Dirk,
Instead of PixeltoY(-y) use AbsPixeltoY(y)
Rene Brun
Dirk Dodt wrote:
>
> Ok Here it is. I'm using just a single Pad on the Canvas, The Output
> generated when moving the mouse over the pad is:
> * Pixel Coordinates,
> * User Coordinates passed back from Pixelto?() [already "corrected" by
> calling -can->PixeltoY(-y)!]
> * and the User Coordinates calculated the way which I understood from
> the root manual they should work.
>
> The "corrected" coordinates seem to be right, but when you click the
> left mouse button the User Coordinate Range is changed and from there on
> the ouput from my defines is different from the -PixeltoY(-y) result.
> (which one is correct now :)?)
>
> kind regards
> dirk
>
> Rene Brun wrote:
> > Dirk,
> >
> > 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.
> >
> >
>
> --------------------------------------------------------------------------------
> TCanvas *can;
> void PixeltoY()
> {
> can = new TCanvas("test","test",500,500);
> can->Range(-85,-85,85,85);
> can->Connect("ProcessedEvent(Int_t,Int_t,Int_t,TObject*)", 0, "", "DisplayGetCoordinates(Int_t, Int_t, Int_t, TObject *)");
> }
> #define PIXELTOX(x) ((x2-x1)*x/can->GetWw()+x1)
> #define PIXELTOY(y) ((y2-y1)*(-y)/can->GetWh()+y2)
>
> void DisplayGetCoordinates(Int_t event, Int_t x, Int_t y, TObject *selected)
> {
> Double_t x1,x2,y1,y2;
> can->GetRange(x1,y1,x2,y2);
> printf("Event %d: at (%3d, %3d)=(%4.1f, %4.1f)=(%3.1f, %3.1f)\n", event,x,y, can->PixeltoX(x), -can->PixeltoY(-y), PIXELTOX(x), PIXELTOY(y));//=(%3.1f, %3.1f)
> switch (event) {
> case 1://ButtonDown
> can->Range(0,0,85,85);
> break;
> }
> }
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