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Obtener atributos de texto mediante UI Automation

  • Artículo

Nota

Esta documentación está dirigida a los desarrolladores de .NET Framework que quieran usar las clases de automatización de la interfaz de usuario administradas definidas en el espacio de nombres System.Windows.Automation. Para ver la información más reciente acerca de la automatización de la interfaz de usuario, consulte Windows Automation API: automatización de la interfaz de usuario.

En este tema se muestra cómo usar Automatización de la interfaz de usuario de Microsoft para obtener atributos de texto de un rango de texto. Un intervalo de texto puede corresponder a la ubicación actual del símbolo de intercalación (o selección degenerada) dentro de un documento, una selección contigua de texto, una colección de selecciones de textos inconexos o todo el contenido textual de un documento.

Ejemplo

En el ejemplo de código siguiente se muestra cómo obtener el valor FontNameAttribute de un intervalo de texto.

/// -------------------------------------------------------------------
/// <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

El patrón de control TextPattern , junto con la clase TextPatternRange , admite atributos de texto básicos, propiedades y métodos. Para la funcionalidad específica del control que no es compatible con TextPattern ni TextPatternRange , la clase AutomationElementofrece métodos para que un cliente de Automatización de la interfaz de usuario acceda al modelo de objeto nativo correspondiente.

Consulte también