Can't send image to QLabel in Windows environment (it works without problems in Linux)

[Helge1980]

Hi!
I can't output the image to QLabel in a Windows environment.
I tried it in two ways. The image size is 144 x 88 pixels (~ 3 KB).

1. using QImage:

const QString tmb_file = "C:\\Users\\User\\thumbnail.jpg";
const QImage img = QImage(tmb_file, "JPG");
const QPixmap pixmap = QPixmap::fromImage(img);
ui->labelThumb->setPixmap(pixmap);

2. directly via QPixmap:

const QString tmb_file = "C:\\Users\\User\\thumbnail.jpg";
const QPixmap pixmap = QPixmap(tmb_file);
ui->labelThumb->setPixmap(pixmap);

[Pl45m4]

@Helge1980 said in Can't send image to QLabel in Windows environment (it works without problems in Linux):

I can't

"I cant" is not a proper description of an issue :)

Try / instead of \\.

[Helge1980]

@Pl45m4

Replacing \ \ with / didn't help

[Christian Ehrlicher]

Then check if the file really exists and is readable.

[JonB]

@Helge1980
As @Christian-Ehrlicher has said. Also, QPixmap(tmb_file) and QPixmap::fromImage(img) will return a pixmap where QPixmap::isNull() == true, and similarly for QImage(tmb_file, "JPG"). You should check for this, both for debugging/because you have a problem and anyway at runtime since you're reading from a file.

[Helge1980]

@Christian-Ehrlicher

Yes, the file exists and is readable

[Christian Ehrlicher]

Did you relocate Qt or similar? Please check if you jpg image plugin is available and check if jpg can be loaded with e.g. QImageReader::supportedFormats()

[Helge1980]

@Christian-Ehrlicher

No, I didn't move the Qt libraries, everything was installed automatically.

Indeed, for some reason there is no support for the JPG format:

qDebug() << QImageReader::supportedImageFormats();

("bmp", "pbm", "pgm", "png", "ppm", "xbm", "xpm")

[Christian Ehrlicher]

The jpeg plugin must be in <QTDIR>/plugins/imageformats

[Pl45m4]

Stupid question:
Is the labelThumb QLabel visible and enabled in your GUI?

@Helge1980 said in Can't send image to QLabel in Windows environment (it works without problems in Linux):

("bmp", "pbm", "pgm", "png", "ppm", "xbm", "xpm")

Edit: Ah ok, so no JPG plugin

[Helge1980]

This post is deleted!

[Helge1980]

I solved the problem by replacing the jpg format with png