我希望接受数字和小数点，但没有符号。
我已经看过使用Windows窗体中的NumericUpDown控件的示例，以及来自微软的这个NumericUpDown自定义控件的示例。但到目前为止，似乎NumericUpDown (WPF是否支持)不会提供我想要的功能。我的应用程序是这样设计的，任何头脑正常的人都不会想弄乱箭头。在我的应用程序中，它们没有任何实际意义。
所以我正在寻找一个简单的方法，使一个标准的WPF文本框只接受我想要的字符。这可能吗?实用吗?
当前回答
这个怎么样?很适合我。希望我没有漏掉任何边缘情况……
MyTextBox.PreviewTextInput += (sender, args) =>
{
if (!int.TryParse(args.Text, out _))
{
args.Handled = true;
}
};
DataObject.AddPastingHandler(MyTextBox, (sender, args) =>
{
var isUnicodeText = args.SourceDataObject.GetDataPresent(DataFormats.UnicodeText, true);
if (!isUnicodeText)
{
args.CancelCommand();
}
var data = args.SourceDataObject.GetData(DataFormats.UnicodeText) as string;
if (!int.TryParse(data, out _))
{
args.CancelCommand();
}
});
其他回答
另一种方法将使用附加的行为，我实现了我的自定义TextBoxHelper类，它可以在我的项目中的所有文本框上使用。因为我认为为此目的订阅每个文本框和每个单独XAML文件中的事件会很耗时。
我实现的TextBoxHelper类有这些特性:
过滤和只接受Double, Int, Uint和自然格式的数字 只过滤和接受偶数或奇数 处理粘贴事件处理程序，以防止将无效文本粘贴到数值文本框中 可以设置一个默认值，这将被用来防止无效的数据作为最后一个镜头订阅的文本框TextChanged事件
下面是TextBoxHelper类的实现:
public static class TextBoxHelper
{
#region Enum Declarations
public enum NumericFormat
{
Double,
Int,
Uint,
Natural
}
public enum EvenOddConstraint
{
All,
OnlyEven,
OnlyOdd
}
#endregion
#region Dependency Properties & CLR Wrappers
public static readonly DependencyProperty OnlyNumericProperty =
DependencyProperty.RegisterAttached("OnlyNumeric", typeof(NumericFormat?), typeof(TextBoxHelper),
new PropertyMetadata(null, DependencyPropertiesChanged));
public static void SetOnlyNumeric(TextBox element, NumericFormat value) =>
element.SetValue(OnlyNumericProperty, value);
public static NumericFormat GetOnlyNumeric(TextBox element) =>
(NumericFormat) element.GetValue(OnlyNumericProperty);
public static readonly DependencyProperty DefaultValueProperty =
DependencyProperty.RegisterAttached("DefaultValue", typeof(string), typeof(TextBoxHelper),
new PropertyMetadata(null, DependencyPropertiesChanged));
public static void SetDefaultValue(TextBox element, string value) =>
element.SetValue(DefaultValueProperty, value);
public static string GetDefaultValue(TextBox element) => (string) element.GetValue(DefaultValueProperty);
public static readonly DependencyProperty EvenOddConstraintProperty =
DependencyProperty.RegisterAttached("EvenOddConstraint", typeof(EvenOddConstraint), typeof(TextBoxHelper),
new PropertyMetadata(EvenOddConstraint.All, DependencyPropertiesChanged));
public static void SetEvenOddConstraint(TextBox element, EvenOddConstraint value) =>
element.SetValue(EvenOddConstraintProperty, value);
public static EvenOddConstraint GetEvenOddConstraint(TextBox element) =>
(EvenOddConstraint)element.GetValue(EvenOddConstraintProperty);
#endregion
#region Dependency Properties Methods
private static void DependencyPropertiesChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
if (!(d is TextBox textBox))
throw new Exception("Attached property must be used with TextBox.");
switch (e.Property.Name)
{
case "OnlyNumeric":
{
var castedValue = (NumericFormat?) e.NewValue;
if (castedValue.HasValue)
{
textBox.PreviewTextInput += TextBox_PreviewTextInput;
DataObject.AddPastingHandler(textBox, TextBox_PasteEventHandler);
}
else
{
textBox.PreviewTextInput -= TextBox_PreviewTextInput;
DataObject.RemovePastingHandler(textBox, TextBox_PasteEventHandler);
}
break;
}
case "DefaultValue":
{
var castedValue = (string) e.NewValue;
if (castedValue != null)
{
textBox.TextChanged += TextBox_TextChanged;
}
else
{
textBox.TextChanged -= TextBox_TextChanged;
}
break;
}
}
}
#endregion
private static void TextBox_PreviewTextInput(object sender, TextCompositionEventArgs e)
{
var textBox = (TextBox)sender;
string newText;
if (textBox.SelectionLength == 0)
{
newText = textBox.Text.Insert(textBox.SelectionStart, e.Text);
}
else
{
var textAfterDelete = textBox.Text.Remove(textBox.SelectionStart, textBox.SelectionLength);
newText = textAfterDelete.Insert(textBox.SelectionStart, e.Text);
}
var evenOddConstraint = GetEvenOddConstraint(textBox);
switch (GetOnlyNumeric(textBox))
{
case NumericFormat.Double:
{
if (double.TryParse(newText, out double number))
{
switch (evenOddConstraint)
{
case EvenOddConstraint.OnlyEven:
if (number % 2 != 0)
e.Handled = true;
else
e.Handled = false;
break;
case EvenOddConstraint.OnlyOdd:
if (number % 2 == 0)
e.Handled = true;
else
e.Handled = false;
break;
}
}
else
e.Handled = true;
break;
}
case NumericFormat.Int:
{
if (int.TryParse(newText, out int number))
{
switch (evenOddConstraint)
{
case EvenOddConstraint.OnlyEven:
if (number % 2 != 0)
e.Handled = true;
else
e.Handled = false;
break;
case EvenOddConstraint.OnlyOdd:
if (number % 2 == 0)
e.Handled = true;
else
e.Handled = false;
break;
}
}
else
e.Handled = true;
break;
}
case NumericFormat.Uint:
{
if (uint.TryParse(newText, out uint number))
{
switch (evenOddConstraint)
{
case EvenOddConstraint.OnlyEven:
if (number % 2 != 0)
e.Handled = true;
else
e.Handled = false;
break;
case EvenOddConstraint.OnlyOdd:
if (number % 2 == 0)
e.Handled = true;
else
e.Handled = false;
break;
}
}
else
e.Handled = true;
break;
}
case NumericFormat.Natural:
{
if (uint.TryParse(newText, out uint number))
{
if (number == 0)
e.Handled = true;
else
{
switch (evenOddConstraint)
{
case EvenOddConstraint.OnlyEven:
if (number % 2 != 0)
e.Handled = true;
else
e.Handled = false;
break;
case EvenOddConstraint.OnlyOdd:
if (number % 2 == 0)
e.Handled = true;
else
e.Handled = false;
break;
}
}
}
else
e.Handled = true;
break;
}
}
}
private static void TextBox_PasteEventHandler(object sender, DataObjectPastingEventArgs e)
{
var textBox = (TextBox)sender;
if (e.DataObject.GetDataPresent(typeof(string)))
{
var clipboardText = (string) e.DataObject.GetData(typeof(string));
var newText = textBox.Text.Insert(textBox.SelectionStart, clipboardText);
var evenOddConstraint = GetEvenOddConstraint(textBox);
switch (GetOnlyNumeric(textBox))
{
case NumericFormat.Double:
{
if (double.TryParse(newText, out double number))
{
switch (evenOddConstraint)
{
case EvenOddConstraint.OnlyEven:
if (number % 2 != 0)
e.CancelCommand();
break;
case EvenOddConstraint.OnlyOdd:
if (number % 2 == 0)
e.CancelCommand();
break;
}
}
else
e.CancelCommand();
break;
}
case NumericFormat.Int:
{
if (int.TryParse(newText, out int number))
{
switch (evenOddConstraint)
{
case EvenOddConstraint.OnlyEven:
if (number % 2 != 0)
e.CancelCommand();
break;
case EvenOddConstraint.OnlyOdd:
if (number % 2 == 0)
e.CancelCommand();
break;
}
}
else
e.CancelCommand();
break;
}
case NumericFormat.Uint:
{
if (uint.TryParse(newText, out uint number))
{
switch (evenOddConstraint)
{
case EvenOddConstraint.OnlyEven:
if (number % 2 != 0)
e.CancelCommand();
break;
case EvenOddConstraint.OnlyOdd:
if (number % 2 == 0)
e.CancelCommand();
break;
}
}
else
e.CancelCommand();
break;
}
case NumericFormat.Natural:
{
if (uint.TryParse(newText, out uint number))
{
if (number == 0)
e.CancelCommand();
else
{
switch (evenOddConstraint)
{
case EvenOddConstraint.OnlyEven:
if (number % 2 != 0)
e.CancelCommand();
break;
case EvenOddConstraint.OnlyOdd:
if (number % 2 == 0)
e.CancelCommand();
break;
}
}
}
else
{
e.CancelCommand();
}
break;
}
}
}
else
{
e.CancelCommand();
}
}
private static void TextBox_TextChanged(object sender, TextChangedEventArgs e)
{
var textBox = (TextBox)sender;
var defaultValue = GetDefaultValue(textBox);
var evenOddConstraint = GetEvenOddConstraint(textBox);
switch (GetOnlyNumeric(textBox))
{
case NumericFormat.Double:
{
if (double.TryParse(textBox.Text, out double number))
{
switch (evenOddConstraint)
{
case EvenOddConstraint.OnlyEven:
if (number % 2 != 0)
textBox.Text = defaultValue;
break;
case EvenOddConstraint.OnlyOdd:
if (number % 2 == 0)
textBox.Text = defaultValue;
break;
}
}
else
textBox.Text = defaultValue;
break;
}
case NumericFormat.Int:
{
if (int.TryParse(textBox.Text, out int number))
{
switch (evenOddConstraint)
{
case EvenOddConstraint.OnlyEven:
if (number % 2 != 0)
textBox.Text = defaultValue;
break;
case EvenOddConstraint.OnlyOdd:
if (number % 2 == 0)
textBox.Text = defaultValue;
break;
}
}
else
textBox.Text = defaultValue;
break;
}
case NumericFormat.Uint:
{
if (uint.TryParse(textBox.Text, out uint number))
{
switch (evenOddConstraint)
{
case EvenOddConstraint.OnlyEven:
if (number % 2 != 0)
textBox.Text = defaultValue;
break;
case EvenOddConstraint.OnlyOdd:
if (number % 2 == 0)
textBox.Text = defaultValue;
break;
}
}
else
textBox.Text = defaultValue;
break;
}
case NumericFormat.Natural:
{
if (uint.TryParse(textBox.Text, out uint number))
{
if(number == 0)
textBox.Text = defaultValue;
else
{
switch (evenOddConstraint)
{
case EvenOddConstraint.OnlyEven:
if (number % 2 != 0)
textBox.Text = defaultValue;
break;
case EvenOddConstraint.OnlyOdd:
if (number % 2 == 0)
textBox.Text = defaultValue;
break;
}
}
}
else
{
textBox.Text = defaultValue;
}
break;
}
}
}
}
下面是一些简单用法的例子:
<TextBox viewHelpers:TextBoxHelper.OnlyNumeric="Double"
viewHelpers:TextBoxHelper.DefaultValue="1"/>
Or
<TextBox viewHelpers:TextBoxHelper.OnlyNumeric="Natural"
viewHelpers:TextBoxHelper.DefaultValue="3"
viewHelpers:TextBoxHelper.EvenOddConstraint="OnlyOdd"/>
注意，我的TextBoxHelper驻留在viewHelpers xmlns别名中。
我希望这个实现可以减轻其他人的工作:)
这是一种改进的WilPs解答。 我的改进是:
改进了删除和退格键的行为 增加了EmptyValue属性，如果空字符串是不合适的 修正了一些小错别字
/// <summary>
/// Regular expression for Textbox with properties:
/// <see cref="RegularExpression"/>,
/// <see cref="MaxLength"/>,
/// <see cref="EmptyValue"/>.
/// </summary>
public class TextBoxInputRegExBehaviour : Behavior<TextBox>
{
#region DependencyProperties
public static readonly DependencyProperty RegularExpressionProperty =
DependencyProperty.Register("RegularExpression", typeof(string), typeof(TextBoxInputRegExBehaviour), new FrameworkPropertyMetadata(".*"));
public string RegularExpression
{
get { return (string)GetValue(RegularExpressionProperty); }
set { SetValue(RegularExpressionProperty, value); }
}
public static readonly DependencyProperty MaxLengthProperty =
DependencyProperty.Register("MaxLength", typeof(int), typeof(TextBoxInputRegExBehaviour),
new FrameworkPropertyMetadata(int.MinValue));
public int MaxLength
{
get { return (int)GetValue(MaxLengthProperty); }
set { SetValue(MaxLengthProperty, value); }
}
public static readonly DependencyProperty EmptyValueProperty =
DependencyProperty.Register("EmptyValue", typeof(string), typeof(TextBoxInputRegExBehaviour), null);
public string EmptyValue
{
get { return (string)GetValue(EmptyValueProperty); }
set { SetValue(EmptyValueProperty, value); }
}
#endregion
/// <summary>
/// Attach our behaviour. Add event handlers
/// </summary>
protected override void OnAttached()
{
base.OnAttached();
AssociatedObject.PreviewTextInput += PreviewTextInputHandler;
AssociatedObject.PreviewKeyDown += PreviewKeyDownHandler;
DataObject.AddPastingHandler(AssociatedObject, PastingHandler);
}
/// <summary>
/// Deattach our behaviour. remove event handlers
/// </summary>
protected override void OnDetaching()
{
base.OnDetaching();
AssociatedObject.PreviewTextInput -= PreviewTextInputHandler;
AssociatedObject.PreviewKeyDown -= PreviewKeyDownHandler;
DataObject.RemovePastingHandler(AssociatedObject, PastingHandler);
}
#region Event handlers [PRIVATE] --------------------------------------
void PreviewTextInputHandler(object sender, TextCompositionEventArgs e)
{
string text;
if (this.AssociatedObject.Text.Length < this.AssociatedObject.CaretIndex)
text = this.AssociatedObject.Text;
else
{
// Remaining text after removing selected text.
