WPF 自定义TextBox，可控制键盘输入内容

public class NumbericBoxWithZero : NumericBox
{
public NumbericBoxWithZero()
: base()
{

}
protected override void SetTextAndSelection(string text)
{
if (text.IndexOf('.') == -1)
{
text = text + ".00";
}
else
{
if (text.IndexOf('.') != text.Length - 1)
{
string front = text.Substring(0,text.IndexOf('.'));
string back = text.Substring(text.IndexOf('.') + 1, text.Length - text.IndexOf('.') - 1);
if(back != "00")
text = string.Format("{0}.{1:d2}",front,int.Parse(back));
}
}
base.SetTextAndSelection(text);
}
}
/// <summary>
/// NumericBox功能设计
/// 只能输入0-9的数字和至多一个小数点；
///能够屏蔽通过非正常途径的不正确输入（输入法，粘贴等）；
///能够控制小数点后的最大位数，超出位数则无法继续输入；
///能够选择当小数点数位数不足时是否补0；
///去除开头部分多余的0（为方便处理，当在开头部分输入0时，自动在其后添加一个小数点）；
///由于只能输入一个小数点，当在已有的小数点前再次按下小数点，能够跳过小数点；
/// </summary>
public class NumericBox : TextBox
{
#region Dependency Properties
/// <summary>
/// 最大小数点位数
/// </summary>
public int MaxFractionDigits
{
get { return (int)GetValue(MaxFractionDigitsProperty); }
set { SetValue(MaxFractionDigitsProperty, value); }
}
// Using a DependencyProperty as the backing store for MaxFractionDigits.  This enables animation, styling, binding, etc...
public static readonly DependencyProperty MaxFractionDigitsProperty =
DependencyProperty.Register("MaxFractionDigits", typeof(int), typeof(NumericBox), new PropertyMetadata(2));

/// <summary>
/// 不足位数是否补零
/// </summary>
public bool IsPadding
{
get { return (bool)GetValue(IsPaddingProperty); }
set { SetValue(IsPaddingProperty, value); }
}
// Using a DependencyProperty as the backing store for IsPadding.  This enables animation, styling, binding, etc...
public static readonly DependencyProperty IsPaddingProperty =
DependencyProperty.Register("IsPadding", typeof(bool), typeof(NumericBox), new PropertyMetadata(true));

#endregion

public NumericBox()
{
TextBoxFilterBehavior behavior = new TextBoxFilterBehavior();
behavior.TextBoxFilterOptions = TextBoxFilterOptions.Numeric | TextBoxFilterOptions.Dot;
Interaction.GetBehaviors(this).Add(behavior);
this.TextChanged += new TextChangedEventHandler(NumericBox_TextChanged);
}

/// <summary>
/// 设置Text文本以及光标位置
/// </summary>
/// <param name="text"></param>
protected virtual void SetTextAndSelection(string text)
{
//保存光标位置
int selectionIndex = this.SelectionStart;
this.Text = text;
//恢复光标位置 系统会自动处理光标位置超出文本长度的情况
this.SelectionStart = selectionIndex;
}

/// <summary>
/// 去掉开头部分多余的0
/// </summary>
private void TrimZeroStart()
{
string resultText = this.Text;
//计算开头部分0的个数
int zeroCount = 0;
foreach (char c in this.Text)
{
if (c == '0') { zeroCount++; }
else { break; }
}

//当前文本中包含小数点
if (this.Text.Contains('.'))
{
//0后面跟的不是小数点，则删除全部的0
if (this.Text[zeroCount] != '.')
{
resultText = this.Text.TrimStart('0');
}
//否则，保留一个0
else if (zeroCount > 1)
{
resultText = this.Text.Substring(zeroCount - 1);
}
}
//当前文本中不包含小数点,则保留一个0，并在其后加一个小数点，并将光标设置到小数点前
else if (zeroCount > 0)
{
resultText = "0." + this.Text.TrimStart('0');
this.SelectionStart = 1;
}

SetTextAndSelection(resultText);
}

void NumericBox_TextChanged(object sender, TextChangedEventArgs e)
{
int decimalIndex = this.Text.IndexOf('.');
if (decimalIndex >= 0)
{
//小数点后的位数
int lengthAfterDecimal = this.Text.Length - decimalIndex - 1;
if (lengthAfterDecimal > MaxFractionDigits)
{
SetTextAndSelection(this.Text.Substring(0, this.Text.Length - (lengthAfterDecimal - MaxFractionDigits)));
}
else if (IsPadding)
{
SetTextAndSelection(this.Text.PadRight(this.Text.Length + MaxFractionDigits - lengthAfterDecimal, '0'));
}
}
TrimZeroStart();
}
}
/// <summary>
/// TextBox筛选行为，过滤不需要的按键
/// </summary>
public class TextBoxFilterBehavior : Behavior<TextBox>
{
private string _prevText = string.Empty;
public TextBoxFilterBehavior()
{
}
#region Dependency Properties
/// <summary>
/// TextBox筛选选项，这里选择的为过滤后剩下的按键
/// 控制键不参与筛选，可以多选组合
/// </summary>
public TextBoxFilterOptions TextBoxFilterOptions
{
get { return (TextBoxFilterOptions)GetValue(TextBoxFilterOptionsProperty); }
set { SetValue(TextBoxFilterOptionsProperty, value); }
}

