SelectionPattern.SelectionPatternInformation.IsSelectionRequired 属性

定义

命名空间:

System.Windows.Automation

程序集:

UIAutomationClient.dll

获取一个值，该值指定容器是否要求至少选择一个子项。

public:
 property bool IsSelectionRequired { bool get(); };

public bool IsSelectionRequired { get; }

member this.IsSelectionRequired : bool

Public ReadOnly Property IsSelectionRequired As Boolean

属性值

Boolean

如果该控件要求至少选择一个项，则为 true；否则为 false。

示例

在以下示例中 SelectionPattern ，从 AutomationElement 获取控件模式，随后用于检索属性值。

///--------------------------------------------------------------------
/// <summary>
/// Obtains a SelectionPattern control pattern from an 
/// automation element.
/// </summary>
/// <param name="targetControl">
/// The automation element of interest.
/// </param>
/// <returns>
/// A SelectionPattern object.
/// </returns>
///--------------------------------------------------------------------
private SelectionPattern GetSelectionPattern(
    AutomationElement targetControl)
{
    SelectionPattern selectionPattern = null;

    try
    {
        selectionPattern =
            targetControl.GetCurrentPattern(SelectionPattern.Pattern)
            as SelectionPattern;
    }
    // Object doesn't support the SelectionPattern control pattern
    catch (InvalidOperationException)
    {
        return null;
    }

    return selectionPattern;
}

'''--------------------------------------------------------------------
''' <summary>
''' Obtains a SelectionPattern control pattern from an 
''' automation element.
''' </summary>
''' <param name="targetControl">
''' The automation element of interest.
''' </param>
''' <returns>
''' A SelectionPattern object.
''' </returns>
'''--------------------------------------------------------------------
Private Function GetSelectionPattern( _
ByVal targetControl As AutomationElement) As SelectionPattern
    Dim selectionPattern As SelectionPattern = Nothing

    Try
        selectionPattern = DirectCast( _
        targetControl.GetCurrentPattern(selectionPattern.Pattern), _
        SelectionPattern)
    ' Object doesn't support the SelectionPattern control pattern
    Catch
        Return Nothing
    End Try

    Return selectionPattern
End Function 'GetSelectionPattern

///--------------------------------------------------------------------
/// <summary>
/// Gets the current property values from target.
/// </summary>
/// <param name="selectionPattern">
/// A SelectionPattern control pattern obtained from 
/// an automation element representing the selection control.
/// </param>
/// <param name="automationProperty">
/// The automation property of interest.
/// </param>
///--------------------------------------------------------------------
private bool GetSelectionObjectProperty(
    SelectionPattern selectionPattern,
    AutomationProperty automationProperty)
{
    if (automationProperty.Id == 
        SelectionPattern.CanSelectMultipleProperty.Id)
    {
        return selectionPattern.Current.CanSelectMultiple;
    }
    if (automationProperty.Id == 
        SelectionPattern.IsSelectionRequiredProperty.Id)
    {
        return selectionPattern.Current.IsSelectionRequired;
    }
    return false;
}

'''--------------------------------------------------------------------
''' <summary>
''' Gets the current property values from target.
''' </summary>
''' <param name="selectionPattern">
''' A SelectionPattern control pattern obtained from 
''' an automation element representing the selection control.
''' </param>
''' <param name="automationProperty">
''' The automation property of interest.
''' </param>
'''--------------------------------------------------------------------
Private Function GetSelectionObjectProperty( _
ByVal selectionPattern As SelectionPattern, _
ByVal automationProperty As AutomationProperty) As Boolean
    If automationProperty.Id = _
    selectionPattern.CanSelectMultipleProperty.Id Then
        Return selectionPattern.Current.CanSelectMultiple
    End If
    If automationProperty.Id = _
    selectionPattern.IsSelectionRequiredProperty.Id Then
        Return selectionPattern.Current.IsSelectionRequired
    End If
    Return False
End Function 'GetSelectionObjectProperty

注解

此属性可以是动态的。 例如，控件的初始状态默认可能未选择任何项，指示 IsSelectionRequired 是 false。 但是，选择某一项后，该控件必须始终具有至少一个选定的项。