使用组合框更改值单位时如何 update/convert 数字文本框值？基于当前单位的价值归一化？
How to update/convert mumeric TextBox value when changing value's unit using a ComboBox? Value normalization based on current unit?
我想要一个适用于我的 Xamarin 和 WPF 项目的转换器系统。我不想在数据库中保存任何单位，所以我想在用户更改单位时直接转换文本框值。
我制作了 public 一些 Observable 集合，例如；
public class AreaList : ObservableCollection<Unit>
{
public AreaList() : base()
{
Add(new Unit("mm²"));
Add(new Unit("cm²"));
Add(new Unit("dm²"));
Add(new Unit("m²"));
}
}
public class Unit
{
private string name;
public Unit(string name)
{
this.name = name;
}
public string Name
{
get { return name; }
set { name = value; }
}
}
在视图中，我将集合绑定到我的组合框。我给了我的 TextBox 他绑定的名称 属性(Text="{Binding TxtBoxValue}" => x:Name="TxtBoxValue")。 ConvertUnitValueCommand 将此名称设置为视图模型中的字符串，以了解转换器函数在更改单位时应使用哪个变量。
查看
<UserControl.Resources>
<c:AreaList x:Key="AreaListData" />
</UserControl.Resources>
<TextBox x:Name="TxtBoxValue"
Text="{Binding Mode=TwoWay, Path=TxtBoxValue, UpdateSourceTrigger=PropertyChanged}">
</TextBox>
<ComboBox IsSynchronizedWithCurrentItem="True"
IsEditable="False"
DisplayMemberPath="Name"
SelectedItem="{Binding Unit,Mode=OneWayToSource}"
ItemsSource="{Binding Source={StaticResource AreaListData}}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="PreviewMouseLeftButtonDown">
<i:InvokeCommandAction Command="{Binding ConvertUnitValueCommand}"
CommandParameter="{Binding ElementName=TxtBoxValue, Path=Name}" />
</i:EventTrigger>
</i:Interaction.Triggers>
</ComboBox>
视图模型
private string ConvertControlName;
private void ConvertUnitValue(object obj)
{
ConvertControlName = obj.ToString();
}
public Unit Unit
{
get => Get<Unit>();
set
{
if (ConvertControlName != null)
{
FieldInfo variable = this.GetType().GetField(ConvertControlName, BindingFlags.Instance | BindingFlags.Public | BindingFlags.Static | BindingFlags.NonPublic);
//Get the Value from setted Binding Variable
double oldValue = (double)variable.GetValue(this);
//Convert the value
if (oldValue > 0)
{
double newValue = Converts.ConvertUnitValue(Unit, value, oldValue);
variable.SetValue(this, newValue);
}
Set(value);
}
}
也许任何人都可以给我一些灵感，让我做得更好。
我不太了解你的代码影响，但我建议你尝试下面的设计，它使用 MVVM 模式，消除了 UI 和后端之间的紧密耦合。
我把这里的东西分开了
您的 XAML 将具有类似
的代码
<TextBox x:Name="unitTextbox"
Text="{Binding Path=Value, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">
</TextBox>
<ComboBox IsSynchronizedWithCurrentItem="True"
IsEditable="False"
DisplayMemberPath="Name"
SelectedItem="{Binding SelectedUnit}"
ItemsSource="{Binding AvailableUnits}">
</ComboBox>
你的 ViewModel 会像
public class MainVm : Observable
{
#region Private Fields
private double _value;
private ObservableCollection<Unit> _availableUnits;
private Unit _selectedUnit;
private Unit _previouslySelected;
#endregion Private Fields
#region Public Constructors
public MainVm()
{
_availableUnits = new ObservableCollection<Unit>()
{
new Unit("mm²"),
new Unit("cm²"),
new Unit("dm²"),
new Unit("m²")
};
}
#endregion Public Constructors
#region Public Properties
public double Value
{
get
{
return _value;
}
set
{
if (_value != value)
{
_value = value;
OnPropertyChanged();
}
}
}
public Unit SelectedUnit
{
get { return _selectedUnit; }
set
{
_previouslySelected = _selectedUnit;
