如何创建有条件地转换用户输入的WPF文本框?
我想创建一个文本框,可以进行测量,并在必要时将其转换为不同的单位(最终结果为类型如何创建有条件地转换用户输入的WPF文本框?,wpf,textbox,imultivalueconverter,Wpf,Textbox,Imultivalueconverter,我想创建一个文本框,可以进行测量,并在必要时将其转换为不同的单位(最终结果为类型double)。转换将由值IsMetric控制。如果IsMetric==true,则“中的36.5将变成927.1(一个双精度表示毫米)。相反,如果IsMetric==false,则“927.1 mm”将变为36.5 我想在常规的文本框上使用IValueConverter,但是ConverterParameter不是依赖属性,因此我无法绑定IsMetric 我尝试了IMultiValueConverter,但是Con
double
)。转换将由值IsMetric
控制。如果IsMetric==true
,则“中的36.5将变成927.1
(一个双精度表示毫米)。相反,如果IsMetric==false
,则“927.1 mm”
将变为36.5
我想在常规的文本框上使用IValueConverter
,但是ConverterParameter
不是依赖属性,因此我无法绑定IsMetric
我尝试了IMultiValueConverter
,但是ConvertBack
函数只接收文本框的当前值,而不是所有绑定值。这意味着在转换用户输入时,我不知道IsMetric
我是否错过了ConvertBack
功能?如果没有,那么我是否需要创建一个从文本框
派生的类?如果这是您唯一想做的事情,请尝试使用converter参数的其他方法。
但是,我会选择这个选项——如果您的textbox中有更多的逻辑,或者倾向于有更多的dependecie——创建从textbox继承的自定义控件,并添加您自己的dependeci属性。然后,您可以使用IsMetric并根据需要在propertychanged等上对其进行转换。您可以使用两个转换器,一个用于从公制转换,另一个用于转换为公制:
public class ToMetricConverter:IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return "(metric) value";
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
public class FromMetricConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return "(Inch) value";
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
并在UI中使用DataTrigger
,根据该布尔值选择适当的转换器:
<Window.Resources>
<wpfApplication13:ToMetricConverter x:Key="ToMetricConverter"/>
<wpfApplication13:FromMetricConverter x:Key="FromMetricConverter"/>
</Window.Resources>
<Grid>
<StackPanel>
<CheckBox IsChecked="{Binding IsMetric,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"></CheckBox>
<TextBox >
<TextBox.Style>
<Style TargetType="TextBox">
<Style.Triggers>
<DataTrigger Binding="{Binding IsMetric,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" Value="True">
<Setter Property="Text" Value="{Binding Val,Converter={StaticResource ToMetricConverter}}"></Setter>
</DataTrigger>
<DataTrigger Binding="{Binding IsMetric,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" Value="False">
<Setter Property="Text" Value="{Binding Val,Converter={StaticResource FromMetricConverter}}"></Setter>
</DataTrigger>
</Style.Triggers>
</Style>
</TextBox.Style>
</TextBox>
</StackPanel>
</Grid>
我现在的结局是这样的。仍然会喜欢一个解决方案,它不需要对每个可能的值都使用DataTrigger
这与@SamTheDev发布的答案有点不同,但大致相同
xaml
用法:
<mynamespace:MeasurementTextBox Measurement="{Binding SomeLength, Mode=TwoWay}"
UseMetric="{Binding IsMetric}"/>
创建自定义控件。这将是一个比使用转换器更优雅的解决方案。还有,当你完成后,把它贴出来,这样我就可以用了:-)注意-我已经回答了(:谢谢,除了我使用了一个转换器外,这与我提出的解决方案是一致的。对于IsMetric可能不仅仅是真的或假的情况,我仍然希望找到一个优雅的解决方案,但这肯定是一个选项。今年,我同意这有点难看:p
using System;
using System.Windows;
using System.Windows.Controls;
namespace MyNamespace.Controls
{
/// <summary>
/// Interaction logic for MeasurementTextBox.xaml
/// </summary>
public partial class MeasurementTextBox : UserControl
{
public MeasurementTextBox()
{
// This call is required by the designer.
