WPF：FindName（）不适用于预定义的XAML代码

Question

我有一个动态布局窗口应用程序，通过更改组合框中的值，文本框中的值也应更改。 文本框是网格的一部分，在<window.resources>定义，并在运行时添加到可视树中：

 grpEditFrame.Content = this.Resources["grdARP"] as Grid; // the text box is inside this grid

所以这就是我所做的：

((grpEditFrame.Content as Grid).
            FindName("txtHardwareType") as TextBox).Text= "some text"

问题在于，由于某种原因， FindName找不到文本框。 通过调试，我看不到它们的存在，但是FindName却不起作用:(

因此，在Google中查找时，我发现问题在于在运行时创建的控件不会自动注册其名称，因此程序员必须自己进行操作。 但是后来我发现了这一点 。

因此，如果控件是由XAML创建的，就像我所做的一样（在<windows.resources>定义了它们），那么问题是什么呢？

此外，如果我没记错的话， <windows.resources>中的控件将在编译时创建！

不管为什么，我认为这些名称必须已注册，所以为什么找不到它们？

这是我对上面网格的<windows.resources>定义：

 <Grid x:Key="grdARP" HorizontalAlignment="Right" Width="572">
        <Label Content="Destination MAC:" HorizontalAlignment="Left" Margin="74,18,0,0" VerticalAlignment="Top"/>
        <Label Content="Source MAC:" HorizontalAlignment="Left" Margin="199,18,0,0" VerticalAlignment="Top"/>
        <Label Content="Ethernet Type:" HorizontalAlignment="Left" Margin="319,18,0,0" VerticalAlignment="Top"/>
        <TextBox HorizontalAlignment="Left" Height="23" Margin="74,41,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="120" MaxLength="12"/>
        <TextBox HorizontalAlignment="Left" Height="23" Margin="199,41,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="120" MaxLength="12"/>
        <TextBox Name="txtEthernetType" HorizontalAlignment="Left" Height="23" Margin="324,41,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="100" MaxLength="4"/>
        <Label Content="0x0000" HorizontalAlignment="Left" Margin="21,41,0,0" VerticalAlignment="Top"/>
        <TextBox Name="txtHardwareType" HorizontalAlignment="Left" Height="23" Margin="429,41,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="110" MaxLength="2"/>
        <Label Content="Hardeware type:" HorizontalAlignment="Left" Margin="429,18,0,0" VerticalAlignment="Top" RenderTransformOrigin="-0.359,0.5"/>
        <Label Content="Protocol type:" HorizontalAlignment="Left" Margin="69,72,0,0" VerticalAlignment="Top"/>
        <Label Content="0x0010" HorizontalAlignment="Left" Margin="21,98,0,0" VerticalAlignment="Top"/>
        <TextBox Name="txtProtocolType" HorizontalAlignment="Left" Height="23" Margin="74,98,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="76" MaxLength="4"/>
        <Label Content="Hardware size:" HorizontalAlignment="Left" Margin="150,72,0,0" VerticalAlignment="Top"/>
        <TextBox Name="txtHardwareSize" HorizontalAlignment="Left" Height="23" Margin="155,98,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="78" MaxLength="2"/>
        <Label Content="Protocol size:" HorizontalAlignment="Left" Margin="234,72,0,0" VerticalAlignment="Top"/>
        <TextBox Name="txtProtocolSize"  HorizontalAlignment="Left" Height="23" Margin="238,98,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="73" MaxLength="2"/>
        <Label Content="Opcode:" HorizontalAlignment="Left" Margin="311,72,0,0" VerticalAlignment="Top"/>
        <TextBox Name="txtOpcode" HorizontalAlignment="Left" Height="23" Margin="316,98,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="50" MaxLength="4"/>
        <Label Content="Sender MAC:" HorizontalAlignment="Left" Margin="366,72,0,0" VerticalAlignment="Top"/>
        <TextBox HorizontalAlignment="Left" Height="23" Margin="371,98,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="93" MaxLength="12"/>
        <Label Content="Sender IP:" Height="26" VerticalAlignment="Top" Margin="459,72,44,0"/>
        <TextBox HorizontalAlignment="Left" Height="23" Margin="464,98,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="75" MaxLength="8"/>
        <Label Content="0x0020" HorizontalAlignment="Left" Margin="21,157,0,0" VerticalAlignment="Top"/>
        <Label Content="Target MAC:" HorizontalAlignment="Left" Margin="74,134,0,0" VerticalAlignment="Top"/>
        <TextBox HorizontalAlignment="Left" Height="23" Margin="74,160,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="102" MaxLength="12"/>
        <Label Content="Target IP:" HorizontalAlignment="Left" Margin="181,134,0,0" VerticalAlignment="Top"/>
        <TextBox HorizontalAlignment="Left" Height="23" Margin="181,160,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="120" MaxLength="8"/>
        <Label Content="RAW: (optional)" HorizontalAlignment="Left" Margin="306,134,0,0" VerticalAlignment="Top" />
        <TextBox HorizontalAlignment="Left" Height="23" Margin="306,160,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="233" MaxLength="12" ToolTip="Any data put here has no effect"/>
        <Label Content="0x0030" HorizontalAlignment="Left" Margin="21,216,0,0" VerticalAlignment="Top"/>
        <TextBox HorizontalAlignment="Left" Margin="74,216,0,10" TextWrapping="Wrap" Text="" Width="465"/>
        <Label Content="RAW : (optional)" HorizontalAlignment="Left" Margin="74,190,0,0" VerticalAlignment="Top"  ToolTip="Any data put here has no effect"/>
    </Grid>

