Root G U I (https://root.cern.ch/root/htmldoc/guides/users-guide/WritingGUI.html#the-root-gui-classes)

[Vasco_Pires]

I am now trying to learn more about of the chapter of G U I of root, provided in the link of the name.

They provide a code with an example for everything they described, applying it to the function f(x) = \frac{sin(x)}{x}. But when I try to run the exact same code in my computer it gives me an error.

The code is in the website, but I will also put it in here:

// example.C

#include <TGClient.h>
#include <TCanvas.h>
#include <TF1.h>
#include <TRandom.h>
#include <TGButton.h>
#include <TGFrame.h>
#include <TRootEmbeddedCanvas.h>
#include <RQ_OBJECT.h>

class MyMainFrame {
   RQ_OBJECT("MyMainFrame")
private:
   TGMainFrame         *fMain;
   TRootEmbeddedCanvas *fEcanvas;
public:
   MyMainFrame(const TGWindow *p,UInt_t w,UInt_t h);
   virtual ~MyMainFrame();
   void DoDraw();
};
MyMainFrame::MyMainFrame(const TGWindow *p,UInt_t w,UInt_t h) {
   // Create a main frame
   fMain = new TGMainFrame(p,w,h);

   // Create canvas widget
   fEcanvas = new TRootEmbeddedCanvas("Ecanvas",fMain,200,200);
   fMain->AddFrame(fEcanvas, new TGLayoutHints(kLHintsExpandX |
                   kLHintsExpandY, 10,10,10,1));
   // Create a horizontal frame widget with buttons
   TGHorizontalFrame *hframe = new TGHorizontalFrame(fMain,200,40);
   TGTextButton *draw = new TGTextButton(hframe,"&Draw");
   draw->Connect("Clicked()","MyMainFrame",this,"DoDraw()");
   hframe->AddFrame(draw, new TGLayoutHints(kLHintsCenterX,
                                            5,5,3,4));
   TGTextButton *exit = new TGTextButton(hframe,"&Exit",
                                "gApplication->Terminate(0)");
   hframe->AddFrame(exit, new TGLayoutHints(kLHintsCenterX,
                                            5,5,3,4));
   fMain->AddFrame(hframe, new TGLayoutHints(kLHintsCenterX,
                                             2,2,2,2));

   // Set a name to the main frame
   fMain->SetWindowName("Simple Example");

   // Map all subwindows of main frame
   fMain->MapSubwindows();

   // Initialize the layout algorithm
   fMain->Resize(fMain->GetDefaultSize());

   // Map main frame
   fMain->MapWindow();
}
void MyMainFrame::DoDraw() {
   // Draws function graphics in randomly chosen interval
   TF1 *f1 = new TF1("f1","sin(x)/x",0,gRandom->Rndm()*10);
   f1->SetLineWidth(3);
   f1->Draw();
   TCanvas *fCanvas = fEcanvas->GetCanvas();
   fCanvas->cd();
   fCanvas->Update();
}
MyMainFrame::~MyMainFrame() {
   // Clean up used widgets: frames, buttons, layout hints
   fMain->Cleanup();
   delete fMain;
}
void example() {
   // Popup the GUI...
   new MyMainFrame(gClient->GetRoot(),200,200);
}

I don’t understand the error, can someone explain it to me?

Thank you in advance.

[bellenot]

Welcome to the ROOT Forum!
How did you install ROOT? Are you using it via ssh? Can you simply open a TBrowser (or a TCanvas)?