WPF样式设置器不工作

Question

我有一个包含组合框的自定义用户控件。我添加了一个ComboBoxWidth依赖属性，允许开发人员根据需要设置宽度。使用样式设置器，我想在另一个用户控件上将所有这些组合框的宽度设置为相同的值，以实现大小一致性。但是，它不起作用。如果我在每个控件上分别设置大小，它就会起作用。当在样式设置器中指定大小时，它将被忽略。如果我将属性字符串从"ComboBoxWidth"更改为"Width"，则所有控件的整个宽度都将更改。因此，看起来样式格式是正确的。我是不是错过了什么？这是我第一次尝试将样式应用于自己的自定义依赖属性。

注意：AngleUserControl基于一个通用用户控件(不包括任何在代码中创建的xaml控件)。ComboBoxWidth问题在泛型基类中。我不确定这是否与此有关。

样式代码(在包含多个AngleUserControl控件的用户控件中)：

<UserControl.Resources>
<Style TargetType="wpfControls:AngleUserControl">
<Setter Property="ComboBoxWidth" Value="400"/>
</Style>
</UserControl.Resources>

UnitControlBase:

/// <summary>
/// Control that displays value in different units depending on selected unit type.
/// </summary>
/// <typeparam name="TSelectionTypeEnum">The enumeration type for all the available units.</typeparam>
/// <typeparam name="TConverterType">The MultiValueConverter that converts the value between the different types of units.</typeparam>
/// <typeparam name="TValueType">The underlying type of the stored value.</typeparam>
public class UnitControlBase<TSelectionTypeEnum, TConverterType, TValueType> : UserControl
where TSelectionTypeEnum : struct, IConvertible
where TConverterType : IMultiValueConverter, new()
{
#region Private Fields
// Metadata for the dependency properties.
private static FrameworkPropertyMetadata valuePropertyMetadata = new FrameworkPropertyMetadata(default(TValueType));
private static FrameworkPropertyMetadata valueTypePropertyMetadata = new FrameworkPropertyMetadata(default(TSelectionTypeEnum));
private static FrameworkPropertyMetadata displayValueTypePropertyMetadata = new FrameworkPropertyMetadata(default(TSelectionTypeEnum));
private static FrameworkPropertyMetadata comboBoxWidthPropertyMetadata = new FrameworkPropertyMetadata(0.0);
private static FrameworkPropertyMetadata valueFormatPropertyMetadata = new FrameworkPropertyMetadata(string.Empty);
#endregion
#region Constructor
/// <summary>
/// Constructor
/// </summary>
public UnitControlBase()
{
ValueFormat = "#,##0.00";
ComboBoxWidth = 75.0;
// Create main grid and add to control.
Grid mainGrid = new Grid();
mainGrid.Name = "LayoutRoot";
this.AddChild(mainGrid);
// Create grid columns.
ColumnDefinition col1 = new ColumnDefinition();
col1.Width = GridLength.Auto;
ColumnDefinition col2 = new ColumnDefinition();
mainGrid.ColumnDefinitions.Add(col1);
mainGrid.ColumnDefinitions.Add(col2);
// Create the text box that will display the value.
Label displayValueLabel = new Label();
displayValueLabel.Name = "DisplayValueLabel";
Grid.SetColumn(displayValueLabel, 0);
mainGrid.Children.Add(displayValueLabel);
// Bind to the multi-value converter that will convert between the types.
MultiBinding mb = new MultiBinding();
mb.Converter = new TConverterType();
mb.Bindings.Add(new Binding("Value") { Source = this });
mb.Bindings.Add(new Binding("ValueType") { Source = this });
mb.Bindings.Add(new Binding("DisplayValueType") { Source = this });
mb.Bindings.Add(new Binding("ValueFormat") { Source = this });
displayValueLabel.SetBinding(Label.ContentProperty, mb);
displayValueLabel.HorizontalContentAlignment = System.Windows.HorizontalAlignment.Right;            
// Create the combo box that will display selected unit.
ComboBox displayValueComboBox = new ComboBox();
displayValueComboBox.Name = "DisplayValueComboBox";
displayValueComboBox.SetBinding(ComboBox.WidthProperty, new Binding("ComboBoxWidth") { Source = this });
Grid.SetColumn(displayValueComboBox, 1);
mainGrid.Children.Add(displayValueComboBox);
// Bind available units and selected units.
displayValueComboBox.ItemsSource = Enum.GetValues(typeof(TSelectionTypeEnum));
displayValueComboBox.SetBinding(ComboBox.SelectedItemProperty, new Binding("DisplayValueType") { Source = this });
}
#endregion
#region Dependency Properties
/// <summary>
/// Value Dependency Property
/// </summary>
public static readonly DependencyProperty ValueProperty =
DependencyProperty.Register("Value", typeof(TValueType), typeof(UnitControlBase<TSelectionTypeEnum, TConverterType, TValueType>), valuePropertyMetadata);
/// <summary>
/// Value Type Dependency Property
/// </summary>
public static readonly DependencyProperty ValueTypeProperty =
DependencyProperty.Register("ValueType", typeof(TSelectionTypeEnum), typeof(UnitControlBase<TSelectionTypeEnum, TConverterType, TValueType>), valueTypePropertyMetadata);
/// <summary>
/// Display Value Type Dependency Property
/// </summary>
public static readonly DependencyProperty DisplayValueTypeProperty =
DependencyProperty.Register("DisplayValueType", typeof(TSelectionTypeEnum), typeof(UnitControlBase<TSelectionTypeEnum, TConverterType, TValueType>), displayValueTypePropertyMetadata);
/// <summary>
/// Combo Box Width Dependency Property
/// </summary>
public static readonly DependencyProperty ComboBoxWidthProperty =
DependencyProperty.Register("ComboBoxWidth", typeof(double), typeof(UnitControlBase<TSelectionTypeEnum, TConverterType, TValueType>), comboBoxWidthPropertyMetadata);
/// <summary>
/// Value Format Dependency Property
/// </summary>
public static readonly DependencyProperty ValueFormatProperty =
DependencyProperty.Register("ValueFormat", typeof(string), typeof(UnitControlBase<TSelectionTypeEnum, TConverterType, TValueType>), valueFormatPropertyMetadata);
#endregion
#region Public Properties
/// <summary>
/// The underlying stored value.
/// </summary>
public TValueType Value
{
get
{
return (TValueType)GetValue(ValueProperty);
}
set
{
SetValue(ValueProperty, value);
}
}
/// <summary>
/// The unit type for the underlying stored value.
/// </summary>
public TSelectionTypeEnum ValueType
{
get
{
return (TSelectionTypeEnum)GetValue(ValueTypeProperty);
}
set
{
SetValue(ValueProperty, value);
}
}
/// <summary>
/// The unit type for the displayed value.
/// </summary>
public TSelectionTypeEnum DisplayValueType
{
get
{
return (TSelectionTypeEnum)GetValue(DisplayValueTypeProperty);
}
set
{
SetValue(DisplayValueTypeProperty, value);
}
}
/// <summary>
/// Width of combo box displaying available units.
/// </summary>
public double ComboBoxWidth
{
get
{
return (double)GetValue(ComboBoxWidthProperty);
}
set
{
SetValue(ComboBoxWidthProperty, value);
}
}
/// <summary>
/// The format of the displayed value.
/// </summary>
public string ValueFormat
{
get
{
return (string)GetValue(ValueFormatProperty);
}
set
{
SetValue(ValueFormatProperty, value);
}
}
#endregion
}

AngleUserControl.cs

/// <summary>
/// Control allowing user to display a value in degrees, radians, or semicircles.
/// </summary>
public class AngleUserControl : UnitControlBase<AngleSelectionType, AngleMultiValueConverter, double>
{
#region Constructor
/// <summary>
/// Constructor.
/// </summary>
public AngleUserControl()
{
this.ComboBoxWidth = 175.0;
}
#endregion
}

Answer 1

依赖属性的所谓"本地值"，如

this.ComboBoxWidth = 175.0;

具有比样式设置程序(如)中的值更高的值优先级

<Setter Property="ComboBoxWidth" Value="400"/>

因此，样式设置器没有任何作用。

您应该通过重写依赖属性元数据来分配一个新的默认值：

public class AngleUserControl : ...
{
static AngleUserControl()
{
ComboBoxWidthProperty.OverrideMetadata(
typeof(AngleUserControl),
new PropertyMetadata(175d));
}
}

请参阅相关性属性值优先级以获取参考。