1. 概述
微软官方有提供自己的密码控件，但是控件默认的行为是输入密码，会立即显示掩码，比如 *。如果像查看真实的文本，需要按查看按钮。
而我现在自定义的密码控件是先显示你输入的字符2s，然后再显示成掩码。当然这种场景并不一定适用于密码，也可以用在Pin码。
a. 微软官方的密码框
b. 自定义的效果
2. 密码框控件实现
要想实现自定义的密码框，我们当然要继承微软的TextBox控件，然后加入我们自己需要的东西。
a. 这里添加了一个加密类型的密码 Password 字段，真实密码文本 RealPassword 字段，一个Timer定时器来控制显示掩码
internal class CustomPasswordBox : TextBox
{
#region Member Variables
public static readonly DependencyProperty PasswordProperty =
DependencyProperty.Register("Password", typeof(SecureString), typeof(CustomPasswordBox), new PropertyMetadata(new SecureString())); public static readonly DependencyProperty RealPasswordProperty =
DependencyProperty.Register("RealPassword", typeof(string), typeof(CustomPasswordBox), new PropertyMetadata(string.Empty)); private DispatcherTimer maskTimer;
#endregion
}
b. 公开控件属性字段
public SecureString Password
{
get
{
return (SecureString)GetValue(PasswordProperty);
} set
{
SetValue(PasswordProperty, value);
}
} public string RealPassword
{
get
{
return (string)GetValue(RealPasswordProperty);
} set
{
SetValue(RealPasswordProperty, value);
}
}
c. 然后再构造函数里添加一个需要相应的事件，还有初始化Timer
public CustomPasswordBox()
{
PreviewKeyDown += CustomPasswordBox_PreviewKeyDown;
CharacterReceived += CustomPasswordBox_CharacterReceived;
BeforeTextChanging += CustomPasswordBox_BeforeTextChanging;
SelectionChanged += CustomPasswordBox_SelectionChanged;
ContextMenuOpening += CustomPasswordBox_ContextMenuOpening;
TextCompositionStarted += CustomPasswordBox_TextCompositionStarted; maskTimer = new DispatcherTimer { Interval = new TimeSpan(, , ) };
maskTimer.Tick += MaskTimer_Tick;
}
在PreviewKeyDown、CharacterReceived、BeforeTextChanging这三个事件里，主要处理字符的输入删除等逻辑。
在SelectionChanged事件里，我们主要处理不让用户选中文本
在ContextMenuOpening，主要是屏蔽右键菜单，比如复制剪切粘贴
在TextCompositionStarted主要屏蔽中文等组合输入法
另外，在我的场景里面，我们只让用户输入数字，所以加入了数字验证，以及在Xbox上开启了InputScope=NumbericPin模式。
d. 添加事件响应代码
private void CustomPasswordBox_PreviewKeyDown(object sender, Windows.UI.Xaml.Input.KeyRoutedEventArgs e)
{
switch (e.OriginalKey)
{
case VirtualKey.Back:
case VirtualKey.Delete:
if (SelectionLength > )
{
RemoveFromSecureString(SelectionStart, SelectionLength);
}
else if (e.OriginalKey == VirtualKey.Delete && SelectionStart < Text.Length)
{
RemoveFromSecureString(SelectionStart, );
}
else if (e.OriginalKey == VirtualKey.Back && SelectionStart > )
{
int caretIndex = SelectionStart;
if (SelectionStart > && SelectionStart < Text.Length)
caretIndex = caretIndex - ;
RemoveFromSecureString(SelectionStart - , );
//SelectionStart = caretIndex;
} e.Handled = true;
break; default:
//e.Handled = true;
break;
}
} private void CustomPasswordBox_CharacterReceived(UIElement sender, Windows.UI.Xaml.Input.CharacterReceivedRoutedEventArgs args)
{
if (!char.IsDigit(args.Character))
return; AddToSecureString(args.Character.ToString());
args.Handled = true;
} private void CustomPasswordBox_BeforeTextChanging(TextBox sender, TextBoxBeforeTextChangingEventArgs args)
{
args.Cancel = args.NewText.Any(c => !char.IsDigit(c) && !char.ToString(c).ToString().Equals("●"));
//if (args.NewText.Replace("●", "") != "")
// AddToSecureString(args.NewText.Replace("●", ""));
} private void CustomPasswordBox_ContextMenuOpening(object sender, ContextMenuEventArgs e)
{
e.Handled = true;
} private void CustomPasswordBox_SelectionChanged(object sender, RoutedEventArgs e)
{
SelectionStart = Text.Length;
SelectionLength = ;
} private void CustomPasswordBox_TextCompositionStarted(TextBox sender, TextCompositionStartedEventArgs args)
{
return;
} private void MaskTimer_Tick(object sender, object e)
{
MaskAllDisplayText();
}
e. 实现Timer里面的2s后将字符串变成掩码
2s后看TextBox里面的字符数，然后设置对应长度的掩码
private void MaskAllDisplayText()
{
maskTimer.Stop();
int caretIndex = SelectionStart;
Text = new string('●', Text.Length);
SelectionStart = caretIndex;
}
f. 添加字符和删除字符
private void AddToSecureString(string text)
{
if (SelectionLength > )
{
RemoveFromSecureString(SelectionStart, SelectionLength);
} if (Password.Length >= || RealPassword.Length >= )
return;
foreach (char c in text)
{
System.Diagnostics.Debug.WriteLine(text);
int caretIndex = SelectionStart;
if (caretIndex - < )
Password.InsertAt(, c);
else
Password.InsertAt(caretIndex - , c);
RealPassword += c.ToString();
//MaskAllDisplayText();
if (caretIndex == Text.Length)
{
maskTimer.Stop();
maskTimer.Start();
//Text = Text.Insert(caretIndex++, c.ToString());
}
else
{
//Text = Text.Insert(caretIndex++, "●");
}
SelectionStart = Text.Length;
}
} private void RemoveFromSecureString(int startIndex, int trimLength)
{
int caretIndex = SelectionStart;
for (int i = ; i < trimLength; ++i)
{
Password.RemoveAt(startIndex);
RealPassword = RealPassword.Remove(startIndex, );
} Text = Text.Remove(startIndex, trimLength);
SelectionStart = caretIndex;
}
3. 控件使用方法
<local:CustomPasswordBox
InputScope="NumericPin"
MaxLength="" />
一个例子
<Grid>
<local:CustomPasswordBox
x:Name="PSW"
InputScope="NumericPin"
Padding="200 0 0 0"
Style="{StaticResource MyTextBox}"
Height="Auto"
MaxLength=""
CharacterSpacing=""
FontSize=""
VerticalAlignment="Top"/>
<TextBlock
x:Name="realPSW"
FontSize=""
Margin="0 200"
HorizontalAlignment="Center"
Text="{Binding ElementName=PSW, Path=RealPassword, Mode=OneWay}"/>
</Grid>