Re: cursor blinking problem

From: Martin Sevior (msevior@physics.unimelb.edu.au)
Date: Fri Aug 02 2002 - 20:49:09 EDT

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    On Sat, 2002-08-03 at 06:54, Tomas Frydrych wrote:
    >
    > Martin sent this to me privately, but I think this needs to go to the list,
    > it raises an important issue -- I hope Martin does not mind.
    >
    > > HI Tomas,
    > > Think this through very very carefully. I'm not saying it can't be
    > > done
    > > but it is not obvious to me right now. The issue is cursor dirt. If
    > > the cursor is on (black) and a clearScreen is called over the cursor
    > > then it gets set to white even though the internal state says it's
    > > black. Then if the blink thread XOR's it now it will turn to black
    > > even though the cursor's internal state says it should be white.
    > >
    > > What is even worse is if the clear screen stops after clear the first
    > > set of vertical pixels. Now the cursor is half white, half back and no
    > > matter what, it looks funny and your guarenteed to get pixel dirt.
    > >
    > > Getting rid of cursor dirt was a real pain, I worry that putting the
    > > blink into a seperate thread will mess it all up.
    > >
    >
    > I do not want the change the actual way the cursor behaves, only
    > put the timer which fires it into a separate thread so that it fires
    > every 500 ms and does not get blocked by some other timer. That's
    > all.
    >

    I don't see how this would help. You'd have to turn the cursor off while
    doing screen updates anyway (like doing spell checking). I think the
    effect would be much the same.

    > I had a look at Mike's cursor class; it looks very good, but it would
    > mean to rip the whole cursor code up, and that's not something I
    > personnally want to do just now.
    >
    > Tomas



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