_selectedUnit = value;
// call to value conversion function
// convert cm² to mm² or anything
Value = UnitConvertor.Convert(_value, _previouslySelected.Name, _selectedUnit.Name);
OnPropertyChanged();
}
}
public ObservableCollection<Unit> AvailableUnits => _availableUnits;
#endregion Public Properties
}
我的 Observable class 会像
public class Observable : INotifyPropertyChanged
{
#region Public Events
public event PropertyChangedEventHandler PropertyChanged;
#endregion Public Events
#region Protected Methods
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
var handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
#endregion Protected Methods
}
最好对单位使用枚举
以下示例将用户输入规范化为基本单位 m²:
Unit.cs
public class Unit
{
public Unit(string name, decimal baseFactor)
{
this.Name = name;
this.BaseFactor = baseFactor;
}
#region Overrides of Object
/// <inheritdoc />
public override string ToString() => this.Name;
#endregion
public string Name { get; set; }
public decimal BaseFactor { get; set; }
}
ViewModel.cs
public class ViewModel : INotifyPropertyChanged
{
public ViewModel()
{
this.Units = new List<Unit>()
{
new Unit("mm²", (decimal) (1 / Math.Pow(1000, 2))),
new Unit("cm²", (decimal) (1 / Math.Pow(100, 2))),
new Unit("dm²", (decimal) (1 / Math.Pow(10, 2))),
new Unit("m²", 1)
};
}
private void NormalizeValue()
{
this.NormalizedValue = this.UnitValue * this.SelectedUnit.BaseFactor;
}
private List<Unit> units;
public List<Unit> Units
{
get => this.units;
set
{
this.units = value;
OnPropertyChanged();
}
}
private Unit selectedUnit;
public Unit SelectedUnit
{
get => this.selectedUnit;
set
{
this.selectedUnit = value;
OnPropertyChanged();
NormalizeValue();
}
}
private decimal unitValue;
public decimal UnitValue
{
get => this.unitValue;
set
{
this.unitValue = value;
OnPropertyChanged();
NormalizeValue();
}
}
private decimal normalizedValue;
public decimal NormalizedValue
{
get => this.normalizedValue;
set
{
this.normalizedValue = value;
OnPropertyChanged();
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
ManiWindow.xaml
<Window>
<Window.DataContext>
<ViewModel />
</Window.DatContext>
<StackPanel>
<!-- Input -->
<TextBox Text="{Binding UnitValue}" />
<ComboBox ItemsSource="{Binding Units}"
SelectedItem="{Binding SelectedUnit}" />
<TextBlock Text="{Binding NormalizedValue}" />
</StackPanel>
</Window>
可重复使用的解决方案
一个可重用的解决方案是创建一个自定义控件，它派生自 TextBox 并封装了规范化逻辑和控件设计。
以下自定义控件 NormalizingNumericTextBox 扩展 TextBox 并将非规范化值和规范化值之间的双向转换。
它基本上是一个 TextBox 与 ComboBox 作为 Unit 选择器对齐。
它可能并不完美，但它已经可以使用了，我只花了大约 10 分钟就将之前的答案合并到这个自定义控件中。
NormalizingNumericTextBox 支持描述数值的任何类型的单位。
只需将 NormalizingNumericTextBox.Units 属性 绑定到任何类型的 Unit 实现的集合，例如重量、长度、货币等
绑定到 NormalizingNumericTextBox.NormalizedValue 到 get/set 标准化值。设置此 属性 会将值转换为当前 NormalizingNumericTextBox.SelectedUnit.
为原始输入值绑定到 NormalizingNumericTextBox.Text。
确保将默认的 Style（见下文）添加到 /Themes/Generic.xaml 内的 ResourceDictionary。自定义此 Style 以自定义外观。
ManiWindow.xaml
<Window>
<Window.DataContext>
<ViewModel />
</Window.DatContext>
<StackPanel>
<!-- Input -->
<NormalizingUnitTextBox NormalizedValue="{Binding NormalizedValue}"
Units="{Binding Units}"
Width="180" />
<!--
Test to show/manipulate current normalized value of the view model.
