自定義控制項，重寫 TextBox 實例

項目中可能會遇到重寫控制項的情況，特此記錄下：

 1 <Window x:Class="WpfApp6.MainWindow"
 2         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 3         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 4         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
 5         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
 6         xmlns:local="clr-namespace:WpfApp6"
 7         mc:Ignorable="d"
 8         Title="MainWindow" Height="157" Width="287">
 9     <Window.Resources>
10         <Style TargetType="local:CustomTextBox">
11             <Setter Property="Template">
12                 <Setter.Value>
13                     <ControlTemplate>
14                         <Grid>
15                             <Grid.ColumnDefinitions>
16                                 <ColumnDefinition />
17                                 <ColumnDefinition Width="auto" />
18                             </Grid.ColumnDefinitions>
19                             <TextBox VerticalContentAlignment="Center" 
20                                      Padding="5"
21                                      Text="{Binding RelativeSource={RelativeSource TemplatedParent},Path=Text}"/>
22                             <Button x:Name="btnclear" Grid.Column="1" Width="30" Margin="3" Content="清空" />
23                         </Grid>
24                     </ControlTemplate>
25                 </Setter.Value>
26             </Setter>
27         </Style>
28     </Window.Resources>
29     <Grid>
30         <StackPanel>
31             <local:CustomTextBox Text="852"/>
32         </StackPanel>
33     </Grid>
34 </Window>

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 using System.Windows;
 7 using System.Windows.Controls;
 8 using System.Windows.Data;
 9 using System.Windows.Documents;
10 using System.Windows.Input;
11 using System.Windows.Media;
12 using System.Windows.Media.Imaging;
13 using System.Windows.Navigation;
14 using System.Windows.Shapes;
15 
16 namespace WpfApp6
17 {
18     /// <summary>
19     /// MainWindow.xaml 的交互邏輯
20     /// </summary>
21     public partial class MainWindow : Window
22     {
23         public MainWindow()
24         {
25             InitializeComponent();
26         }
27     }
28 
29 
30     public class CustomTextBox : TextBox
31     {
32         public override void OnApplyTemplate()
33         {
34             base.OnApplyTemplate();
35 
36             var btnclear = GetTemplateChild("btnclear") as Button;
37             btnclear.Click += Btnclear_Click;
38         }
39 
40         private void Btnclear_Click(object sender, RoutedEventArgs e)
41         {
42             Text = string.Empty;
43         }
44     }
45 }