a template without the ToggleButton; it's up to you to add the code to handle clicks on the editable template. (Or if you don't need to edit, you can just coerce IsEditable to false and be done with it.)
所有 WPF 控件都是“无外观的”，因此您可以完全重新定义它们的外观。然而，ComboBox 并不简单，更不简单。ComboBox 使用两个模板之一，具体取决于它是否可编辑。不可编辑的版本使用 ToggleButton 作为控件外观，因此您可以删除箭头绘图（见下文）。可编辑版本使用 TextBox 和 ToggleButton，如果没有 ToggleButton，则不会打开。所以这是一个没有 ToggleButton 的模板；您可以添加代码来处理可编辑模板上的点击。（或者，如果您不需要编辑，您可以将 IsEditable 强制为 false 并完成它。）
Caveat: This is the Aero template and uses Aero chrome, so it will not display in other themes. For that to happen you would need to pull the templates for each theme and make the appropriate changes or remove the theme chrome and draw your own borders.
警告：这是 Aero 模板并使用 Aero 镀铬，因此不会在其他主题中显示。为此，您需要为每个主题拉取模板并进行适当的更改或删除主题镶边并绘制自己的边框。
Add this namespace definition and add a reference to PresentationFramework.Aero:
添加此命名空间定义并添加对 PresentationFramework.Aero 的引用：
xmlns:t="clr-namespace:Microsoft.Windows.Themes;assembly=PresentationFramework.Aero"
Then add the following to your Window/Control Resources:
然后将以下内容添加到您的窗口/控件资源中：
<Style x:Key="ComboBoxFocusVisual">
<Setter Property="Control.Template">
<Setter.Value>
<ControlTemplate>
<Rectangle Stroke="Black" StrokeDashArray="1 2" StrokeThickness="1" Margin="4,4,21,4" SnapsToDevicePixels="true"/>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<LinearGradientBrush x:Key="ButtonNormalBackground" EndPoint="0,1" StartPoint="0,0">
<GradientStop Color="#F3F3F3" Offset="0"/>
<GradientStop Color="#EBEBEB" Offset="0.5"/>
<GradientStop Color="#DDDDDD" Offset="0.5"/>
<GradientStop Color="#CDCDCD" Offset="1"/>
</LinearGradientBrush>
<SolidColorBrush x:Key="ButtonNormalBorder" Color="#FF707070"/>
<Geometry x:Key="DownArrowGeometry">M 0 0 L 3.5 4 L 7 0 Z</Geometry>
<Style x:Key="ComboBoxReadonlyToggleButton" TargetType="{x:Type ToggleButton}">
<Setter Property="OverridesDefaultStyle" Value="true"/>
<Setter Property="IsTabStop" Value="false"/>
<Setter Property="Focusable" Value="false"/>
<Setter Property="ClickMode" Value="Press"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ToggleButton}">
<t:ButtonChrome x:Name="Chrome" SnapsToDevicePixels="true" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" RenderMouseOver="{TemplateBinding IsMouseOver}" RenderPressed="{TemplateBinding IsPressed}">
<!-- Remove ToggleButton appearance; we still need the ToggleButton because it displays the content.
