我正在开发一个用于货币编辑的自定义文本框
我已经看到一些随时可以使用的，但它们很复杂和/或实际上不可用，迫使你采取不良做法（例如硬编码应该在控件上使用的名称） ）。
所以我自己决定这样做，但是我无法使用绑定选项，因为分配给绑定属性的属性必须是小数，但TextBox控件的Text属性接受字符串。
我想的答案可能是覆盖基类（TextBox）中Text属性的访问方法（getter和setter），但是不允许这样做。
我的绑定应该设置为值，它将TextBox的text属性设置为文本（带有货币符号和所有内容），但是将其转换回Get方法的数值数据类型。
这是我到目前为止所取得的成就：
public class CurrencyTextBox : TextBox
{
private bool IsValidKey(Key key)
{
int k = (int)key;
return ((k >= 34 && k <= 43) //digits 0 to 9
|| (k >= 74 && k <= 83) //numeric keypad 0 to 9
|| (k == 2) //back space
|| (k == 32) //delete
);
}
private void Format()
{
//formatting decimal to currency text here
//Done! no problems here
}
private void FormatBack()
{
//formatting currency text to decimal here
//Done! no problems here
}
private void ValueChanged(object sender, TextChangedEventArgs e)
{
this.Format();
}
private void MouseClicked(object sender, MouseButtonEventArgs e)
{
this.Format();
// Prevent changing the caret index
this.CaretIndex = this.Text.Length;
e.Handled = true;
}
private void MouseReleased(object sender, MouseButtonEventArgs e)
{
this.Format();
// Prevent changing the caret index
this.CaretIndex = this.Text.Length;
e.Handled = true;
}
private void KeyPressed(object sender, KeyEventArgs e)
{
if (IsValidKey(e.Key))
e.Handled = true;
if (Keyboard.Modifiers != ModifierKeys.None)
return;
this.Format();
}
private void PastingEventHandler(object sender, DataObjectEventArgs e)
{
// Prevent copy/paste
e.CancelCommand();
}
public override void OnApplyTemplate()
{
base.OnApplyTemplate();
// Disable copy/paste
DataObject.AddCopyingHandler(this, PastingEventHandler);
DataObject.AddPastingHandler(this, PastingEventHandler);
this.CaretIndex = this.Text.Length;
this.PreviewKeyUp += KeyPressed;
this.PreviewMouseDown += MouseClicked;
this.PreviewMouseUp += MouseReleased;
this.TextChanged += ValueChanged;
this.Format();
}
}
这是XAML：
<MyNamespace:CurrencyTextBox x:Name="TxbCurrency" Text="{Binding Path=DataContext.Element.Currency, ValidatesOnDataErrors=True}" />
到目前为止一切顺利！从十进制属性到TextBox文本的绑定是＆＃34;右边的＆＃34;。但是如何在文本编辑之后从文本中取回小数现在是问题 从十进制到.Text的绑定使用装箱来隐藏ToString（）方法 问题： 在这种情况下如何从小数重载Parse（）方法以使用我的FormatBack（）方法从TextBox的文本中获取小数？
答案 0 :(得分：6)
嗯，为了将来的目的，如果有人遇到同样的问题，请在此处查看货币文本框的完整代码。随意使用，修改，出售（不要认为它有价值，你），或者随意玩它！
/*
* the necessary usings:
* using System.Globalization;
* using System.Windows;
* using System.Windows.Controls;
* using System.Windows.Input;
* using System.Threading;
* And don't forget to change the currency settings on the XAML
* or in the defaults (on the contructor)
* It's set by default to Brazilian Real (R$)
*/
public class CurrencyTextBox : TextBox
{
public CurrencyTextBox()
{
CurrencySymbol = "R$ ";
CurrencyDecimalPlaces = 2;
DecimalSeparator = ",";
ThousandSeparator = ".";
Culture = "pt-BR";
}
public string CurrencySymbol { get; set; }
private int CurrencyDecimalPlaces { get; set; }
public string DecimalSeparator { get; set; }
public string ThousandSeparator { get; set; }
public string Culture { get; set; }
private bool IsValidKey(int k)
{
return (k >= 34 && k <= 43) //digits 0 to 9
|| (k >= 74 && k <= 83) //numeric keypad 0 to 9
|| (k == 2) //back space
|| (k == 32) //delete
;
}
private string Format(string text)
{
string unformatedString = text == string.Empty ? "0,00" : text; //Initial state is always string.empty
unformatedString = unformatedString.Replace(CurrencySymbol, ""); //Remove currency symbol from text
unformatedString = unformatedString.Replace(DecimalSeparator, ""); //Remove separators (decimal)
unformatedString = unformatedString.Replace(ThousandSeparator, ""); //Remove separators (thousands)
decimal number = decimal.Parse(unformatedString) / (decimal)Math.Pow(10, CurrencyDecimalPlaces); //The value will have 'x' decimal places, so divide it by 10^x
unformatedString = number.ToString("C", CultureInfo.CreateSpecificCulture(Culture));
return unformatedString;
}
private decimal FormatBack(string text)
{
string unformatedString = text == string.Empty ? "0.00" : text;
unformatedString = unformatedString.Replace(CurrencySymbol, ""); //Remove currency symbol from text
unformatedString = unformatedString.Replace(ThousandSeparator, ""); //Remove separators (thousands);
CultureInfo current = Thread.CurrentThread.CurrentUICulture; //Let's change the culture to avoid "Input string was in an incorrect format"
Thread.CurrentThread.CurrentUICulture = CultureInfo.CreateSpecificCulture(Culture);
decimal returnValue = decimal.Parse(unformatedString);
Thread.CurrentThread.CurrentUICulture = current; //And now change it back, cuz we don't own the world, right?
