loading image file into label

Natural_Bugger

Hi,

i loaded via designer a "jpeg" file into a label and everything is fine.
but after compiling the nothing shows up.

i used the code code from this topic:
link text

QImageReader read("123.jpeg");
QImage image = read.read();

if (!image.isNull()){
    QMessageBox::information(this, "is loaded","",QMessageBox::Ok);
}
else{
    QMessageBox::information(this, "not loaded","",QMessageBox::Ok);
}

but the "not" loaded Messagebox appears.

the image file resides in the project folder.

do you need to do something special like in Visual Studio, add to Recources?
i have added the file into the project as "add eisting file".

kind regards.

mrjj

Hi
Just as a note.
Unless you really want QImage first and use QImageReader etc then
this is also working

ui->label_picture->setPixmap(QPixmap(":/123.jpeg"));
Let the pixmap load it directly by self.

mrjj

Hi
The path is wrong
When the program is run, the current folder is the build folder
and not the project folder so it won't be able to find the "123.jpeg" in the project folder.

The easy way is to include a resource file to the project and then add the image to the resource file
and then use the correct syntax

QImageReader read(":/123.jpeg");
notice the :/ in front

J.Hilk

to add to @mrjj
here are further information about Qt's resource system

https://doc.qt.io/qt-5/resources.html

also make sure to rerun qmake after adding a new resource file and/or resource to your resource file

Natural_Bugger

@mrjj

thnx, that worked.

    QPixmap pixmap;
    QImageReader read(":/123.jpeg");
    QImage image = read.read();

    if (!image.isNull()){
        QMessageBox::information(this, "is loaded","",QMessageBox::Ok);
        ui->label_picture->pixmap(pixmap.fromImage(image));
    }
    else{
        QMessageBox::information(this, "not loaded","",QMessageBox::Ok);
    }

the image is loaded, but ...

ui->label_picture->pixmap(pixmap.fromImage(image));

results in:

error: no matching function for call to 'QLabel::pixmap(QPixmap)'
         ui->label_picture->pixmap(pixmap.fromImage(image));
                                                          ^

i also tried:

ui->label_picture->pixmap.load(image);

but also no working:

error: '((MainWindow*)this)->MainWindow::ui->Ui::MainWindow::<anonymous>.Ui_MainWindow::label_picture->QLabel::pixmap' does not have class type
         ui->label_picture->pixmap.load(image);
         ^

J.Hilk

@Natural_Bugger

setPixmap is the setter function.

ui->label_picture->setPixmap(Pixmap::fromImage(image));

Natural_Bugger

@J-Hilk

thnx for your help.

        QPixmap pixmap;
        QImageReader read(":/123.jpeg");
        QImage image = read.read();
        pixmap.fromImage(image);
    
        if (!image.isNull()){
            QMessageBox::information(this, "is loaded","",QMessageBox::Ok);

            ui->label_picture->setPixmap(pixmap);
        }
        else{
            QMessageBox::information(this, "not loaded","",QMessageBox::Ok);
        }

QMessageBox = "is loaded"
but still doesn't show up in the label / user interface, although it compiles without errors and executes.

J.Hilk

@Natural_Bugger
I deliberitly wrote Pixmap::fromImage(image) because fromPixmap returns a pixmap. It does not apply it on itself!

mrjj

Hi
Just as a note.
Unless you really want QImage first and use QImageReader etc then
this is also working

ui->label_picture->setPixmap(QPixmap(":/123.jpeg"));
Let the pixmap load it directly by self.

Natural_Bugger

@J-Hilk

i tried that, but ...

ui->label_picture->setPixmap(Pixmap::fromImage(image));

results in:

error: 'Pixmap' has not been declared
         ui->label_picture->setPixmap(Pixmap::fromImage(image));
                                      ^

i tried to solve it and i changed Pixmap into pixmap, which resulted in:

error: 'pixmap' is not a class, namespace, or enumeration
         ui->label_picture->setPixmap(pixmap::fromImage(image));
                                      ^

i'm rusty

J.Hilk

@Natural_Bugger
I'm terribly sorry, I think the auto correction removed the Qfrom QPixmap

ui->label_picture->setPixmap(QPixmap::fromImage(image));

Natural_Bugger

@mrjj

thnx, that worked.

@J-Hilk

thnx, now it's working.