<Grid HorizontalAlignment="Right" Width="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}">
<Path x:Name="Arrow" Fill="Black" HorizontalAlignment="Center" Margin="3,1,0,0" VerticalAlignment="Center" Data="{StaticResource DownArrowGeometry}"/>
</Grid>
-->
</t:ButtonChrome>
<ControlTemplate.Triggers>
<Trigger Property="IsChecked" Value="true">
<Setter Property="RenderPressed" TargetName="Chrome" Value="true"/>
</Trigger>
<!-- Remove ToggleButton appearance trigger
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Fill" TargetName="Arrow" Value="#AFAFAF"/>
</Trigger>
-->
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<LinearGradientBrush x:Key="TextBoxBorder" EndPoint="0,20" StartPoint="0,0" MappingMode="Absolute">
<GradientStop Color="#ABADB3" Offset="0.05"/>
<GradientStop Color="#E2E3EA" Offset="0.07"/>
<GradientStop Color="#E3E9EF" Offset="1"/>
</LinearGradientBrush>
<Style x:Key="ComboBoxEditableTextBox" TargetType="{x:Type TextBox}">
<Setter Property="OverridesDefaultStyle" Value="true"/>
<Setter Property="AllowDrop" Value="true"/>
<Setter Property="MinWidth" Value="0"/>
<Setter Property="MinHeight" Value="0"/>
<Setter Property="FocusVisualStyle" Value="{x:Null}"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TextBox}">
<ScrollViewer x:Name="PART_ContentHost" Background="Transparent" Focusable="false" HorizontalScrollBarVisibility="Hidden" VerticalScrollBarVisibility="Hidden"/>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style x:Key="ComboBoxToggleButton" TargetType="{x:Type ToggleButton}">
<Setter Property="OverridesDefaultStyle" Value="true"/>
<Setter Property="IsTabStop" Value="false"/>
<Setter Property="Focusable" Value="false"/>
<Setter Property="ClickMode" Value="Press"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ToggleButton}">
<t:ButtonChrome x:Name="Chrome" Width="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}" SnapsToDevicePixels="true" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" RenderMouseOver="{TemplateBinding IsMouseOver}" RenderPressed="{TemplateBinding IsPressed}" RoundCorners="false">
<Path x:Name="Arrow" Fill="Black" HorizontalAlignment="Center" Margin="0,1,0,0" VerticalAlignment="Center" Data="{StaticResource DownArrowGeometry}"/>
</t:ButtonChrome>
<ControlTemplate.Triggers>
<Trigger Property="IsChecked" Value="true">
<Setter Property="RenderPressed" TargetName="Chrome" Value="true"/>
</Trigger>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Fill" TargetName="Arrow" Value="#AFAFAF"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<ControlTemplate x:Key="ComboBoxEditableTemplate" TargetType="{x:Type ComboBox}">
<Grid x:Name="Placement" SnapsToDevicePixels="true">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<Popup x:Name="PART_Popup" AllowsTransparency="true" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" Placement="Bottom" PopupAnimation="{DynamicResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Grid.ColumnSpan="2">
<t:SystemDropShadowChrome x:Name="Shdw" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=Placement}" Color="Transparent">
<Border x:Name="DropDownBorder" Background="{DynamicResource {x:Static SystemColors.WindowBrushKey}}" BorderBrush="{DynamicResource {x:Static SystemColors.WindowFrameBrushKey}}" BorderThickness="1">
<ScrollViewer>
<ItemsPresenter SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" KeyboardNavigation.DirectionalNavigation="Contained"/>
</ScrollViewer>
</Border>
</t:SystemDropShadowChrome>
</Popup>
<t:ListBoxChrome x:Name="Border" Grid.ColumnSpan="2" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" RenderFocused="{TemplateBinding IsKeyboardFocusWithin}" RenderMouseOver="{TemplateBinding IsMouseOver}"/>
<TextBox x:Name="PART_EditableTextBox" Margin="{TemplateBinding Padding}" Style="{StaticResource ComboBoxEditableTextBox}" HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" IsReadOnly="{Binding IsReadOnly, RelativeSource={RelativeSource TemplatedParent}}"/>
<!-- Remove the ToggleButton button; now you make the textbox clickable....
