在 UI 自动化提供程序中支持控件模式
更新：2007 年 11 月
本主题演示如何针对 UI 自动化提供程序实现一个或多个控件模式，以便客户端应用程序可以操作控件并从这些控件获取数据。
支持控件模式
为该元素支持的控件模式实现相应的接口，例如，为 InvokePattern 实现 IInvokeProvider。
返回一个对象，其中包含 IRawElementProviderSimple.GetPatternProvider 实现中的每个控件接口的实现。
示例
下面的示例演示了单选自定义列表框的 ISelectionProvider 实现。该示例将返回三个属性，并获取当前选择的项。
#Region "ISelectionProvider Members"
''' <summary>
''' Specifies whether selection of more than one item at a time is supported.
''' </summary>
Public ReadOnly Property CanSelectMultiple() As Boolean _
Implements ISelectionProvider.CanSelectMultiple
Get
Return False
End Get
End Property
''' <summary>
''' Specifies whether the list has to have an item selected at all times.
''' </summary>
Public ReadOnly Property IsSelectionRequired() As Boolean _
Implements ISelectionProvider.IsSelectionRequired
Get
Return True
End Get
End Property
''' <summary>
''' Returns the automation provider for the selected list item.
''' </summary>
''' <returns>The selected item.</returns>
''' <remarks>
''' MyList is an ArrayList collection of providers for items in the list box.
''' SelectedIndex is the index of the selected item.
''' </remarks>
Public Function GetSelection() As IRawElementProviderSimple() _
Implements ISelectionProvider.GetSelection
If SelectedIndex >= 0 Then
Dim itemProvider As IRawElementProviderSimple = DirectCast(MyList(SelectedIndex), IRawElementProviderSimple)
Dim providers(1) As IRawElementProviderSimple
providers(0) = itemProvider
Return providers
Else
Return Nothing
End If
End Function 'GetSelection
#End Region
Private Members As ISelectionProvider
#region ISelectionProvider Members
/// <summary>
/// Specifies whether selection of more than one item at a time is supported.
/// </summary>
public bool CanSelectMultiple
{
get
{
return false;
}
}
/// <summary>
/// Specifies whether the list has to have an item selected at all times.
/// </summary>
public bool IsSelectionRequired
{
get
{
return true;
}
}
/// <summary>
/// Returns the automation provider for the selected list item.
/// </summary>
/// <returns>The selected item.</returns>
/// <remarks>
/// MyList is an ArrayList collection of providers for items in the list box.
/// SelectedIndex is the index of the selected item.
/// </remarks>
public IRawElementProviderSimple[] GetSelection()
{
if (SelectedIndex >= 0)
{
IRawElementProviderSimple itemProvider = (IRawElementProviderSimple)MyList[SelectedIndex];
IRawElementProviderSimple[] providers = { itemProvider };
return providers;
}
else return null;
}
#endregion ISelectionProvider Members
下面的示例演示 GetPatternProvider 的一个实现，该实现将返回可实现 ISelectionProvider 的类。大多数列表框控件还支持其他模式，但是，该示例将针对所有其他模式标识符返回空引用（在 Microsoft Visual Basic .NET 中返回 Nothing）。
''' <summary>
''' Returns the object that supports the specified pattern.
''' </summary>
''' <param name="patternId">ID of the pattern.</param>
''' <returns>Object that implements IInvokeProvider.</returns>
''' <remarks>
''' In this case, the ISelectionProvider interface is implemented in another provider-defined class,
''' ListPattern. However, it could be implemented in the base provider class, in which case the
''' method would simply return "this".
''' </remarks>
Function GetPatternProvider(ByVal patternId As Integer) As Object _
Implements IRawElementProviderSimple.GetPatternProvider
If patternId = SelectionPatternIdentifiers.Pattern.Id Then
Return New ListPattern(myItems, SelectedIndex)
Else
Return Nothing
End If
End Function 'IRawElementProviderSimple.GetPatternProvider
/// <summary>
/// Returns the object that supports the specified pattern.
/// </summary>
/// <param name="patternId">ID of the pattern.</param>
/// <returns>Object that implements IInvokeProvider.</returns>
/// <remarks>
/// In this case, the ISelectionProvider interface is implemented in another provider-defined class,
/// ListPattern. However, it could be implemented in the base provider class, in which case the
/// method would simply return "this".
/// </remarks>
object IRawElementProviderSimple.GetPatternProvider(int patternId)
{
if (patternId == SelectionPatternIdentifiers.Pattern.Id)
{
return new ListPattern(myItems, SelectedIndex);
}
else
{
return null;
}
}