Dear experts
I wonder if one can add buttons on a TGraph, to be more specific, I have a event display of drift chamber like this:
Any suggestion will be helpful! Even just telling me “It’s impossible”
Hi Siyuan,
Very interesting use case!
I do not think it’s something ROOT supports out of the box. I am adding our experts in the loop @linev @bellenot .
Best,
D
Hi @Crisps,
maybe this part on the TGraphPainter can be useful.
And maybe you could have a look also a these tutorials
Tutorial 1
Tutorial2
Thank you for the reply! Which part you mean “this part”? maybe you forgot to add link on it…?
I have read through these two tutorials, and I got what you mean “this part”, now I have one question related to the function in TCanvas::HighlightConnect() : UserFunction(TVirtualPad* pad, TObject* obj, Int_t ihp, Int_t y)
In my understanding this function will be called when the mouse is pointing to the ith point on the TGraph (or histogram). But what I need is:
I have a map of TGraphs which is channel to waveform (not all channels have waveform), so I use TGraph::SetPoint(channel, x, y) to set the point on the TGraph. The problem is the point that I didn’t set (let’s say I set 2,4,6th point) will be created automatically and result on the TGraph, is there a way to disable auto creation?
I solved the problem above by moving unused points out of window (99999, 99999). If you have better (or decent) solution please teach me!
Now I got another question:
I want to make the HighlightGraph(TVirtualPad* pad, TObject* obj, Int_t ihp, Int_t y) as a member function in the same class, but when I connected it to canvas:
c->HighlightConnect("HighlightGraph(TVirtualPad* pad, TObject* obj, Int_t ihp, Int_t y)");
it is never called at runtime even I can see the circle highlight on the TGraph.
then I was thinking maybe class member function is different from function pointer, so I made it a function pointer:
std::function<void(TVirtualPad* pad, TObject* obj, Int_t ihp, Int_t y)> func = [this](TVirtualPad* pad, TObject* obj, Int_t ihp, Int_t y){
this->HighlightGraph(pad, obj, ihp, y);
};
c->HighlightConnect("func(TVirtualPad* pad, TObject* obj, Int_t ihp, Int_t y)");
but it still didn’t work…any help?
And I also tried this:
c->Connect("Highlighted(TVirtualPad*, TObject*, Int_t, Int_t)", "EventDisplay", this, "HighlightGraph(TVirtualPad*, TObject*, Int_t, Int_t)");
g->SetHighlight();
but didn’t work 
Hi,
TCanvas::HighlightConnect() method is simplified version which only allows to connect global functions, but not objects methods. See docu. You can use TQObject::Connect():
auto receiver = new ReceiverClass("receiver");
auto Canvas = new TCanvas("Canvas", "Canvas", 0, 0, 700, 500);
Canvas->Connect("Highlighted(TVirtualPad*,TObject*,Int_t,Int_t)",
"ReceiverClass", receiver, "HighlightHisto(TVirtualPad*,TObject*,Int_t,Int_t)");
I attach modified version of hlGraph1.C tutorial macro:
hlGraph1.C (1.8 KB)
Do you have dictionary for your class?
Thank you for the reply, I have tried this method (my last post) but it didn’t work and give this:
Error in <TQObject::CheckConnectArgs>: slot HighlightGraph(TVirtualPad*,TObject*,int,int) does not exist
But as you pointed my class EventDisplay is no derived from ROOT classes, so there is no dictionary of it. Should I derive it from TNamed and make a dictionary?
Hi,
When code runs as macro ROOT automatically creates dictionary for all used classes.
If you build and run your application differently - you need to create dictionary for your EventDisplay class. It is not necessary to derive it from TObject.
Regards,
Sergey
I tried to add this line in my code:
gInterpreter->GenerateDictionary("EventDisplay", "EventDisplay.hxx");
but got this:
fatal error: ‘EventDisplay.hxx’ file not found
#include “EventDisplay.hxx”
then I modified to:
gInterpreter->GenerateDictionary("EventDisplay", "/Users/siyuan/Physics/comet/crt/tracking/src/EventDisplay.hxx");
but still got the same error…
No, you need to add ROOT_GENERATE_DICTIONARY to your CMakeLists.txt file.