An entered normalized value will be converted back to the current NormalizingNumericTextBox.Unit -->
<TextBox Background="Red" Text="{Binding NormalizedUnitValue}"/>
</StackPanel>
</Window>
Unit.cs
public class Unit
{
public Unit(string name, decimal baseFactor)
{
this.Name = name;
this.BaseFactor = baseFactor;
}
#region Overrides of Object
/// <inheritdoc />
public override string ToString() => this.Name;
#endregion
public string Name { get; set; }
public decimal BaseFactor { get; set; }
}
ViewModel.cs
public class ViewModel : INotifyPropertyChanged
{
public ViewModel()
{
this.Units = new List<Unit>()
{
new Unit("m²", 1),
new Unit("dm²", (decimal) (1/Math.Pow(10, 2))),
new Unit("cm²", (decimal) (1/Math.Pow(100, 2))),
new Unit("mm²", (decimal) (1/Math.Pow(1000, 2)))
};
}
public List<Unit> Units { get; set; }
private decimal normalizedValue;
public decimal NormalizedValue
{
get => this.normalizedValue;
set
{
this.normalizedValue = value;
OnPropertyChanged();
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
NormalizingNumericTextBox.cs
[TemplatePart(Name = "PART_UnitsItemsHost", Type = typeof(ItemsControl))]
public class NormalizingNumericTextBox : TextBox
{
public static readonly DependencyProperty UnitsProperty = DependencyProperty.Register(
"Units",
typeof(IEnumerable<Unit>),
typeof(NormalizingNumericTextBox),
new PropertyMetadata(default(IEnumerable<Unit>), NormalizingNumericTextBox.OnUnitsChanged));
public IEnumerable<Unit> Units
{
get => (IEnumerable<Unit>) GetValue(NormalizingNumericTextBox.UnitsProperty);
set => SetValue(NormalizingNumericTextBox.UnitsProperty, value);
}
public static readonly DependencyProperty SelectedUnitProperty = DependencyProperty.Register(
"SelectedUnit",
typeof(Unit),
typeof(NormalizingNumericTextBox),
new FrameworkPropertyMetadata(
default(Unit),
FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
NormalizingNumericTextBox.OnSelectedUnitChanged));
public Unit SelectedUnit
{
get => (Unit) GetValue(NormalizingNumericTextBox.SelectedUnitProperty);
set => SetValue(NormalizingNumericTextBox.SelectedUnitProperty, value);
}
public static readonly DependencyProperty NormalizedValueProperty = DependencyProperty.Register(
"NormalizedValue",
typeof(decimal),
typeof(NormalizingNumericTextBox),
new FrameworkPropertyMetadata(
default(decimal),
FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
NormalizingNumericTextBox.OnNormalizedValueChanged));
public decimal NormalizedValue
{
get => (decimal) GetValue(NormalizingNumericTextBox.NormalizedValueProperty);
set => SetValue(NormalizingNumericTextBox.NormalizedValueProperty, value);
}
private ItemsControl PART_UnitsItemsHost { get; set; }
private bool IsNormalizing { get; set; }
static NormalizingNumericTextBox()
{
FrameworkElement.DefaultStyleKeyProperty.OverrideMetadata(
typeof(NormalizingNumericTextBox),
new FrameworkPropertyMetadata(typeof(NormalizingNumericTextBox)));
}
public NormalizingNumericTextBox()
{
}
private static void OnNormalizedValueChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var _this = d as NormalizingNumericTextBox;
_this.ConvertNormalizedValueToNumericText();
}
private static void OnSelectedUnitChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
(d as NormalizingNumericTextBox).NormalizeNumericText();
}
private static void OnUnitsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var _this = d as NormalizingNumericTextBox;
_this.SelectedUnit = _this.Units.FirstOrDefault();
}
/// <inheritdoc />
public override void OnApplyTemplate()
{
base.OnApplyTemplate();
this.PART_UnitsItemsHost = GetTemplateChild("PART_UnitsItemsHost") as ItemsControl;
if (this.PART_UnitsItemsHost == null)
{
throw new InvalidOperationException($"{nameof(this.PART_UnitsItemsHost)} not found in ControlTemplate");
}
this.PART_UnitsItemsHost.SetBinding(
Selector.SelectedItemProperty,
new Binding(nameof(this.SelectedUnit)) {Source = this});
