using QThreads, but i cant access a method of another class

[Tio]

hello everyone
i am new here, so if i've made something wrong, my apologizes ^^
Plus, i dont speak english a very well, so, i am sorry for wrong write =P
well...i have a problem.
I am using the QThreads to launch some threads. Basicaly, i have 2 classes: MainWindow, which is responsible for the window, and MyThread, for one thread.
I am going a very well, launch a thread and every else. But now, i need access some resources of the MainWindow from the MyThread. Actually, i have on the window a lcdNumber, which must be refreshed every number found in the thread. Someone knows how to make it?
here is the code (comments is in portuguese, my language, didnt mind =P):


#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QThread>
#include "mythread.h"


int num = 1;
int num2 = 1000000;
int cont = 0;

int MyThread::primo(int n){
int i;

if( n == 1 ) return 0; // por definicao...

for(i=2; i*i <= n;i++){
if (n % i == 0) return 0; // NAO eh primo
}

return 1; // EH primo
}

MyThread::MyThread(QObject *parent, int num, int num2)
: QThread(parent)
{
this->num = num;
this->num2 = num2;
}

void MyThread::run()
{
qDebug() << "Executing a new independant thread, GUI is NOT blocked";

int i;
cont = 0;

for(i=num; i<num2; i++){
if(primo(i) == 1) cont++; //every time that find it, must refresh the lcdNumber <--------
}

qDebug() << "Encontrados:" << cont;

//exec();
}

int MyThread::retorno(){
return cont;
}

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);

QString temp;
temp.setNum(num);
ui->lineEdit->setText(temp);

temp.setNum(num2);
ui->lineEdit_2->setText(temp);
}

MainWindow::~MainWindow()
{
delete ui;
}

void MainWindow::changeEvent(QEvent *e)
{
QMainWindow::changeEvent(e);
switch (e->type()) {
case QEvent::LanguageChange:
ui->retranslateUi(this);
break;
default:
break;
}
}

void MainWindow::on_inicio_clicked() //button to start thread
{
QString txt;
txt = ui->lineEdit->text();
num = txt.toInt();
txt = ui->lineEdit_2->text();
num2 = txt.toInt();
lancaThread();
}

void MainWindow::on_fim_clicked() //button to terminate thread, if user needs
{
thread->terminate();
qDebug() << "Operacao cancelada";
}

void MainWindow::lancaThread()
{
int res = 0;
// create new thread (on heap) and start it
thread = new MyThread(this, num, num2);

thread->start(); // after this, thread's run() method starts

qDebug() << "Feito";
ui->lcdNumber->display(res);
}

the last line is, basically, what i need to do up there. The "ui" is public, but i cant access. ive tried to use:
MainWindow::ui->lcdNumber->display(anumber);
but didnt work...
if someone could help me, i will be very grateful ^^
if needs more information, just ask =D
and sorry for anything

[Lesiok]

You can't get access from another thread to UI. So in MyThread You must create signal with int parameter connected to slot in MainWindow. In this slot You can set new value for lcdNumber.

[Tio]

thanks for the answer Lesiok =)
can you gimme a sample how i make it?

[Tio]

i ve done it =D
thanks for the help ^^