WPF FrameworkElement.FindName 根据名字查找控件
运行环境:Window7 64bit,NetFramework4.7,C# 7.0, 编者:乌龙哈里 2017-10-04
参考:
章节:
正文:
最近写个小玩意,本来是想用 TabControl 标明标签,然后 TabItem 做容器里面放些控件,但是我 TabItem里面的控件完全一样,用 TabItem 来做容器似乎太笨重了,于是想用个 StackPanel 来放标签,其他控件用个 Grid 来包裹就成了。测试的时候发现 FindName() 找不到后台程序生成的 RadioButton。程序如下:
Xaml 界面程序
<Window x:Class="学习FindName.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"
mc:Ignorable="d"
Title="MainWindow" Height="300" Width="300">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="6*"/>
<RowDefinition Height="1*"/>
<RowDefinition Height="32"/>
</Grid.RowDefinitions>
<ListBox Name="lstShow" Grid.Row="0"/>
<StackPanel Name="stackpanel" Orientation="Horizontal" Grid.Row="1"/>
<Grid Grid.Row="2">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="1*"/>
<ColumnDefinition Width="1*"/>
</Grid.ColumnDefinitions>
<Button Name="btnAdd" Content="添加" Margin="3" Grid.Column="0" Click="btnAdd_Click" />
<Button Name="btnDrop" Content="删除" Margin="3" Grid.Column="1" Click="btnDrop_Click" />
</Grid>
</Grid>
</Window>
C# 后台程序:
using System.Windows;
using System.Windows.Controls;
namespace 学习FindName
{
/// <summary>
/// MainWindow.xaml 的交互逻辑
/// </summary>
public partial class MainWindow : Window
{
private int RadioButtonNum = 0;
public MainWindow()
{
InitializeComponent();
}
//---添加 radiobutton
private void btnAdd_Click(object sender, RoutedEventArgs e)
{
RadioButtonNum++;
string s = "rbn" + RadioButtonNum.ToString();
RadioButton rbn = new RadioButton{ Name = s, Content = s,Margin=new Thickness(3)};
rbn.Click += RadioButton_Click;
stackpanel.Children.Add(rbn);
}
//---删除 radiobutton
private void btnDrop_Click(object sender, RoutedEventArgs e)
{
string s = "rbn" + RadioButtonNum.ToString();
RadioButton rbn = stackpanel.FindName(s) as RadioButton;
stackpanel.Children.Remove(rbn);
}
private void RadioButton_Click(object sender, RoutedEventArgs e)
{
//(sender as RadioButton).IsChecked = true;
string s = (sender as RadioButton).Name;
RadioButtonNum = int.Parse(s[s.Length - 1].ToString());
lstShow.Items.Add(s);
}
}
}
运行效果如下:
但是删除的时候,发现 FindName() 返回的值为 null,没有找到控件。找了半天资料,才发现不在前台 Xaml 里面定义的控件名字,要用 RegisterName() 方式来注册一下名字,后面的 FindName() 才能找到。
更改程序如下:
//---添加 radiobutton
private void btnAdd_Click(object sender, RoutedEventArgs e)
{
RadioButtonNum++;
string s = "rbn" + RadioButtonNum.ToString();
RadioButton rbn = new RadioButton{ Name = s, Content = s,Margin=new Thickness(3)};
rbn.Click += RadioButton_Click;
stackpanel.Children.Add(rbn);
//注册一下名字,没有这句后面的 FindName() 将找不到控件
stackpanel.RegisterName(s, rbn);
}
//---删除 radiobutton
private void btnDrop_Click(object sender, RoutedEventArgs e)
{
string s = "rbn" + RadioButtonNum.ToString();
RadioButton rbn = stackpanel.FindName(s) as RadioButton;
rbn.Click -= RadioButton_Click;//事件如果不注销,容易引起内存泄漏
stackpanel.Children.Remove(rbn);
}
private void RadioButton_Click(object sender, RoutedEventArgs e)
{
//(sender as RadioButton).IsChecked = true;
string s = (sender as RadioButton).Name;
RadioButtonNum = int.Parse(s[s.Length - 1].ToString());
lstShow.Items.Add(s);
}
运行效果如下: