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?
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
现在我知道这个问题有一个公认的答案,但就我个人而言,我觉得它有点令人困惑,我相信它应该比这更容易。所以我会试着演示我是如何做到最好的:
在Windows窗体中,有一个叫KeyPress的事件非常适合这类任务。但这在WPF中不存在,因此,我们将使用PreviewTextInput事件。此外,为了验证,我相信可以使用foreach来遍历文本框。Text并检查它是否匹配;)条件,但老实说,这就是正则表达式的用途。
在我们深入讨论神圣的法典之前还有一件事。对于要触发的事件,可以做两件事:
使用XAML告诉程序调用哪个函数:<PreviewTextInput="textBox_PreviewTextInput/> . 做它在加载事件的形式(文本框是在): 文本框。PreviewTextInput += onlyNumeric;
我认为第二种方法更好,因为在这种情况下,你会被要求应用相同的条件(正则表达式)到多个文本框,你不想重复自己!
最后,你可以这样做:
private void onlyNumeric(object sender, TextCompositionEventArgs e)
{
string onlyNumeric = @"^([0-9]+(.[0-9]+)?)$";
Regex regex = new Regex(onlyNumeric);
e.Handled = !regex.IsMatch(e.Text);
}
其他回答
我们可以对文本框更改事件进行验证。下面的实现可以防止除数字和一个小数点以外的按键输入。
private void textBoxNumeric_TextChanged(object sender, TextChangedEventArgs e)
{
TextBox textBox = sender as TextBox;
Int32 selectionStart = textBox.SelectionStart;
Int32 selectionLength = textBox.SelectionLength;
String newText = String.Empty;
int count = 0;
foreach (Char c in textBox.Text.ToCharArray())
{
if (Char.IsDigit(c) || Char.IsControl(c) || (c == '.' && count == 0))
{
newText += c;
if (c == '.')
count += 1;
}
}
textBox.Text = newText;
textBox.SelectionStart = selectionStart <= textBox.Text.Length ? selectionStart : textBox.Text.Length;
}
e.Handled = (int)e.Key >= 43 || (int)e.Key <= 34;
在预览文本框的按键事件。
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>
在使用这里的一些解决方案一段时间后,我开发了自己的解决方案,该解决方案适用于我的MVVM设置。注意,在允许用户输入错误字符的意义上,它不像其他一些那样动态,但它阻止用户按下按钮,从而阻止他们做任何事情。这很好地配合了我的主题,即当操作无法执行时将按钮变灰。
我有一个文本框,用户必须输入一些文档页面要打印:
<TextBox Text="{Binding NumberPagesToPrint, UpdateSourceTrigger=PropertyChanged}"/>
...使用这个绑定属性:
private string _numberPagesToPrint;
public string NumberPagesToPrint
{
get { return _numberPagesToPrint; }
set
{
if (_numberPagesToPrint == value)
{
return;
}
_numberPagesToPrint = value;
OnPropertyChanged("NumberPagesToPrint");
}
}
我还有一个按钮:
<Button Template="{DynamicResource CustomButton_Flat}" Content="Set"
Command="{Binding SetNumberPagesCommand}"/>
...使用此命令绑定:
private RelayCommand _setNumberPagesCommand;
public ICommand SetNumberPagesCommand
{
get
{
if (_setNumberPagesCommand == null)
{
int num;
_setNumberPagesCommand = new RelayCommand(param => SetNumberOfPages(),
() => Int32.TryParse(NumberPagesToPrint, out num));
}
return _setNumberPagesCommand;
}
}
然后是SetNumberOfPages()方法,但对于本主题不重要。它在我的案例中工作得很好,因为我不需要向视图的代码隐藏文件中添加任何代码,并且它允许我使用Command属性控制行为。
我在一个简单的项目中使用的是未绑定的盒子,所以我不能使用标准的绑定方法。因此,我创建了一个简单的黑客,其他人可能会发现非常方便,只需扩展现有的TextBox控件:
namespace MyApplication.InterfaceSupport
{
public class NumericTextBox : TextBox
{
public NumericTextBox() : base()
{
TextChanged += OnTextChanged;
}
public void OnTextChanged(object sender, TextChangedEventArgs changed)
{
if (!String.IsNullOrWhiteSpace(Text))
{
try
{
int value = Convert.ToInt32(Text);
}
catch (Exception e)
{
MessageBox.Show(String.Format("{0} only accepts numeric input.", Name));
Text = "";
}
}
}
public int? Value
{
set
{
if (value != null)
{
this.Text = value.ToString();
}
else
Text = "";
}
get
{
try
{
return Convert.ToInt32(this.Text);
}
catch (Exception ef)
{
// Not numeric.
}
return null;
}
}
}
}
显然,对于浮动类型,您希望将其解析为浮动类型等等。同样的原则也适用。
然后在XAML文件中,你需要包含相关的命名空间:
<UserControl x:Class="MyApplication.UserControls.UnParameterisedControl"
[ Snip ]
xmlns:interfaceSupport="clr-namespace:MyApplication.InterfaceSupport"
>
之后,你可以把它作为一个常规的控制:
<interfaceSupport:NumericTextBox Height="23" HorizontalAlignment="Left" Margin="168,51,0,0" x:Name="NumericBox" VerticalAlignment="Top" Width="120" >