Handle Unzoom signal on yaxis of TH2

ROOT
#1

Hi,

I juste realized that the Unzoom method of TAxis didn’t emit the signal in the case of an y axis for a TH2 histogram… What is the reason for that, and is there an other way to re-implement the TAxis class to solve this problem ?

Thanks in advance

Cheers

Jérémie

ROOT Version: v6-10-06
Platform: Ubuntu 16.04
Compiler: 5.4.0

#2

I do not see why the y axis should be special . Does it work for X ? do you have a small code showing this behaviour ?

#3

Look in the core : if axis is not “xaxis” and hobj1->GetDimension() == 2, it returns, and the signal is not send

void TAxis::UnZoom()
{
if (!gPad) return;
gPad->SetView();

//unzoom object owning this axis
SetRange(0,0);
TH1 *hobj1 = (TH1*)GetParent();
if (!strstr(GetName(),"xaxis")) {
   if (!hobj1) return;
   if (hobj1->GetDimension() == 2) {
      if (strstr(GetName(),"zaxis")) {
         hobj1->SetMinimum();
         hobj1->SetMaximum();
         hobj1->ResetBit(TH1::kIsZoomed);
      }
      return;
   }
   if (strcmp(hobj1->GetName(),"hframe") == 0 ) {
      hobj1->SetMinimum(fXmin);
      hobj1->SetMaximum(fXmax);
   } else {
      if (fXmin==hobj1->GetMinimum() && fXmax==hobj1->GetMaximum()) {
         hobj1->SetMinimum(fXmin);
         hobj1->SetMaximum(fXmax);
      } else {
         hobj1->SetMinimum();
         hobj1->SetMaximum();
      }
      hobj1->ResetBit(TH1::kIsZoomed);
   }
}
//must unzoom all histograms in the pad
TIter next(gPad->GetListOfPrimitives());
TObject *obj;
while ((obj= next())) {
   if (!obj->InheritsFrom(TH1::Class())) continue;
   TH1 *hobj = (TH1*)obj;
   if (hobj == hobj1) continue;
   if (!strstr(GetName(),"xaxis")) {
      if (hobj->GetDimension() == 2) {
         if (strstr(GetName(),"zaxis")) {
            hobj->SetMinimum();
            hobj->SetMaximum();
            hobj->ResetBit(TH1::kIsZoomed);
         } else {
            hobj->GetYaxis()->SetRange(0,0);
         }
         return;
      }
      if (strcmp(hobj->GetName(),"hframe") == 0 ) {
         hobj->SetMinimum(fXmin);
         hobj->SetMaximum(fXmax);
      } else {
         hobj->SetMinimum();
         hobj->SetMaximum();
         hobj->ResetBit(TH1::kIsZoomed);
      }
   } else {
      hobj->GetXaxis()->SetRange(0,0);
   }
}

gPad->UnZoomed();

}

#4

And yes it works for x, and for y in case of TH1 histograms

#5

Yes it seems there is not special case for the y-axis. I have no answer right away.

#6

And is there a way to get the signal from the click on the TAxis contextmenu ?

#7

May be @bellenot can help you.

#8

You can use the TCanvas::ProcessedEvent(Int_t event, Int_t x, Int_t y, TObject *selected); signal, and check for the kButton3Up event

#9

Yes but this will not tell me that this is the command Unzoom that has been launched

#10

You’re right. And I’m afraid there is no other solution than using the gPad->UnZoomed() one. And if it doesn’t work properly, then it should be fixed…

#11

@dudouet May be you can make a Jira report about this issue.

#12

Ok so for your information, see below the solution I found for this, but this is quite nasty. I am working with a canvas divided in 36 pads, and I want that when an unzoom is made on one pad, it is applied to all of them:

void MyClass::HandleMovement(Int_t EventType, Int_t EventX, Int_t EventY, TObject *selected){

///To get the signal correctly
if(selected != nullptr && (EventType == kButton3Down || EventType == kButton1Down) && selected->InheritsFrom("TAxis")){

    fLastAxis = (TAxis*)selected;

    TH1 *hist = (TH1*)fLastAxis->GetParent();
    if(EventType == kButton3Down && ((TString)fLastAxis->GetName())=="yaxis" && hist && hist->GetDimension()==2){
        fLastAxis->SetName("xaxis");
        fDoY_TH2_Unzoom = true;
    }
}


///To rename the yaxis correctly just after clicking on unzoom
if(fLastAxis && ( selected !=fLastSelected ) && fDoY_TH2_Unzoom){
    fDoY_TH2_Unzoom = false;
    fLastAxis->SetName("yaxis");
}

fLastSelected = selected;
}
#13

May be the new HighLight mechanism can be of some help in your case:

https://root.cern/doc/master/classTHistPainter.html#HP30
https://root.cern/doc/master/hlHisto1_8C.html
https://root.cern/doc/master/hlHisto2_8C.html
https://root.cern/doc/master/hlHisto3_8C.html
https://root.cern/doc/master/hlHisto4_8C.html
https://root.cern/doc/master/hlGraph2_8C.html

#14

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