WPF 高级篇 MVVM 附加属性

原文: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"/>