this.PART_UnitsItemsHost.SetBinding(
ItemsControl.ItemsSourceProperty,
new Binding(nameof(this.Units)) {Source = this});
this.SelectedUnit = this.Units.FirstOrDefault();
}
#region Overrides of TextBoxBase
/// <inheritdoc />
protected override void OnTextChanged(TextChangedEventArgs e)
{
base.OnTextChanged(e);
if (this.IsNormalizing)
{
return;
}
NormalizeNumericText();
}
/// <inheritdoc />
protected override void OnTextInput(TextCompositionEventArgs e)
{
// Suppress non numeric characters
if (!decimal.TryParse(e.Text, NumberStyles.Number, CultureInfo.CurrentCulture, out decimal _))
{
e.Handled = true;
return;
}
base.OnTextInput(e);
}
#endregion Overrides of TextBoxBase
private void NormalizeNumericText()
{
this.IsNormalizing = true;
if (decimal.TryParse(this.Text, NumberStyles.Number, CultureInfo.CurrentCulture, out decimal numericValue))
{
this.NormalizedValue = numericValue * this.SelectedUnit.BaseFactor;
}
this.IsNormalizing = false;
}
private void ConvertNormalizedValueToNumericText()
{
this.IsNormalizing = true;
decimal value = this.NormalizedValue / this.SelectedUnit.BaseFactor;
this.Text = value.ToString(CultureInfo.CurrentCulture);
this.IsNormalizing = false;
}
}
Generic.xaml
<ResourceDictionary>
<Style TargetType="NormalizingNumericTextBox">
<Setter Property="BorderThickness" Value="1" />
<Setter Property="BorderBrush" Value="DarkGray" />
<Setter Property="HorizontalAlignment" Value="Left"/>
<Setter Property="VerticalContentAlignment" Value="Center"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="local:NormalizingNumericTextBox">
<Border BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
Background="{TemplateBinding Background}"
Padding="{TemplateBinding Padding}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>
<ScrollViewer x:Name="PART_ContentHost" Grid.Column="0" Margin="0" />
<ComboBox x:Name="PART_UnitsItemsHost" Grid.Column="1" BorderThickness="0" HorizontalAlignment="Right" />
</Grid>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ResourceDictionary>
我想要一个适用于我的 Xamarin 和 WPF 项目的转换器系统。我不想在数据库中保存任何单位，所以我想在用户更改单位时直接转换文本框值。
我制作了 public 一些 Observable 集合，例如；
public class AreaList : ObservableCollection<Unit>
{
public AreaList() : base()
{
Add(new Unit("mm²"));
Add(new Unit("cm²"));
Add(new Unit("dm²"));
Add(new Unit("m²"));
}
}
public class Unit
{
private string name;
public Unit(string name)
{
this.name = name;
}
public string Name
{
get { return name; }
set { name = value; }
}
}
在视图中，我将集合绑定到我的组合框。我给了我的 TextBox 他绑定的名称 属性(Text="{Binding TxtBoxValue}" => x:Name="TxtBoxValue")。 ConvertUnitValueCommand 将此名称设置为视图模型中的字符串，以了解转换器函数在更改单位时应使用哪个变量。
查看
<UserControl.Resources>
<c:AreaList x:Key="AreaListData" />
</UserControl.Resources>
<TextBox x:Name="TxtBoxValue"
Text="{Binding Mode=TwoWay, Path=TxtBoxValue, UpdateSourceTrigger=PropertyChanged}">
</TextBox>
<ComboBox IsSynchronizedWithCurrentItem="True"
IsEditable="False"
DisplayMemberPath="Name"
SelectedItem="{Binding Unit,Mode=OneWayToSource}"
ItemsSource="{Binding Source={StaticResource AreaListData}}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="PreviewMouseLeftButtonDown">
<i:InvokeCommandAction Command="{Binding ConvertUnitValueCommand}"
CommandParameter="{Binding ElementName=TxtBoxValue, Path=Name}" />
</i:EventTrigger>
</i:Interaction.Triggers>
</ComboBox>
视图模型
private string ConvertControlName;
private void ConvertUnitValue(object obj)
{
ConvertControlName = obj.ToString();
}
public Unit Unit
{
get => Get<Unit>();
set
{
if (ConvertControlName != null)
{
FieldInfo variable = this.GetType().GetField(ConvertControlName, BindingFlags.Instance | BindingFlags.Public | BindingFlags.Static | BindingFlags.NonPublic);
//Get the Value from setted Binding Variable
double oldValue = (double)variable.GetValue(this);
//Convert the value
if (oldValue > 0)
{
double newValue = Converts.ConvertUnitValue(Unit, value, oldValue);
variable.SetValue(this, newValue);
