Lines drawn at runtime disapear

[simonkue]

Still cannot search, so don't know if this has already been answered....

When I draw a line on a form at run time, then place another window on top of this form (eg Word, or Explorer) by using Alt-Tab (ie nothing to do with this app), the lines beneath the new window are removed. All design time controls are left on the form.

I have tried this with lines directly on the form and via a picture box and get the same result.

It's as if the form is re-drawn when it becomes active again, rather than staying in the state I left it with the extra lines.

Does anyone know how/why this happens and whether there is something I'm not doing or there is a workaround. I need to construct an image at run-time comprising a number of lines that can be displayed on a form - ideally via VB?

Thanks in anticipation.

 

[LazyMe]

There are two solutions for this problem:

1:
Set the AutoRedraw property of your form to True
This has a slight impact on performance, since the runtime needs to update your form as well as an in-memory image.

2:
Draw your lines (and everything else you put on your form at runtime, like text) in the OnPaint event.
Greetings,
Rick

 

[sunaj]

Hi,

Set the autodraw property of the form to true. Sunaj
'The gap between theory and practice is not as wide in theory as it is in practice'

 

[simonkue]

Sunaj & Lazyme,

Thanks for this. I just discovered this as I was going through the form properties, changing them to see what happens. This was a last resort having spent all day working through manuals and MSDN for clues and finding none.

By the way Sunaj, your signature quote is great!