Qpainter Help

I have created a ui window(mainwindow.ui). then i have added 3 qframe(Frame1, Frame2,Frame3) on the ui. then i placed an background image on the frame2.
Then i have created a class frame on the mainwindow.h. I have created a paintEvent of Qframe on the header in frame class. My purpose is to create a Qframe on the class frame. Then place that frame into the frame2 of the mainwindow.ui. So that i can draw over the background image of frame2. i don want painting in the frame1 & frame3. I frame2 i have to draw over the background image.


I coded and when i run my project the mainwindow.ui & frame class will run in 2different window.

main.cpp

Code:

---

#include <QtGui/QApplication>
#include "mainwindow.h"
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    Frame m;
    m.show();
    return a.exec();
}

---

mainwindow.h

Code:

---

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QMainWindow>
#include<QtGui>
#include<QtCore>
#include<QtDebug>
#include<QFrame>
 
namespace Ui {
    class MainWindow;
    class Frame;
}
 
class MainWindow : public QMainWindow
{    
    Q_OBJECT
 
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
 
private:
    Ui::MainWindow *ui;
};
    class Frame : public QFrame{
                Q_OBJECT
        public:
                Frame( QWidget * parent = NULL ) : QFrame(parent){
 
                }
        protected:
                void paintEvent( QPaintEvent * event );
        };
 
#endif // MAINWINDOW_H

---

mainwindow.cpp

Code:

---

#include "mainwindow.h"
#include "ui_mainwindow.h"
 
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}
 
 
MainWindow::~MainWindow()
{
    delete ui;
}
 
void Frame::paintEvent( QPaintEvent * event )
{
QFrame::paintEvent(event);
QPainter painter(this);
QPen linepen(Qt::red);
linepen.setCapStyle(Qt::RoundCap);
linepen.setWidth(25);
painter.setRenderHint(QPainter::Antialiasing,true);
painter.setRenderHint(QPainter::SmoothPixmapTransform,true);
painter.setPen(linepen);
painter.drawLine(100,100,300,300);
 
}

---

Quote:

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I coded and when i run my project the mainwindow.ui & frame class will run in 2different window.

---

That is correct, since your code is creating to top level widgets (windows).

Code:

---

#include "mainwindow.h"
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show(); //<--- here you open the main window.
    Frame m;
    m.show(); //<--- her you open m as a top level window.
    return a.exec();
}

---

If you want to have one widget to be "in" another, you have to make it a child widget.

how can i make my qframe as child widget

Read the basics of C++ specifically what is a member variable.
You can do it also as a non member, by giving the parent at construction time.
But you better start with C++ basics first.