<ToggleButton Style="{StaticResource ComboBoxToggleButton}" Grid.Column="1" IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}"/>
-->
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsKeyboardFocusWithin" Value="true">
<Setter Property="Foreground" Value="Black"/>
</Trigger>
<Trigger Property="IsDropDownOpen" Value="true">
<Setter Property="RenderFocused" TargetName="Border" Value="true"/>
</Trigger>
<Trigger Property="HasItems" Value="false">
<Setter Property="Height" TargetName="DropDownBorder" Value="95"/>
</Trigger>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
<Setter Property="Background" Value="#FFF4F4F4"/>
</Trigger>
<Trigger Property="IsGrouping" Value="true">
<Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
</Trigger>
<Trigger Property="HasDropShadow" SourceName="PART_Popup" Value="true">
<Setter Property="Margin" TargetName="Shdw" Value="0,0,5,5"/>
<Setter Property="Color" TargetName="Shdw" Value="#71000000"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
<Style x:Key="ButtonlessComboBoxStyle" TargetType="{x:Type ComboBox}">
<Setter Property="FocusVisualStyle" Value="{StaticResource ComboBoxFocusVisual}"/>
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.WindowTextBrushKey}}"/>
<Setter Property="Background" Value="{StaticResource ButtonNormalBackground}"/>
<Setter Property="BorderBrush" Value="{StaticResource ButtonNormalBorder}"/>
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto"/>
<Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
<Setter Property="Padding" Value="4,3"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBox}">
<Grid x:Name="MainGrid" SnapsToDevicePixels="true">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition MinWidth="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}" Width="0"/>
</Grid.ColumnDefinitions>
<Popup x:Name="PART_Popup" Margin="1" AllowsTransparency="true" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" Placement="Bottom" PopupAnimation="{DynamicResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Grid.ColumnSpan="2">
<t:SystemDropShadowChrome x:Name="Shdw" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=MainGrid}" Color="Transparent">
<Border x:Name="DropDownBorder" Background="{DynamicResource {x:Static SystemColors.WindowBrushKey}}" BorderBrush="{DynamicResource {x:Static SystemColors.WindowFrameBrushKey}}" BorderThickness="1">
<ScrollViewer CanContentScroll="true">
<ItemsPresenter SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" KeyboardNavigation.DirectionalNavigation="Contained"/>
</ScrollViewer>
</Border>
</t:SystemDropShadowChrome>
</Popup>
<ToggleButton Style="{StaticResource ComboBoxReadonlyToggleButton}" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" Grid.ColumnSpan="2" IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}"/>
<ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" IsHitTestVisible="false" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" Content="{TemplateBinding SelectionBoxItem}" ContentStringFormat="{TemplateBinding SelectionBoxItemStringFormat}" ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}" ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}"/>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="HasDropShadow" SourceName="PART_Popup" Value="true">
<Setter Property="Margin" TargetName="Shdw" Value="0,0,5,5"/>
<Setter Property="Color" TargetName="Shdw" Value="#71000000"/>
</Trigger>
<Trigger Property="HasItems" Value="false">
<Setter Property="Height" TargetName="DropDownBorder" Value="95"/>
</Trigger>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
<Setter Property="Background" Value="#FFF4F4F4"/>
</Trigger>
<Trigger Property="IsGrouping" Value="true">
<Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
<Trigger Property="IsEditable" Value="true">
<Setter Property="BorderBrush" Value="{StaticResource TextBoxBorder}"/>
<Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.WindowBrushKey}}"/>
<Setter Property="IsTabStop" Value="false"/>
<Setter Property="Padding" Value="3"/>
<Setter Property="Template" Value="{StaticResource ComboBoxEditableTemplate}"/>
</Trigger>
</Style.Triggers>
</Style>
Then use:
然后使用：
<ComboBox HorizontalAlignment="Left" Width="120" Style="{DynamicResource ButtonlessComboBoxStyle}">
<ComboBox.Items>
<ComboBoxItem>One</ComboBoxItem>
<ComboBoxItem>Two</ComboBoxItem>
<ComboBoxItem>Three</ComboBoxItem>
</ComboBox.Items>
</ComboBox>
<ComboBox HorizontalAlignment="Left" Width="120" IsEditable="True" Style="{DynamicResource ButtonlessComboBoxStyle}">
<ComboBox.Items>
<ComboBoxItem>One</ComboBoxItem>
<ComboBoxItem>Two</ComboBoxItem>
<ComboBoxItem>Three</ComboBoxItem>
</ComboBox.Items>
</ComboBox>
Note: Styles are referenced as DynamicResourcebecause they rely on theme chrome so need to respond to changes in the OS visual style. If you remove the chrome and use WPF borders then you should reference these as StaticResourcefor performance.
注意：引用样式是DynamicResource因为它们依赖于主题镶边，因此需要响应操作系统视觉样式的变化。如果您移除镶边并使用 WPF 边框，那么您应该参考这些以StaticResource提高性能。