// Using a DependencyProperty as the backing store for TextBoxFilterOptions.  This enables animation, styling, binding, etc...
public static readonly DependencyProperty TextBoxFilterOptionsProperty =
DependencyProperty.Register("TextBoxFilterOptions", typeof(TextBoxFilterOptions), typeof(TextBoxFilterBehavior), new PropertyMetadata(TextBoxFilterOptions.None));
#endregion

protected override void OnAttached()
{
base.OnAttached();
this.AssociatedObject.KeyDown += new KeyEventHandler(AssociatedObject_KeyDown);
this.AssociatedObject.TextChanged += new TextChangedEventHandler(AssociatedObject_TextChanged);
}

protected override void OnDetaching()
{
base.OnDetaching();
this.AssociatedObject.KeyDown -= new KeyEventHandler(AssociatedObject_KeyDown);
this.AssociatedObject.TextChanged -= new TextChangedEventHandler(AssociatedObject_TextChanged);
}

#region Events

/// <summary>
/// 处理通过其它手段进行的输入
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void AssociatedObject_TextChanged(object sender, TextChangedEventArgs e)
{
//如果符合规则，就保存下来
if (IsValidText(this.AssociatedObject.Text))
{
_prevText = this.AssociatedObject.Text;
}
//如果不符合规则，就恢复为之前保存的值
else
{
int selectIndex = this.AssociatedObject.SelectionStart - (this.AssociatedObject.Text.Length - _prevText.Length);
this.AssociatedObject.Text = _prevText;

if (selectIndex < 0)
selectIndex = 0;

this.AssociatedObject.SelectionStart = selectIndex;
}

}

/// <summary>
/// 处理按键产生的输入
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void AssociatedObject_KeyDown(object sender, KeyEventArgs e)
{
bool handled = true;
//不进行过滤
if (TextBoxFilterOptions == TextBoxFilterOptions.None ||
KeyboardHelper.IsControlKeys(e.Key))
{
handled = false;
}
//数字键
if (handled && TextBoxFilterOptions.ContainsOption(TextBoxFilterOptions.Numeric))
{
handled = !KeyboardHelper.IsDigit(e.Key);
}
//小数点
//if (handled && TextBoxFilterOptions.ContainsOption(TextBoxFilterOptions.Dot))
//{
//    handled = !(KeyboardHelper.IsDot(e.Key, e.PlatformKeyCode) && !_prevText.Contains("."));
//    if (KeyboardHelper.IsDot(e.Key, e.PlatformKeyCode) && _prevText.Contains("."))
//    {
//        //如果输入位置的下一个就是小数点，则将光标跳到小数点后面
//        if (this.AssociatedObject.SelectionStart< this.AssociatedObject.Text.Length && _prevText[this.AssociatedObject.SelectionStart] == '.')
//        {
//            this.AssociatedObject.SelectionStart++;
//        }
//    }
//}
if (handled && TextBoxFilterOptions.ContainsOption(TextBoxFilterOptions.Dot))
{
handled = !(KeyboardHelper.IsDot(e.Key) && !_prevText.Contains("."));
if (KeyboardHelper.IsDot(e.Key) && _prevText.Contains("."))
{
//如果输入位置的下一个就是小数点，则将光标跳到小数点后面
if (this.AssociatedObject.SelectionStart < this.AssociatedObject.Text.Length && _prevText[this.AssociatedObject.SelectionStart] == '.')
{
this.AssociatedObject.SelectionStart++;
}
}
}
//字母
if (handled && TextBoxFilterOptions.ContainsOption(TextBoxFilterOptions.Character))
{
handled = !KeyboardHelper.IsDot(e.Key);
}
e.Handled = handled;
}

#endregion

#region Private Methods
/// <summary>
/// 判断是否符合规则
/// </summary>
/// <param name="c"></param>
/// <returns></returns>
private bool IsValidChar(char c)
{
if (TextBoxFilterOptions == TextBoxFilterOptions.None)
{
return true;
}
else if (TextBoxFilterOptions.ContainsOption(TextBoxFilterOptions.Numeric) &&
'0' <= c && c <= '9')
{
return true;
}
else if (TextBoxFilterOptions.ContainsOption(TextBoxFilterOptions.Dot) &&
c == '.')
{
return true;
}
else if (TextBoxFilterOptions.ContainsOption(TextBoxFilterOptions.Character))
{
if (('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z'))
{
return true;
}
}
return false;
}

