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Re: Weird scaling bug - any ideas ?

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In message <8f897550-9fd7-4bb7-9765-5f0da2c786d4@a26g2000vbo.googlegro 
ups.com>
          Martin Hansen <mhh@shrewsbury.org.uk> wrote:

> Eureeka !

> I think I've sorted it.
> It is to do with that OS-Sprite_Op 60 and the
> save area, as Martin Avison suggests.

> Adopting a minimalist approach, if I add a local variable savearea% as
> follows the problem vanishes.

Yes, that fixes the problem that you did not pass the original 
context's save area when switching back, which meant that the original 
VDU state could not be restored.

> WHILE more%
> SYS "OS_SpriteOp", 512+60, usa2%, vblue%, 0 TO , , partial% , savearea
> %
> $scof% = "v"+STR$(5*(barlength%+1)
> SYS "OS_SpriteOp", 256+24, usa2%, scof% TO , , addscof%
> SYS "OS_SpriteOp", 512+28, usa2%, addscof%
> SYS "OS_SpriteOp", 512+60, usa2%, partial%, savearea%
> SYS "Wimp_GetRectangle", 0, scrap% TO more%
> ENDWHILE

> This has sorted the problem on the Iyonix.

Maybe, but
a) The above code is still wrong. As has been pointed out you should 
pass all three values that are returned to you by OS_SpriteOp 60 into 
your call to switch back. You are still passing your own sprite area 
pointer in the call that switches back.

b) You should not call any non-X SWIs while output is switched. You 
must check for errors and switch back if there is an error, else any 
error is likely to crash the machine.

c) It is still completely unclear what the above code is meant to 
achieve in the first place. You tell the Wimp you want to update a 
window, you go through the redraw loop, but you do not draw anything 
to the window, so why go to all the trouble? Inside your "redraw" 
loop, all you do is switch output to a sprite and plot some other 
sprite into it.

-- 
Martin
---------------------------------------------------------------------
Martin Wuerthner         MW Software      http://www.mw-software.com/
        RISC OS Software for Design, Printing and Publishing
---------------------------------------------------------------------

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Thread

Weird scaling bug - any ideas ? Martin Hansen <mhh@shrewsbury.org.uk> - 2011-04-05 12:28 -0700
  Re: Weird scaling bug - any ideas ? Martin Wuerthner <spamtrap@mw-software.com> - 2011-04-05 21:59 +0200
    Re: Weird scaling bug - any ideas ? Martin Hansen <mhh@shrewsbury.org.uk> - 2011-04-05 17:30 -0700
      Re: Weird scaling bug - any ideas ? Rick Murray <heyrickmail-usenet@yahoo.co.uk> - 2011-04-06 05:23 +0200
        Re: Weird scaling bug - any ideas ? Martin Hansen <mhh@shrewsbury.org.uk> - 2011-04-06 02:23 -0700
          Re: Weird scaling bug - any ideas ? Martin <News03@avisoft.f9.co.uk> - 2011-04-06 10:53 +0100
            Re: Weird scaling bug - any ideas ? Martin Hansen <mhh@shrewsbury.org.uk> - 2011-04-06 03:59 -0700
              Re: Weird scaling bug - any ideas ? Martin Wuerthner <spamtrap@mw-software.com> - 2011-04-06 14:50 +0200
                Re: Weird scaling bug - any ideas ? Martin Hansen <mhh@shrewsbury.org.uk> - 2011-04-06 09:31 -0700
                Re: Weird scaling bug - any ideas ? Steve Fryatt <news@stevefryatt.org.uk> - 2011-04-06 18:19 +0100
                Re: Weird scaling bug - any ideas ? Martin Wuerthner <spamtrap@mw-software.com> - 2011-04-07 13:14 +0200
                Re: Weird scaling bug - any ideas ? Martin Hansen <mhh@shrewsbury.org.uk> - 2011-04-07 09:49 -0700
          Re: Weird scaling bug - any ideas ? Rick Murray <heyrickmail-usenet@yahoo.co.uk> - 2011-04-06 14:23 +0200
          Re: Weird scaling bug - any ideas ? Steve Fryatt <news@stevefryatt.org.uk> - 2011-04-06 18:20 +0100
  Re: Weird scaling bug - any ideas ? Gerph <gerph@gerph.org> - 2011-04-09 05:06 -0700

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