See it in ROOT examples: root/test/periodic/CMakeLists.txt at master · root-project/root · GitHub
Thank you, in that CMakeLists.txt, what is NdbLinkDef.h?
should I write #pragma link C++ class EventDisplay+; in that header file?
Yes, you need to create new LinkDef.h file with minimal content:
#ifdef __CLING__
#pragma link off all globals;
#pragma link off all classes;
#pragma link off all functions;
#pragma link C++ class EventDisplay+;
#endif
You can include your other classes - if it is required.
I tried to make a similar version CMakeLists.txt but got totally lost…
What does these variables refer…?
file(GLOB DBsources RELATIVE ${CMAKE_SOURCE_DIR} Ndb*.cxx)
file(GLOB XSsources RELATIVE ${CMAKE_SOURCE_DIR} XS*.cxx)
file(GLOB headers RELATIVE ${CMAKE_SOURCE_DIR} *.h)
list(REMOVE_ITEM headers NdbLinkDef.h)
for example I have EventDisplay.hxx, EventDisplay.cxx and EventDisplay_LinkDef.h, which one should fill in where?
Surely the approach you are following now is possible one. However, let me propose another one. I modified an example I have (graphtext3.C) to retrieve which point has been clicked in a TGraph. Once you have it, you are then free to draw whatever you want. In this example, I redraw the graph (as I mentioned, this is an example I already had).
const int Npoints = 3; // Number of points in the graph
const double x[Npoints] = {1.0, 2.0, 5.0};
const double y[Npoints] = {0.5, 1.0, 2.0};
const char *c[Npoints] = {"a","b","c"};
void graphtext3() {
TGraph *gr = new TGraph(Npoints, x, y);
gr->SetMarkerStyle(kCircle);
TExec *ex = new TExec("ex","DrawText();");
gr->GetListOfFunctions()->Add(ex);
gr->Draw("ALP");
gr->GetXaxis()->SetLabelSize(0);
gr->GetXaxis()->SetTickLength(0);
}
void DrawText()
{
Int_t i,n;
Double_t x,y;
TLatex *t;
TLine *l;
double eps = 0.01;
TGraph *g = (TGraph*)gPad->GetListOfPrimitives()->FindObject("Graph");
// Get event information
int event = gPad->GetEvent();
int px = gPad->GetEventX();
int py = gPad->GetEventY();
// Get the coordinates
double xd = gPad->AbsPixeltoX(px);
double yd = gPad->AbsPixeltoY(py);
float xp = gPad->PadtoX(xd);
float yp = gPad->PadtoY(yd);
n = g->GetN();
for (i=0; i<n; i++) {
g->GetPoint(i,x,y);
if (TMath::Abs(x-xp)<eps && TMath::Abs(y-yp)<eps) printf("Point %d has been clicked\n",i);
}
double ymin = g->GetHistogram()->GetMinimum();
double ymax = g->GetHistogram()->GetMaximum();
double dy = (ymax-ymin);
for (i=0; i<n; i++) {
g->GetPoint(i,x,y);
t = new TLatex(x, ymin-0.03*dy, Form("%s (%4.2f,%4.2f)",c[i],x,y));
t->SetTextSize(0.025);
t->SetTextFont(42);
t->SetTextAlign(21);
t->Paint();
l = new TLine(x,ymin,x,ymin+0.03*dy);
l->Paint();
}
}
Thank you @couet and @linev, I tried to make dictionary by adding this command in my CMakeLists.txt:
ROOT_GENERATE_DICTIONARY(G__EventDisplay LINKDEF ${CMAKE_CURRENT_SOURCE_DIR}/src/EventDisplay_LinkDef.h)
and then
add_library(lib other_cxx_files ${CMAKE_CURRENT_SOURCE_DIR}/build/G__EventDisplay.cxx)
it compiled successfully but I got runtime error:
Error in <TQObject::CheckConnectArgs>: slot HighlightGraph(TVirtualPad*,TObject*,int,int) does not exist
where I confirmed many time that I have no typo of this function name or parameter.
