Obtain Text Attributes Using 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 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. 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 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
/// -------------------------------------------------------------------
/// <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>
/// 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>
/// Outputs the FontNameAttribute value for a range of text.
/// </summary>
/// <param name="targetTextElement">
/// The AutomationElment 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());
}
}
}
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.
See Also
Tasks
Add Content to a Text Box Using UI Automation
Find and Highlight Text Using UI Automation
Concepts
UI Automation TextPattern Overview
UI Automation Control Patterns Overview
UI Automation Control Patterns for Clients