Passing additional variables to signal slot.

[Zelber]

Hello.

I extended Qlabel class with mousePressEvent to create my_qlabel:

my_qlabel.cpp

#include "my_qlabel.h"
#include <QMouseEvent>
#include <QDebug>
 
my_qlabel::my_qlabel(QWidget* parent) : QLabel(parent)
{
 
}
 
void my_qlabel::mousePressEvent(QMouseEvent *event)
{
    {
        if(event->button() == Qt::LeftButton)
            {
            int xwsp=event->x();
            int ywsp=event->y();
            emit leftClickAction(xwsp,ywsp);
            }
        else if(event->button() == Qt::RightButton)
            emit rightClickAction();
    }
 
}

#include "my_qlabel.h"
#include <QMouseEvent>
#include <QDebug>

my_qlabel::my_qlabel(QWidget* parent) : QLabel(parent)
{

}

void my_qlabel::mousePressEvent(QMouseEvent *event)
{
    {
        if(event->button() == Qt::LeftButton)
            {
            int xwsp=event->x();
            int ywsp=event->y();
            emit leftClickAction(xwsp,ywsp);
            }
        else if(event->button() == Qt::RightButton)
            emit rightClickAction();
    }

}

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mainwindow.cpp

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    connect(ui->label, SIGNAL(leftClickAction(int,int)), this, SLOT(leftclick(int,int)));
    connect(ui->label, SIGNAL(rightClickAction()), this, SLOT(rightclick()));
    QPixmap pix("filelocation");
    QPixmap pixr = pix.scaledToHeight(600,Qt::SmoothTransformation);
    QPixmap * wsk_pixr;
    QPixmap * wsk_pix;
    wsk_pixr = & pixr;
    wsk_pix= & pix;
    setrs(wsk_pixr);// sets resized pix on myqlabel.
}

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    connect(ui->label, SIGNAL(leftClickAction(int,int)), this, SLOT(leftclick(int,int)));
    connect(ui->label, SIGNAL(rightClickAction()), this, SLOT(rightclick()));
    QPixmap pix("filelocation");
    QPixmap pixr = pix.scaledToHeight(600,Qt::SmoothTransformation);
    QPixmap * wsk_pixr;
    QPixmap * wsk_pix;
    wsk_pixr = & pixr;
    wsk_pix= & pix;
    setrs(wsk_pixr);// sets resized pix on myqlabel.
}

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Everything is working fine, but the question is: how can i pass "pix" or pointer to "pix"(Images are supposed to be around 10 mb each , so I assume passing pointer is much more time efficient than passing whole image.) created on program startup to "leftclick" or "rightclick" functions?

[anda_skoa]

QPixmap uses a pointer internally, so you can just copy its instances without much overhead.

Both your functions are methods of MainWindow so you don't need to "pass" anything to them, just store the two pixmaps as members of MainWindow.

Cheers,
_