Draw text to the background of a control by accessing the control's DrawingContext. : DrawingGroup « Windows Presentation Foundation « VB.Net Tutorial

1. VB.Net Tutorial
2. Windows Presentation Foundation
3. DrawingGroup

<Window x:Class="WpfApplication1.Window1"
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  Title="Draw Text to a Control's Background"
  Background="FloralWhite"
  Width="800" 
  Loaded="WindowLoaded">

  <StackPanel>
      <Label Name="myLabel" Width="200" Height="36" />
      <TextBox Name="myTextBox" MaxLength="25" >Sample Text</TextBox>
      <Button Name="myButton" Click="OnButtonClick" Width="160" Height="40" />
      <Canvas Name="myCanvas" Width ="760" Height="300"/>
  </StackPanel>
</Window>

//File:Window.xaml.vb

Imports System
Imports System.Globalization
Imports System.Windows
Imports System.Windows.Media

Namespace WpfApplication1
  Public Partial Class Window1
    Inherits Window
    Public Sub New()
      MyBase.New()
      InitializeComponent()
    End Sub

    Private Sub WindowLoaded(sender As Object, e As EventArgs)
      myLabel.Background = New DrawingBrush(DrawMyText("My Custom Label"))
      myButton.Background = New DrawingBrush(DrawMyText("Display Text"))
    End Sub
    Private Function DrawMyText(textString As String) As Drawing
      Dim drawingGroup As New DrawingGroup()
      Using drawingContext As DrawingContext = drawingGroup.Open()
        Dim formattedText As New FormattedText(textString, CultureInfo.GetCultureInfo("en-us"), FlowDirection.LeftToRight, New Typeface("Comic Sans MS Bold"), 48, Brushes.Black)
        Dim textGeometry As Geometry = formattedText.BuildGeometry(New Point(20, 0))
        drawingContext.DrawRoundedRectangle(Brushes.PapayaWhip, Nothing, New Rect(New Size(formattedText.Width + 50, formattedText.Height + 5)), 5.0, 5.0)
        drawingContext.DrawGeometry(Brushes.Gold, New Pen(Brushes.Maroon, 1.5), textGeometry)
        Return drawingGroup
      End Using
    End Function
    Public Sub OnButtonClick(sender As Object, e As EventArgs)
      myCanvas.Background = New DrawingBrush(DrawMyText(myTextBox.Text))
    End Sub
  End Class
End Namespace

16.86.DrawingGroup
	16.86.1.	Draw text to the background of a control by accessing the control's DrawingContext.