Updating QPlot's curve with Qthread

[jendral_hxr]

Pardon me, I am new here.

There's been similar threads with similar problem, but there's yet real answer.

I have a class which contains both QwtPlot, QwtPlotCurve and its array of data. I have certain function to update 'em.

Calling the function manually yields the desired result: last value of graph is updated while data are shifted to 'front'.

xGraph->updateCurve(xGraph->getValue()+2.4);
xGraph->updateCurve(xGraph->getValue()+3.4);
xGraph->updateCurve(xGraph->getValue()-9.8);
xGraph->updateCurve(xGraph->getValue()+2.8);....

xGraph->updateCurve(xGraph->getValue()+2.4);
xGraph->updateCurve(xGraph->getValue()+3.4);
xGraph->updateCurve(xGraph->getValue()-9.8);
xGraph->updateCurve(xGraph->getValue()+2.8);....

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But using QThread (which I badly need to update the plot realtime), after I started the thread, the plot's just updated once. It's also no luck with me with QTimer timeout() signal--it yields similar result.

class graphthread : public QThread{
    public:
        graphs *yeah;
 
        graphthread(graphs *hereitis){
        yeah=hereitis;
        }
 
        void run(){
            while (1){
        yeah->updateCurve(yeah->getValue()+0.4);  
     //   printf("%f\n",yeah->getValue()); // the plot won't update but this's repeatedly printed
        msleep(2000);
        }
        }
    };

class graphthread : public QThread{
    public:
        graphs *yeah;

        graphthread(graphs *hereitis){
        yeah=hereitis;
        }

        void run(){
            while (1){
        yeah->updateCurve(yeah->getValue()+0.4);  
     //   printf("%f\n",yeah->getValue()); // the plot won't update but this's repeatedly printed
        msleep(2000);
        }
        }
    };

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note that there's little elevation in the rightmost

'd anyone like to show me where I am doing wrong?
Any help would be appreciated.