Re: [boost] Sparse Bit Vectors

From: David Abrahams (david.abrahams_at_[hidden])
Date: 2001-06-20 21:16:52

----- Original Message -----
From: "joel de guzman" <isis-tech_at_[hidden]>

> -> Macintosh style graphical regions. A vector of sparse bit
>     vectors can represent something like Regions in the Mac.
>     in fact the Mac-Region inspired this implementation. [  I
>     am aware that this is patented. I don't know if my
>      implementation infringes on this patent. But I am also
>      aware that this patent will expire soon (now)? ]

I think the Mac implementation uses a some kind of difference encoding from
row-to-row, so that, e.g., a gray halftone (checkerboard) is actually very
cheap to encode. If you're not doing that, you probably don't infringe.

> -> Compresses bitmaps. Ok, same as above :-)

Or at least bitmasks...

> -> This is interesting... A set of floating point numbers
>     and ranges. Say we want a set of floating point numbers
>     from -1 to 1 except 0. You'd write:
>
>        fs = range<float>(-1.0,+1.0) - 0.0;

Hmm, we should talk. There is a nearly-finished implementation of half-open
ranges in CVS. This work is at least related.

-Dave