如何将 WPF 控件放置在具有当前焦点的控件旁边？答案

【问题标题】：How to position WPF control next to the control with current focus?如何将 WPF 控件放置在具有当前焦点的控件旁边？
【发布时间】：2016-10-04 15:24:49
【问题描述】：

我有一个典型的edit form (user control)，有几个输入框。我需要一个ListBox，它必须显示在当前焦点的TextBox 正下方，因此它需要动态移动。我尝试了一些绑定，但没有任何反应

<local:MyList x:Name="myList"
       Canvas.Left="{Binding (FocusManager.FocusedElement).Canvas.Left,RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}}"
       Canvas.Top="{Binding (FocusManager.FocusedElement).Canvas.Bottom,RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}}"
/>

【问题讨论】：

标签： c# wpf wpf-positioning

【解决方案1】：

使用Popup，因为它可以让您方便地将其显示在您想要的位置。它的Placement = Bottom 将显示在PlacementTarget 的正下方。

处理GotFocus 和LostFocus 的TextBox。

        <TextBox Grid.Column="1" HorizontalAlignment="Left" Height="23" Margin="10,19,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120" GotFocus="TextBox_GotFocus_1" LostFocus="TextBox_LostFocus_1"/>
        <TextBox Grid.Column="1" HorizontalAlignment="Left" Height="23" Margin="10,57,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120" GotFocus="TextBox_GotFocus_1" LostFocus="TextBox_LostFocus_1"/>
        <TextBox Grid.Column="1" HorizontalAlignment="Left" Height="23" Margin="10,96,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120"/>
        <TextBox Grid.Column="1" HorizontalAlignment="Left" Height="23" Margin="10,136,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120" GotFocus="TextBox_GotFocus_1" LostFocus="TextBox_LostFocus_1"/>
        <TextBox Grid.Column="1" HorizontalAlignment="Left" Height="23" Margin="10,174,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120"/>

        <Popup Placement="Bottom" x:Name="LsbPopup">
            <ListBox>
                <ListBoxItem>item1</ListBoxItem>
                <ListBoxItem>item1</ListBoxItem>
                <ListBoxItem>item1</ListBoxItem>
                <ListBoxItem>item1</ListBoxItem>
                <ListBoxItem>item1</ListBoxItem>
                <ListBoxItem>item1</ListBoxItem>
                <ListBoxItem>item1</ListBoxItem>
            </ListBox>
        </Popup>

处理程序：

private void TextBox_GotFocus_1(object sender, RoutedEventArgs e)
{
    LsbPopup.PlacementTarget = sender as TextBox;
    LsbPopup.IsOpen = true;
}

private void TextBox_LostFocus_1(object sender, RoutedEventArgs e)
{
    LsbPopup.IsOpen = false;
}

【讨论】：