Traverse Text Using UI Automation
This topic shows how to use Microsoft UI Automation to traverse the textual content of a document by TextUnit increments.
Example
The following code example demonstrates how to traverse the content of a UI Automation text provider. The Move method moves the Start and End endpoints of a TextPatternRange. This text range is typically a degenerate range representing the text insertion point.
.gif) Note: |
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Since only text-based embedded objects are considered part of the text stream embedded objects such as images do not affect Move or its return value. |
'--------------------------------------------------------------------
' <summary>
' Starts the target application.
' </summary>
' <param name="app">
' The application to start.
' </param>
' <returns>The automation element for the app main window.</returns>
' <remarks>
' Three WPF documents, a rich text document, and a plain text document
' are provided in the Content folder of the TextProvider project.
' </remarks>
'--------------------------------------------------------------------
Private Function StartApp(ByVal app As String) As AutomationElement
' Start application.
Dim p As Process = Process.Start(app)
' Give the target application some time to start.
' For Win32 applications, WaitForInputIdle can be used instead.
' Another alternative is to listen for WindowOpened events.
' Otherwise, an ArgumentException results when you try to
' retrieve an automation element from the window handle.
Thread.Sleep(2000)
targetResult.Content = WPFTarget + " started. " + vbLf + vbLf + _
"Please load a document into the target application and click " + _
"the 'Find edit control' button above. " + vbLf + vbLf + _
"NOTE: Documents can be found in the 'Content' folder of the FindText project."
targetResult.Background = Brushes.LightGreen
' Return the automation element for the app main window.
Return AutomationElement.FromHandle(p.MainWindowHandle)
End Function 'StartApp
...
'--------------------------------------------------------------------
' <summary>
' Finds the text control in our target.
' </summary>
' <param name="src">The object that raised the event.</param>
' <param name="e">Event arguments.</param>
' <remarks>
' Initializes the TextPattern object and event handlers.
' </remarks>
'--------------------------------------------------------------------
Private Sub FindTextProvider_Click( _
ByVal src As Object, ByVal e As RoutedEventArgs)
' Set up the conditions for finding the text control.
Dim documentControl As New PropertyCondition( _
AutomationElement.ControlTypeProperty, ControlType.Document)
Dim textPatternAvailable As New PropertyCondition( _
AutomationElement.IsTextPatternAvailableProperty, True)
Dim findControl As New AndCondition(documentControl, textPatternAvailable)
' Get the Automation Element for the first text control found.
' For the purposes of this sample it is sufficient to find the
' first text control. In other cases there may be multiple text
' controls to sort through.
targetDocument = targetWindow.FindFirst(TreeScope.Descendants, findControl)
' Didn't find a text control.
If targetDocument Is Nothing Then
targetResult.Content = _
WPFTarget + " does not contain a Document control type."
targetResult.Background = Brushes.Salmon
startWPFTargetButton.IsEnabled = False
Return
End If
' Get required control patterns
targetTextPattern = DirectCast( _
targetDocument.GetCurrentPattern(TextPattern.Pattern), TextPattern)
' Didn't find a text control that supports TextPattern.
If targetTextPattern Is Nothing Then
targetResult.Content = WPFTarget + _
" does not contain an element that supports TextPattern."
targetResult.Background = Brushes.Salmon
startWPFTargetButton.IsEnabled = False
Return
End If
' Text control is available so display the client controls.
infoGrid.Visibility = Visibility.Visible
targetResult.Content = "Text provider found."
targetResult.Background = Brushes.LightGreen
' Initialize the document range for the text of the document.
documentRange = targetTextPattern.DocumentRange
' Initialize the client's search buttons.
If targetTextPattern.DocumentRange.GetText(1).Length > 0 Then
searchForwardButton.IsEnabled = True
End If
' Initialize the client's search TextBox.
searchString.IsEnabled = True
' Check if the text control supports text selection
If targetTextPattern.SupportedTextSelection = SupportedTextSelection.None Then
targetResult.Content = "Unable to select text."
targetResult.Background = Brushes.Salmon
Return
End If
' Edit control found so remove the find button from the client.
findEditButton.Visibility = Visibility.Collapsed
' Initialize the client with the current target selection, if any.
NotifySelectionChanged()
' Search starts at beginning of doc and goes forward
searchBackward = False
' Initialize a text changed listener.
' An instance of TextPatternRange will become invalid if
' one of the following occurs:
' 1) The text in the provider changes via some user activity.
