Transfer paint event to QScrollarea

[vinithr]

Hi all,

I am trying to draw a graph in QT application using a paintevent.

I could be able to draw in the wisget. But i need to transfer that paintevent to QScroll Area that is present in MainWindow.h.

Could anyone help me to sort out thius issue.Here i am pasting my code for your reference.


main.cpp

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

#include <QtGui/QApplication>
#include "mainwindow.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    
    return a.exec();
}

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mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QtGui>
#include<QPainter>
 
 
#define XAXISLABEL 340
#define XAXISSTARTWIDTH 100   //start width from the left corner
#define XAXISSTDWIDTH 40     //width betwen each label in the x axis
#define XAXISCORRECTION 20    //correction value for the xaxis lable display
 
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}
 
MainWindow::~MainWindow()
{
    delete ui;
}
 
void MainWindow::paintEvent(QPaintEvent * /*event*/)
{
    QPainter painter(this);
 //   painter.translate(scrollArea);
  //  painter.setWindow(scrollArea);
    int i=1000;
 
    const int start = 100;
    const int act_unit_w = 1;
    const int act_unit_h = 10;
 
    QFontMetrics metrics(font());
    QColor color;
 
    QBrush Brush1(Qt::red,Qt::SolidPattern);
    QBrush Brush2(Qt::green,Qt::SolidPattern);
 
    int ReferenceValue[22]={12,44,55,66,77,88,99,11,10,13,78,87,66,56,76,67,89,67,56,67,67};
    int PCValue[22]={12,44,40,20,77,88,32,11,10,13,78,87,66,56,76,67,89,67,56,67,67};
 
    int myvalue=20;
    int refvalue=40;
    int MyTemp1=25;
    int MyTemp2=40;
 
    int width=15;
    int height=3;
 
    for(int k=0;k<21;k++)
    {
        myvalue=ReferenceValue[k];
        painter.fillRect((XAXISSTARTWIDTH+MyTemp1),(320-(myvalue*height)),width,(myvalue*height),Brush1);
        MyTemp1=MyTemp1+40;
 
    }
 
    for(int m=0;m<21;m++)
    {
        refvalue=PCValue[m];
        painter.fillRect((XAXISSTARTWIDTH+MyTemp2),(320-(refvalue*height)),width,(refvalue*height),Brush2);
        MyTemp2=MyTemp2+40;
 
    }
    painter.save();
//	painter.setBrush(badBrush);
    painter.setPen(QColor(Qt::black));
 
 
//fill x axis
    for( int j=start; j< 1000+start ; j += act_unit_w*XAXISSTDWIDTH ){
        painter.drawLine(j,320,j,325);
    //    painter.drawText(j,340,QString::number(j-start,10));
    }
 
    //X Axis text
 
    painter.drawText((XAXISSTARTWIDTH +0)-XAXISCORRECTION,XAXISLABEL,QString("0"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *1))-XAXISCORRECTION,XAXISLABEL,QString("3-4"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *2))-XAXISCORRECTION,XAXISLABEL,QString("4-5"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *3))-XAXISCORRECTION,XAXISLABEL,QString("5-6"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *4))-XAXISCORRECTION,XAXISLABEL,QString("6-7"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *5))-XAXISCORRECTION,XAXISLABEL,QString("7-8"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *6))-XAXISCORRECTION,XAXISLABEL,QString("8-9"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *7))-XAXISCORRECTION,XAXISLABEL,QString("9-10"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *8))-XAXISCORRECTION,XAXISLABEL,QString("10-11"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *9))-XAXISCORRECTION,XAXISLABEL,QString("11-12"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *10))-XAXISCORRECTION,XAXISLABEL,QString("12-13"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *11))-XAXISCORRECTION,XAXISLABEL,QString("13-14"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *12))-XAXISCORRECTION,XAXISLABEL,QString("14-15"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *13))-XAXISCORRECTION,XAXISLABEL,QString("15-16"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *14))-XAXISCORRECTION,XAXISLABEL,QString("16-17"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *15))-XAXISCORRECTION,XAXISLABEL,QString("17-18"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *16))-XAXISCORRECTION,XAXISLABEL,QString("18-19"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *17))-XAXISCORRECTION,XAXISLABEL,QString("19-XAXISCORRECTION"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *18))-XAXISCORRECTION,XAXISLABEL,QString("XAXISCORRECTION-21"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *19))-XAXISCORRECTION,XAXISLABEL,QString("21-22"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *20))-XAXISCORRECTION,XAXISLABEL,QString("22-23"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *21))-XAXISCORRECTION,XAXISLABEL,QString("23-24"));
 
