WPF ComboBox
WPF ComboBox，可编辑
<Window ...>
<Window.Resources>
<!--ToggleButton 样式-->
<ControlTemplate x:Key="LoginComboBoxToggleButton" TargetType="ToggleButton">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition Width="20" />
</Grid.ColumnDefinitions>
<Border x:Name="Border" Grid.ColumnSpan="2" CornerRadius="2" Background="Transparent" BorderBrush="Transparent" BorderThickness="1" />
<Border Grid.Column="0" Visibility="Hidden" CornerRadius="2,0,0,2" Margin="1" Background="#FFF" BorderBrush="#444" BorderThickness="0,0,1,0" />
<Path x:Name="Arrow" Grid.Column="1" Fill="#444" HorizontalAlignment="Center" VerticalAlignment="Center" Data="M 0 0 L 4 4 L 8 0 Z"/>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsEnabled" Value="False">
<Setter TargetName="Border" Property="Background" Value="#EEE" />
<Setter TargetName="Border" Property="BorderBrush" Value="#AAA" />
<Setter Property="Foreground" Value="#888"/>
<Setter TargetName="Arrow" Property="Fill" Value="#888" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
<ControlTemplate x:Key="ComboBoxTextBox" TargetType="TextBox">
<Border x:Name="PART_ContentHost" Focusable="False" Background="{TemplateBinding Background}" />
</ControlTemplate>
<!--ComboBox样式-->
<Style x:Key="ComboBoxUserNameStyle" TargetType="ComboBox">
<Setter Property="IsEditable" Value="True"/>
<Setter Property="FocusVisualStyle" Value="{x:Null}"/>
<Setter Property="SnapsToDevicePixels" Value="true"/>
<Setter Property="OverridesDefaultStyle" Value="true"/>
<Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto"/>
<Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
<Setter Property="ScrollViewer.CanContentScroll" Value="true"/>
<Setter Property="Width" Value="100"/>
<Setter Property="Height" Value="28"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ComboBox">
<Border BorderBrush="#888" BorderThickness="1">
<Grid>
<ToggleButton Name="ToggleButton" Template="{StaticResource LoginComboBoxToggleButton}" Focusable="false"
IsChecked="{Binding Path=IsDropDownOpen,Mode=TwoWay,RelativeSource={RelativeSource TemplatedParent}}" ClickMode="Press">
</ToggleButton>
<ContentPresenter Name="ContentSite" IsHitTestVisible="False" Content="{TemplateBinding SelectionBoxItem}" ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}"
ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}" VerticalAlignment="Center" HorizontalAlignment="Left" />
<TextBox x:Name="PART_EditableTextBox" Style="{x:Null}" Template="{StaticResource ComboBoxTextBox}" HorizontalAlignment="Left" VerticalAlignment="Center"
Focusable="True" Background="Transparent" Visibility="Hidden" IsReadOnly="{TemplateBinding IsReadOnly}"/>
<Popup Name="Popup" Placement="Bottom" IsOpen="{TemplateBinding IsDropDownOpen}" AllowsTransparency="True" Focusable="False" PopupAnimation="Slide">
<Grid Name="DropDown" SnapsToDevicePixels="True" MinWidth="{TemplateBinding ActualWidth}" MaxHeight="{TemplateBinding MaxDropDownHeight}">
<Border x:Name="DropDownBorder" BorderThickness="1" CornerRadius="0" BorderBrush="#888"/>
<ScrollViewer Margin="1,5,1,5" SnapsToDevicePixels="True">
<StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Contained" />
</ScrollViewer>
</Grid>
</Popup>
</Grid>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="HasItems" Value="false">
<Setter TargetName="DropDownBorder" Property="MinHeight" Value="95"/>
</Trigger>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Foreground" Value="#444"/>
</Trigger>
<Trigger Property="IsGrouping" Value="true">
<Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
</Trigger>
<Trigger SourceName="Popup" Property="Popup.AllowsTransparency" Value="true">
<Setter TargetName="DropDownBorder" Property="CornerRadius" Value="0"/>
<Setter TargetName="DropDownBorder" Property="Margin" Value="0,2,0,0"/>
</Trigger>
<Trigger Property="IsEditable" Value="true">
<Setter Property="IsTabStop" Value="false"/>
<Setter TargetName="PART_EditableTextBox" Property="Visibility" Value="Visible"/>
<Setter TargetName="ContentSite" Property="Visibility" Value="Hidden"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
</Style.Triggers>
</Style>
</Window.Resources>
<Grid Width="500" Height="350">
<ComboBox Name="cmbUsername" SelectedIndex="0" Style="{StaticResource ComboBoxUserNameStyle}" ItemsSource="{Binding}"/>
</Grid>
</Window>
样式二
<!-- ComboBoxItem样式 -->
<Style x:Key="ComboBoxItemStyle" TargetType="ComboBoxItem">
<Setter Property="VerticalContentAlignment" Value="Center"/>
<Setter Property="Height" Value="30"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ComboBoxItem">
<Border Name="Back" Background="Transparent" BorderThickness="0,0,0,0" BorderBrush="#FF6A6A6A" >
<ContentPresenter ContentSource="{Binding Source}" Margin="{TemplateBinding Padding}" HorizontalAlignment="Left" VerticalAlignment="Center"></ContentPresenter>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsHighlighted" Value="True">
<Setter TargetName="Back" Property="Background" Value="#f5f5f5"></Setter>
</Trigger>
<Trigger Property="IsSelected" Value="True">
<Setter TargetName="Back" Property="Background" Value="#e9e7e6"></Setter>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<!-- ToggleButton样式（折叠展开按钮） -->
<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}">
