c++ - How in Qt to add text to a text editor using a thread -

for project working on in qt need make several things happen @ same time. 1 of these events take temperature reading , display reading in text edit box along time stamp. temp , time stamp not display until while loop wrote finishes. know while loop blocking trying write thread display time , temp, can not figure out how write gui thread.

here start thread , while loop

qthread cthread; timetempobject cobject;  cobject.dosetup(cthread); cobject.movetothread(&cthread); cthread.start();  while(flowtime > 0) {     // set 0 pin high while flowtime more 0     digitalwrite(0,1);     displaycurrenttime();      // set second pin led flash according dutycycle     digitalwrite(2,1);     delay(ontime);     // displaycurrenttime();     ui->temptimenoheatmode->append(temp);      digitalwrite(2,0);     delay(offtime);      flowtime--; } 

noheatmode.h

namespace ui { class noheatmode; }  class noheatmode : public qwidget {     q_object  public:     explicit noheatmode(qwidget *parent = 0);     ~noheatmode();  private slots:     void on_startbuttonnoheatmode_clicked();      void on_noheatmodeback_clicked();  public slots:     void displaycurrenttime();  private:     ui::noheatmode *ui; };  #endif // noheatmode_h 

timetempobject.h thread

class timetempobject : public qobject {     q_object  public:     explicit timetempobject(qobject *parent = 0);     void dosetup(qthread &cthread);  public slots:     void dowork(); };  #endif // timetempobject_h 

timetempobject.cpp

timetempobject::timetempobject(qobject *parent) : qobject(parent) { }  void timetempobject::dosetup(qthread &cthread) {     connect(&cthread,signal(started()),this,slot(dowork())); }  void timetempobject::dowork() {     qtimer *timer = new qtimer(this);     connect(timer, signal(timeout()), this, slot(displaycurrenttime()));      // delay set space out time readings, can adjusted     timer->start(1500);      // gets time     qtime time = qtime::currenttime();      // converts string chosen format     qstring stime = time.tostring("hh:mm:ss:ms");      // displays current time in text edit box     ui::noheatmode* noheatmode::ui->temptimenoheatmode->append(stime); } 

how alter thread can write text editor in gui?

since qtextedit::append slot, it's easy call other threads:

void temptimeobject::dowork() {   ...   qmetaobject::invokemethod(ui->temptimenoheatmode, "append",                              qt::queuedconnection, q_arg(qstring, temp));   ... } 

if wished execute arbitrary code, boils down "how execute functor in given thread", thread being main thread. answers this question provide multiple ways of doing it.

the simplest way on qt 5 be:

void temptimeobject::dowork() {   ...   {     qobject signalsource;     qobject::connect(&signalsource, &qobject::destroyed, qapp, [=](qobject *){       ui->temptimenoheatmode->append(text);       ... // other gui manipulations     });   } // here signalsource emits signal , posts functor gui thread   ... }