QLabel snap to ScrollBar

Mikeeeeee

Good afternoon. I have a QLabel. I asked a QLabel the picture:

border-image: url(:/Images/Images/map Main.png) 0 0 0 0 stretch stretch;

With these functions I change the size of QLabel:

void MainWindow::on_test Button 1_clicked()
{
        qDebug()<<ui->label Map->width()<<ui->label Map->height();
        ui->label Map->setFixedHeight(ui->label Map->height()*2);
        ui->label Map->setFixedWidth(ui->label Map->width()*2);
}
 
void MainWindow::on_test Button 2_clicked()
{
        qDebug()<<ui->label Map->width()<<ui->label Map->height();
        ui->label Map->setFixedHeight(ui->label Map->height()/2);
        ui->label Map->setFixedWidth(ui->label Map->width()/2);
}

QLabel how to bind the ScrollBar to be at increased QLabel to change the zoomed area using ScrollBar. Or maybe it can be achieved in another way? In the future, you will need to make buttons on top of QLabel.Maybe you should use QML for this?

mrjj

Hi
You could do as in
https://doc.qt.io/qt-5/qtwidgets-widgets-imageviewer-example.html
and use a ScrollArea with the label inside.
However, this is for normal scrolling when the image is bigger than area where its
displayed.
It sounds a bit like you have some other sort of zoom in mind ?

Mikeeeeee

Thanks.
I included ImageViewer in the project. But how to use ImageViewer?
I tried to create a QWidget and change the class to ImageViewer, but got an error.

mrjj

Hi
You can just new an instance put where you want it
ImageViewer * MyImg = new ImageViewer(this);

Mikeeeeee

@mrjj said in QLabel snap to ScrollBar:

ImageViewer * MyImg = new ImageViewer(this);

So I get the error: no matching constructor for initialization of 'ImageViewer'

mrjj

@Mikeeeeee
well its constructor is
ImageViewer();
so it doesn't take a parent. you change that so it can be imbedded into what you like.

Mikeeeeee

How to set picture? Need a method to move from private to public?

mrjj

@Mikeeeeee
hi
yes you can make setImage public

Mikeeeeee

I did so:

    QImage mapImage(":/Images/Images/mapMain.png");
    ImageViewer* myImageViewer  = new ImageViewer();
    myImageViewer->setImage(mapImage);

I have a label: ui->labelMap
How do I set to myImageViewer to ui->labelMap?

mrjj

@Mikeeeeee
You cannot put whole viewer into a Label.
However, you can use myImageViewer instead of
ui->labelMap

Mikeeeeee

But how to use? How to do this?

mrjj

@Mikeeeeee
well do you have ui->labelMap in layout ?
then just insert myImageViewer into that.

Mikeeeeee

How to do this? I created ui->label Map in the designer.

mrjj

@Mikeeeeee
but is it a layout?

Mikeeeeee

I appent ui->label in the ui->gridLayout_2

Mikeeeeee

Also I have an empty ui->verticalLayout

mrjj

@Mikeeeeee said in QLabel snap to ScrollBar:

ui->gridLayout_2

ok then do
ui->gridLayout_2->addWidget(myImageViewer);
You can delete the label if u wish.

Mikeeeeee

Cool, works. And how to reconfigure the mouse wheel to zoom in?

mrjj

@Mikeeeeee
Its not a configure option. Its new code :)
You can override (add) wheelEvent ( QWheelEvent * event ) to the
ImageViewer class and change the size of the inner QLabel *imageLabel;
to create a zoom in effect.
Or create your on drawing function like here
https://stackoverflow.com/questions/6650219/zooming-function-on-a-qwidget

Mikeeeeee

I tried to do so, but it does not work. Please tell me how to set up the signal?

connect(imageLabel, &QWidget:: wheelEvent(), this, &ImageViewer::zoomIn);