Obtain Text Attributes Using UI Automation
Note
This documentation is intended for .NET Framework developers who want to use the managed UI Automation classes defined in the System.Windows.Automation namespace. For the latest information about UI Automation, see Windows Automation API: UI Automation.
This topic shows how to use Microsoft UI Automation to obtain text attributes from a text range. A text range can correspond to the current location of the caret (or degenerate selection) within a document, a contiguous selection of text, a collection of disjoint text selections, or the entire textual content of a document.
Example
The following code example demonstrates how to obtain the FontNameAttribute from a text range.
/// -------------------------------------------------------------------
/// <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
The TextPattern control pattern, in tandem with the TextPatternRange class, supports basic text attributes, properties, and methods. For control-specific functionality that is not supported by TextPattern or TextPatternRange the AutomationElement, class provides methods for a UI Automation client to access the corresponding native object model.