这是我的C＃代码背后的功能：

        private void cmdArpHardwareTypes_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        //set the hardware type in txtHardwareType text box
        ((grpEditFrame.Content as Grid).
            FindName("txtHardwareType") as TextBox).Text = ((Int16)Enum.Parse(
                                                                              typeof(ArpHardwareTypes),
                                                                              (sender as ComboBox).SelectedItem.ToString()))

                                                                              .ToString("x4");//4 chars hex format
        //set hardware size to 6 only if harware type is ethernet
        if ((sender as ComboBox).SelectedItem.ToString() == ArpHardwareTypes.Ethernet10MB.ToString())
            ((grpEditFrame.Content as Grid).
            FindName("txtHardwareType") as TextBox).Text = ArpHardwareSize.Ethernet.ToString();

    }

编辑

Hoplese建议添加UpdateLayout，所以这就是我所做的（并且不起作用...）

    void cmbEthernetIItypes_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        //clear the editf frame grid
        grpEditFrame.Content = null;
        //clear son of parent (trviEthernetII)
        (trviRoot.Items.GetItemAt(0)/*trivEtherntII*/ as TreeViewItem).Items.Clear();

        switch ((sender as ComboBox).SelectedItem.ToString())
        {
            case "RAW":
                grpEditFrame.Content = this.Resources["grdEthernetIIraw"] as Grid;
                grpEditFrame.UpdateLayout();
                grpEditFrame.InvalidateArrange();
                grpEditFrame.InvalidateMeasure();
                grpEditFrame.InvalidateVisual();
                    break;
            case "ARP":
                //set the edit grpup box
                grpEditFrame.Content = this.Resources["grdARP"] as Grid;
                grpEditFrame.UpdateLayout();
                grpEditFrame.InvalidateArrange();
                grpEditFrame.InvalidateMeasure();
                grpEditFrame.InvalidateVisual();
                //set the tree view item
                (trviRoot.Items.GetItemAt(0)/*trivEtherntII*/ as TreeViewItem).Items.Add(this.Resources["trviARP"]);
                trviRoot.UpdateLayout();
                break;
            default:

                break;
        }
    }