SVANVOORST@... wrote:

> Ian:
>
> Thank you for your recent post re:scrollingGWorlds.  It is a nicely done
> demo.  Do you know a way to place a colored bar across the scrolling text and
> then have the text invert or change color as it passes beneath the bar? (see
> code below)  I have stuck an EF in this position for demo purposes, but it is
> opaque.
>
> I appreciate your time and efforts.
>
> Steve Van Voorst
>
>

Hi Steve

You are probably going to need another gWorld in the size and position of the
editfield. Call it the ChangeRect
You can then copy to the ChangeRect from the copy Rect - do the pixel
manipulation that you want, and copy the ChangeRect Back to the CopyRect, before
copying the CopyRect to the screen.

Alternatively, you could create another Pict gWorld with the inverted picture in
it and run this as a scrolling gWorld inside the first one.

This is more complicated in the Rect manipulation but avoids inverting or messing
with the pixels. If you are doing this at startup only then the memory used may
not be important.

Anyway every year computers get faster and have more memory.

Good Luck

Ian

PS I'll copy this to the list - it's on subject - and let everyone suggest better
ways. You may have already done this - I'll know at 10 this morning.