On Wed, 2009-01-14 at 17:08 +0100, ptk wrote:
> Hi all,> > I'm using a Canvas widget to emulate a raster graphics display.> I'm setting pixels by drawing lines of length 1.> > Unfortunately the Canvas gets slow exponentially when> a lot of such line items are added. If there are more than> about 8000 it's getting very slow, and above 12000 it's getting> extremely slow...> > If I wait until everything's drawn and then delete everything and> draw again, it is a bit faster. Maybe this points to an influence of> some cache.> > Does somebody know of a solution to this. Or is there a better> widget to emulate a raster graphics display?
I believe I've used Tk::Photo for that sort of thing. It lets you
get/set pixel values, among other things. I used it for the UI on
the image database I started on about eight years ago. My image
cropping code uses a rubber band box that gets re-drawn on each
mouse movement event. It's fast enough to be perfectly smooth.
Paul Allen
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