Erick Gallesio wrote:
>
> Hi Paolo,
>
> > What's the simplest--and possibly most efficient--way of drawing a _single_
> > pixel in a Canvas widget? The only one I can think of is to draw a 1 pixel
> > wide rectangle item.
>
> The simplest and not too efficient way to draw a single pixel is to
> use a line of length 1 pixel.
>
Yes... yuck! There is a much touted set of patches collectively called
the "dash patch" which includes a number of performance improvements for
canvases. They are actively maintained by Jan.Nijtmans_at_cmg.nl and you
can find them by following pointers at any of the Tcl/Tk archive sites.
Unfortunately I found that it was very difficult to reconcile these
against the STk source tree :-(
And I don't know enough about patch to try and manually unbundle
individual components of the full patch.
>
> In the Tk distrib there is (was ?) some code for making lines on a
> widget. This code was in #ifdef which wer not active by default. If
> you have a lot of points to draw, I could have a look to see if it is
> a practicable solution.
I also recal that someone released a "raster" widget for Tk with just
this purpose in mind.
> Another probable solution consists to allocate an image and make draw
> you points in it. I'm not sure that it is simple but if I remember
> someone has already tried this solution (I don't remember if it produces
> something)
My narray code (under contrib on kaolin) can be used for this purpose.
In that you can create an array and use it as a :data argument to a
regualar image create or configure call. It does have a number of
limitations however, not the least of which is that it won't compile
with gcc 2.8 (or egcs) but requires 2.7.X (for the c++ part)
Sorry... no simple solution.
--
Mr Andrew Dorrell *
Envision Computing /---\ Whoo? *
http://www.pnc.com.au/~enviscom (o o) / *
( : ) .
^ ^
*
Received on Fri Feb 26 1999 - 22:25:05 CET