string remainingTextAfterRemoveSelection;
text = TreatSelectedText(out remainingTextAfterRemoveSelection)
? remainingTextAfterRemoveSelection.Insert(AssociatedObject.SelectionStart, e.Text)
: AssociatedObject.Text.Insert(this.AssociatedObject.CaretIndex, e.Text);
}
e.Handled = !ValidateText(text);
}
/// <summary>
/// PreviewKeyDown event handler
/// </summary>
void PreviewKeyDownHandler(object sender, KeyEventArgs e)
{
if (string.IsNullOrEmpty(this.EmptyValue))
return;
string text = null;
// Handle the Backspace key
if (e.Key == Key.Back)
{
if (!this.TreatSelectedText(out text))
{
if (AssociatedObject.SelectionStart > 0)
text = this.AssociatedObject.Text.Remove(AssociatedObject.SelectionStart - 1, 1);
}
}
// Handle the Delete key
else if (e.Key == Key.Delete)
{
// If text was selected, delete it
if (!this.TreatSelectedText(out text) && this.AssociatedObject.Text.Length > AssociatedObject.SelectionStart)
{
// Otherwise delete next symbol
text = this.AssociatedObject.Text.Remove(AssociatedObject.SelectionStart, 1);
}
}
if (text == string.Empty)
{
this.AssociatedObject.Text = this.EmptyValue;
if (e.Key == Key.Back)
AssociatedObject.SelectionStart++;
e.Handled = true;
}
}
private void PastingHandler(object sender, DataObjectPastingEventArgs e)
{
if (e.DataObject.GetDataPresent(DataFormats.Text))
{
string text = Convert.ToString(e.DataObject.GetData(DataFormats.Text));
if (!ValidateText(text))
e.CancelCommand();
}
else
e.CancelCommand();
}
#endregion Event handlers [PRIVATE] -----------------------------------
#region Auxiliary methods [PRIVATE] -----------------------------------
/// <summary>
/// Validate certain text by our regular expression and text length conditions
/// </summary>
/// <param name="text"> Text for validation </param>
/// <returns> True - valid, False - invalid </returns>
private bool ValidateText(string text)
{
return (new Regex(this.RegularExpression, RegexOptions.IgnoreCase)).IsMatch(text) && (MaxLength == int.MinValue || text.Length <= MaxLength);
}
/// <summary>
/// Handle text selection
/// </summary>
/// <returns>true if the character was successfully removed; otherwise, false. </returns>
private bool TreatSelectedText(out string text)
{
text = null;
if (AssociatedObject.SelectionLength <= 0)
return false;
var length = this.AssociatedObject.Text.Length;
if (AssociatedObject.SelectionStart >= length)
return true;
if (AssociatedObject.SelectionStart + AssociatedObject.SelectionLength >= length)
AssociatedObject.SelectionLength = length - AssociatedObject.SelectionStart;
text = this.AssociatedObject.Text.Remove(AssociatedObject.SelectionStart, AssociatedObject.SelectionLength);
return true;
}
#endregion Auxiliary methods [PRIVATE] --------------------------------
}
用法非常简单:
<i:Interaction.Behaviors>
<behaviours:TextBoxInputRegExBehaviour RegularExpression="^\d+$" MaxLength="9" EmptyValue="0" />
</i:Interaction.Behaviors>
添加一个验证规则，以便在文本更改时检查数据是否是数字，如果是，则允许继续处理，如果不是，则提示用户该字段中只接受数字数据。
请参阅Windows演示基础中的验证
这是唯一需要的代码:
void MyTextBox_PreviewTextInput(object sender, TextCompositionEventArgs e)
{
e.Handled = new Regex("[^0-9]+").IsMatch(e.Text);
}
这只允许在文本框中输入数字。
若要允许使用小数点或负号，可以将正则表达式更改为[^0-9.-]+。
添加预览文本输入事件。像这样:<TextBox PreviewTextInput="PreviewTextInput" />。
然后在这个set中，如果文本不被允许，e。handled。e.Handled = ! istextallows (e.Text);
我在istextalered方法中使用一个简单的正则表达式来查看我是否应该允许他们键入的内容。在我的例子中，我只允许数字、点和破折号。
private static readonly Regex _regex = new Regex("[^0-9.-]+"); //regex that matches disallowed text
private static bool IsTextAllowed(string text)
{
return !_regex.IsMatch(text);
}
如果您希望防止粘贴不正确的数据，请连接数据对象。粘贴事件数据对象。粘贴="TextBoxPasting"如下所示(代码摘录):
// Use the DataObject.Pasting Handler
private void TextBoxPasting(object sender, DataObjectPastingEventArgs e)
{
if (e.DataObject.GetDataPresent(typeof(String)))
{
String text = (String)e.DataObject.GetData(typeof(String));
if (!IsTextAllowed(text))
{
e.CancelCommand();
}
}
else
{
e.CancelCommand();
}
}
