Line drawing with mouse coordinate in Qt

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Article Metadata

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Tested with

Devices(s): S60 Emulator

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Compatibility

Platform(s): Qt

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Article

Keywords: QGraphicsScene,QGraphicsView

Created: mind_freak (23 Jun 2009)

Last edited: hamishwillee (11 Oct 2012)

Overview

This code will show you the line drawing in the QGraphicsScene by getting the end points of line with the help of mouseMove() Event.

When the mouse is moved on the widget at that time the mouse coordinates are catched and use to draw line from center to that specific coordinate.

Source Code

Source.h

#ifndef EVE1_H
#define EVE1_H
 
#include <QtGui/QWidget>
#include<QMouseEvent>
#include<QGraphicsLineItem>
#include<QGraphicsScene>
#include<QGraphicsView>
#include<QGraphicsItem>
#include<QHBoxLayout>
class EVE1 : public QWidget
{
    Q_OBJECT
 
public:
    EVE1(QWidget *parent = 0);
    ~EVE1();
 
private:
    QHBoxLayout *lay;
    QGraphicsScene *scene;
     QGraphicsItem *item;
     QGraphicsView *view;
private slots:
    void mouseMoveEvent(QMouseEvent *);
};
 
#endif // EVE1_H

Source.cpp

#include "eve1.h"
#include "ui_eve1.h"
 
EVE1::EVE1(QWidget *parent)
    : QWidget(parent)
{
     lay=new QHBoxLayout(this);
    scene=new QGraphicsScene(this);
    scene->setSceneRect(0,0,250,250);
    view=new QGraphicsView(scene,this);
    view->show();
    setMouseTracking(1);//Enable Mouse tracking on widget.
    lay->addWidget(view);
    setLayout(lay);
 
}
 
EVE1::~EVE1()
{
     // No need to delete any object that has got a parent which is properly deleted.
}
void EVE1::mouseMoveEvent(QMouseEvent *event)
{
    int X=event->x();
    int Y=event->y();
    int Z=scene->height()/2;
    int W=scene->width()/2;
    scene->addLine(Z,W,X,Y);
 
}

ScreenShot

NOTE:MOVE YOUR MOUSE AROUND THE WIDGET, NOT ON THE WIDGET....