Cómo: Dibujar texto en el fondo de un control

Puede dibujar directamente el texto en el fondo de un control; para ello, convierta una cadena de texto en un objeto FormattedText y, a continuación, dibuje el objeto en el objeto DrawingContext del control. También puede utilizar esta técnica para dibujar en el fondo de objetos derivados de Panel, tales como Canvas y StackPanel.

Ejemplo de controles con fondos de texto personalizados

Ejemplo

Para dibujar en el fondo de un control, cree un nuevo objeto DrawingBrush y dibuje el texto convertido en el DrawingContext del objeto. A continuación, asigne el nuevo DrawingBrush a la propiedad de fondo del control.

En el ejemplo de código siguiente se muestra cómo crear un objeto FormattedText y dibujar en el fondo de un objeto Label y un objeto Button.

        ' Handle the WindowLoaded event for the window.
        Private Sub WindowLoaded(ByVal sender As Object, ByVal e As EventArgs)
            ' Update the background property of the label and button.
            myLabel.Background = New DrawingBrush(DrawMyText("My Custom Label"))
            myButton.Background = New DrawingBrush(DrawMyText("Display Text"))
        End Sub

        ' Convert the text string to a geometry and draw it to the control's DrawingContext.
        Private Function DrawMyText(ByVal textString As String) As Drawing
            ' Create a new DrawingGroup of the control.
            Dim drawingGroup As New DrawingGroup()

            ' Open the DrawingGroup in order to access the DrawingContext.
            Using drawingContext As DrawingContext = drawingGroup.Open()
                ' Create the formatted text based on the properties set.
                Dim formattedText As New FormattedText(textString, CultureInfo.GetCultureInfo("en-us"), FlowDirection.LeftToRight, New Typeface("Comic Sans MS Bold"), 48, Brushes.Black) ' This brush does not matter since we use the geometry of the text.

                ' Build the geometry object that represents the text.
                Dim textGeometry As Geometry = formattedText.BuildGeometry(New Point(20, 0))

                ' Draw a rounded rectangle under the text that is slightly larger than the text.
                drawingContext.DrawRoundedRectangle(Brushes.PapayaWhip, Nothing, New Rect(New Size(formattedText.Width + 50, formattedText.Height + 5)), 5.0, 5.0)

                ' Draw the outline based on the properties that are set.
                drawingContext.DrawGeometry(Brushes.Gold, New Pen(Brushes.Maroon, 1.5), textGeometry)

                ' Return the updated DrawingGroup content to be used by the control.
                Return drawingGroup
            End Using
        End Function

// Handle the WindowLoaded event for the window.
private void WindowLoaded(object sender, EventArgs e) 
{
    // Update the background property of the label and button.
    myLabel.Background = new DrawingBrush(DrawMyText("My Custom Label"));
    myButton.Background = new DrawingBrush(DrawMyText("Display Text"));
}

// Convert the text string to a geometry and draw it to the control's DrawingContext.
private Drawing DrawMyText(string textString)
{
    // Create a new DrawingGroup of the control.
    DrawingGroup drawingGroup = new DrawingGroup();

    // Open the DrawingGroup in order to access the DrawingContext.
    using (DrawingContext drawingContext = drawingGroup.Open())
    {
        // Create the formatted text based on the properties set.
        FormattedText formattedText = new FormattedText(
            textString,
            CultureInfo.GetCultureInfo("en-us"),
            FlowDirection.LeftToRight,
            new Typeface("Comic Sans MS Bold"),
            48,
            System.Windows.Media.Brushes.Black // This brush does not matter since we use the geometry of the text. 
            );

        // Build the geometry object that represents the text.
        Geometry textGeometry = formattedText.BuildGeometry(new System.Windows.Point(20, 0));

        // Draw a rounded rectangle under the text that is slightly larger than the text.
        drawingContext.DrawRoundedRectangle(System.Windows.Media.Brushes.PapayaWhip, null, new Rect(new System.Windows.Size(formattedText.Width + 50, formattedText.Height + 5)), 5.0, 5.0);

        // Draw the outline based on the properties that are set.
        drawingContext.DrawGeometry(System.Windows.Media.Brushes.Gold, new System.Windows.Media.Pen(System.Windows.Media.Brushes.Maroon, 1.5), textGeometry);

        // Return the updated DrawingGroup content to be used by the control.
        return drawingGroup;
    }
}

Vea también

Referencia

FormattedText

Conceptos

Dibujar texto con formato