WPF TextBox模仿PasswordBox的密码显示功能(二)(升级版)

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WPF TextBox模仿PasswordBox的密码显示功能(二)(升级版)

这并不是多此一举，因为WPF的PasswordBox不支持继承，所以想扩展PasswordBox的属性就没法实现，所以有了本文内容，当然这个思路也可以扩展到其他语言。

一、新建自定义控件
在这里插入图片描述二、下面是完整的类(这是创建了一个“自定义控件”)

using System.Windows;

namespace SuperControl
{ 
   
    /// <summary>
    /// SuperPasswordBoxPro
    /// </summary>
    public class SuperPasswordBoxPro : TextBox
    { 
   
        static SuperPasswordBoxPro()
        { 
   
            DefaultStyleKeyProperty.OverrideMetadata(typeof(SuperPasswordBoxPro), new FrameworkPropertyMetadata(typeof(STextBox)));
            //重写Text属性改变回调方法
            TextProperty.OverrideMetadata(typeof(SuperPasswordBoxPro), new FrameworkPropertyMetadata(new PropertyChangedCallback(TextChangedCallback)));
        }

        //Text属性改变回调方法
        private static void TextChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs e)
        { 
   
            SuperPasswordBoxPro instance = (SuperPasswordBoxPro)d;
            //新的前端密码文本
            string text = e.NewValue.ToString();
            //已键入的文本长度
            int textLength = text.Length;
            //已保存的密码长度
            int psdLength = instance.Password.Length;
            //判断密码是否已修改
            if (textLength == psdLength && text == new string(instance.PasswordChar, text.Length)) return;
            //记住光标位置(设置完Text后会丢失，所以现在要记住)
            int selectionStart = instance.SelectionStart;
            //起始修改位置
            int startIndex = -1;
            for (int i = 0; i < textLength; i++)
            { 
   
                if (text[i] != instance.PasswordChar)
                { 
   
                    startIndex = i;
                    break;
                }
            }
            //结束修改位置
            int stopIndex = -1;
            for (int i = textLength - 1; i >= 0; i--)
            { 
   
                if (text[i] != instance.PasswordChar)
                { 
   
                    stopIndex = i;
                    break;
                }
            }
            //添加或修改了一个或连续的多个值
            if (startIndex != -1)
            { 
   
                //累计修改长度
                int alterLength = stopIndex - startIndex + 1;
                //长度没变化，单纯的修改了一个或连续的多个值
                if (textLength == psdLength)
                { 
   
                    instance.Password = instance.Password.Substring(0, startIndex) + text.Substring(startIndex, alterLength) + instance.Password.Substring(stopIndex + 1);
                }
                //新增了内容
                else
                { 
   
                    //新增且修改了原来内容
                    if (alterLength > textLength - psdLength)
                    { 
   
                        //计算未修改密码个数 textLength - alterLength
                        //计算已修改密码个数 = 原密码长度 - 未修改密码个数 psdLength - (textLength - alterLength)
                        //原密码该保留的后半部分的索引 = 已修改密码个数 + 起始修改位置
                        instance.Password = instance.Password.Substring(0, startIndex) + text.Substring(startIndex, alterLength) + instance.Password.Substring(psdLength - (textLength - alterLength) + startIndex);
                    }
                    //单纯的新增了一个或多个连续的值
                    else
                    { 
   
                        instance.Password = instance.Password.Substring(0, startIndex) + text.Substring(startIndex, alterLength) + instance.Password.Substring(startIndex);
                    }

                }
            }
            //删除了一个或连续的多个值
            else
            { 
   
                //已删除的数据长度 SelectionStart 为 TextBox 的属性(获取或设置当前所选内容的起始位置的字符索引)
                int length = psdLength - textLength;
                if (instance.SelectionStart < textLength)
                { 
   
                    //改变了中间的数据
                    instance.Password = instance.Password.Substring(0, instance.SelectionStart) + instance.Password.Substring(instance.SelectionStart + length);
                }
                else
                { 
   
                    //删除了结尾的数据
                    instance.Password = instance.Password.Substring(0, instance.SelectionStart);
                }
            }
            //设置光标位置
            instance.SelectionStart = selectionStart;
        }

        /// <summary>
        /// 密码
        /// </summary>
        public string Password
        { 
   
            get { 
    return (string)GetValue(PasswordProperty); }
            set { 
    SetValue(PasswordProperty, value); }
        }
        public static readonly DependencyProperty PasswordProperty =
            DependencyProperty.Register("Password", typeof(string), typeof(SuperPasswordBoxPro), new PropertyMetadata("", new PropertyChangedCallback(PasswordChangedCallback)));
        //Password属性改变回调方法
        private static void PasswordChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs e)
        { 
   
            SuperPasswordBoxPro instance = (SuperPasswordBoxPro)d;
            instance.Text = new string(instance.PasswordChar, e.NewValue.ToString().Length);
        }

        /// <summary>
        /// 密码显示字符
        /// </summary>
        public char PasswordChar
        { 
   
            get { 
    return (char)GetValue(PasswordCharProperty); }
            set { 
    SetValue(PasswordCharProperty, value); }
        }
        public static readonly DependencyProperty PasswordCharProperty =
            DependencyProperty.Register("PasswordChar", typeof(char), typeof(SuperPasswordBoxPro), new PropertyMetadata('●'));
    }
}