I also attach part of my EventDisplay.cxx:
void EventDisplay::HighlightGraph(TVirtualPad* pad, TObject* obj, Int_t ihp, Int_t y){
c_waveform = (TCanvas*)gROOT->GetListOfCanvases()->FindObject("c_waveform");
std::cout<<"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<<std::endl;
if(!c_waveform){
std::cout<<"Make new Canvas for ADC waveform"<<std::endl;
c_waveform = new TCanvas("c_waveform", "ADC waveform", 505, 0, 600, 400);
}
if(ihp == -1){
delete c_waveform;
return;
}
if(waveforms.size() != 0 && waveforms.find(ihp) != waveforms.end()){
c_waveform->cd();
waveforms.at(ihp)->Draw("AP");
gPad->Update();
}
}
void EventDisplay::DrawHits(CDCHitContainer* hits, int event){
TCanvas* c = new TCanvas();
fCanvases.push_back(c);
// c->HighlightConnect("HighlightGraph(TVirtualPad* pad, TObject* obj, Int_t ihp, Int_t y)");
c->Connect("Highlighted(TVirtualPad*, TObject*, Int_t, Int_t)", "EventDisplay", this, "HighlightGraph(TVirtualPad*, TObject*, Int_t, Int_t)");
...
g->SetHighlight();
}
It would be easy if you can provide access to your source code.
May be method is not public?
Or cmake file has other problems
I finally solved it and now it runs fine…Thank you all so much!!!
It’s not fatal but I got seg fault when the Highlight function is called:
*** Break *** segmentation violation
[/usr/lib/system/libsystem_platform.dylib] _sigtramp (no debug info)
[/Users/siyuan/Physics/root/install/lib/libHistPainter.so] THistPainter::DistancetoPrimitive(int, int) (no debug info)
[/Users/siyuan/Physics/root/install/lib/libGpad.so] TPad::Pick(int, int, TObjLink*&) (no debug info)
[/Users/siyuan/Physics/root/install/lib/libGpad.so] TPad::Pick(int, int, TObjLink*&) (no debug info)
[/Users/siyuan/Physics/root/install/lib/libGpad.so] TCanvas::Pick(int, int, TObject*) (no debug info)
[/Users/siyuan/Physics/root/install/lib/libGpad.so] TCanvas::HandleInput(EEventType, int, int) (no debug info)
[/Users/siyuan/Physics/root/install/lib/libGui.so] TRootContainer::HandleMotion(Event_t*) (no debug info)
[/Users/siyuan/Physics/root/install/lib/libGui.so] TGFrame::HandleEvent(Event_t*) (no debug info)
[/Users/siyuan/Physics/root/install/lib/libGui.so] TGClient::HandleEvent(Event_t*) (no debug info)
[/Users/siyuan/Physics/root/install/lib/libGui.so] TGClient::ProcessOneEvent() (no debug info)
[/Users/siyuan/Physics/root/install/lib/libGui.so] TGInputHandler::Notify() (no debug info)
[/Users/siyuan/Physics/root/install/lib/libCore.so] TMacOSXSystem::DispatchOneEvent(bool) (no debug info)
[/Users/siyuan/Physics/root/install/lib/libCore.so] TSystem::InnerLoop() (no debug info)
[/Users/siyuan/Physics/root/install/lib/libCore.so] TSystem::Run() (no debug info)
[/Users/siyuan/Physics/root/install/lib/libCore.so] TApplication::Run(bool) (no debug info)
[/Users/siyuan/Physics/comet/crt/tracking/build/CRTTracking] main (no debug info)
[/usr/lib/dyld] start (no debug info)
but it still works when I moving my mouse to next point, do you know why this seg fault happens…?