Create An object that draw a circle (QPainter)
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Hello all, I would like to create a circles matrix in MainWindow. With this purpose, I want to create an objet that draws a circle in MainWindow. I don't reach. Please can somebody help me to fix my code?
Thanks in advance
(ampel.h)
//*********************************************
#ifndef AMPEL_H
#define AMPEL_H
#include <QWidget>class ampel : public QWidget
{
public:
explicit ampel(QWidget *parent = 0);
protected:
void paintEvent(QPaintEvent *e);
private:
int x;
void doPainting();};
#endif // AMPEL_H
//***********************************************(ampel.cpp)
//***********************************************
#include "ampel.h"
#include <QPainter>
//#include<mainwindow.h>ampel::ampel(QWidget parent): QWidget(parent)
{
x=0;
}
//**********************************************
void ampel::paintEvent(QPaintEvent *e){
Q_UNUSED(e);doPainting();}
//***********************************************
void ampel::doPainting(){
QPainter dc(this);
QBrush pintada(Qt::green, Qt::SolidPattern);
pintada.setColor(Qt::red);
dc.setRenderHint(QPainter::Antialiasing,true);
dc.setPen(QPen(Qt::black,3, Qt::DashLine, Qt::RoundCap));
dc.setBrush(QBrush(pintada));// QBrush(Qt::green, Qt::SolidPattern)
dc.drawEllipse(x,x,25,25);
}
//*********************************************(MainWindow.h)
//**********************************************
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include "ampel.h"namespace Ui {
class MainWindow;
}class MainWindow : public QMainWindow
{
Q_OBJECTpublic:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();private:
Ui::MainWindow *ui;};
#endif // MAINWINDOW_H
//*******************************************(MainWindow.cpp)
//*******************************************
#include "mainwindow.h"
#include "ui_mainwindow.h"MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
this->setFixedSize(1024,768);
ampel a(this);
} -
@yczo said:
Hi
Code looks fine Butampel a(this);
this is a local variable and it will be deleted !
as soon as constructor is fully run.
so here
ampel a(this);
} <<--- here a is deleted as it runs out of scope.You must make it using new
ampel *a=new ampel (this);
ampel->resize(100,100); // set some size
ampel->show(); // ask it to be shown
setCentralWidget(ampel); // insert into mainwindows central widget.
Mainwindow is special as it has a central place holder widget.
