之前的教程中曾使用Graphics.DrawString绘制文字，这个示例来说明如何绘制一个透明的文字水印。
设计界面：
其中，一个HScrollBar控件用于控制透明度，取值范围为0-255
当调整HScrollBar时，在label上显示实际的值：
Private Sub HScrollBar1_Scroll(sender As Object,e As ScrollEventArgs) Handles HScrollBar1.Scroll
Label2.Text = HScrollBar1.Value.ToString
End Sub
Private Sub Button1_Click(sender As Object,e As EventArgs) Handles Button1.Click
Dim logoOpacity As Integer = HScrollBar1.Value
Dim logoText As String = TextBox1.Text
Dim logoFont As New Font(New FontFamily("隶书"),40,FontStyle.Bold)
Dim logoBrush As New SolidBrush(Color.FromArgb(logoOpacity,255,255))
Dim logoLeft As Integer = 10
Dim logoTop As Integer = 10
Dim imgDest As Bitmap = PictureBox1.Image.Clone
Dim g As Graphics = Graphics.FromImage(imgDest)
g.DrawString(logoText,logoFont,logoBrush,logoLeft,logoTop)
g.Dispose()
PictureBox3.Image = imgDest
End Sub
运行效果：
下面对代码稍作分析：
1、Dim imgDest As Bitmap = PictureBox1.Image.Clone
为什么要用Clone，大家可以修改为 Dim imgDest As Bitmap = PictureBox1.Image ，当绘制水印完毕后，最小化程序窗口，再恢复窗口看一下。
2、透明度是由drawstring中颜色参数来控制的：