<Border x:Name="templateRoot" CornerRadius="4" SnapsToDevicePixels="true" Background="{TemplateBinding Background}" BorderThickness="{TemplateBinding BorderThickness}" BorderBrush="#FF565656">
<Border x:Name="splitBorder" CornerRadius="4" Width="40" SnapsToDevicePixels="true" Margin="0" HorizontalAlignment="Right"
BorderThickness="{TemplateBinding BorderThickness}" BorderBrush="#FF565656">
<Border.Background>
<LinearGradientBrush EndPoint="0,1" StartPoint="0,0">
<GradientStop Color="White" Offset="0"/>
<GradientStop Color="White" Offset="0.75"/>
</LinearGradientBrush>
</Border.Background>
<Path x:Name="arrow" VerticalAlignment="Center" Margin="9,0,0,0" Stretch="Fill" Height="12" Width="16" HorizontalAlignment="Left" Fill="#FF565656" Data="M 50,50 L 0,0 100,0 z"/>
</Border>
</Border>
<ControlTemplate.Triggers>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding IsEditable, RelativeSource={RelativeSource AncestorType={x:Type ComboBox}}}" Value="true"/>
<Condition Binding="{Binding IsMouseOver, RelativeSource={RelativeSource Self}}" Value="false"/>
<Condition Binding="{Binding IsPressed, RelativeSource={RelativeSource Self}}" Value="false"/>
<Condition Binding="{Binding IsEnabled, RelativeSource={RelativeSource Self}}" Value="true"/>
</MultiDataTrigger.Conditions>
<Setter Property="BorderBrush" TargetName="templateRoot" Value="#FF565656"/>
</MultiDataTrigger>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Fill" TargetName="arrow" Value="#FFADADAD"/>
<Setter Property="BorderBrush" TargetName="templateRoot" Value="#FFADADAD"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<!-- ComboBox Template样式 -->
<ControlTemplate x:Key="ComboBoxTemplate" TargetType="{x:Type ComboBox}">
<Grid x:Name="templateRoot" SnapsToDevicePixels="true">
<Grid.ColumnDefinitions>
<ColumnDefinition/>
<ColumnDefinition Width="0"/>
</Grid.ColumnDefinitions>
<Popup x:Name="PART_Popup" AllowsTransparency="true" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Margin="1" PopupAnimation="{DynamicResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
<Border x:Name="dropDownBorder" BorderBrush="#EcEcEc" BorderThickness="1 0 1 1" Background="{DynamicResource {x:Static SystemColors.WindowBrushKey}}" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}">
<ScrollViewer x:Name="DropDownScrollViewer">
<Grid x:Name="grid" RenderOptions.ClearTypeHint="Enabled">
<Canvas x:Name="canvas" HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
<Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}"/>
</Canvas>
<StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Continue" Background="#FFFFFFFF"/>
<!--<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>-->
</Grid>
</ScrollViewer>
</Border>
</Popup>
<Border Grid.ColumnSpan="2" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" CornerRadius="2">
<Grid>
<ToggleButton x:Name="toggleButton" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="0" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Style="{StaticResource ComboBoxToggleButton}"/>
<ContentPresenter x:Name="contentPresenter" ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}" ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}"
Content="{TemplateBinding SelectionBoxItem}" ContentStringFormat="{TemplateBinding SelectionBoxItemStringFormat}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
IsHitTestVisible="false" Margin="{TemplateBinding Padding}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
</Grid>
</Border>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="HasItems" Value="false">
<Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
</Trigger>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="IsGrouping" Value="true"/>
<Condition Property="VirtualizingPanel.IsVirtualizingWhenGrouping" Value="false"/>
</MultiTrigger.Conditions>
<Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
</MultiTrigger>
<Trigger Property="ScrollViewer.CanContentScroll" SourceName="DropDownScrollViewer" Value="false">
<Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}"/>
<Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
<Style x:Key="ComboBoxSetterStyle" TargetType="{x:Type ComboBox}">
<Setter Property="Margin" Value="5"/>
<Setter Property="Padding" Value="5"/>
<Setter Property="Background">
<Setter.Value>
<LinearGradientBrush EndPoint="0,1" StartPoint="0,0">
<GradientStop Color="White" Offset="0"/>
<GradientStop Color="White" Offset="0.75"/>
</LinearGradientBrush>
</Setter.Value>
</Setter>
<Setter Property="BorderBrush" Value="#EcEcEc"/>
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.WindowTextBrushKey}}"/>
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto"/>
<Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
<Setter Property="ScrollViewer.CanContentScroll" Value="true"/>
<Setter Property="ScrollViewer.PanningMode" Value="Both"/>
<Setter Property="Stylus.IsFlicksEnabled" Value="False"/>
<Setter Property="VerticalContentAlignment" Value="Center"/>
<Setter Property="ItemContainerStyle" Value="{DynamicResource ComboBoxItemStyle}"/>
<Setter Property="Template" Value="{StaticResource ComboBoxTemplate}"/>
</Style>
设置第一项为默认项
comboBox.SelectedIndex = 0;
避免SelectionChanged事件的第一次执行
private void ComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
if (e.RemovedItems.Count > 0)
{
//事件响应
}
}
参考：https://www.cnblogs.com/xiaomingg/p/8748286.html
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