On Jan 08, 2007, at 22:48 UTC, Phil Heycock wrote:

> I olden days, the Quickdraw Toolbox had something called
> 'graphics mode' (I think) which applied a boolean expression
> to graphics drawing objects. I think 'XOR' was the default
> mode, and 'OR' mode (if I recall correctly) does exactly what
> you describe... flips whatever is being drawn over a black
> background to white.

It was the other way around; you want XOR mode for something like this.

However, I wouldn't try digging down into declares to deprecated
drawing architectures to solve this problem.  A more modern solution is
to assume the user is not using a 1-bit monitor, and make use of color
(e.g., draw black text over a red and white thermometer.  Or, if you
can't do that and really want to switch the text color mid-word, then
you would:

1. Draw two offscreen thermometers: one entirely filled with black,
with white text; and the other entirely white, with black text.

2. Copy the portion of the black thermometer corresponding to the
current temperature to the screen (DrawPicture does this just dandy if
you use all nine parameters).

3. Copy the portion of the white thermometer corresponding the the
upper portion (above the current temperature) to the screen.

Cheers,
- Joe


 There were (are?) 8 modes to choose from. I don't know
> whether this has been deprecated, or not. If not, perhaps this can
still be
> invoked via Declares. You should probably search the Apple tech
resources.
> 
> P.
> 
> 
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--
Joe Strout -- [EMAIL PROTECTED]
Verified Express, LLC     "Making the Internet a Better Place"
http://www.verex.com/

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