public delegate bool ValidateValueCallback(object value)

1.  
   public partial class MainWindow
2.  
   {
3.  
   public MainWindow()
4.  
   {
5.  
   InitializeComponent();
6.  
    
7.  
   SetTextBinding();
8.  
   }
9.  
    
10.  
    private void SetTextBinding()
11.  
    {
12.  
    var binding = new Binding
13.  
    {
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    Source = this,
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    Path = new PropertyPath("MyAge")
16.  
    };
17.  
    TestTextBox.SetBinding(TextBox.TextProperty, binding);
18.  
    }
19.  
     
20.  
    public int MyAge
21.  
    {
22.  
    get { return (int)GetValue(MyAgeProperty); }
23.  
    set { SetValue(MyAgeProperty, value); }
24.  
    }
25.  
     
26.  
    //这里注册一个MyAge的依赖属性用于前台绑定，指定默认值为18
27.  
    public static readonly DependencyProperty MyAgeProperty =
28.  
    DependencyProperty.Register("MyAge", typeof(int), typeof(MainWindow),
29.  
    new PropertyMetadata(18, PropertyChangedCallback, CoerceValueCallback), ValidateValueCallback);
30.  
     
31.  
    //当赋值成功的时候就改变TextBox的边框颜色
32.  
    private static void PropertyChangedCallback(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
33.  
    {
34.  
    var window = dependencyObject as Window;
35.  
    var textBox = window?.FindName("TestTextBox") as TextBox;
36.  
    if (textBox != null) textBox.BorderBrush = Brushes.Cyan;
37.  
    }
38.  
     
39.  
    //当进行赋值的时候，如果值不在18~100之间，强制将值恢复为18，表示该值不合要求
40.  
    private static object CoerceValueCallback(DependencyObject dependencyObject, object baseValue)
41.  
    {
42.  
    var value = (int)baseValue;
43.  
    return value < 18 ? 18 : value;
44.  
    }
45.  
     
46.  
    //在开始赋值前对值进行检查，如果值超过100就弹个错误框显示
47.  
    private static bool ValidateValueCallback(object o)
48.  
    {
49.  
    var value = (int)o;
50.  
    if (value > 100)
51.  
    MessageBox.Show("年龄有点大哈");
52.  
    return value < 100;
53.  
    }
54.  
     
55.  
    //当儿童选项被勾选的时候去更改属性的元数据
56.  
    private void ChildCheckBox_OnChecked(object sender, RoutedEventArgs e)
57.  
    {
58.  
    ChildAge.Instance.ChangeMetadata(sender);
59.  
    }
60.  
     
61.  
    //当取消勾选的时候，应该恢复为原来的属性值绑定才能正确显示
62.  
    private void ChildCheckBox_OnUnchecked(object sender, RoutedEventArgs e)
63.  
    {
64.  
    SetTextBinding();
65.  
    }
66.  
    }
67.  
     
68.  
    //重新定义一个Child类继承MainWindow
69.  
    public class ChildAge : MainWindow
70.  
    {
71.  
    public static ChildAge Instance
72.  
    {
73.  
    get { return _instance ?? (_instance = new ChildAge()); }
74.  
    }
75.  
     
76.  
    private static ChildAge _instance;
77.  
     
78.  
    private static Window _containerWindow;
79.  
    public void ChangeMetadata(object sender)
80.  
    {
81.  
    var item = sender as CheckBox;
82.  
    if (item == null) return;
83.  
     
84.  
    //更改属性元数据，默认值为1，对应的值处理检查方法也需重新定义
85.  
    MyAgeProperty.OverrideMetadata(typeof(ChildAge),
86.  
    new PropertyMetadata(1, ChildAgePropertyChangedCallback, ChildCoerceValueCallback));
87.  
     
88.  
    ///////////这里因为前台数据是和后台绑定的，因此如果对应的属性改变了，前台绑定的源也应该随之改变
89.  
    _containerWindow = GetWindow(item);
90.  
    if (_containerWindow != null)
91.  
    {
92.  
    var binding = new Binding
93.  
    {
94.  
    Source = this,
95.  
    Path = new PropertyPath("MyAge")
96.  
    };
97.  
    var textBox = _containerWindow.FindName("TestTextBox") as TextBox;
98.  
    textBox?.SetBinding(TextBox.TextProperty, binding);
99.  
    }
100.  
     }
101.  
      
102.  
     private static object ChildCoerceValueCallback(DependencyObject dependencyObject, object baseValue)
103.  
     {
104.  
     var value = (int)baseValue;
105.  
     return (value < 1 || value >= 18) ? 1 : value;
106.  
     }
107.  
      
108.  
     private static void ChildAgePropertyChangedCallback(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
109.  
     {
110.  
     var textBox = _containerWindow?.FindName("TestTextBox") as TextBox;
111.  
     if (textBox != null) textBox.BorderBrush = Brushes.DarkGreen;
112.  
     }
113.  
     }