' 2) ValuePattern.SetValue is used to programatically change
' the value of the text in the provider.
' The only way the client application can detect if the text
' has changed (to ensure that the ranges are still valid),
' is by setting a listener for the TextChanged event of
' the TextPattern. If this event is raised, the client needs
' to update the targetDocumentRange member data to ensure the
' user is working with the updated text.
' Clients must always anticipate the possibility that the text
' can change underneath them.
Dim onTextChanged As AutomationEventHandler = _
New AutomationEventHandler(AddressOf TextChanged)
Automation.AddAutomationEventHandler( _
TextPattern.TextChangedEvent, targetDocument, TreeScope.Element, onTextChanged)
' Initialize a selection changed listener.
' The target selection is reflected in the client.
Dim onSelectionChanged As AutomationEventHandler = _
New AutomationEventHandler(AddressOf OnTextSelectionChange)
Automation.AddAutomationEventHandler( _
TextPattern.TextSelectionChangedEvent, targetDocument, _
TreeScope.Element, onSelectionChanged)
End Sub 'FindTextProvider_Click
...
'--------------------------------------------------------------------
' <summary>
' Handles the navigation item selected event.
' </summary>
' <param name="sender">The object that raised the event.</param>
' <param name="e">Event arguments.</param>
'--------------------------------------------------------------------
Private Sub NavigationUnit_Change( _
ByVal sender As Object, ByVal e As SelectionChangedEventArgs)
Dim cb As ComboBox = CType(sender, ComboBox)
navigationUnit = CType(cb.SelectedValue, TextUnit)
End Sub 'NavigationUnit_Change
'--------------------------------------------------------------------
' <summary>
' Handles the Navigate button click event.
' </summary>
' <param name="sender">The object that raised the event.</param>
' <param name="e">Event arguments.</param>
'--------------------------------------------------------------------
Private Sub Navigate_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
Dim moveSelection As Button = CType(sender, Button)
Dim navDirection As Integer
' Which direction is the user searching through the text control?
If (CType(moveSelection.Tag, traversalDirection) = traversalDirection.Forward) Then
navDirection = 1
Else
navDirection = -1
End If
' Obtain the ranges to move.
Dim selectionRanges As TextPatternRange() = targetTextPattern.GetSelection()
' Iterate throught the ranges for a text control that supports
' multiple selections and move the selections the specified text
' unit and direction.
Dim textRange As TextPatternRange
For Each textRange In selectionRanges
textRange.Move(navigationUnit, navDirection)
textRange.Select()
Next textRange
' The WPF target doesn't show selected text as highlighted unless
' the window has focus.
targetDocument.SetFocus()
End Sub 'Navigate_Click
///--------------------------------------------------------------------
/// <summary>
/// Starts the target application.
/// </summary>
/// <param name="app">
/// The application to start.
/// </param>
/// <returns>The automation element for the app main window.</returns>
/// <remarks>
/// Three WPF documents, a rich text document, and a plain text document
/// are provided in the Content folder of the TextProvider project.
/// </remarks>
///--------------------------------------------------------------------
private AutomationElement StartApp(string app)
{
// Start application.
Process p = Process.Start(app);
// Give the target application some time to start.
// For Win32 applications, WaitForInputIdle can be used instead.
// Another alternative is to listen for WindowOpened events.
// Otherwise, an ArgumentException results when you try to
// retrieve an automation element from the window handle.
Thread.Sleep(2000);
targetResult.Content =
WPFTarget +
" started. \n\nPlease load a document into the target " +
"application and click the 'Find edit control' button above. " +
"\n\nNOTE: Documents can be found in the 'Content' folder of the FindText project.";
targetResult.Background = Brushes.LightGreen;
// Return the automation element for the app main window.
return (AutomationElement.FromHandle(p.MainWindowHandle));
}
...
///--------------------------------------------------------------------
/// <summary>
/// Finds the text control in our target.
/// </summary>
/// <param name="src">The object that raised the event.</param>
/// <param name="e">Event arguments.</param>
/// <remarks>
/// Initializes the TextPattern object and event handlers.
/// </remarks>
///--------------------------------------------------------------------
private void FindTextProvider_Click(object src, RoutedEventArgs e)
{
// Set up the conditions for finding the text control.
PropertyCondition documentControl = new PropertyCondition(
AutomationElement.ControlTypeProperty,
ControlType.Document);
PropertyCondition textPatternAvailable = new PropertyCondition(
AutomationElement.IsTextPatternAvailableProperty, true);
AndCondition findControl =
new AndCondition(documentControl, textPatternAvailable);
// Get the Automation Element for the first text control found.