return returnValue;
}
private void ValueChanged(object sender, TextChangedEventArgs e)
{
// Keep the caret at the end
this.CaretIndex = this.Text.Length;
}
private void MouseClicked(object sender, MouseButtonEventArgs e)
{
// Prevent changing the caret index
e.Handled = true;
this.Focus();
}
private void MouseReleased(object sender, MouseButtonEventArgs e)
{
// Prevent changing the caret index
e.Handled = true;
this.Focus();
}
private void KeyReleased(object sender, KeyEventArgs e)
{
this.Text = Format(this.Text);
this.Value = FormatBack(this.Text);
}
private void KeyPressed(object sender, KeyEventArgs e)
{
if (IsValidKey((int)e.Key))
return;
e.Handled = true;
this.CaretIndex = this.Text.Length;
}
private void PastingEventHandler(object sender, DataObjectEventArgs e)
{
// Prevent/disable paste
e.CancelCommand();
}
public override void OnApplyTemplate()
{
base.OnApplyTemplate();
DataObject.AddCopyingHandler(this, PastingEventHandler);
DataObject.AddPastingHandler(this, PastingEventHandler);
this.CaretIndex = this.Text.Length;
this.KeyDown += KeyPressed;
this.KeyUp += KeyReleased;
this.PreviewMouseDown += MouseClicked;
this.PreviewMouseUp += MouseReleased;
this.TextChanged += ValueChanged;
this.Text = Format(string.Empty);
}
public decimal? Value
{
get { return (decimal?)this.GetValue(ValueProperty); }
set { this.SetValue(ValueProperty, value); }
}
public static readonly DependencyProperty ValueProperty = DependencyProperty.Register(
"Value",
typeof(decimal?),
typeof(CurrencyTextBox),
new FrameworkPropertyMetadata(new decimal?(), FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, new PropertyChangedCallback(ValuePropertyChanged)));
private static void ValuePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
((CurrencyTextBox)d).Value = ((CurrencyTextBox)d).FormatBack(e.NewValue.ToString());
}
}
和xaml：
<myNamespace:CurrencyTextBox
Value="{Binding Path=DataContext.MyDecimalProperty, ValidatesOnDataErrors=True, UpdateSourceTrigger=PropertyChanged}"
CurrencySymbol="R$ "
Culture="pt-BR"
CurrencyDecimalPlaces="2"
DecimalSeparator=","
ThousandSeparator="." />
答案 1 :(得分：2)
像这样创建新的Dependency Property
public static readonly DependencyProperty ValueProperty =
DependencyProperty.Register(
"Value",
typeof(decimal?),
typeof(CurrencyTextBox),
new FrameworkPropertyMetadata(
new decimal?(),
FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
new PropertyChangedCallback(ValuePropertyChanged)));
private static void ValuePropertyChanged(
DependencyObject d,
DependencyPropertyChangedEventArgs e)
{
CurrencyTextBox x = (CurrencyTextBox)d;
x.Value = (decimal?)e.NewValue;
}
然后绑定到这个新属性
答案 2 :(得分：0)
看看这篇文章，我认为它会对你有所帮助。 http://www.codeproject.com/Articles/15239/Validation-in-Windows-Presentation-Foundation
或者你可以把这个
private static bool IsTextAllowed(string text)
{
Regex regex = new Regex("[^0-9.-]+"); //regex that matches disallowed text
return !regex.IsMatch(text);
}
并在PreviewTextInput事件中将此
e.Handled =！IsTextAllowed（e.Text）;
答案 3 :(得分：0)
我认为这实际上是不可能的，除了一个只允许数字的盒子的简单情况。理想情况下，您想要一个只能包含有效条目的框，但小数字包含一些对其无效的字符（例如＆＃39; - ＆＃39;和＆＃39;。＆＃39;）拥有。用户无法通过输入＆＃39; - ＆＃39;不将盒子置于无效状态。
同样，他们可以输入＆＃39; 1.＆＃39;，然后删除1并使该框保持不确定状态。当然，它会导致验证错误和红色边框，但您的视图模型仍然认为值为1，并且不知道问题。
对于正整数，您只能允许数字并在空白时自动插入零（虽然这有点不友好）
对于小数和负整数，我认为你能做的最好的事情就是约束用户可以键入的键，但你仍然需要将你的数字属性包装在一个字符串中并验证它 - 当按下OK按钮时，或理想情况下实现INotifyDataError以显示错误并禁用“确定”按钮。