QImage to byte array doesn't work

[Gh0stShell]

Hey,

I try to get the raw Bytes from pictre from a QImage like

QImage preview;
QByteArray ba;
QBuffer buffer(&ba);
buffer.open(QIODevice::WriteOnly);
qDebug() << "Saved: " << preview.save(&buffer);

Yes, there is something in the QImage, I can display it.

But save function returns a false.

I need this to send a char array to my ESP8266 where use C so it can show the picture on an E-Paper Display

[Pl45m4]

@Gh0stShell said in QImage to byte array doesn't work:

qDebug() << "Saved: " << preview.save(&buffer);

Have you tried using a file extension / an image format?
preview.save(&buffer, "JPEG"); or "PNG"

Does buffer.open(....) return true?

[JonB]

@Gh0stShell
Since the example for this at https://doc.qt.io/qt-5/qimage.html#save-1 shows

image.save(&buffer, "PNG"); // writes image into ba in PNG format

I presume as @Pl45m4 says you must specify the desired format to save in since you are not using a filename with a suffix.

[Gh0stShell]

When I do this, my programm is unexpectedly finishing

I am thinking about to read the picture pixel by pixel and then convert the int to char

[Bonnie]

QImage::save() doesn't get the raw bytes of the image, it converts the image to a file format.
If you really want the raw bytes, do something like

QByteArray ba((const char *)preview.constBits(), preview.byteCount());