Re: [ROOT] bug in gPad->PixeltoY()?

From: Rene Brun (
Date: Wed Jun 23 2004 - 14:38:18 MEST


Could you send a simple script showing your problem?

It could be that you are using PixeltoX where you should use AbsPixeltoX.
There is a difference if you have a canvas divided into subpads.

Rene brun

Dirk Dodt wrote:
> I have the feeling the TPad::PixeltoX Method Or Rather the underlying
> method whichs sets the needed Coefficients might be buggy.
> The mistake (if any) can sometimes(!) be corrected by using
> -1*..->PixeltoY(-y).
> Maybe I have not fully understand everything concerning the different
> coordinate systems, but if someone else is having similar problems it
> might be worth looking into it. (For my own case I already have found a
> workaround.)
> For Completeness:
> I'm using a TRootEmbeddedCanvas in Root 3.10_03 (Suse 7.3/=Desy linux 4)
> inside a QT Gui to Display some Detector Information.
> In order to do a Zoom into the Detector, I Connected the
> ProcessedEvent(Int_t,Int_t,Int_t,TObject*) Slot with my code, that uses
> PixeltoX and PixeltoY to transform the x,y[pixel] provided by the signal
> into user coordinates and set a new ...->Range(x1,y1,x2,y2) for the Pad.

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