我的Combobox只有3个项目：Planing,Progress和Done,

<ComboBox SelectedIndex="0>
    <ComboBoxItem Content="Planing"/>
    <ComboBoxItem Content="Progress"/>
    <ComboBoxItem Content="Done"/>
</ComboBox>

我如何更改ComboBox的背景颜色(由defult Gradiant设计)取决于选择了哪个项目.

例如：紫色表示“ Planing”,蓝色表示“ Progress”,绿色表示“ Done”.

注意：我的意思是ComboBox背景,而不是ComboBox项目列表.

谢谢

解决方法:

1)使用selectionChanged事件

您可以在comboBox_SelectionChanged事件中进行设置

private void comboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    if (comboBox.SelectedItem.ToString() == "Planning")
    {
        comboBox.Background = Brushes.Purple;
    }
    else if (comboBox.SelectedItem.ToString() == "Progress")
    {
        comboBox.Background = Brushes.Blue;
    }
    else if (comboBox.SelectedItem.ToString() == "Done")
    {
        comboBox.Background = Brushes.Green;
    }
}

每次更改组合框中的选定值时,都会调用comboBox_SelectionChanged事件.在其中,您可以简单地验证所选项目的值并应用所需的颜色.

这将是Combobox的xaml

<ComboBox x:Name="comboBox" SelectionChanged="comboBox_SelectionChanged"/>

2)在XAML中使用DataTriggers

也可以通过在Style上设置多个DataTrigger来通过xaml完成.

<ComboBox x:Name="mycombobox">
    <ComboBox.Style>
        <Style TargetType="{x:Type ComboBox}">
            <Style.Triggers>
                <DataTrigger Binding="{Binding Path=SelectedItem.Content, ElementName=mycombobox}" Value="Planning">
                    <Setter Property="Background" Value="Purple" />
                </DataTrigger>
                <DataTrigger Binding="{Binding Path=SelectedItem.Content, ElementName=mycombobox}" Value="Progress">
                    <Setter Property="Background" Value="Blue" />
                </DataTrigger>
                <DataTrigger Binding="{Binding Path=SelectedItem.Content, ElementName=mycombobox}" Value="Done">
                    <Setter Property="Background" Value="Green" />
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </ComboBox.Style>
    <ComboBoxItem Content="Planning"/>
    <ComboBoxItem Content="Progress"/>
    <ComboBoxItem Content="Done"/>
</ComboBox>

More information on DataTriggers:

Represents a trigger that applies property values or performs actions when the bound data meets a specified condition.