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rcanvas_mt.cxx File Reference

Detailed Description

This macro demonstrate usage of ROOT7 graphics from many threads Three different canvases in three different threads are started and regularly updated.

Extra thread created in background and used to run http protocol, in/out websocket communications and process http requests Main application thread (CLING interactive session) remains fully functional

/*************************************************************************
* Copyright (C) 1995-2021, Rene Brun and Fons Rademakers. *
* All rights reserved. *
* *
* For the licensing terms see $ROOTSYS/LICENSE. *
* For the list of contributors see $ROOTSYS/README/CREDITS. *
*************************************************************************/
#include "ROOT/RCanvas.hxx"
#include "TRandom3.h"
#include "TEnv.h"
#include "TROOT.h"
#include <thread>
#include <iostream>
using namespace ROOT::Experimental;
void draw_canvas(const std::string &title, RColor col)
{
// Create histograms
RAxisConfig xaxis(100, -10., 10.);
auto pHist = std::make_shared<RH1D>(xaxis);
auto pHist2 = std::make_shared<RH1D>(xaxis);
TRandom3 random;
Float_t px, py;
for (int n = 0; n < 10000; ++n) {
random.Rannor(px, py);
pHist->Fill(px - 2);
pHist2->Fill(py + 2);
}
// Create a canvas to be displayed.
auto canvas = RCanvas::Create(title);
canvas->Draw<RFrameTitle>(title);
canvas->Draw(pHist)->line.color = col;
canvas->Draw(pHist2)->line.color = RColor::kBlue;
int maxloop = 100;
canvas->Show();
std::cout << title << " started" <<std::endl;
for (int loop = 0; loop < maxloop; ++loop) {
for (int n = 0; n < 10000; ++n) {
random.Rannor(px, py);
pHist->Fill(px - 2);
pHist2->Fill(py + 2);
}
canvas->Modified();
canvas->Update();
canvas->Run(0.2); // let run canvas code for next 0.5 seconds
// if (loop == 0)
// canvas->SaveAs(title + "_first.png");
// if (loop == maxloop - 1)
// canvas->SaveAs(title + "_last.png");
}
std::cout << title << " completed" <<std::endl;
// remove from global list, will be destroyed with thread exit
canvas->Remove();
}
void rcanvas_mt(bool block_main_thread = true)
{
if (block_main_thread) {
// let use special http thread to process requests, do not need main thread
// required while gSystem->ProcessEvents() will be blocked
gEnv->SetValue("WebGui.HttpThrd", "yes");
// let create special threads for data sending, optional
gEnv->SetValue("WebGui.SenderThrds", "yes");
}
// create instance in main thread, used to assign thread id as well
std::thread thrd1(draw_canvas, "First canvas", RColor::kRed);
std::thread thrd2(draw_canvas, "Second canvas", RColor::kBlue);
std::thread thrd3(draw_canvas, "Third canvas", RColor::kGreen);
if (block_main_thread) {
// wait until threads execution finished
thrd1.join();
thrd2.join();
thrd3.join();
} else {
// detach threads and return to CLING
thrd1.detach();
thrd2.detach();
thrd3.detach();
}
}
float Float_t
Definition RtypesCore.h:57
R__EXTERN TEnv * gEnv
Definition TEnv.h:170
Objects used to configure the different axis types.
The color class.
Definition RColor.hxx:33
static std::shared_ptr< RWebWindowsManager > & Instance()
Returns default window manager Used to display all standard ROOT elements like TCanvas or TFitPanel.
virtual void SetValue(const char *name, const char *value, EEnvLevel level=kEnvChange, const char *type=nullptr)
Set the value of a resource or create a new resource.
Definition TEnv.cxx:736
Random number generator class based on M.
Definition TRandom3.h:27
virtual void Rannor(Float_t &a, Float_t &b)
Return 2 numbers distributed following a gaussian with mean=0 and sigma=1.
Definition TRandom.cxx:507
const Int_t n
Definition legend1.C:16
void EnableThreadSafety()
Enable support for multi-threading within the ROOT code in particular, enables the global mutex to ma...
Definition TROOT.cxx:501
Date
2018-08-16
Warning
This is part of the ROOT 7 prototype! It will change without notice. It might trigger earthquakes. Feedback is welcome!
Author
Sergey Linev s.lin.nosp@m.ev@g.nosp@m.si.de

Definition in file rcanvas_mt.cxx.