Hi guys,
i want the color of a rectangle drwan on central widget to change depending on the input i give, the code is wrkin if i embed the color value in de code, but I have no clue how to pass this value at run time and I want the color to change instantaneously....Thanx in advance

code:


Qt Code: 
  1. #include "mainwindow.h"
  2. #include "ui_mainwindow.h"
  3. #include"QWidget"
  4. #include <QtGui>
  5. #include "QPixmap"
  6. #include"QPen"
  7. #include<iostream>
  8. using namespace std;
  9. class MyWidget : public QWidget
  10. {
  11. public:
  12.    MyWidget();
  13.  
  14. protected:
  15.     void paintEvent(QPaintEvent *);
  16.  
  17. };
  18.  
  19. MyWidget::MyWidget()
  20. {
  21.  
  22. }
  23.  
  24.  
  25. void MyWidget::paintEvent(QPaintEvent *event)
  26. {
  27.     QRectF rectangle(50,50,300,300);
  28.  
  29.     QPainter painter(this);
  30.     painter.setRenderHint(QPainter::Antialiasing);
  31.     QPen pen(Qt::green, 30, Qt::SolidLine, Qt::RoundCap, Qt::RoundJoin);
  32.  
  33. 	int input=75;
  34.     int level=input/20;
  35.     int rem=input-level*20;
  36.     float a;
  37.     switch(level)
  38.     {
  39.     case 0:
  40.  
  41.  
  42.  
  43. 			pen.setColor(QColor(0,255,0,255));
  44.  
  45.              painter.setPen(pen);
  46.  
  47.             a=.1*rem;
  48.             painter.setOpacity(a);
  49.             painter.drawRect(50, 50, 300, 300);
  50.             break;
  51.  
  52.  
  53.     case 1:
  54.  
  55.         pen.setColor(QColor(rem*6,255,0,255));
  56.  
  57.             painter.setPen(pen);
  58.             a=.4;
  59.             painter.setOpacity(a);
  60.             painter.drawRect(50, 50, 300, 300);
  61.             break;
  62.     case 2:
  63.  
  64.         pen.setColor(QColor(127+rem*6,255,0,255));
  65.  
  66.             painter.setPen(pen);
  67.             a=.6;
  68.             painter.setOpacity(a);
  69.             painter.drawRect(50, 50, 300, 300);
  70.             break;
  71.     case 3:
  72.  
  73.     pen.setColor(QColor(255,255-rem*6,0,255));
  74.  
  75.     painter.setPen(pen);
  76.       a=.8;
  77.             painter.setOpacity(a);
  78.             painter.drawRect(50, 50, 300, 300);
  79.            break;
  80.     case 4:
  81.  
  82.     pen.setColor(QColor(255,127-rem*6,0,255));
  83.  
  84.     painter.setPen(pen);
  85.       a=.8;
  86.             painter.setOpacity(a);
  87.             painter.drawRect(50, 50, 300, 300);
  88.            break;
  89.  
  90.     default:
  91.         pen.setColor(QColor(255,0,0,255));
  92.  
  93.         painter.setPen(pen);
  94.           a=1;
  95.                 painter.setOpacity(a);
  96.                 painter.drawRect(50, 50, 300, 300);
  97.                break;
  98.  
  99.  
  100.  
  101.  
  102.     }
  103.  
  104.  
  105. }
  106.  
  107. MainWindow::MainWindow(QWidget *parent) :
  108.     QMainWindow(parent),
  109.     ui(new Ui::MainWindow)
  110. {
  111.     ui->setupUi(this);
  112.     //setStyleSheet("MainWindow {background-image:url('/Users/sandeep_hyd123/Qt sandy/first/photo.jpeg');background-repeat: repeat;background-position: top right;}");
  113.    setStyleSheet("MainWindow {border-width: 4px; border-image:url('/Users/sandeep_hyd123/Qt sandy/first/photo.jpeg') 4 4 4 4 stretch stretch;}");
  114.  
  115.  
  116. MyWidget* my_widget = new MyWidget();
  117.   QWidget::setFixedSize ( 400, 400 );
  118.  
  119. setCentralWidget(my_widget);
  120. setWindowTitle(QApplication::translate("toplevel", "Main widget"));
  121.  
  122.  
  123.  
  124. }
  125.  
  126. MainWindow::~MainWindow()
  127. {
  128.     delete ui;
  129. }
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