Can a background image be set on a Winforms TextBox?

Question

Is it possible to change the background image of a Windows Forms TextBox in C#? There is no BackgroundImage property. Should I override the Paint method somehow?

Ranaerancagua

WinForms, post updated, thanks – Ja

Answer 1

It isn't possible. If you try by overriding TextBox and calling SetStyle(ControlStyles.UserPaint, true) in the constructor so you can override OnPaintBackground and draw the image, you'll be in for several rude surprises. Falling back to legacy rendering mode is just one of them.

TextBox dates from the very early days of Windows, back when it still had to run on 386SUX hardware. One particular crime it commits to work reasonably on such limited hardware was to draw itself without using the WM_PAINT event. This destroys the background image.

There's a project at CodeProject.com that provides one. I cannot recommend it.

Liatrice

Thank you for short and very informative answer. Do you know some workaround, i.e. transparent background? – Ja

Workaround: Create a UserControl with a background image. Put a transparent RichTextBox on top of it. To produce a transparent RichTextBox, Copy Hans Passant's Code but inherit from RichTextBox instead of Label. Note that inheriting from TextBox won't work for this trick. You might be able to give a RichTextBox a background image in a cleaner way than this; it is a more powerful control than TextBox. – Moton

Answer 2

If you're up to some native coding, you could try to use the technique mentioned here: http://www.codedblog.com/2007/09/17/owner-drawing-a-windowsforms-textbox (Edit: original link is down, thnx Zyo, replaced it with link to archived copy in the wayback machine.)

Although the article is about drawing something in a textbox after the textbox is drawn (not before), perhaps it could be modified to accomplish what you need.

Quintinquintina