Question

我已经构建了一个自定义ComboBox，它在设置ReadOnly时显示为TextBox：

<local:BoolToVisibilityConverter FalseValue="Hidden" TrueValue="Visible" x:Key="BoolVis" />
<local:BoolToVisibilityConverter FalseValue="Visible" TrueValue="Hidden" x:Key="BoolVisRev" />

<Style TargetType="{x:Type local:ComboBoxG}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type local:ComboBoxG}">
                <Border Background="{TemplateBinding Background}"
                        BorderBrush="{TemplateBinding BorderBrush}"
                        BorderThickness="{TemplateBinding BorderThickness}">
                    <Grid>
                        <ComboBox ItemsSource="{TemplateBinding ItemsSource}"
                                  DisplayMemberPath="{TemplateBinding DisplayMemberPath}"
                                  SelectedValuePath="{TemplateBinding SelectedValuePath}"
                                  SelectedIndex="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=SelectedIndex, Mode=TwoWay}"
                                  Visibility="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=IsReadOnly, Converter={StaticResource BoolVisRev}}"
                                  IsDropDownOpen="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=IsDropDownOpen, Mode=TwoWay}"
                                  IsTabStop="False">
                        </ComboBox>
                        <TextBox Text="{TemplateBinding Text}" 
                                 Visibility="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=IsReadOnly, Converter={StaticResource BoolVis}}"
                                 IsTabStop="False">
                        </TextBox>
                    </Grid>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

它工作得很好，除了我实例化并一次性设置一个值。这不起作用......

private void One_OnClick(object sender, RoutedEventArgs e)
{
    cmb = new ComboBoxG();
    Stack.Children.Add(cmb);

    var dict = new Dictionary<int, string> { { 0, "aaa" }, { 1, "bbb" }, { 2, "ccc" }, { 3, "ddd" }, };
    cmb.ItemsSource = dict;
    cmb.DisplayMemberPath = "Value";
    cmb.SelectedValuePath = "Key";
    cmb.SelectedValue = 3;
}

......而这确实......

private void One_OnClick(object sender, RoutedEventArgs e)
{
    cmb = new ComboBoxG();
    Stack.Children.Add(cmb);

    var dict = new Dictionary<int, string> { { 0, "aaa" }, { 1, "bbb" }, { 2, "ccc" }, { 3, "ddd" }, };
    cmb.ItemsSource = dict;
    cmb.DisplayMemberPath = "Value";
    cmb.SelectedValuePath = "Key";
    cmb.Loaded += cmb_Loaded;
}

private void cmb_Loaded(object sender, RoutedEventArgs e)
{
    cmb.SelectedValue = 3;
}

所以我可以解决它，但它使这个控件的一些用途变得尴尬。有什么建议吗？

Answer 1

我之前也遇到过这个问题，到目前为止，唯一的半愉快解决方法是在一个方法中完成这一切是让消息队列通过Loaded阶段排出。请注意，我并不为此感到骄傲，但WPF分阶段做事，有时你更喜欢把所有东西放在一起。您可以将cmd.SelectedValue = 3放入我认为的委托中，但这是一个品味问题......

        cmb = new ComboboxG();
        theStack.Children.Add(cmb);

        var dict = new Dictionary<int, string> { { 0, "aaa" }, { 1, "bbb" }, { 2, "ccc" }, { 3, "ddd" }, };
        cmb.ItemsSource = dict;
        cmb.DisplayMemberPath = "Value";
        cmb.SelectedValuePath = "Key";

        Dispatcher.Invoke(new Action(() => { }), DispatcherPriority.Loaded);

        cmb.SelectedValue = 3;

请注意这将允许事件运行，所以要小心重入！

Answer 2

您是否尝试过设置所选索引？

private void One_OnClick(object sender, RoutedEventArgs e)
{
    cmb = new ComboBoxG();
    Stack.Children.Add(cmb);

    var dict = new Dictionary<int, string> { { 0, "aaa" }, { 1, "bbb" }, { 2, "ccc" }, { 3, "ddd" }, };
    cmb.ItemsSource = dict;
    cmb.DisplayMemberPath = "Value";
    cmb.SelectedValuePath = "Key";
    cmb.SelectedIndex = 3;
}

Answer 3

尝试设置SelectedItem而不是Index

WPF自定义ComboBox初始值设置

3 个答案: