使用 UI 自动化获取文本特性
备注
本文档适用于想要使用 System.Windows.Automation 命名空间中定义的托管 UI 自动化类的 .NET Framework 开发人员。 有关 UI 自动化的最新信息，请参阅 Windows 自动化 API：UI 自动化。
本主题演示如何使用 Microsoft UI 自动化从文本范围中获取文本特性。 文本范围可以与文档、连续选择的文本、非连续选择的文本集合或文档的整个文本内容中的插入符号的当前位置相对应（或使选择范围退化）。
示例
下面的代码示例演示如何从文本范围中获取 FontNameAttribute 。
/// -------------------------------------------------------------------
/// <summary>
/// Starts the target application and returns the AutomationElement
/// obtained from the targets window handle.
/// </summary>
/// <param name="exe">
/// The target application.
/// </param>
/// <param name="filename">
/// The text file to be opened in the target application
/// </param>
/// <returns>
/// An AutomationElement representing the target application.
/// </returns>
/// -------------------------------------------------------------------
private AutomationElement StartTarget(string exe, string filename)
{
// Start text editor and load with a text file.
Process p = Process.Start(exe, filename);
// targetApp --> the root AutomationElement.
AutomationElement targetApp =
AutomationElement.FromHandle(p.MainWindowHandle);
return targetApp;
}
''' -------------------------------------------------------------------
''' <summary>
''' Starts the target application and returns the AutomationElement
''' obtained from the targets window handle.
''' </summary>
''' <param name="exe">
''' The target application.
''' </param>
''' <param name="filename">
''' The text file to be opened in the target application
''' </param>
''' <returns>
''' An AutomationElement representing the target application.
''' </returns>
''' -------------------------------------------------------------------
Private Function StartTarget( _
ByVal exe As String, ByVal filename As String) As AutomationElement
' Start text editor and load with a text file.
Dim p As Process = Process.Start(exe, filename)
' targetApp --> the root AutomationElement.
Dim targetApp As AutomationElement
targetApp = AutomationElement.FromHandle(p.MainWindowHandle)
Return targetApp
End Function
/// -------------------------------------------------------------------
/// <summary>
/// Obtain the text control of interest from the target application.
/// </summary>
/// <param name="targetApp">
/// The target application.
/// </param>
/// <returns>
/// An AutomationElement that represents a text provider..
/// </returns>
/// -------------------------------------------------------------------
private AutomationElement GetTextElement(AutomationElement targetApp)
{
// The control type we're looking for; in this case 'Document'
PropertyCondition cond1 =
new PropertyCondition(
AutomationElement.ControlTypeProperty,
ControlType.Document);
// The control pattern of interest; in this case 'TextPattern'.
PropertyCondition cond2 =
new PropertyCondition(
AutomationElement.IsTextPatternAvailableProperty,
true);
AndCondition textCondition = new AndCondition(cond1, cond2);
AutomationElement targetTextElement =
targetApp.FindFirst(TreeScope.Descendants, textCondition);
// If targetText is null then a suitable text control was not found.
return targetTextElement;
}
''' -------------------------------------------------------------------
''' <summary>
''' Obtain the text control of interest from the target application.
''' </summary>
''' <param name="targetApp">
''' The target application.
''' </param>
''' <returns>
''' An AutomationElement. representing a text control.
''' </returns>
''' -------------------------------------------------------------------
Private Function GetTextElement(ByVal targetApp As AutomationElement) As AutomationElement
' The control type we're looking for; in this case 'Document'
Dim cond1 As PropertyCondition = _
New PropertyCondition( _
AutomationElement.ControlTypeProperty, _
ControlType.Document)
' The control pattern of interest; in this case 'TextPattern'.
Dim cond2 As PropertyCondition = _
New PropertyCondition( _
AutomationElement.IsTextPatternAvailableProperty, _
True)
Dim textCondition As AndCondition = New AndCondition(cond1, cond2)
Dim targetTextElement As AutomationElement = _
targetApp.FindFirst(TreeScope.Descendants, textCondition)
' If targetText is null then a suitable text control was not found.
Return targetTextElement
End Function
/// -------------------------------------------------------------------
/// <summary>
/// Outputs the FontNameAttribute value for a range of text.
/// </summary>
/// <param name="targetTextElement">
/// The AutomationElement that represents a text control.
/// </param>
/// -------------------------------------------------------------------
private void GetFontNameAttribute(AutomationElement targetTextElement)
{
TextPattern textPattern =
targetTextElement.GetCurrentPattern(TextPattern.Pattern) as TextPattern;
if (textPattern == null)
{
// Target control doesn't support TextPattern.
return;
}
// If the target control doesn't support selection then return.
// Otherwise, get the text attribute for the selected text.
// If there are currently no selections then the text attribute
// will be obtained from the insertion point.
TextPatternRange[] textRanges;
if (textPattern.SupportedTextSelection == SupportedTextSelection.None)
{
return;
}
else
{
textRanges = textPattern.GetSelection();
}
foreach (TextPatternRange textRange in textRanges)
{
Object textAttribute =
textRange.GetAttributeValue(
TextPattern.FontNameAttribute);
if (textAttribute == TextPattern.MixedAttributeValue)
{
// Returns MixedAttributeValue if the value of the
// specified attribute varies over the text range.
Console.WriteLine("Mixed fonts.");
}
else if (textAttribute == AutomationElement.NotSupported)
{
// Returns NotSupported if the specified attribute is
// not supported by the provider or the control.
Console.WriteLine(
"FontNameAttribute not supported by provider.");
}
else
{
Console.WriteLine(textAttribute.ToString());
}
}
}
''' -------------------------------------------------------------------
''' <summary>
''' Outputs the FontNameAttribute value for a range of text.
''' </summary>
''' <param name="targetTextElement">
''' The AutomationElement. that represents the text provider.
''' </param>
''' -------------------------------------------------------------------
Private Sub GetFontNameAttribute( _
ByVal targetTextElement As AutomationElement)
Dim targetTextPattern As TextPattern = _
DirectCast(targetTextElement.GetCurrentPattern( _
TextPattern.Pattern), TextPattern)
If (targetTextPattern Is Nothing) Then
' Target control doesn't support TextPattern.
Return
End If
' If the target control doesn't support selection then return.
' Otherwise, get the text attribute for the selected text.
' If there are currently no selections then the text attribute
' will be obtained from the insertion point.
Dim textRanges() As TextPatternRange
If (targetTextPattern.SupportedTextSelection = SupportedTextSelection.None) Then
Return
Else
textRanges = targetTextPattern.GetSelection()
End If
Dim textRange As TextPatternRange
For Each textRange In textRanges
Dim textAttribute As Object = _
textRange.GetAttributeValue( _
TextPattern.FontNameAttribute)
If (textAttribute = TextPattern.MixedAttributeValue) Then
' Returns MixedAttributeValue if the value of the
' specified attribute varies over the text range.
Console.WriteLine("Mixed fonts.")
ElseIf (textAttribute = AutomationElement.NotSupported) Then
' Returns NotSupported if the specified attribute is
' not supported by the provider or the control.
Console.WriteLine( _
"FontNameAttribute not supported by provider.")
Else
Console.WriteLine(textAttribute.ToString())
End If
Next
End Sub
与 TextPattern 类结合使用时， TextPatternRange 控件模式支持基本的文本特性、属性和方法。 对于 TextPattern 或 TextPatternRange 不支持的特定于控件的功能， AutomationElement类将为 UI 自动化客户端提供访问相应本机对象模型的方法。