    //Y axis text
    painter.drawText(50,20,QString("100"));
    painter.drawText(50,80,QString("80"));
    painter.drawText(50,140,QString("60"));
    painter.drawText(50,200,QString("40"));
    painter.drawText(50,260,QString("20"));
    painter.drawLine(start,20,1000,20);
    painter.drawLine(start,80,1000,80);
    painter.drawLine(start,140,1000,140);
    painter.drawLine(start,200,1000,200);
    painter.drawLine(start,260,1000,260);
    //   painter.drawText(0,0,640,50,Qt::AlignCenter,QString("Power Curve"));
    painter.drawLine(start,20,start,320);
    painter.drawLine(start,320,1000,320);
 
    painter.restore();
}

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QtGui>
#include<QPainter>


#define XAXISLABEL 340
#define XAXISSTARTWIDTH 100   //start width from the left corner
#define XAXISSTDWIDTH 40     //width betwen each label in the x axis
#define XAXISCORRECTION 20    //correction value for the xaxis lable display


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

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

void MainWindow::paintEvent(QPaintEvent * /*event*/)
{
    QPainter painter(this);
 //   painter.translate(scrollArea);
  //  painter.setWindow(scrollArea);
    int i=1000;

    const int start = 100;
    const int act_unit_w = 1;
    const int act_unit_h = 10;

    QFontMetrics metrics(font());
    QColor color;

    QBrush Brush1(Qt::red,Qt::SolidPattern);
    QBrush Brush2(Qt::green,Qt::SolidPattern);

    int ReferenceValue[22]={12,44,55,66,77,88,99,11,10,13,78,87,66,56,76,67,89,67,56,67,67};
    int PCValue[22]={12,44,40,20,77,88,32,11,10,13,78,87,66,56,76,67,89,67,56,67,67};

    int myvalue=20;
    int refvalue=40;
    int MyTemp1=25;
    int MyTemp2=40;

    int width=15;
    int height=3;

    for(int k=0;k<21;k++)
    {
        myvalue=ReferenceValue[k];
        painter.fillRect((XAXISSTARTWIDTH+MyTemp1),(320-(myvalue*height)),width,(myvalue*height),Brush1);
        MyTemp1=MyTemp1+40;

    }

    for(int m=0;m<21;m++)
    {
        refvalue=PCValue[m];
        painter.fillRect((XAXISSTARTWIDTH+MyTemp2),(320-(refvalue*height)),width,(refvalue*height),Brush2);
        MyTemp2=MyTemp2+40;

    }
    painter.save();
//	painter.setBrush(badBrush);
    painter.setPen(QColor(Qt::black));


//fill x axis
    for( int j=start; j< 1000+start ; j += act_unit_w*XAXISSTDWIDTH ){
        painter.drawLine(j,320,j,325);
    //    painter.drawText(j,340,QString::number(j-start,10));
    }

    //X Axis text

    painter.drawText((XAXISSTARTWIDTH +0)-XAXISCORRECTION,XAXISLABEL,QString("0"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *1))-XAXISCORRECTION,XAXISLABEL,QString("3-4"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *2))-XAXISCORRECTION,XAXISLABEL,QString("4-5"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *3))-XAXISCORRECTION,XAXISLABEL,QString("5-6"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *4))-XAXISCORRECTION,XAXISLABEL,QString("6-7"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *5))-XAXISCORRECTION,XAXISLABEL,QString("7-8"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *6))-XAXISCORRECTION,XAXISLABEL,QString("8-9"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *7))-XAXISCORRECTION,XAXISLABEL,QString("9-10"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *8))-XAXISCORRECTION,XAXISLABEL,QString("10-11"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *9))-XAXISCORRECTION,XAXISLABEL,QString("11-12"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *10))-XAXISCORRECTION,XAXISLABEL,QString("12-13"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *11))-XAXISCORRECTION,XAXISLABEL,QString("13-14"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *12))-XAXISCORRECTION,XAXISLABEL,QString("14-15"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *13))-XAXISCORRECTION,XAXISLABEL,QString("15-16"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *14))-XAXISCORRECTION,XAXISLABEL,QString("16-17"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *15))-XAXISCORRECTION,XAXISLABEL,QString("17-18"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *16))-XAXISCORRECTION,XAXISLABEL,QString("18-19"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *17))-XAXISCORRECTION,XAXISLABEL,QString("19-XAXISCORRECTION"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *18))-XAXISCORRECTION,XAXISLABEL,QString("XAXISCORRECTION-21"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *19))-XAXISCORRECTION,XAXISLABEL,QString("21-22"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *20))-XAXISCORRECTION,XAXISLABEL,QString("22-23"));
    painter.drawText((XAXISSTARTWIDTH +(XAXISSTDWIDTH *21))-XAXISCORRECTION,XAXISLABEL,QString("23-24"));

