看名字就知道，它是一個彈出控件，顧名思義，我們可以用它來實現(xiàn)類似Combobox那種，點擊后彈出下面選項列表的操作。

記錄：

需求：有一個文本框 ，鼠標(biāo)點擊后，彈出一個Popup。

我編寫了以下xaml

<Grid><TextBox PreviewMouseDown="text_PreviewMouseDown" x:Name="text" Text="666" BorderBrush="Red" BorderThickness="1" HorizontalAlignment="Left" VerticalAlignment="Top"Width="100" FontSize="30" HorizontalContentAlignment="Center" VerticalContentAlignment="Center"/><Popup Placement="Bottom" PlacementTarget="{Binding ElementName=text}"IsOpen="{Binding IsOpen1}"AllowsTransparency="True" StaysOpen="False" Width="200" Height="200"><Border Margin="10" Background="Green"><TextBox Text="彈出內(nèi)容1" FontSize="30" HorizontalAlignment="Center" VerticalAlignment="Center"/></Border></Popup> </Grid>

這時，奇怪的現(xiàn)象出現(xiàn)了，我鼠標(biāo)點擊textbox后，一松開，popup就消失了。。。

經(jīng)過一番研究，發(fā)現(xiàn)。

問題出在textbox的點擊事件上，在PreviewMouseDown事件執(zhí)行完畢之后，焦點會移到textbox上，這里popup就失去焦點了。。

編寫以下MainWindow.xaml:

<Window x:Class="wpfcore.MainWindow"xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"xmlns:d="http://schemas.microsoft.com/expression/blend/2008"xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"xmlns:local="clr-namespace:wpfcore"mc:Ignorable="d"Title="MainWindow" Height="450" Width="800"><Grid><Grid.ColumnDefinitions><ColumnDefinition/><ColumnDefinition/></Grid.ColumnDefinitions><Grid><TextBox PreviewMouseUp="text_PreviewMouseDown" x:Name="text" Text="666" BorderBrush="Red" BorderThickness="1" HorizontalAlignment="Left" VerticalAlignment="Top"Width="100" FontSize="30" HorizontalContentAlignment="Center" VerticalContentAlignment="Center"/><Popup Placement="Bottom" PlacementTarget="{Binding ElementName=text}"IsOpen="{Binding IsOpen1}"AllowsTransparency="True" StaysOpen="False" Width="200" Height="200"><Border Margin="10" Background="Green"><TextBox Text="彈出內(nèi)容1" FontSize="30" HorizontalAlignment="Center" VerticalAlignment="Center"/></Border></Popup></Grid><Grid Grid.Column="1"><TextBlock MouseUp="textBlock_PreviewMouseDown" x:Name="textblock" Text="666" Background="LightBlue" HorizontalAlignment="Left" VerticalAlignment="Top"Width="100" FontSize="30" TextAlignment="Center"/><Popup Placement="Bottom" PlacementTarget="{Binding ElementName=textblock}"IsOpen="{Binding IsOpen2}"AllowsTransparency="True" StaysOpen="False" Width="200" Height="200"><Border Margin="10" Background="Green"><TextBox Text="彈出內(nèi)容2" FontSize="30" HorizontalAlignment="Center" VerticalAlignment="Center"/></Border></Popup></Grid></Grid> </Window>

MainWindow.cs代碼如下：

using System.Windows; using System.Windows.Input;namespace wpfcore {public partial class MainWindow : Window{public bool IsOpen1{get { return (bool)GetValue(IsOpen1Property); }set { SetValue(IsOpen1Property, value); }}public static readonly DependencyProperty IsOpen1Property =DependencyProperty.Register("IsOpen1", typeof(bool), typeof(MainWindow), new PropertyMetadata(false));public bool IsOpen2{get { return (bool)GetValue(IsOpen2Property); }set { SetValue(IsOpen2Property, value); }}public static readonly DependencyProperty IsOpen2Property =DependencyProperty.Register("IsOpen2", typeof(bool), typeof(MainWindow), new PropertyMetadata(false));public MainWindow(){InitializeComponent();DataContext = this;}private void text_PreviewMouseDown(object sender, MouseButtonEventArgs e){IsOpen1 = true;}private void textBlock_PreviewMouseDown(object sender, MouseButtonEventArgs e){IsOpen2 = true;}} }

通過對比可以發(fā)現(xiàn)，使用一個TextBlock的效果比textbox好多了。。

以下是對比效果：

記錄下來，備查。

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