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# Automatically generated by qmake (3.1) Wed Mar 29 15:18:09 2017
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TEMPLATE = app
TARGET = qimageBehaviorForStackOverflowQuestion
INCLUDEPATH += .
QT += widgets

# Input
HEADERS += qimageBehaviorForStackOverflowQuestion.h
SOURCES += qimageBehaviorForStackOverflowQuestion.cpp

#include <iostream>
#include <QApplication>
#include <QWidget>
#include <QTimer>
#include <QPainter>
#include <QPushButton>
#include <QImage>
#include <QTime>

class MyWidget : public QWidget {
  Q_OBJECT
 private:
  QImage *image;
  int px, py;
  uchar d[100*100*4];
  QTimer *timer;
  QTime time;
public:
  MyWidget();
  void paintEvent(QPaintEvent * event);
public slots:
  void doPaint();
};

#include "qimageBehaviorForStackOverflowQuestion.h"

int my_counter = 0;

MyWidget::MyWidget() : QWidget(0), px(0), py(0){
  image = new QImage(d, 100, 100, QImage::Format_ARGB32);
  for(int cnt = 0, a, r, g, b; cnt < 100*100*4;){
    a = 255; //alpha
    r = 0;   //red
    g = 0;   //green
    b = 0;   //blue

    d[cnt] = b; cnt++;
    d[cnt] = g; cnt++;
    d[cnt] = r; cnt++;
    d[cnt] = a; cnt++;
  }
  // connect QTimer.timeout to my doPaint method
  timer = new QTimer();
  connect(timer, SIGNAL(timeout()), this, SLOT(doPaint()));
  timer->start(1);
};

void MyWidget::doPaint(){
  // manipulate the positions of the points
  if(px < 100){
    int cnt = 0, b = 255, g = 255, r = 255, a = 255;
    d[4 * px + cnt] = b; cnt++;
    d[4 * px + cnt] = g; cnt++;
    d[4 * px + cnt] = r; cnt++;
    d[4 * px + cnt] = a; cnt++;
    px++;
  }
  // update the window
  update();
};

void MyWidget::paintEvent(QPaintEvent * event){
    QPainter painter(this);
    painter.drawImage(0, 0, *image);
}

int main(int argc, char *argv[]){
  QApplication app(argc, argv);
  MyWidget *widget = new MyWidget();
  widget->show();
  return app.exec();
}