    //Y axis text
    painter.drawText(50,20,QString("100"));
    painter.drawText(50,80,QString("80"));
    painter.drawText(50,140,QString("60"));
    painter.drawText(50,200,QString("40"));
    painter.drawText(50,260,QString("20"));
    painter.drawLine(start,20,1000,20);
    painter.drawLine(start,80,1000,80);
    painter.drawLine(start,140,1000,140);
    painter.drawLine(start,200,1000,200);
    painter.drawLine(start,260,1000,260);
    //   painter.drawText(0,0,640,50,Qt::AlignCenter,QString("Power Curve"));
    painter.drawLine(start,20,start,320);
    painter.drawLine(start,320,1000,320);

    painter.restore();
}

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mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QMainWindow>
#include <QScrollArea>
 
namespace Ui {
class MainWindow;
}
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
 
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
public slots:
 
protected:
    void paintEvent(QPaintEvent *event);
    QSize size;
    //void timerEvent(QTimerEvent *event);
 
public:
    QScrollArea *scrollArea;
 
 
private:
    Ui::MainWindow *ui;
};
 
#endif // MAINWINDOW_H

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QScrollArea>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT
    
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
public slots:

protected:
    void paintEvent(QPaintEvent *event);
    QSize size;
    //void timerEvent(QTimerEvent *event);

public:
    QScrollArea *scrollArea;


private:
    Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H

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mainwindow.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>1024</width>
    <height>600</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralWidget">
   <widget class="QScrollArea" name="scrollArea">
    <property name="geometry">
     <rect>
      <x>60</x>
      <y>60</y>
      <width>451</width>
      <height>291</height>
     </rect>
    </property>
    <property name="minimumSize">
     <size>
      <width>451</width>
      <height>291</height>
     </size>
    </property>
    <property name="maximumSize">
     <size>
      <width>451</width>
      <height>291</height>
     </size>
    </property>
    <property name="widgetResizable">
     <bool>true</bool>
    </property>
    <widget class="QWidget" name="scrollAreaWidgetContents">
     <property name="geometry">
      <rect>
       <x>0</x>
       <y>0</y>
       <width>449</width>
       <height>289</height>
      </rect>
     </property>
    </widget>
   </widget>
  </widget>
  <widget class="QMenuBar" name="menuBar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>1024</width>
     <height>25</height>
    </rect>
   </property>
  </widget>
  <widget class="QToolBar" name="mainToolBar">
   <attribute name="toolBarArea">
    <enum>TopToolBarArea</enum>
   </attribute>
   <attribute name="toolBarBreak">
    <bool>false</bool>
   </attribute>
  </widget>
  <widget class="QStatusBar" name="statusBar"/>
 </widget>
 <layoutdefault spacing="6" margin="11"/>
 <resources/>
 <connections/>
</ui>

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>1024</width>
    <height>600</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralWidget">
   <widget class="QScrollArea" name="scrollArea">
    <property name="geometry">
     <rect>
      <x>60</x>
      <y>60</y>
      <width>451</width>
      <height>291</height>
     </rect>
    </property>
    <property name="minimumSize">
     <size>
      <width>451</width>
      <height>291</height>
     </size>
    </property>
    <property name="maximumSize">
     <size>
      <width>451</width>
      <height>291</height>
     </size>
    </property>
    <property name="widgetResizable">
     <bool>true</bool>
    </property>
    <widget class="QWidget" name="scrollAreaWidgetContents">
     <property name="geometry">
      <rect>
       <x>0</x>
       <y>0</y>
       <width>449</width>
       <height>289</height>
      </rect>
     </property>
    </widget>
   </widget>
  </widget>
  <widget class="QMenuBar" name="menuBar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>1024</width>
     <height>25</height>
    </rect>
   </property>
  </widget>
  <widget class="QToolBar" name="mainToolBar">
   <attribute name="toolBarArea">
    <enum>TopToolBarArea</enum>
   </attribute>
   <attribute name="toolBarBreak">
    <bool>false</bool>
   </attribute>
  </widget>
  <widget class="QStatusBar" name="statusBar"/>
 </widget>
 <layoutdefault spacing="6" margin="11"/>
 <resources/>
 <connections/>
</ui>

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Thanks in Advance.

Regards
Vinithr

[ChrisW67]

Create a custom widget that has your painting code and make an instance of that widget the central widget of a generic QMainWindow.

[BalaQT]

If u r trying to create graphs , u can use qwt
qwt.sourceforge.net

hope it helps
Bala