Clickable Drawn Object

Shoaib Muhammad

Good day all,

I am a beginner programmer student for C++ and Qt and I am getting close to the project deadline. I don't have much time to research and learn the answers so I would appreciate the simplest answer (some sample code would be nice).

I am using an am437x board with Qt4.6 Yocto tools.
My app requires a drawn circle (using Qpainter 'drawEllipse') to be clickable to display information into a Qlabel. What would be the best method to make this circle clickable?

My sample code is as follows:

mainheader.h

#pragma once

#include <QWidget>
#include <QPainter>
#include <QApplication>
#include <QLabel>
#include<Qt>

class CGui : public QWidget {

  Q_OBJECT

  public:
    CGui(QWidget *parent = 0);

  private slots:
    void showInfo();

  private:
    Qlabel *lInfo;

  protected:
    void paintEvent(QPaintEvent *e);
    void drawCircle(QPainter *painter);
}

mainheader.cpp

CGui::CGui(QWidget *parents)
    : QWidget(parent)  {

  lInfo = new Qlabel("Not Clicked",this);
  lInfo ->setGeometry(150, 15, 150, 50);

  /* Code for clicking circle maybe goes here invoking the showInfo() function*/ 
}

void CGui::paintEvent(QPaintEvent *e){
  Q_UNUSED(e);

  QPainter painter(this);

  drawCircle(&painter);
}

void CGui::drawCircle(QPainter *painter){
  painter->setPen(Qt::red);
  painter->setBrush(Qt::red);

  painter->drawEllipse(350, 190,100,100);
}

void CGui::showInfo(){
  lInfo->setText("Clicked");
}

main.cpp

#include "mainheader.h"

int main(int argc, char *argv[]) {
  QApplication app(argc,argv);

  CGui window;
  window.ShowFullScreen();

  return app.exec();
}

Please also not that the position of the circle may change upon every call for update(); therefore the position of the clickable are must vary with the position of the circle.
Thank you everyone. Any help is appreciated.

Kind regards,
Shoaib

jsulm

@Shoaib-Muhammad You can override https://doc.qt.io/qt-5/qwidget.html#mousePressEvent and check the cursor position there to decide whether it is over your circle or not.

Shoaib Muhammad

Thank you jsulm,

I will reply here for further problems I encounter on the topic. I have never done this method before.

Kind regards,
Shoaib