// For the purposes of this sample it is sufficient to find the
// first text control. In other cases there may be multiple text
// controls to sort through.
targetDocument =
targetWindow.FindFirst(TreeScope.Descendants, findControl);
// Didn't find a text control.
if (targetDocument == null)
{
targetResult.Content =
WPFTarget +
" does not contain a Document control type.";
targetResult.Background = Brushes.Salmon;
startWPFTargetButton.IsEnabled = false;
return;
}
// Get required control patterns
targetTextPattern =
targetDocument.GetCurrentPattern(
TextPattern.Pattern) as TextPattern;
// Didn't find a text control that supports TextPattern.
if (targetTextPattern == null)
{
targetResult.Content =
WPFTarget +
" does not contain an element that supports TextPattern.";
targetResult.Background = Brushes.Salmon;
startWPFTargetButton.IsEnabled = false;
return;
}
// Text control is available so display the client controls.
infoGrid.Visibility = Visibility.Visible;
targetResult.Content =
"Text provider found.";
targetResult.Background = Brushes.LightGreen;
// Initialize the document range for the text of the document.
documentRange = targetTextPattern.DocumentRange;
// Initialize the client's search buttons.
if (targetTextPattern.DocumentRange.GetText(1).Length > 0)
{
searchForwardButton.IsEnabled = true;
}
// Initialize the client's search TextBox.
searchString.IsEnabled = true;
// Check if the text control supports text selection
if (targetTextPattern.SupportedTextSelection ==
SupportedTextSelection.None)
{
targetResult.Content = "Unable to select text.";
targetResult.Background = Brushes.Salmon;
return;
}
// Edit control found so remove the find button from the client.
findEditButton.Visibility = Visibility.Collapsed;
// Initialize the client with the current target selection, if any.
NotifySelectionChanged();
// Search starts at beginning of doc and goes forward
searchBackward = false;
// Initialize a text changed listener.
// An instance of TextPatternRange will become invalid if
// one of the following occurs:
// 1) The text in the provider changes via some user activity.
// 2) ValuePattern.SetValue is used to programatically change
// the value of the text in the provider.
// The only way the client application can detect if the text
// has changed (to ensure that the ranges are still valid),
// is by setting a listener for the TextChanged event of
// the TextPattern. If this event is raised, the client needs
// to update the targetDocumentRange member data to ensure the
// user is working with the updated text.
// Clients must always anticipate the possibility that the text
// can change underneath them.
Automation.AddAutomationEventHandler(
TextPattern.TextChangedEvent,
targetDocument,
TreeScope.Element,
TextChanged);
// Initialize a selection changed listener.
// The target selection is reflected in the client.
Automation.AddAutomationEventHandler(
TextPattern.TextSelectionChangedEvent,
targetDocument,
TreeScope.Element,
OnTextSelectionChange);
}
...
///--------------------------------------------------------------------
/// <summary>
/// Handles the navigation item selected event.
/// </summary>
/// <param name="sender">The object that raised the event.</param>
/// <param name="e">Event arguments.</param>
///--------------------------------------------------------------------
private void NavigationUnit_Change(object sender, SelectionChangedEventArgs e)
{
ComboBox cb = (ComboBox)sender;
navigationUnit = (TextUnit)cb.SelectedValue;
}
///--------------------------------------------------------------------
/// <summary>
/// Handles the Navigate button click event.
/// </summary>
/// <param name="sender">The object that raised the event.</param>
/// <param name="e">Event arguments.</param>
///--------------------------------------------------------------------
private void Navigate_Click(object sender, RoutedEventArgs e)
{
Button moveSelection = (Button)sender;
// Which direction is the user searching through the text control?
int navDirection =
((traversalDirection)moveSelection.Tag == traversalDirection.Forward) ? 1 : -1;
// Obtain the ranges to move.
TextPatternRange[] selectionRanges =
targetTextPattern.GetSelection();
// Iterate throught the ranges for a text control that supports
// multiple selections and move the selections the specified text
// unit and direction.
foreach (TextPatternRange textRange in selectionRanges)
{
textRange.Move(navigationUnit, navDirection);
textRange.Select();
}
// The WPF target doesn't show selected text as highlighted unless
// the window has focus.
targetDocument.SetFocus();
}
Any method using TextUnit will defer to the next largest TextUnit supported if the given TextUnit is not supported by the control.
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