WPF 高级篇 MVVM 附加属性

WPF 特性之一 附加属性 在本文里实现文本框内容的验证

public  class TextBoxHelper:DependencyObject




    {



 



        public static bool GetisOnlyNumber(DependencyObject obj)




        {



            return (bool)obj.GetValue(isOnlyNumberProperty);



        }



 



        public static void SetisOnlyNumber(DependencyObject obj, bool value)




        {



            obj.SetValue(isOnlyNumberProperty, value);



        }



 



        // Using a DependencyProperty as the backing store for isOnlyNumber.  This enables animation, styling, binding, etc...




        public static readonly DependencyProperty isOnlyNumberProperty =



            DependencyProperty.RegisterAttached("isOnlyNumber", typeof(bool), typeof(TextBoxHelper), new PropertyMetadata(false,OnIsOnlyNumberChange));



 



        private static void OnIsOnlyNumberChange(DependencyObject d, DependencyPropertyChangedEventArgs e)




        {



            var text = d as TextBox;



            if ((bool)e.NewValue) 



            {



                text.PreviewTextInput += text_PreviewTextInput;



            }else{



                text.PreviewTextInput -= text_PreviewTextInput;



            }



        }



 



        static void text_PreviewTextInput(object sender, System.Windows.Input.TextCompositionEventArgs e)




        {



            e.Handled = IsNotNumber(e.Text);



        }



 



        private static bool IsNotNumber(string content) 




        {



            Regex regex = new Regex("[^0-9]");



            return regex.IsMatch(content);



        }



        



        



    }

引用命名空间

xmlns:bhx ="clr-namespace:WPF.Behaviors"

<TextBox bhx:TextBoxHelper.isOnlyNumber="True" HorizontalAlignment="Left" Height="23" Margin="10,131,0,0" TextWrapping="Wrap" Text="{Binding CurrentBook.Pages}" VerticalAlignment="Top" Width="120"/>