/// <summary>
/// 判断文本是否符合规则
/// </summary>
/// <param name="text"></param>
/// <returns></returns>
private bool IsValidText(string text)
{
//只能有一个小数点
if (text.IndexOf('.') != text.LastIndexOf('.'))
{
return false;
}
foreach (char c in text)
{
if (!IsValidChar(c))
{
return false;
}
}
return true;
}
#endregion
}
/// <summary>
/// TextBox筛选选项
/// </summary>
[Flags]
public enum TextBoxFilterOptions
{
/// <summary>
/// 不采用任何筛选
/// </summary>
None = 0,
/// <summary>
/// 数字类型不参与筛选
/// </summary>
Numeric = 1,
/// <summary>
/// 字母类型不参与筛选
/// </summary>
Character = 2,
/// <summary>
/// 小数点不参与筛选
/// </summary>
Dot = 4,
/// <summary>
/// 其它类型不参与筛选
/// </summary>
Other = 8
}

/// <summary>
/// TextBox筛选选项枚举扩展方法
/// </summary>
public static class TextBoxFilterOptionsExtension
{
/// <summary>
/// 在全部的选项中是否包含指定的选项
/// </summary>
/// <param name="allOptions">所有的选项</param>
/// <param name="option">指定的选项</param>
/// <returns></returns>
public static bool ContainsOption(this TextBoxFilterOptions allOptions, TextBoxFilterOptions option)
{
return (allOptions & option) == option;
}
}
/// <summary>
/// 键盘操作帮助类
/// </summary>
public class KeyboardHelper
{
/// <summary>
/// 键盘上的句号键
/// </summary>
public const int OemPeriod = 190;

#region Fileds

/// <summary>
/// 控制键
/// </summary>
private static readonly List<Key> _controlKeys = new List<Key>
{
Key.Back,
Key.CapsLock,
//Key.Ctrl,
Key.Down,
Key.End,
Key.Enter,
Key.Escape,
Key.Home,
Key.Insert,
Key.Left,
Key.PageDown,
Key.PageUp,
Key.Right,
//Key.Shift,
Key.Tab,
Key.Up
};

#endregion

/// <summary>
/// 是否是数字键
/// </summary>
/// <param name="key">按键</param>
/// <returns></returns>
public static bool IsDigit(Key key)
{
bool shiftKey = (Keyboard.Modifiers & ModifierKeys.Shift) != 0;
bool retVal;
//按住shift键后，数字键并不是数字键
if (key >= Key.D0 && key <= Key.D9 && !shiftKey)
{
retVal = true;
}
else
{
retVal = key >= Key.NumPad0 && key <= Key.NumPad9;
}
return retVal;
}

/// <summary>
/// 是否是控制键
/// </summary>
/// <param name="key">按键</param>
/// <returns></returns>
public static bool IsControlKeys(Key key)
{
return _controlKeys.Contains(key);
}

/// <summary>
/// 是否是小数点
/// Silverlight中无法识别问号左边的那个小数点键
/// 只能识别小键盘中的小数点
/// </summary>
/// <param name="key">按键</param>
/// <returns></returns>
public static bool IsDot(Key key)
{
bool shiftKey = (Keyboard.Modifiers & ModifierKeys.Shift) != 0;
bool flag = false;
if (key == Key.Decimal)
{
flag = true;
}
if (key == Key.OemPeriod && !shiftKey)
{
flag = true;
}
return flag;
}

/// <summary>
/// 是否是小数点
/// </summary>
/// <param name="key">按键</param>
/// <param name="keyCode">平台相关的按键代码</param>
/// <returns></returns>
public static bool IsDot(Key key, int keyCode)
{

//return IsDot(key) || (key == Key.Unknown && keyCode == OemPeriod);
return IsDot(key) || (keyCode == OemPeriod);
}

/// <summary>
/// 是否是字母键
/// </summary>
/// <param name="key">按键</param>
/// <returns></returns>
public static bool IsCharacter(Key key)
{
return key >= Key.A && key <= Key.Z;
}
}

<Controls:NumericBox Grid.Column="3" Grid.Row="11"
Width="200"  Height="30" Text="{Binding old,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"
CustomTextWrapping="NoWrap" CustomTextHeight="26" CustomTextWidth="170"
BgForeground="{StaticResource DialogTextBgForeground}"
CustomBorderColor="{StaticResource DialogTextBorderColor}" CustomBgColor="{StaticResource DialogTextBgColor}" >
<i:Interaction.Behaviors>
<Controls:TextBoxFilterBehavior TextBoxFilterOptions="Numeric"/>  <!--可以选择输入数字，小数点等-->
</i:Interaction.Behaviors>
</Controls:NumericBox>