InitializeComponent();
}
public bool UseMetric {
get { return Convert.ToBoolean(GetValue(UseMetricProperty)); }
set { SetValue(UseMetricProperty, value); }
}
public static readonly DependencyProperty UseMetricProperty = DependencyProperty.Register("UseMetric", typeof(bool), typeof(MeasurementTextBox), new PropertyMetadata(MeasurementTextBox.UseMetricChanged));
private static void UseMetricChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
}
public double Measurement {
get { return (double)GetValue(MeasurementProperty); }
set { SetValue(MeasurementProperty, value); }
}
public static readonly DependencyProperty MeasurementProperty = DependencyProperty.Register("Measurement", typeof(double), typeof(MeasurementTextBox), new PropertyMetadata(MeasurementTextBox.MeasurementPropertyChanged));
private static void MeasurementPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
}
}
}
using System;
using System.Windows;
using System.Windows.Data;
namespace MyNamespace.Converters
{
class MeasurementConverter : IValueConverter
{
const double MILLIMETERS_IN_ONE_INCH = 25.4;
const string INCHES_ABBREVIATION = "in";
const string MILLIMETERS_ABBREVIATION = "mm";
const double ONE_THIRTY_SECOND = 0.03125;
const double ONE_SIXTEENTH = 0.0625;
const double ONE_EIGHTH = 0.125;
const double ONE_FOURTH = 0.25;
const double ONE_HALF = 0.5;
const double ONE = 1;
public double RoundToNearest(double value, int unitPrecision)
{
double fraction = 0;
int reciprocal = 0;
switch (unitPrecision)
{
case 0:
fraction = ONE;
reciprocal = (int)ONE;
break;
case 1:
fraction = ONE;
reciprocal = (int)ONE;
break;
case 2:
fraction = ONE_HALF;
reciprocal = (int)(1 / ONE_HALF);
break;
case 3:
fraction = ONE_FOURTH;
reciprocal = (int)(1 / ONE_FOURTH);
break;
case 4:
fraction = ONE_EIGHTH;
reciprocal = (int)(1 / ONE_EIGHTH);
break;
case 5:
fraction = ONE_SIXTEENTH;
reciprocal = (int)(1 / ONE_SIXTEENTH);
break;
case 6:
fraction = ONE_THIRTY_SECOND;
reciprocal = (int)(1 / ONE_THIRTY_SECOND);
break;
}
return Math.Round(value * reciprocal, MidpointRounding.AwayFromZero) * fraction;
}
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
return value;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
string strValue = (string)value;
bool isMetric = (bool)parameter;
double enteredValue = 0;
bool enteredValueIsImperial = false;
if (strValue.EndsWith(INCHES_ABBREVIATION))
{
enteredValueIsImperial = true;
strValue = strValue.Substring(0, strValue.Length - INCHES_ABBREVIATION.Length);
}
else if (strValue.EndsWith(MILLIMETERS_ABBREVIATION))
{
enteredValueIsImperial = false;
strValue = strValue.Substring(0, strValue.Length - MILLIMETERS_ABBREVIATION.Length);
}
else if (isMetric)
{
enteredValueIsImperial = false;
}
else
{
enteredValueIsImperial = true;
}
try
{
enteredValue = double.Parse(strValue);
}
catch (FormatException)
{
return DependencyProperty.UnsetValue;
}
if (isMetric)
{
if (enteredValueIsImperial)
{
//inches to mm
return RoundToNearest(enteredValue * MILLIMETERS_IN_ONE_INCH, 0);
//0 is mm
}
else
{
//mm to mm
return RoundToNearest(enteredValue, 0);
//0 is mm
}
}
else
{
if (enteredValueIsImperial)
{
//inches to inches
return RoundToNearest(enteredValue, 5);
}
else
{
//mm to inches
return RoundToNearest(enteredValue / MILLIMETERS_IN_ONE_INCH, 5);
}
}
}
}
}
<mynamespace:MeasurementTextBox Measurement="{Binding SomeLength, Mode=TwoWay}"
UseMetric="{Binding IsMetric}"/>