}
Set(value);
}
}
也许任何人都可以给我一些灵感，让我做得更好。
我不太了解你的代码影响，但我建议你尝试下面的设计，它使用 MVVM 模式，消除了 UI 和后端之间的紧密耦合。 我把这里的东西分开了
您的 XAML 将具有类似
的代码 <TextBox x:Name="unitTextbox"
Text="{Binding Path=Value, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">
</TextBox>
<ComboBox IsSynchronizedWithCurrentItem="True"
IsEditable="False"
DisplayMemberPath="Name"
SelectedItem="{Binding SelectedUnit}"
ItemsSource="{Binding AvailableUnits}">
</ComboBox>
你的 ViewModel 会像
public class MainVm : Observable
{
#region Private Fields
private double _value;
private ObservableCollection<Unit> _availableUnits;
private Unit _selectedUnit;
private Unit _previouslySelected;
#endregion Private Fields
#region Public Constructors
public MainVm()
{
_availableUnits = new ObservableCollection<Unit>()
{
new Unit("mm²"),
new Unit("cm²"),
new Unit("dm²"),
new Unit("m²")
};
}
#endregion Public Constructors
#region Public Properties
public double Value
{
get
{
return _value;
}
set
{
if (_value != value)
{
_value = value;
OnPropertyChanged();
}
}
}
public Unit SelectedUnit
{
get { return _selectedUnit; }
set
{
_previouslySelected = _selectedUnit;
_selectedUnit = value;
// call to value conversion function
// convert cm² to mm² or anything
Value = UnitConvertor.Convert(_value, _previouslySelected.Name, _selectedUnit.Name);
OnPropertyChanged();
}
}
public ObservableCollection<Unit> AvailableUnits => _availableUnits;
#endregion Public Properties
}
我的 Observable class 会像
public class Observable : INotifyPropertyChanged
{
#region Public Events
public event PropertyChangedEventHandler PropertyChanged;
#endregion Public Events
#region Protected Methods
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
var handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
#endregion Protected Methods
}
最好对单位使用枚举
以下示例将用户输入规范化为基本单位 m²:
Unit.cs
public class Unit
{
public Unit(string name, decimal baseFactor)
{
this.Name = name;
this.BaseFactor = baseFactor;
}
#region Overrides of Object
/// <inheritdoc />
public override string ToString() => this.Name;
#endregion
public string Name { get; set; }
public decimal BaseFactor { get; set; }
}
ViewModel.cs
public class ViewModel : INotifyPropertyChanged
{
public ViewModel()
{
this.Units = new List<Unit>()
{
new Unit("mm²", (decimal) (1 / Math.Pow(1000, 2))),
new Unit("cm²", (decimal) (1 / Math.Pow(100, 2))),
new Unit("dm²", (decimal) (1 / Math.Pow(10, 2))),
new Unit("m²", 1)
};
}
private void NormalizeValue()
{
this.NormalizedValue = this.UnitValue * this.SelectedUnit.BaseFactor;
}
private List<Unit> units;
public List<Unit> Units
{
get => this.units;
set
{
this.units = value;
OnPropertyChanged();
}
}
private Unit selectedUnit;
public Unit SelectedUnit
{
get => this.selectedUnit;
set
{
this.selectedUnit = value;
OnPropertyChanged();
NormalizeValue();
}
}
private decimal unitValue;
public decimal UnitValue
{
get => this.unitValue;
set
{
this.unitValue = value;
OnPropertyChanged();
NormalizeValue();
}
}
private decimal normalizedValue;
public decimal NormalizedValue
{
get => this.normalizedValue;
set
{
this.normalizedValue = value;
OnPropertyChanged();
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
ManiWindow.xaml
<Window>
<Window.DataContext>
<ViewModel />
</Window.DatContext>
<StackPanel>
<!-- Input -->
<TextBox Text="{Binding UnitValue}" />
<ComboBox ItemsSource="{Binding Units}"
SelectedItem="{Binding SelectedUnit}" />
<TextBlock Text="{Binding NormalizedValue}" />
</StackPanel>
</Window>
可重复使用的解决方案
一个可重用的解决方案是创建一个自定义控件，它派生自 TextBox 并封装了规范化逻辑和控件设计。
以下自定义控件 NormalizingNumericTextBox 扩展 TextBox 并将非规范化值和规范化值之间的双向转换。
它基本上是一个 TextBox 与 ComboBox 作为 Unit 选择器对齐。
它可能并不完美，但它已经可以使用了，我只花了大约 10 分钟就将之前的答案合并到这个自定义控件中。
NormalizingNumericTextBox 支持描述数值的任何类型的单位。
只需将 NormalizingNumericTextBox.Units 属性 绑定到任何类型的 Unit 实现的集合，例如重量、长度、货币等
绑定到 NormalizingNumericTextBox.NormalizedValue 到 get/set 标准化值。设置此 属性 会将值转换为当前 NormalizingNumericTextBox.SelectedUnit.
为原始输入值绑定到 NormalizingNumericTextBox.Text。
确保将默认的 Style（见下文）添加到 /Themes/Generic.xaml 内的 ResourceDictionary。自定义此 Style 以自定义外观。
ManiWindow.xaml
<Window>
<Window.DataContext>
<ViewModel />
</Window.DatContext>
<StackPanel>
<!-- Input -->
<NormalizingUnitTextBox NormalizedValue="{Binding NormalizedValue}"
Units="{Binding Units}"
Width="180" />
<!--
Test to show/manipulate current normalized value of the view model.
An entered normalized value will be converted back to the current NormalizingNumericTextBox.Unit -->
<TextBox Background="Red" Text="{Binding NormalizedUnitValue}"/>
</StackPanel>
</Window>
Unit.cs
public class Unit
{
public Unit(string name, decimal baseFactor)
{
this.Name = name;
this.BaseFactor = baseFactor;
}
#region Overrides of Object
/// <inheritdoc />
public override string ToString() => this.Name;
#endregion
public string Name { get; set; }
public decimal BaseFactor { get; set; }
}
ViewModel.cs
public class ViewModel : INotifyPropertyChanged
{
public ViewModel()
{
this.Units = new List<Unit>()
{
new Unit("m²", 1),
new Unit("dm²", (decimal) (1/Math.Pow(10, 2))),
new Unit("cm²", (decimal) (1/Math.Pow(100, 2))),
new Unit("mm²", (decimal) (1/Math.Pow(1000, 2)))
};
}
public List<Unit> Units { get; set; }
private decimal normalizedValue;
public decimal NormalizedValue
{
get => this.normalizedValue;
set
{
this.normalizedValue = value;
OnPropertyChanged();
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
NormalizingNumericTextBox.cs
[TemplatePart(Name = "PART_UnitsItemsHost", Type = typeof(ItemsControl))]
public class NormalizingNumericTextBox : TextBox
{
public static readonly DependencyProperty UnitsProperty = DependencyProperty.Register(
"Units",
typeof(IEnumerable<Unit>),
typeof(NormalizingNumericTextBox),
new PropertyMetadata(default(IEnumerable<Unit>), NormalizingNumericTextBox.OnUnitsChanged));
public IEnumerable<Unit> Units
{
get => (IEnumerable<Unit>) GetValue(NormalizingNumericTextBox.UnitsProperty);
set => SetValue(NormalizingNumericTextBox.UnitsProperty, value);
}
public static readonly DependencyProperty SelectedUnitProperty = DependencyProperty.Register(
"SelectedUnit",
typeof(Unit),
typeof(NormalizingNumericTextBox),
new FrameworkPropertyMetadata(
default(Unit),
FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
NormalizingNumericTextBox.OnSelectedUnitChanged));
public Unit SelectedUnit
{
get => (Unit) GetValue(NormalizingNumericTextBox.SelectedUnitProperty);
set => SetValue(NormalizingNumericTextBox.SelectedUnitProperty, value);
}
public static readonly DependencyProperty NormalizedValueProperty = DependencyProperty.Register(
"NormalizedValue",
typeof(decimal),
typeof(NormalizingNumericTextBox),
new FrameworkPropertyMetadata(
default(decimal),
FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
NormalizingNumericTextBox.OnNormalizedValueChanged));
public decimal NormalizedValue
{
get => (decimal) GetValue(NormalizingNumericTextBox.NormalizedValueProperty);
set => SetValue(NormalizingNumericTextBox.NormalizedValueProperty, value);
}
private ItemsControl PART_UnitsItemsHost { get; set; }
private bool IsNormalizing { get; set; }
static NormalizingNumericTextBox()
{
FrameworkElement.DefaultStyleKeyProperty.OverrideMetadata(
typeof(NormalizingNumericTextBox),
new FrameworkPropertyMetadata(typeof(NormalizingNumericTextBox)));
}
public NormalizingNumericTextBox()
{
}
private static void OnNormalizedValueChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var _this = d as NormalizingNumericTextBox;
_this.ConvertNormalizedValueToNumericText();
}
private static void OnSelectedUnitChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
(d as NormalizingNumericTextBox).NormalizeNumericText();
}
private static void OnUnitsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var _this = d as NormalizingNumericTextBox;
_this.SelectedUnit = _this.Units.FirstOrDefault();
}
/// <inheritdoc />
public override void OnApplyTemplate()
{
base.OnApplyTemplate();
this.PART_UnitsItemsHost = GetTemplateChild("PART_UnitsItemsHost") as ItemsControl;
if (this.PART_UnitsItemsHost == null)
{
throw new InvalidOperationException($"{nameof(this.PART_UnitsItemsHost)} not found in ControlTemplate");
}
this.PART_UnitsItemsHost.SetBinding(
Selector.SelectedItemProperty,
new Binding(nameof(this.SelectedUnit)) {Source = this});
this.PART_UnitsItemsHost.SetBinding(
ItemsControl.ItemsSourceProperty,
new Binding(nameof(this.Units)) {Source = this});
this.SelectedUnit = this.Units.FirstOrDefault();
}
#region Overrides of TextBoxBase
/// <inheritdoc />
protected override void OnTextChanged(TextChangedEventArgs e)
{
base.OnTextChanged(e);
if (this.IsNormalizing)
{
return;
}
NormalizeNumericText();
}
/// <inheritdoc />
protected override void OnTextInput(TextCompositionEventArgs e)
{
// Suppress non numeric characters
if (!decimal.TryParse(e.Text, NumberStyles.Number, CultureInfo.CurrentCulture, out decimal _))
{
e.Handled = true;
return;
}
base.OnTextInput(e);
}
#endregion Overrides of TextBoxBase
private void NormalizeNumericText()
{
this.IsNormalizing = true;
if (decimal.TryParse(this.Text, NumberStyles.Number, CultureInfo.CurrentCulture, out decimal numericValue))
{
this.NormalizedValue = numericValue * this.SelectedUnit.BaseFactor;
}
this.IsNormalizing = false;
}
private void ConvertNormalizedValueToNumericText()
{
this.IsNormalizing = true;
decimal value = this.NormalizedValue / this.SelectedUnit.BaseFactor;
this.Text = value.ToString(CultureInfo.CurrentCulture);
this.IsNormalizing = false;
}
}
Generic.xaml
<ResourceDictionary>
<Style TargetType="NormalizingNumericTextBox">
<Setter Property="BorderThickness" Value="1" />
<Setter Property="BorderBrush" Value="DarkGray" />
<Setter Property="HorizontalAlignment" Value="Left"/>
<Setter Property="VerticalContentAlignment" Value="Center"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="local:NormalizingNumericTextBox">
<Border BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
Background="{TemplateBinding Background}"
Padding="{TemplateBinding Padding}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>
<ScrollViewer x:Name="PART_ContentHost" Grid.Column="0" Margin="0" />
<ComboBox x:Name="PART_UnitsItemsHost" Grid.Column="1" BorderThickness="0" HorizontalAlignment="Right" />
</Grid>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ResourceDictionary>