How to get position or mouse click event in QLabel

ManiRon28

I have been trying to get the mouse click event on a QLabel

ClickableLabel.h

#ifndef CLICKABLELABEL_H
#define CLICKABLELABEL_H

#include <QWidget>
#include <QLabel>

class ClickableLabel : public QLabel
{
Q_OBJECT

public:
    explicit ClickableLabel(QWidget* parent = 0, Qt::WindowFlags f = Qt::WindowFlags());
     ~ClickableLabel();

signals:
    void clicked(QPoint pos);

protected:
    void mousePressEvent(QMouseEvent* event);

};
#endif // CLICKABLELABEL_H

ClickableLabel.cpp

#include<ClickableLabel.h>
#include<QMouseEvent>

ClickableLabel::ClickableLabel(QWidget* parent, Qt::WindowFlags f): QLabel(parent) {

}

ClickableLabel::~ClickableLabel() {}

void ClickableLabel::mousePressEvent(QMouseEvent* ev)
{
emit clicked(ev->pos());
}

Mainwindow.cpp

connect(&obj_ClickLabel,SIGNAL(clicked(QPoint)),this, SLOT(getData(QPoint)));

jsulm

@ManiRon28 said in How to get position or mouse click event in QLabel:

I have been trying to get the mouse click event on a QLabel

And what does not work?
Is mousePressEvent called?

ManiRon28

@jsulm The mouse press event is called but emit signal is not happening, cause I perform an emit , and I have promoted the Qlabel also

QObject::connect: No such signal ClickableLabel::clicked(ClickableLabel) in mainwindow.cpp:12
QObject::connect: (receiver name: 'MainWindow')

I am facing this issue

ManiRon28

@jsulm

Actually I made some changes to the code, Kindly refer to this code

ClickableLabel.h

#ifndef CLICKABLELABEL_H
#define CLICKABLELABEL_H

#include <QWidget>
#include <QLabel>

class ClickableLabel : public QLabel
{
Q_OBJECT

public:
    explicit ClickableLabel(QWidget* parent = 0, Qt::WindowFlags f = Qt::WindowFlags());
     ~ClickableLabel();

Q_SIGNALS:
    void clicked(ClickableLabel *click);

protected:
    void mousePressEvent(QMouseEvent* event);

};
#endif // CLICKABLELABEL_H

ClickableLable.cpp

#include<ClickableLabel.h>
#include<QMouseEvent>

ClickableLabel::ClickableLabel(QWidget* parent, Qt::WindowFlags f): QLabel(parent) {

}

ClickableLabel::~ClickableLabel() {}

void ClickableLabel::mousePressEvent(QMouseEvent* )
{
qDebug("DATA");
emit clicked(this);
}

jsulm

@ManiRon28 said in How to get position or mouse click event in QLabel:

Actually I made some changes to the code

And does it work now? If not: what is the issue now? Please provide needed information when asking.

JonB

@ManiRon28
If you get the qDebug("DATA"); output then you know the emit clicked(this); will be executed.

What makes you think it is not? There is nothing in your code as shown to tell you this.

Show your connect() statement. Show that is executed. And do yourself a favour and stop using SIGNAL/SLOT() old-style connection syntax, there is a reason it was replaced a decade ago....

P.S.
Please use the forum's Code tags around your code, it makes it easier for others.

ManiRon28

@JonB , @jsulm
Hi
My connect call

connect(ui->label,SIGNAL(clickedlabel(QPoint &)),this, SLOT(points(QPoint &)));

Clicklabel.h

#ifndef CLICKLABEL_H
#define CLICKLABEL_H

#include <QLabel>
#include <QObject>
#include <QWidget>
#include<QMouseEvent>
#include<QPoint>

class Clicklabel : public QLabel
{
    Q_OBJECT
public:
    Clicklabel(QWidget* parent = 0);
    ~Clicklabel();

protected:
    void mousePressEvent(QMouseEvent *mouseEvent);
signals:
    void clickedlabel(QPoint &);
};

#endif // CLICKLABEL_H

Clicklabel.cpp

void Clicklabel::mousePressEvent(QMouseEvent *mouseEvent)
{
    QPoint  mouse_pos = mouseEvent->pos();

    if(mouse_pos.x() <= this->size().width() && mouse_pos.y()<= this->size().height())
    {
        if(mouse_pos.x() >0 && mouse_pos.y()>0)
        {
            emit clickedlabel(mouse_pos);
        }
    }
}

Mainwindow.cpp

void MainWindow::points(QPoint &pos)
{
    qDebug("DataVal",pos.x(),pos.y());
}

Now I am able to view the debug print "DataVal" but I am not able to get the values of X and Y

JonB

@ManiRon28 said in How to get position or mouse click event in QLabel:

but I am not able to get the values of X and Y

What does this actually mean? Your qDebug() does print out pos.x(),pos.y(), so you do "get values"....

ManiRon28

@JonB no I dont get any values from the X and Y , only the DataVal string gets printed

This is how mu print is coming

jsulm

@ManiRon28 Please use qDebug properly:

void MainWindow::points(QPoint &pos)
{
    qDebug() << "DataVal" << pos.x() << pos.y();
}

JonB

@ManiRon28
That is because your call to qDebug() is incorrect.

qDebug() << "DataVal" << pos.x() << pos.y());

ManiRon28

@JonB, @jsulm oh sorry thanks for correcting me,

I have one more doubt

Is there any way to differentiate between left and right mouse click

jsulm

@ManiRon28 It's all in the documentation:

ManiRon28

@jsulm, @JonB Thanks for providing me the necessary details

I have a qlabel and now I am able to detect the click/press event in label, but I want to capture the coordinates based on image size

For example
The image size is 100x100 and the qlabel size is 200x200, I should get coordinates when I press on the image and not on the other part of qlabel which doesnt have image or empty

JonB

@ManiRon28
I assume by "image" you mean QLabel::pixmap()? So you need to find where that is within the label. I don't know, but if you start with qDebug() << this->pixmap()->rect() what does that tell you, can you get from that where the pixmap is positioned within the label?

ManiRon28

@JonB Yes the image is loaded using pixmap

JonB

@ManiRon28 Good.

ManiRon28

@JonB

I get the ouput like this

x = pos.x();
y=pos.y();

    int XVal = ui->labelImage->pixmap().rect().x();
    int YVal = ui->labelImage->pixmap().rect().y();
    int widthVal = ui->labelImage->pixmap().rect().width();
    int heightVal = ui->labelImage->pixmap().rect().height();


    QString qsVal = "x = " + QString::number(XVal) + ", y = " + QString::number(YVal) + ", Width = " + QString::number(widthVal) + ", height = " + QString::number(heightVal);

x = 522, y =78, Button = LEFT, 
Rect - x = 0, y = 0, Width = 1379, height = 516

jsulm

@ManiRon28 If you know where the pixmap is located inside the QLabel and you get the mouse coordinates inside the QLabel then it is simple math to get the coordinates inside the pixmap, right?

ManiRon28

@jsulm
Can you please specify the procedure which would be helpful