Re: [ROOT] When things get small.

From: Rene Brun (Rene.Brun@cern.ch)
Date: Sat Apr 28 2001 - 10:54:30 MEST


Hi Brett,
In the CVS version, I have modified TPad::PaintBox to force the
box/width/heigth to be at least one pixel.

Rene Brun

On Fri, 27 Apr 2001, Brett Viren wrote:

> Hi Rene,
> 
> Rene Brun writes:
>  > TPad::PaintBox could be easily modified to set a minimum number
>  > of pixels for the box.
> 
> Ah, yes, I see this now.
> 
>  > However, you seem to imply that currently you have cases where
>  > you do not see the box at all, not even one pixel !
>  > Could you send me a very short macro with the box parameters
>  > and the canvas/pad size to reproduce this problem ?
> 
> I can't hit on the right parameters, but you can see the problem by
> doing the following:
> 
> 1) At ROOT prompt, create a box, ie, with:
> 
>    {
> 	gROOT->Reset();
> 	TBox* b = new TBox(0.499999999999,0.4999999999,0.5,0.5);
> 	b->SetFillStyle(0);
> 	b->SetFillColor(1);
> 	b->Draw();
>    }
> 
> this will give you a 1 or 2 pixel size ``box''.
> 
> 2) Resize (shrink) window.  At, about 75% the original size I start to
> see the 1 pixel ``box'' start to disappear.  Further shrinking and it
> cycles between appearance and disappearance (hmm, oscillating pixels,
> add this to MINOS's possible studies).
> 
> I looked through TPad::PaintBox() and TGX11::DrawBox() but don't see
> any checks for the x1==x2 or y1==y2.  I don't know what happens when
> XDrawRectangle() is called in this case ?
> 
> -Brett.
> 



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